Geologie en Mijnbouw portal
Content 1961 – 2004
| Title | Year | Authors | Vol (No) | Abstract |
|---|---|---|---|---|
| The central alteration body of the Casapalca mines, Peru | 1961 | Overweel, C.J. | 40(1) | The Casapalca mining district in central Peru is a source of lead, zinc, silver and copper ores of the lepthothermal type. In the centre of the mine in the single zone of the most conspicuous parallel vein system a body of rock has been intersected that does not fit in the stratigraphical sequence. Various opinions about the origin have been brought forward. The results of a systematical thin-slide study of the rock type under discussion are in favour of alteration. The coincidence of ore shoots and alteration body with certain structural elements of the Casapalca anticlinorium is discussed. |
| Heavy residues of some Egyptian soils | 1961 | Khadr, M. | 40(1) | The size-distribution analyses and the heavy mineral analyses of seventeen surface samples have been studied. The results are given in Figures 1-7. An outline is liven of the most important means of sediment transport and deposition in the Nile-Valley. Under normal conditions transport of sediment in the channel is directed largely towards the sea. Only during floods and owing to the systems of irrigation practiced are sediments supplied to the soils. The coarser fluviatile sediments are especially well defined in this area by granulometric analyses. Seven types (C 1-2-3, F 4-8) are distinguished, according to the distribution of grain size, to which all the sediments in the fluviatile environments could be allocated. It appears that, in the Nile environment, all types may be represented' The heavy mineral analyses of all the samples have been formulated in Table 2. Except sample no. 31 and no. 10, no qualitative variations of the main mineral species occur and quantitative variations are not significant. One mineral association, viz. Augite-hornblende-epidote association is proposed. |
| A palaeomagnetic study of the Permian volcanics in the Nahe region (SW. Germany) | 1961 | Nijenhuis, G.H.W. | 40(1) | Two magnetic poles are determined for the lower Middle Permian based on measurements of 57 rock samples taken from two lava flows in the Permian volcanic series of the Nahe region in SW. Germany. The use of the palaeomagnetic measurements for tectonical analysis is demonstrated. It is emphasized that ,,magnetical cleaning" should always be applied, in order to remove younger induced magnetic orientations. |
| Kort verslag van het 21e internationaal geologisch congres, Kopenhagen 15-25 augustus 1960 | 1961 | Koeningswald, G.H.R. von | 40(1) | |
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| Rheo-ignimbrite of the Ramnes volcano, Permian, Oslo graben | 1961 | Rutten, M.G.; Everdingen, R.O. van | 40(2) | The Ramnes structure lies within the Permian igneous rocks of the Oslo Graben, west of Tönsberg. A granular inner oval of kjelsåsite is surrounded by porphyric rocks of a more acid composition. Originally interpreted as a laccolite with its acid marginal facies, we think it is a cross section through an ignimbritic volcano. The potphyritic mantle is formed by former ignimbrite fluidised tuff flows, and shows rheo-ignimbritic structures. The core is formed by the crater filling, which melted when the eruption stopped and then recrystallised as a granular rock. The difference in chemical composition between core and mantle rocks is thought to be due to selective degassing during eruption. |
| Zircons of some metamorphic and intrusive rocks from the aston- and hospitalet massifs (central Pyrenees) | 1961 | Verspyck, G.W. | 40(2) | It is believed that the shape of zircon gives valuable information on the origin of metamorphic rocks; therefore several rocks have been examined on the habit of their zircons. Intrusive granodiorites and two types of metamorphic rocks all have different zircon. Several ways of representing the different observations have been used. The results of this study do not contradict the data compiled before, but form a valuable complement. Migmatites and quartzdiorites seem to have originated from a, possibly pelitic, sediment. Leucocratic gneisses possibly originated from a more sandy sediment. |
| Some arched and spiral structures in sediments | 1961 | Kuenen, P.H. | 40(2) | It is argued that certain small structures described by Carozzi from sedimentary rocks are not produced mechanically by compaction and slumping, as he suggests, but result from burrowing and, or coprolites. |
| Het resultaat van een palynologisch onderzoek van een Eemien-afzetting bij Liessel (N.-Br) | 1961 | Mente, A. | 40(2) | Palynological investigations by Florschütz and mrs. Anker-van Someren (1956), established a scheme and zone-division for deposits of Eemian-age in the southeastern Netherlands. These results have been obtained from analysis of samples gathered in various localities. The recent discovery of almost the complete zonation of the same scheme, this time however being the result of the analysis of a continuous series of examples coming from one boring, strongly confirmed the picture of Eemian-deposits, as revealed by Florschütz and mrs. Anker-van Someren. |
| Remarks on the tectonic position of the betic of Málaga in SE Spain and on its relation to the subbetic | 1961 | Booy, T. de; Egeler, C.G. | 40(2) | |
| Geologisch en mijnbouwkundig nieuws | 1961 | 40(2) | ||
| Boekbesprekingen | 1961 | 40(2) | ||
| Ten geleide, speciale uitgave veiligheid in de mijnen | 1961 | Raedts, C.E.P.M. | 40(3) | |
| De ontwikkeling van wettelijke regelingen betreffende de veiligheid, de arbeid en de gezondheid in de Nederlandse mijnindustrie | 1961 | Martens, A.H.W.; Geven, J.L. | 40(3) | |
| Het Nederlandse staatstoezicht op de mijnen en zijn gezagsdragers | 1961 | Raedts, C.E.P.M. | 40(3) | |
| Taak en werkwijze van de veiligheidsdienst van de staatsmijnen in Limburg | 1961 | Dresen, J.P.A. | 40(3) | |
| Werkzaamheden van het centraal proefstation van de staatsmijnen ten behoeve van de veiligheid en hygiëne | 1961 | Braaf, W. de | 40(3) | |
| Gezondheidszorg in het bedrijf | 1961 | Mey, A.V.M. | 40(3) | |
| Het staatstoezicht op de mijnen en het stofvraagstuk in de mijnen | 1961 | Matla, W.P.M. | 40(3) | |
| Het reddingswezen bij de Limburgse steenkolenmijnen | 1961 | Roos, G. | 40(3) | |
| De veiligheid in het olie- en gaswinningsbedrijf | 1961 | Asselbergs, J. | 40(3) | |
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| Deep or not deep, fore-deep or "after-deep" | 1961 | Gillavry, H.J.M. | 40(4) | This anniversary address discusses the history and situation of some geosynclines of intermediate type which do not fit into the standard Classification presented by Aubouin. Such intermediate geosynclines are not uncommon and their analysis leads to conclusions of more general significance. The discussion is primarily based upon the geology of the upper Paleozoic of the Baixo Alemtejo province (southern Portugal) and of the province of Huelva (southwest Spain). A comparison is made with the upper Paleozoic of the Rheinische Schiefergebirge, with the Cretaceous of Curaçao, and with the Ordovician-silurian of Wales and England. The acid rocks of the Alemtejo-HueIva area are initial volcanics of uppermost Devonian or lowermost Carboniferous age. They are not synorogenic intrusions as has often been thought. They are associated with radiolarites, and comprise rhyolitic rocks, keratophytes, spilites and diabases. The acid rocks predominate. and no serpentine has been found. The manganese and pyrite ores are thought to be primarily connected with the initial volcanism. It is suggested that the sea 'was shallow during the phase of submarine volcanism' This phase would thus not represent a periode de vacuité as conceived by Aubouin. During a later phase part of the original shallow basin would have subsided, another part would have been raised. Since volcanism has ceased by this time, it is thought that these movements are caused by compressional forces, whereas tensional forces would have reigned during the phase of volcanism' In the subsiding part of the area greywacke deposition took place; the phase of graywacke deposition is thus a phase of subsidence and not a période de comblement. The detritus in the graywackes is not derived from a pre-existing ridge or borderland, but from the rising part of the previous basin, and consists largely of rocks deposited during the preceding phase (radiolarite, rhyolite, keratophyre and spilite). This implies a flank supply, as also suggested by the presence of slump channels and intercalated conglomerates. The frequently observed occurrence of the radiolarite-ophiolite association as detritus in subsequent graywackes is an additional argument for a shallow-water deposition of this association in such cases. Disposition, facies distribution and direction of folding are the reverse of the situation usually considered as normal, and are not in favour of the theory of a continent growing through the successive addition of marginal geosynclines. The area contrasts sharply with the meseta to the north of it, the meseta proper. It is thought that the meseta proper is separated from the Alemtejo-Huelva province by a tectonic contact of the first order. An attempt to determine a minimum depth for graywacke deposition by means of a sequential analysis upwards from a reputed erosional hiatus of Tournaisian age fails, because such a hiatus could not be found. Conodonts found near Mertola suggest that Tournaisian sediments are present. |
| The skew frequency-curve of some ore minerals | 1961 | Agterberg, F.P. | 40(4) | This paper deals with the following subjects: A - The theoretical meaning of the lognormal distribution of some ore minerals. B- The connection between sampling distance and frequency-curve, C - A discussion of the theory of de Wijs on the skew frequency-curves in ore assays. D - The variation of the mean concentration within an ore deposit, A - In statistics normal distribution often occurs. If x represents the concentration of a component in a certain rock, z = In x is sometimes normally distributed for this component. If we assume that the gradual addition of a certain constituent to a rock is proportional to its existing concentration, this lognormal distribution of x is to be expected. B - The mutual dependence of adjacent samples can be determined in an exact way by the determination of correlation coefficients. As this dependence gradually diminishes with the distance we can introduce the concept of the independent cell distance. The size of an independent cell is defined in such a way that its deviation from the mean concentration of all samples together is only negligibly dependent on the concentration of the adjacent cells. If the ratio between independent ceil distance and sampling distance is called a, we find that in the case a ≥ 1 the histogram resembles the curve of the lognormal distribution. In the case of stoping units with a < 1 another frequency-curve appears the shape of which can be approximated by a lognormal frequency-curve with a smaller dispersion, as found by Krige. C - It is demonstrated that de Wijs's theory of repeating division into halves of an ore deposit, while the parameter d remains constant, is not an explanation for the skew frequency-curves of ore minerals. If this d was constant, it would not mean that the distribution of the samples equals a lognormal or a logarithmic binomial curve, but only that the curve showing the variation of the mean concentration within the deposit would have a logarithmic binomial shape. The parameter d is used for an analysis of the logarithmic binomial distribution. D- Gramberg called attention to the variations of the mean concentration within an ore deposit. We propose to find this variation by, means of Fourier analysis after a preliminary drawing of the variation curve by approximation. In this way the principle of a probably gradually varying mean is maintained. When the variations of the mean are great, the skewness of the frequency-curve may be caused by the positive correlation between the mean concentration and the dispersion in a certain place. For the correlation coefficient (r) probably holds r = 1. When the dispersion around the mean is about the same in ail places of the deposit, we show that a lognormal distribution of the varying men concentration is sometimes probable. |
| Nordic boulders in Pre-Holtstein sediments in the netherlands (Complex of Hattem) | 1961 | Lüttig, G.W.; Maarleveld, G.C. | 40(4) | In the region of Hattem, Nijverdal and Lemele (southeast of the IJssel-sea) coarse sands have been found in a buckled position. These sands are without bedding and carry Nordic boulders. With certainty they are older than the Holstein Interglacial, they belong to the formation of the ,,white sands" – probably to the sediments of the type Noord-Nederland (zone of Enschede) - which are assigned by many research workers at least to the Elster-age. The material of the gravel fraction as far as there is no influence of the river Rhine, comes from the Weser basin. Extraordinary is that the composition of the nordic boulder mass has values that the opposite to those hitherto stated for sediments of the pre-Saale glacial epoch. Not the east fennoskandian province of the key boulders is strongly represented but the south suedish. In connection with this determination attention is drawn to the fact that, up to the present, the assignment of the Netherland glacial sediments to the pre-Saale (Riss) is based solely on the predominance of the east fennoskandian boulders. The bedding complex did not allow to classify these sediments stratigraphically. We nominate these newly discovered boulder horizons in which, for the first time in the Netherlands, coarse, nordic material has been proved before the Hoistein stage, the ,,Complex of Hattem". |
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| Het voorkomen van schuifstenen in de duinen | 1961 | 40(4) | ||
| Boekbesprekingen | 1961 | 40(4) | ||
| Late Cretaceous and Tertiary stratigraphy and tectogenesis of the Colombian Andes. | 1961 | Hammen, T. van der | 40(5) | This article deals with the general results of a study of the Upper Cretaceous and Tertiary of the Colombian Andes. A number (maximum 10) of rather constant and important sandstone (or conglomerate) horizons may be-distinguished, which are often excellent guide horizons. The bases of these sandstones approximately coincide with the limits of periods and epochs, but are situated in general at least several metres higher than the palynological time-limits (based on climatic changes), The constant sandstones are related to tectonic-orogenetic phases. A group of pre-andean phases (Lower and Middle Eocene), a- proto-andean phase (Upper Oligocene) and a group of eu-andean phases (Miocene and Pliocene) can be-distinguished. The Tertiary (mainly terrestrial) sedimentation as a whole representing the continuation and termination of the (mainly marine) Cretaceous geosynclinal sedimentation, may be defined as synorogenetic. |
| Late Cretaceous and Tertiary stratigraphy and tectogenesis of the Colombian Andes. | 1961 | Hammen, T. van der | 40(5) | Plate (I) |
| Late Cretaceous and Tertiary stratigraphy and tectogenesis of the Colombian Andes. | 1961 | Hammen, T. van der | 40(5) | Plate (II) |
| Late Cretaceous and Tertiary stratigraphy and tectogenesis of the Colombian Andes. | 1961 | Hammen, T. van der | 40(5) | Plate (III) |
| Viridine, a rare constituent of Pleistocene sands | 1961 | Crommelin, R.D.; Plas, L. van der | 40(5) | The heavy fraction of some sandy deposits in the Netherlands contains conspicuous crystals of a remarkable pleochroism ranging from golden yellow to emerald green. The optical properties might indicate at first sight the presence of a member of the epidote group. In all of 9 cases observed, however, this mineral has proved to be viridine, a manganian andalusite. Its optical properties are described and the X-ray powder pattern is given. Possible source localities are indicated. |
| Barnsteen | 1961 | Faber, F.J. | 40(5) | |
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| #REF! | 1961 | 40(5) | Jaarverslag KNGMG 1960 | |
| The occurrence of Betic of Málaga in the Sierras de Almagro, Cabrera and Alhamilla (SE Spain) | 1961 | Booy, T. de; Egeler, C.G. | 40(6) | In the Sierras de Almagro, Cabrera and Alhamilla a considerable number of isolated outcrops occur of rocks belonging to the Betic of Málaga. The various elements distinguished tectonically overlie low-grade metamorphic rocks of the Alpujarrides. In the western part of the Sierra de Almagro (southeast of Huércal-Overa) distinction was made between: (1) a Graywacke Formation (Devono-Carboniferous); (2) sandstones and conglomerates (presumably Permo-Triassic); and (3) limestones (Mesozoic (post-Triassic) and early Tertiary). |
| On the contribution of the Amazon river to accretion of the coast of the Guianas | 1961 | Reyne, A. | 40(6) | Arguments are adduced to support Lyell's view, that the recent marine alluvium of the Guianas is mainly derived from the Amazon River. Samples of surfacewater were taken in the Atlantìc Ocean off the coast of Surinam on voyages from Paramaribo to Amsterdam in 1922 and 1924,These samples showed a strip of low salinity at a distance of 85-170 km from the coast, which is almost certainly due to Amazon-water. The sediment of a sample, taken 37 km offshore, was examined by means of an X-ray diffraction diagram; its composition was similar to that of the clay-soils on the coast of Surinam. Some data are reported about the yearly accretion or erosion of the coast of the Guianas, especially of the district Coronie in Surinam (see fig. 1). |
| in memoriam prof. dr. Jozef Zwierzycki | 1961 | Westerveld, J. | 40(6) | |
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| Complementary wrench faults and related structures in the crystalline rockso of the Belledonne Massif (French Alps) | 1961 | Kalsbeek, F.; Koning, H.; Tex, E. den | 40(7) | Recent work in the central portion of the Belledonne Massif, French Alps, has established the presence of two sets of wrench faults - one dextral, the other sinistral – with corresponding shear joints, strike-slip cleavages and microfabric S-planes, the latter virtually restricted to the main Sept-Laux granite. It is pointed out that megascopic ,,fish" structures, phyllonites and tension joints, observed in the same general area, are compatible with the movements on these wrench fault systems and fit in with a flattening deformation due to WNW-ESE compression having developed a subvertical B-axis. The age relations of the flattening phenomena with regard to folding, metamorphism and plutonic activity in the ,,Hercynian" basement of Belledonne are discussed and it is concluded that folding and progressive metamorphism are older than the flattening deformation, and that emplacement of the main Sept-Iaux granite is pene-contemporaneous with it. A brief comparison is made with similar features in other parts of the Alps and the possible occurence of more than one phase of flattening is explored. |
| Notes on continuous parallel slope retreat | 1961 | Ruxton, B.P.; Landewijk, J.E.J.M. van | 40(7) | Continuous parallel slope retreat is defined as a continuous translation of all the slope facets above a plain resulting in a constant slope pattern. In the eastcentral Sudan the clay plain may be taken as a plane and the granite hills rising from this are best explained on the theory of continuous parallel slope retreat. Detailed measurements on one small hill, Jebel Qasim, give support for this theory. Continuous parallel slope retreat cannot occur unless the footslope retreats as rapidly as the slope facets above it. In the translation theory we have an inspace-consant velocity of retreat along the translation vector, the rate. Most theories of slope retreat- assume that the footslope retreats at a slower rate than the slope facets above because it is protected by a migtatory layer of rock-waste. In general, footslopes retreat in three ways, by lateral planation, by gradual incorporation of the sedentary weathered rock into the migratory layer, and by subsurface erosion. At Jebel Qasim subsurface erosion, including-mechanical eluviation, is the main agent responsible for continuous parallel slope retreat. |
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| Geologische bibliografie van Nederland | 1961 | 40(7) | ||
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| Stratigrafische ontwikkeling en correlatie van de koollagen van de Baarlo Groep, Onder-Westfalien A, in Zuid-Limburg met een vergelijking tot die in omliggende gebieden. | 1961 | Kimpe, W.F.M. | 40(8) | |
| Stratigrafische ontwikkeling en correlatie van de koollagen van de Baarlo Groep, Onder-Westfalien A, in Zuid-Limburg met een vergelijking tot die in omliggende gebieden. | 1961 | Kimpe, W.F.M. | 40(8) | Large enclosure B1 |
| Stratigrafische ontwikkeling en correlatie van de koollagen van de Baarlo Groep, Onder-Westfalien A, in Zuid-Limburg met een vergelijking tot die in omliggende gebieden. | 1961 | Kimpe, W.F.M. | 40(8) | Large enclosure B2 |
| Stratigrafische ontwikkeling en correlatie van de koollagen van de Baarlo Groep, Onder-Westfalien A, in Zuid-Limburg met een vergelijking tot die in omliggende gebieden. | 1961 | Kimpe, W.F.M. | 40(8) | Large enclosure B3 |
| Stratigrafische ontwikkeling en correlatie van de koollagen van de Baarlo Groep, Onder-Westfalien A, in Zuid-Limburg met een vergelijking tot die in omliggende gebieden. | 1961 | Kimpe, W.F.M. | 40(8) | Large enclosure B4 |
| Geologisch en mijnbouwkundig nieuws | 1961 | 40(8) | ||
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| Applied science in the mining industry in Great Britain | 1961 | Metcalf, B.L. | 40(9) | |
| Preliminary note on the geology of the Cordillera Vilcabamba (SE Peru), with ephasis on the essentially Pre-Andean origin of the structure | 1961 | Egeler, C.G.; Booy, T. de | 40(9) | The stratigraphic column and the tectonic evolution of the Cordillera Vilcabamba in south-eastern Peru are discussed. New data are given on the pre-Carboniferous stratigraphy. Attention is drawn to the pre-Carboniferous age of the widespread volcanic rocks of acid to intermediate character, hitherto assumed to be Permian. The Vilcabamba batholith is proved to be of Paleozoic age (post-Middle Devonian and pre-Middle Permian); it is assumed that the batholitic invasion is related to the major orogeny which marked the close of the Lower Paleozoic. The Mitu volcanic rocks (Permian) prove to be exclusively of intermediate to basic character. Six important orogenic phases are inferred and an estimation is made of their role in the development of the present structure pattern of the Cordillera. This leads to the conclusion that the structural evolution was largely completed prior to the deposition of the Cretaceous sequence. It is clear that the influence of the Andean movements in south-eastern Peru has been unduly stressed in the past. |
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| Geologie and mining in the Netherlands | 1961 | Schieferdecker, A.A.G. | 40(10) | |
| Directional effects of winds, waves and currents along the Dutch North Sea Coast | 1961 | Straaten, L.M.J.U. van | 40(10) | As yet very little is known about the movements of sediment along the Dutch North Sea coast. In this paper new data are presented regarding the directions in which sediment transport seems to take place. Some of the main conclusions are as follows. The directions of Dutch coastal dunes appear to vary with a) the primary orientation of the foredunes and b) the relative effect of winds of moderate strength blowing from angles that differ from those of the stronger but less frequent winds. The magnitude of this effect depends on the width of the wind-formed depressions in the dune areas. Wave observations show that sand drift must be strong along the northern barrier islands (from west to east), but that its importance must be small along the more south-north directed part of the coast between Katwijk and Texel. This conclusion seems to agree with direct sedimentological evidence. Comparison of meteorological data with beach measurements between Scheveningen and Bergen reveals that the relatively frequent westerly and southwesterly winds in the second half of the 19th century resulted in an important (temporary) landward shift of the low tide line. |
| In memoriam, Dr. Ir. P. Tesch m.i. | 1961 | Thiadens, A.A. | 40(10) | |
| Het booreiland Triton | 1961 | 40(10) | ||
| Geologisch en mijnbouwkundig nieuws | 1961 | 40(10) | ||
| Boekbesprekingen | 1961 | 40(10) | ||
| Genootschapszaken | 1961 | 40(10) | ||
| Coal mining section section steinkohlenbergbau Heerlen | 1961 | Schieferdecker, A.A.G. | 40(11) | |
| Directional effects of winds, waves and currents along the Dutch North Sea Coast | 1961 | Straaten, L.M.J.U. van | 40(11) | |
| Preliminary note on the geology of the Cordillera Vilcabamba (SE Peru), with ephasis on the essentially Pre-Andean origin of the structure | 1961 | Egeler, C.G.; Booy, T. de | 40(11) | |
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| Jubilee convention - Geology and mining in the Netherlands | 1961 | Schieferdecker, A.A.G. | 40(12) | |
| Volcanology and geology of ignimbrites in Indonesia, North Italy and the U.S.A. | 1961 | Bemmelen, R.W. van | 40(12) | (1) An analysis of the orogenic and plutono-volcanic evolution of the Sumatra - Java arc of Indonesia, shows that three impulses of orogenic uplift occurred after its mesozoic geosynclinal subsidence. All three were accompanied by the rise and occasional ignimbritic eruptions of acid magma. Volcanic activity, producing igneous rocks of intermediary composition, developed during the intervening periods (Table I and fig. 1); the latter is the normal type of orogenic volcanism. The ignimbritic type of eruptions differs from the normal orogenic volcanism (Table II). The former produce extensive and voluminous sheets of acid "floodtuffs", which bury the landscape and which are partly welded and recrystallized during their cooling' These ignimbrite deposits are the synorogenic acid counterpart of the post-orogenic, basic plateau basalts, or "flood' basalts", as they were termed by Tyrrell. This ignimbrite type of eruptions may not be compared with "nuée ardente" eruptions. They represent different groups in the classification of volcanic eruptions according to viscosity and gas content of the magma (Table III). However, transitions will occur between ladu's and ignimbrites, between pumiceous air all tuffs produced by Plinian outbursts and ignimbrites, as well as between lava flows and ignimbrites (tufolavas, foam or froth lavas). (2) The quartz-latitic ignimbrites of the Bolzano province in North Italy are related with a cauldron, about 65 km in diameter. From this basin ignimbrite flows of over 100 km length radiate in various directions. These ignimbrites erupted during an acme of volcanism of relative short duration, after an initial phase of volcanism, which had an intermediary composition. The total volume of the Bolzano ignimbrites amounts to several thousands of cubic kilometres. This volcanism was the final act of the hercynic era of orogenesis. (3) The cenozoic ignimbrites of the Cordilleran system have their greatest development in the Great Basin District. Their total volume is estimated at 140.000-200.000 cb.km. These ignimbrite deposits are probably related with crustal stretching in the crestal part of the Cordilleran tumor as is schematically indicated in a section (fig.2). |
| On the geology and petrology of the Cape Smith - Wakeham Bay belt, Ungava, Quebec | 1961 | Stam, J.C. | 40(12) | The geology and petrology of an area in the western part of the Cape Smith-Wakeham Bay Belt, Quebec is described. A comparison of the various formations and their metamorphic characteristics is made and a cross-section is given, indicating the tectonic structure of the Belt. |
| Boekbesprekingen | 1961 | 40(12) | ||
| Geologisch en mijnbouwkundig nieuws | 1961 | 40(12) | ||
| Jubilee convention - Geology and mining in the Netherlands | 1962 | Schieferdecker, A.A.G. | 41(1) | |
| Beachrock at Limani Chersonisos, Crete | 1962 | Boekschoten, G.J. | 41(1) | Recent beachrock from Crete is described. The origin of the cementation here is thought to be caused by upwelling calciferous fresh ground water. Aquafacts have been modelled from the pebbles fixed firmly in the rock. |
| Autoradiographic ore analyses | 1962 | Hermans, J.M.A. | 41(1) | Quantitative analyses of uranium- and thorium ores by nuclear emulsion methods is a simple statistical procedure. A. thin nuclear emulsion coating exposed to a mixture of uranium and thorium ore with plaster of Paris, provides an alpha track pattern that is measured. Poisson's distribution is applied to this track pattern. |
| The emplacement of the Late Hercynian granites in Portugal: a reply | 1962 | Schermerhorn, L.J.G. | 41(1) | A recent explanation of the emplacement of the late Hercynian granites of North and Central Portugal in terms of ring intrusions, cauldron subsidence and major stoping caused by tensional fracturing of the crust is discussed. It is argued that the tin-tungsten granite province of Portugal is not comparable to ring-complex provinces elsewhere that wrench-faulting took place, that granite emplacement here can be explained by uplift of the roof with subordinate forceful intrusion and piecemeal stoping, not wholesale crustal collapse, and that the vertical foliation in the porphyritic granites was caused by oriented growth in situ, not by magmatic flow. |
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| Jubilee convention - Geology and mining in the Netherlands | 1962 | 41(2) | ||
| Het voorkomen van mijngas en de strijd tegen te hoge concentraties bij de staatsmijnen in Limburg | 1962 | Arets, L.A.G.L.; Maas, W.; Muysken, P.J.; Stuffken, J.; Wijffels, F.C.M. | 41(2) | The first part describes the laboratory experiments carried out to determine the amounts of gas that can be adsorbed to the various Dutch coals (as characterized by their volatile matter contents) as a function of pressure and temperature. It further deals with experiments performed to measure the amounts of gas actually adsorbed to coal extracted underground. Whenever in these experiments coal was used that had been subjected to great mechanical pressure variations, whether during extraction or in the stages preparatory to extraction, very low values were found. However, with coal obtained from deep drillings and consequently virtually uninfluenced, the amount of adsorped gas could immediately be measured with fairly great accuracy. The second part gives data on firedamp release during extraction, collected over years, and on the influence on seams under and over the coal seam worked. These data are used for determining the maximum amount of firedamp to be expected in the coal seams of the Dutch mines. By the use of all this information (including the curve relating to the influence on neighbouring seams) it was possible to develop a method of predicting gas release during coalgetting. This part closes with a discussion of some instances in which firedamp had leaked away through breakages in the surrounding rock before extraction starred. The third part describes the efforts made to reduce the firedamp hazard by means of gas drainage. A discussion is given of the various methods employed, and of their merits and limitations. It goes on to deal with the difficulties encountered at the start and at the termination of extraction in a panel. Finally there follows a survey of results obtained with firedamp drainage from various types of face and under various conditions of ventilation. The fourth part is concerned with the variation of the firedamp concentration in the ventilation air during extraction by various methods, both with and without application of firedamp drainage. Then follows a section devoted to the difficulties arising at the place where the firedamp enters the air stream, if the air speed is too low, and a discussion of the solution indicated by S.M.R.E. A table shows how often unduly low air speeds are involved in firedamp explosions. Finally this part deals with the grounds on which requests to be allowed to raise the maximum firedamp concentration in the main ventilation current to 2% were made and granted, and describes some of the experience gained under this condition. The fifth part discusses firedamp release at development and preparation points, particularly at those points where shotfiring is carried out. The sixth and final pair gives, a discussion of some uncommon cases of firedamp release, and deals with possible causes and with the safety measures used. |
| Le captage et la valorisation du Grisou en Belgique | 1962 | Vandeloise, R.; Rosen-Meyer, P. de | 41(2) | |
| Enige technische aspecten van recente ontwikkelingen in de gasindustrie | 1962 | Theron-Mulder, J.C. | 41(2) | Beside the gases based on coal, which have been distributed for many years, a number of gases originating from the oil industry have come forward of late. Their combustion properties often show a strong deviation from those of the classical town gases. Several requirements are mentioned to be met by the combustion when the gas type is changed in a distribution grid. An explanation is given of the way in which a flame is stabilized on the burner mouth. A final exposition shows how burners can be adapted to other gas types by changing the orifice, provided the pressure and the Wobbe number of the gases are related |
| On joint-patterns in domes | 1962 | Schuiling, D.D. | 41(2) | |
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| Enige gedachten over het onderwijs op de mijnschool te Heerlen | 1962 | Haverschmidt, R. | 41(3) | |
| Structural development of the Arabian shield in Palestine | 1962 | Ulbo de Sitter, L. | 41(3) | The Palestine region occupies the western, and part of the northern slope of the Arabian shield. Basement faults play a dominant role in its structural features often masked at the surface by warping of the Cretaceous rocks over the deeper seated fault throws. Typical are the monocline structures. The Jordan rift is perhaps originally a large wrench fault, the later subsidence of the Dead Sea is due to a tensional stress field causing normal faulting on the wester border. Superposed successive stress fields of pre-Cretaceous, Pre-Eocene- and Pre-Neogene age can explain the particular features of the fold and fault pattern. |
| A mixed Rhine-Meuse deposit of the Holsteinian age from the south-eastern part of the Netherlands | 1962 | Ridder, N.A. de; Zagwijn, W.H. | 41(3) | This paper deals with a transitional mineralogical zone found intercalated between the zones of Sterksel and Veghel, which were deposited by the Rhine and the Meuse respectively in the S.E. Netherlands. This transitional zone, for which the name of "Zone of Rosmalen" is proposed, could be traced by means of heavy-mineral assemblages. Pollen-analytical investigations of a clay deposit, found near Rosmalen, prove this zone of mixed Rhine and Meuse sediments to be of Holsteinian (= Needian) age. |
| A mixed Rhine-Meuse deposit of the Holsteinian age from the south-eastern part of the Netherlands | 1962 | Ridder, N.A. de; Zagwijn, W.H. | 41(3) | Enclosure |
| Un aspect de la végétation en espagne méridionale durant la derniére glaciation et l'holocène | 1962 | Menéndez Amor, J.; Florschütz, F. | 41(3) | This paper deals with the results of a palynological analysis of a 20m layer of peat, calcareous mud and clay near Granada in southern Spain. Obviously, it has been formed during the whole last glaciation and a part of the Holocene |
| On the so-called "konglomeratische mergel" in the Sierra de Los Filabres (SE Spain) | 1962 | 41(3) | ||
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| 50 jaar Koninklijk Nederlands Geologisch Mijnbouwkundig Genootschap 1912-1962 | 1962 | Sitter, L.U. de | 41(4) | |
| A dive into the history of the Royal Geological and mining society of the Netherlands | 1962 | Wijs, H.J. de | 41(4) | |
| Presentation of the Van Waterschoot van der Gracht medal to Doctor E. Anderheggen, Doctor E. Kündig, Professor F.B. Hinsley, Professor P. Pruvost. | 1962 | 41(4) | ||
| Past, present and future subsidence | 1962 | Faber, F.J. | 41(4) | |
| Geological research at the universities of the Netherlands 1877-1962 | 1962 | Pannekoek, A.J. | 41(4) | |
| Development of geo-hydrological knowledge and research in the Netherlands | 1962 | Krul, W.F.J.M. | 41(4) | |
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| #REF! | 1962 | 41(4) | Veiligheid in kolenmijnen | |
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| Ansprache von Herrn A. Hellemans, generaldirektor der staatsmijnen | 1962 | 41(5) | ||
| Die neueste entwicklung der Technik des Streckenvortriebes in den Limburgischen Steinkohlenbergwerken | 1962 | Debets, G.B. | 41(5) | The development, the preparatory work and the coalgetting required per 1000 n.t. production, since 1958 the driving of about 15 m roadway in the rock and in the coal. The roadways are generally trapezoidal with a working face of ca 9 m2 in the rock and of 5-8 m2 in the coal seams. The driving of roadways in the seams before the coalgetting has started has increased owing to a more extensive application of the retreating or semi-retreating system. The driving of roadways in advance of the face has consequently diminished. In order to obtain a decrease of the cost of driving the roadways, an increase of both the daily advance of the roadhead and its advance per manshift has been aimed at. In driving horizontal stone drifts an average daily advance of circ. 300 cm and an output per manshift of 28 cm have been attained by the application of higher speed drills, simultaneous loading of the muck by 2 throw shovel loaders or of high capacity shovel loaders. The introduction of safety explosives, class II and III enabled the blasting in one round of the complete lift consisting of coal and stone in the roads. For mechanical loading in the non-horizontal straight gate roads the scraper loader is mostly used. In these roadways, an average daily advance of 431 cm was obtained during the first half of 1961 with an output per manshift (all transportshifts included) of 30,5 cm. The corresponding results in gate roads in advance of the face were 298 and 29,2 cm. Machines suitable for breaking the coal and the stone and simultaneous loading are not yet applied in the Limburg coal district. |
| Der stand der Fördertechnik in den Nierderlanden | 1962 | Clercq, H. le | 41(5) | |
| Forschung und entwicklung im Bergbau | 1962 | Braaf, W. de | 41(5) | The fifty years that have elapsed since the establishment of the "Koninklijk Nederlands Geologisch Mijnbouwkundig Genootschap" have witnessed a considerable advance in mining techniques. The more complicated the techniques became the greater was the necessity carefully to make a quantitative analysis of the facts and to base the work of development on the results of this analysis. In the Netherlands, where somewhere about 1930 research work has begun to be carried out in a more organised and centralised form at Staatsmijnen, the interest went out especially to the improvement of coal preparation methods at first. Later the underground workings, too, were brought within the scope of the research work, which led amongst other things to the development of the Titan Servo-prop. Afterwards, about 1950, with a view to the flew shafts that had to be sunk, a large part of the available capacity was used to introduce improvements in the way of shaft linings and shaft sinking procedures. About 1957 the emphasis was placed on the increase of the productivity. Some characteristic aspects of the mining research work at Staatsmijnen are: 1) The necessity to make a choice from the great number of problems, which is due to the comparatively small size of the industry. The cost of research amount to half a guilder per ton as it is. 2) The close proximity of the mines to each other. I Coal face support After a fatal accident at Maurits Colliery in 1958 a jack ring (Fig. 1) was developed, permitting the Titan Servo-props to be put in piece with an initial load of 10 tons. Immediately after the introduction of hydraulic props in 1957 leakage of the relief pressure valve gave rise to difficulties. The design of this valve was therefore so changed, that it is now proof against polluted water (Fig.2). II. Mechanical getting of coal The idea that the coal getting machine should be as narrow as possible led to the construction of the multiplough. For a long time a considerable percentage of the coal mechanically won by Staatsmijnen has been produced by this plough, which in the last few years is, however, being superseded by the rapid plough. A more systematic investigation into the mechanics of the coal getting equipment was begun by studying the planing of coal and slate on a planing bench specially designed for this purpose. Afterwards measurements at the ploughing equipment in the underground workings were conducted. Several instruments were developed to this purpose (Figs. 3 and 4). A clearer insight into the phenomena was only obtained after the above measurements had been completed by model tests on a small scale (1 : 4) (Fig. 5) in the laboratory and by tests carried out with a full-scale test set-up on the surface (Fig. 6). Owing to these investigations several particulars regarding the action of the rapid plough could be explained (Figs. 7, 8, 9), and the design of the plough be improved (Fig. 10). The power consumption of thea conveyor and the plough was analysed (Fig. 11), so that the forces determinative of the power needed to drive the conveyor and the plough can be calculated. The properties of the system consisting in electric mains-motor-coupling-tool were also subjected to a quantitative analysis. III. Support of roadways and large spaces. In the last few years rather much time has been spent on an investigation, subsidised by the Coal and Steel Community, that has for its aim the improvement of the support of roadways, more in particular the reduction of maintenance costs in that respect. In a roadway which was divided into a number of test sections, all being supported in different ways, the movements of and the loads on the supports were measured (Figs. 12 to 17). For several years past investigations have been conducted into the influence of rock pressure on the concrete lining of shaft stations. Attempts are being made to draw conclusions from these measurements regarding the mechanical constants of the rock in situ (Fig. 21). lV. Communication; automation: signalling; transmission of measuring data. It is already some years ago that a duplex communication system was developed to maintain the communication between the control room and the engine drivers of a level (Fig. 22). A subsequent development is the electro-magnetic car detector (Fig 23). After these developments which are of a more incidental nature some larger projects are now in hand: 1) The automation of the disconnecting of mine cats, the tipping of the full cars in a tippler, the loading of a skip, and the connecting of the empty cats (Fig. 24, 25). 2) The automation of locomotive haulage at the shaft stations (Fig. 26). 3) The development of a control centre to be located at the district, showing and/or recording the principal data about the coal getting installation, so as to ensure the most efficient operation of this installation. V. Firedamp. The investigations made into the problems associated with firedamp were originally concerned with the forecasting of the quantities of methane that could be expected when new parts of a coalfield were to be worked (Fig. 27). With the assistance of the figures collected over a period of more than 30 years a method was developed permitting of calculating in advance, With sufficient accuracy for practical purposes, the quantities of CH4 that could be expected, provided the rank and the stratigraphic profile of the coal field in question be known. As a consequence of the ever more concentrated getting of coal the methane released threatened to impose a limit on the production of some district. This gave rise to the development of methane drainage installations at two mines. However, in recent years the production per district has risen to such an extent that, notwithstanding the drainage of methane, the regulation that the CH4 concentration in the air must not exceed 1½ % set a limit to the output of some districts. An extensive study of the nature of the gas emission in a district and the work already done in this field by the S.M.R.E. of Sheffield made it clear that no objections were attached to raising the allowed percentage to 2%, provided the air velocity is not lower than 2 m/sec. The emission of methane in places where preparatory works are going on is being studied, too. VI. Heat. For several years past investigations have been carried out into the question of how the climate in the underground workings comes about under influence of the various sources of heat and humidity. By recording temperature and humidity over a longer period of time (Fig. 33) heat balances can be drawn up for several airways, When these balances tally this means that the valuation of the sources of heat and humidity has been correct. A further study was made of the heat emitted by the rock round a roadway (Fig. 34). The investigation has now so fat progressed that the climate at new faces can be predicted with sufficient accuracy for practical purposes and the effect which certain measures have on the climate can be calculated in advance. Vll Concluding remarks. In this lecture an attempt has been made to give an idea of the contributions the largest Dutch mining company has made to the research and the development in mining. The above results could only be obtained thanks to services, this co-operation being strongly promoted by the fact that the research establishment is situated in the midst of the mines. |
| Der derzeitige stand in der mechanisierung der kohlengewinnung im Limburgischen steinkohlenrevier und ausblick auf die zukunft | 1962 | Snell, A.W. | 41(5) | The present stage of the mechanization of coal getting in the Limburg mining district, and expected future developments. The rise inwages and social overheads, added to the shortage of labour, has necessitated the introduction of far-reaching mechanization programmes in the mining industry. The object of mechanization in coal getting can be described as: extracting the largest possible amount of coal per 24 hours and per working point by the use of mechanical means in an economically justified way with the employment of the smallest possible number of men. The various coal-getting installations used are discussed in succession. They include: the scraper box installation, the single standard plough, the multiplough, the rapid plough, and the Peissenberg ramming installation. A sketch describing the developments in face supporting makes it clear that excellent results are expected to be obtained With the hydraulic self-advancing support, which is now being introduced at an increased rate. The second part (Results obtained, and expected future developments) deals with the various aspects of the attainment of the object of mechanized coal getting stated above, viz. the degree of mechanization, the saving in manshifts, the concentration, and the improvement in the size variation. For each aspect a discussion is given of: - the results achieved so far; - the ways in which these results were obtained; - mining-technical and constructional problems, and the ways in which they are expected to be solved. Finally, some remarks are given on the signalling of operating troubles by remote control systems, the capacity of the conveyors for product removal, and the training of personnel. |
| 60 jaren staatsmijnen in Limburg | 1962 | 41(5) | ||
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| Anwendung von sintronic hartmetall im bergbau | 1962 | Berndt, F. | 41(5) | |
| The inaugural session of the jubilee convention knight's hall (ridderzaal), the Hague, april 26th, 1962 | 1962 | 41(6) | ||
| Igneous and structural features of Thailand | 1962 | Klompé, T.H.F. | 41(6) | This paper presents a survey of the igneous and structural features of Thailand and their possible ages of emplacement and development. Three groups of igneous rocks are distinguished. Oldest are mafic to ultra-mafic rocks in North Thailand, intrusive in the Silurian-Lower-Carboniferous Kanchanaburi Series, they might represent the results of an initial geosynclinal magmatic activity. The Mesozoic granites are represented by an older, Upper Triassic granite in the eastern, and a younger tin-bearing granite in the western part of the country. The age of this last granite is considered to be post-Triassic. Recent age determinations on granites from Billiton .and Singkep have revealed that they were emplaced some 145-155 m.y.ago. The youngest representatives are various kinds of effusives and some dioritic intrusions of Upper Tertiary and Pleistocene age, they are related to important faulting features. Structurally Thailand can be divided in a western and northern mountainbelt, the Korat plateau in the east, and the depression of the Gulf of Thailand in between. The first unit consists of a conformable Paleozoic- sequence, locally conformably capped by Triassic deposits. The disconformities in the sequence are ascribed to epirogenic movements at times when in areas further east, important orogenic movements took place. The regularity of this sequence, the age of the granites and the unconformable contact between the folded layers and the overlying late Jurassic to early Cretaceous deposits in adjacent areas (Malaya, Borneo, Sumatra), favour an Upper Jurassic (young-cimmerian) phase of mountainbuilding. In the Korat Plateau the folded paleozoic sequence is unconformably overlain by the almost horizontal Rhaetic-Liassic and younger members of the Korat Series. This unconformity and the age of the granites favour an Upper Triassic (old-cimmerian) phase of diastrophism for the basement in the eastern part of the country. The depression of the Gulf of Thailand is the result of faulting. The northern part of this depression is gradually filled with alluvial deposits and the coastline is pushed southward approximately 4 to 5 meters per year. The structural features of Thailand and adjacent areas form an excellent example of zonal growth in this part of Asia. |
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| Preliminary note on the origin of the so-called "Konglomeratische mergel" and associated "Rauhwackes", in the region of Menas de Serón, Sierra de los Filabres (SE Spain) | 1962 | Leine, L.; Egeler, C.G. | 41(7) | The origin is discussed of the problematic rock types within the Triassic of the Sierra de los Filabres, that are usually referred to in the literature as "konglomeratische Mergel" (conglomeratic marls). An explanation is suggested for the considerable variation in character and the often heterogeneous composition of these rocks, which in the Menas region are represented as concordant discontinuous bands and masses in epimetamorphic as well mesometamorphic structural units. Arguments are provided for a tectonic origin, the rocks being interpreted as breccias resulting from differential movements within the rock sequence during intensive thrusting – a process in which the lithology of the initial sequence and especially the presence of highly incompetent beds of anhydrite or gypsum, perhaps in association with other salts has played an essential role. It is shown that the brecciation proceeded, at least for an important part, during a relatively advanced stage of the tectonic evolution, i.e. after the kinematic stage of the regional metamorphism, which is tentatively linked with overthrust movements leading towards the development of the nappe structures. These structures are considerably disturbed by late overthrusting and the provisional results seem to suggest that the provisional largely during these late movements. Special attention is drawn to a superimposed static metamorphism, which has a contributed in considerable measure to the ultimate character of the breccias by giving rise to the growth of a number of new minerals. The close relation between the heterogeneous type of breccias and the associated “Rauhwackes” is pointed out and it is suggested that the latter are tectonic breccias very poor in or devoid of fragments other than of dolomite, selective weathering having accentuated the breccia-structure. |
| The occurrence of gneissic amphibolites in southwest Puerto Rico | 1962 | Renz, O.; Verspyck, G.W. | 41(7) | Quartz-bearing amphibolites and metamorphosed basic dyke rocks are described and are compared with amphibolites known from the literature concerning the area. The presence of sodic plagioclase and blue-green hornblende seems to indicate that medium-grade regional metamorphism occurred. The age of the rocks is briefly discussed and their relation with the surrounding serpentinites reviewed |
| Sur la genèse du dôme gneissique de l'agout (dépts. Tarn et Hérault) | 1962 | Schuiling, R.D.; Widt, M.J. de | 41(7) | Tectonical and microtectonical data suggest that the emplacement of the gneissic dome de l’Agout took place under increase of volume, simultaneously with subsidence of the bordering schists. There can be no doubt that the gneisses possess a sedimentary frame, although their mineralogy shows a clear difference between schists and gneisses, which is also evident from a series of partial chemical analyses (Na, K, Cr). One is bound to suppose that here has been an important addition of mobile elements (in the order of 60-70%). These mobile elements, the “mobilisate” were expelled from the deeper levels of the micaschists (hence subsidence of these) along the planes of schistosity to higher structural levels, where they caused swelling of the schists in the places of deposition and their transformation into gneisses. The most mobile elements (Na, Si, B) were deposited in particular just below the schist-gneiss boundary (the front of migmatization). Chrome, a refractory element, is diluted beyond detectability in this particular outer zone; otherwise, compared to the schists, it is diluted 2-3 times in the normal gneissic succession. The rapid succession of metamorphic zones (biotite, garnet, andalusite, staurolite) surrounding the dome is indicative of a strong thermal gradient, i.e. a kind of contact-metamorphism. It is impossible to say whether this thermal metamorphism is mainly due to the tectonical emplacement of hot deep-level rocks in colder epizonal schists, with concomitant stretching and thinning of the limbs of the dome, or whether it was the hot “mobilisate” that was the principal cause of this metamorphism. |
| #REF! | 1962 | 41(7) | ||
| Geologisch en mijnbouwkundig nieuws | 1962 | 41(7) | Terugtrekken van de gletschers in het Carstenszgebergte (Nederlands Nieuw-Guinea) | |
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| Palynological and sedimentary petrological data of a section in ice pushed deposits (Southern Veluwe, Netherlands) | 1962 | Polak, B.; Maarleveld, G.C.; Nota, D.J.G. | 41(8) | A section of ice-pushed deposits in the southern Veluwe area was investigated. It was possible to ascertain its stratigraphical position by means of a combined palynological and sedimentary petrological study. The palynological data agree rather well with those of the warm-temperate section of the Cromer interglacial period, but show some similarity with Saalian (Eucomnia, Carya type). The results of the sedimentary petrological study have been summarised in Table 3. |
| Cinérites of the Mont Dore, Central France | 1962 | Rutten, M.G. | 41(8) | Cinérite is a local name for acid ash and tephra deposits of the mid- to late Tertiary volcanic region of the southeastern Massif Central, France. The two varieties distinguished, viz. fine grained cinérite and cinérite à blocs, are generically different. The former represent ash falls on a low, waterlogged peneplain, outside the actual volcanoes. The other is a laharic breccia formed on the cones of stratovolcanoes. |
| Cleavage-Boudinage in Precambrian rocks at Jasper, Alberta | 1962 | Charlesworth, H.A.K.; Evans, C.R. | 41(8) | Slaty cleavage in the argillaceous strata of the Precambrian Old Fort Point formation is arranged in a fan-like manner about the axial planes of folds. The origin of the cleavage-fan may result from the tendency of cleavage to lag behind folding or from that of the maximum principal stress-axis trajectories to be refracted towards bedding. Deviation from the regular cleavage-fan may be caused by variation in competency of the argillaceous layers and by the effect of interbedded competent strata. Cleavage-boudinage, restricted to thin siltstones surrounded by cleaved argillaceous rocks, is present in the steep limbs of asymmetrical folds. An analysis of the extension involved in the development of the boudinage suggests that shear parallel to cleavage occurred during at least part of the fold-history. On the other hand, rotation of the boudins into the plane of slaty cleavage indicates that considerable shortening perpendicular to cleavage may also have taken place. |
| Geologische bibliografie van Nederland | 1962 | 41(8) | ||
| #REF! | 1962 | 41(8) | Aardgasnota | |
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| Gegenwärtiger stand und entwicklungstendenzen der mechanisierung der abbaubetriebe im Ruhrgebiet bei verschiedenen lagerungsverhältnissen | 1962 | Brandi, K. | 41(9) | |
| Geology of West Amberbaken (New Guinea) | 1962 | Valk, W. | 41(9) | In West Amberbaken andesitic rocks prevail. They are propylitized and mineralized, but no ore deposits of economic value have been formed. After andesitic vulcanism had come to an end, tilting and faulting in late Tertiary time created a bold relief. Then followed the deposition of a sedimentary series starting with coarse conglomerates. Folding of the sedimentary basin took place during the Mio-pliocene or Pliocene. |
| A survey of the Efar-Sidoas mountain ridge in Northern Netherlands New Guinea | 1962 | Dun, F.W.P. van | 41(9) | Data obtained during earlier surveys (Zwierzycki, 1921) rendered it necessary to renew the geological explorarion of the hinterland of Sarmi, where the central part of the Efar-Sidoas anticline was reported to consist mainly of basement (igneous rocks and crystalline schists). It appeared, however, that the Efar-Sidoas mountain ridge is made up almost entirely of Neogene folded sediments; the crystalline core occurring only in a few isolated areas. Consequently the attached sketchmap differs considerably from Zwier zycki's map. No mineralizations were detected neither in the basement nor in the Neogene sediments. |
| Indrukken van het derde I.M.A.-congres, Washington, 17-20 April 1962 | 1962 | Uytenbogaardt, W. | 41(9) | Indrukken van het derde I.M.A.-congres, Washington, 17-20 April 1962 |
| Boekbesprekingen | 1962 | 41(9) | ||
| Geologisch en mijnbouwkundig nieuws | 1962 | 41(9) | ||
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| in memoriam Prof. Dr. Ir. J. Westerveld | 1962 | Roever, W.P. de | 41(10) | |
| Some applications of Faber's method for grain size analysis by counting | 1962 | Mabesoone, J.M. | 41(10) | The method for the determination of size frequency distribution of sands by counting individual quartz grains, as developed by Faber, is compared with other methods in which either sieving or counting techniques are used. It appears that the results obtained by Faber's method have no ¡elation to those obtained by the other methods, because the approach is fundamentally different. Faber's method is applied to determine roundness, spread, and median grain diameter of various fluvial deposits. Then a number of samples from the Netherlands is compared with the former. It appears that these Dutch sediments are much better rounded. It is presumed that they were derived from rocks which contained already rounded grains. Finally the method is applied to deposits of the marshy coastal plain of the Guadalete river in S.Spain. It is concluded that the former estuary of the river has been filled up by this river itself, and not by the sea. |
| Preliminary note on the presence of distinct tectonic units in the Betic of Málaga of the Vélez Rubio region (SE Spain) | 1962 | Roep, T.B.; Gillavry, H.J.M. | 41(10) | The Betic of Málaga is considered to be complex and to consist of a number of distinct tectonic units. These are from north to south: the Salud, Castillos, Cerro Colorado, and Casolidad units. The northernmost (uppermost) Salud unit is characterised by the presence of Oligocene transgressively overlying Triassic or Permo-Triassic. The Castillos unit, directly to the south of the former, is characterised by Eocene transgressively overlying Cretaceous or Upper Jurassic; its Mesozoic stratigraphy corresponds with that described from the region of Málaga (Azéma, 1961) and from the Sierra de Espuña (N. & Y. Peyre, 1960); Novakia- limestone intercalations in the Upper Paleozoic, and Carboniferous conglomerates of the Marbella-conglomerate type, seem to be restricted to this unit. The Cerro Colorado unit contains Paleozoic, Permo-Triassic sandy formations and Triassic dolomite. The Casolidad unit, situated furthest south, contains only Paleozoic and Permo-Triassic, the latter being characterised by the occurrence of thick, coarse quartz conglomerate intercalations; it shows some Alpine metamorphism. The separation of the two last-named units is still tentative. The stratigraphic and tectonic implications are discussed. It is suggested that the Betic of MáIaga was imbricated by thrust movements after deposition of the Salud Oligocene, prior to the first nappe-movements of the Betic of MáIaga complex as a whole. |
| Lead isotope studies of the lead-zinc deposits in southern Limburg, The Netherlands | 1962 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Boerboom, A.J.H. | 41(10) | Among the galenas of the lead-zinc ores in southern Limburg two groups of lead model ages can be distinguished, one averaging 430.106 years (Upper Ordovician-Lower Gothlandian) and the other averaging 345.106 years (Lower Carboniferous). This points to Caledonian and early Hercynian ages of generation of the lead ore. The ore deposits were emplaced in post-Westphalian time, at least in part during the Upper Cretaceous, so that we are dealing with B-type anomalous lead. This supports the hypothesis of a genesis of the ore by regeneration from older deposits. The calculation methods and some geochemical implications are discussed. |
| Boekbesprekingen | 1962 | 41(10) | ||
| Geologisch en mijnbouwkundig nieuws | 1962 | 41(10) | ||
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| Stofgrenzen | 1962 | Matla, W.P.M. | 41(11) | The first part, an introduction, gives an indication of changing opinions on dust limits which may be expressed in terms of weight, surface or number of dust particles, or in other parameters. The second part mentions foreign limits, adopted, recommended or derived. It is not always possible to give the motivation or the origin of the limits since, in many cases, this has not been published. 'the third part treats the dust limits adopted by the Netherlands Coal Mines on the advice of the Stofinstituut van de Gezamenlijke Steenkolenmijnen in Limburg (Dust Institute of the Association of the Netherlands Coal Mines); other dutch opinions on dust limits are given too. The fourth part gives, on the basis of available data, comparisons between different dust limits, in the first place comparisons between foreign dust limits and those recommended by the Stofinstituut. The fifth part considers the re-employment of pneumoconiosis cases. The sixth part is a list of references. To avoid possible misunderstandings the author makes ample use of literal foreign texts. Commentary is not given, and the report does not close with a conclusion by the author. |
| #REF! | 1962 | 41(11) | ||
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| Geologie en geofysica (werkwijze en enige resultaten) | 1962 | Bemmelen, R.W. van | 41(12) | The stages of cosmic evolution are characterized by leading principles of development. During the stellar evolution nuclear reactions , producing the chemical elements, were the leading principle. During the planetary evolution the energy production is chiefly based on molecular integrations (reactions of the electronic shells of the elements) and nuclear desintegrations (natural radioactivity). The successive stages of the universal of evolution with emergent principles of development are: galactic, stellar, planetary, biotic, and psychic (van Bemmelen, 1948; Teilhard de Chardin, 1958). For the scientific research of these stages the prognosis-diagnosis method can be applied (Fig.2). For instance, the model of a layered earth leads to the expectation that the earth will have a specific spectrum of vibrations, when struck like a bell by a heavy earthquake. The frequencies calculated by Pekeris and others are a prognosis which has been verified by the diagnostic observations at the observations at the occasion of the Chili-earthquake of May 1960. A fair correspondence between prognosis and diagnosis has been found up to the 38th overtone. This means a check of the correctness of our mental picture about the structure and physical of the inner part of the earth. Paleomagnetism is a new method of measuring geophysical properties, which provides the geologist with diagnostic observations for testing geotectonic concepts. It appears that indeed polar wandering and continental drift, as suggested by Wegener half a century ago, did occur on a grand scale during the geological evolution. A synthesis of our concepts concerning the geological evolution can be based on two leading principles: (A) Physico-chemical processes are the source of the endogenic energy of the earth (plutonism sensu largo); (B) these processes are accompanied by changes of density, which cause accumulations of potential energy. The resulting stress fields will give rise to flow-circuits of matter of various dimensions (gravity tectonics sensu largo) (van Bemmelen, 1958). Thus the prognosos-diagnosis method leads us to the insight that the geotectonic evolution does not occur solely according to the fixistic concept or the mobilistic concept; but rather according to a combination of both, fixism and mobilism. |
| Memorandum betreffende het energiebeleid | 1962 | 41(12) | ||
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| In memoriam Dr. G. Zijlstra | 1963 | 42(1) | ||
| De geologie van het eiland Waigeo | 1963 | Wegen, G. van der | 42(1) | Waigeo, Batanta, Salawati and numerous smaller islets of the western tip of the mainland of New Guinea form the Radja Ampat archipelago. Waigeo and its surrounding islands were visited for the first time by Verbeek in 1908, during his geological reconnaissance of the eastern part of the former Dutch East-Indies. Neither Verbeek nor subsequent visiting geologists (Brouwer, Molengraaff, oil geologists a.o.) penetrated deeply into the island's interior. We have, nevertheless, a reasonable clear insight into its geology, which is mainly due to Verstappen's geological interpretations of aerial photographs. Ultrabasic rocks are present in a narrow belt along the north and west coasts of Waigeo and on some of th islets in the inmediate vicinity. They were followed by other basic and intermediate rocks, among which such charateristic effusiva as spilites and keratophyres. These ingneous rocks accompany the initial geosynclinals subsidence and present its simatic magmatism to a high degree of completeness. Together with pelagic limestones, pelites, radiolarites and chert they were strongly folded. Deposition of graywackes, conglomerates, volcanic breccias, quartz-) andesites and tuffs, cut by basalt dikes followed the folding. According to the oil geologists who visited some of the coastal areas of Waigeo the above mentioned rocks, with the exception of the ultrabasic rocks, belong to the so-called Batanta-formation and are of Oligocene to early-Miocene age. There are reasons to assume an uncomformity within the Batanta-formation. This intraformational uncomformity points to synorogentic conditions of sedimentation which, although of limited extent, led to the flysch sedimentation during early Miocene time. In a fully developed eugeosynclinal cycle the initial magmatic phase is followed by a synorogenetic or sialic and a final, simatic or basaltic phase. There are some indications of magmatic actvities during the Lower-Miocene. Limestones and marls of the Waigeo-formation (Upper-Miocene and Pliocene) indicate a very extensive transgression during the Upper Tertiary of Western New-Guinea. |
| #REF! | 1963 | 42(1) | ||
| #REF! | 1963 | 42(1) | ||
| #REF! | 1963 | 42(1) | KNGMG Jaarverslag 1961 | |
| Coastal sediments and coastal development near Cádiz (Spain) | 1963 | Mabesoone, J.M. | 42(2) | The coastal area of the W part of the province of Cádiz (Spain) shows various beaches alternating with some cliffs; near the city of Cádiz the Guadalete river flows into the sea. This coast can be divided into three parts: (1) the part N of Sta. Catalina, (2) the part S of Cádiz, and (3) the inner part of the bay. Recent beach sands point to a supply from the adjacent land, particularly where cliffs are exposed. The south-easterly longshore current had only a minor influence. These features are presented by means of socalled historiograms. The dunes received their material from the adjacent beaches by the action of onshore winds. Bottom dedosits of the bay show a Pliocene sediment, sometimes mixed with younger material. Beach and dune sands can be distinguished by means of the skewness values of their grain size distribution, following indications provided by Mason & Folk. By means of this method a distinction between beach rock and eolianite could also be made with respect to the cemented deposits found alongside the modern shore. From ancient beach and dune sediments at various levels and the height of the cliffs, four stages of Quaternary coasts could be mapped. The oldest coast from the Milazzian time survives at present only in some isles in the investigated area, During later stages the coasts approached the site of the present one, although this latter, which is in retreat, lies somewhat landward from that presumed in the Tyrrhenian II and III periods. |
| Europa und die Energie | 1963 | 42(2) | ||
| 10e Leobener Bergmannstag - 12-16 spetember 1962 | 1963 | Martens, A.H.W. | 42(2) | |
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| Indications for large scale grabenformation along the continental margin of the eastern United States | 1963 | Engelen, G.B. | 42(3) | Geophysical, geological and topographical data about the continental margins of the northern Atlantic and the Arctic Ocean, collected by Heezen, Holtedahl and others, were studied by applying various working hypotheses to these primary data. In this way the picture of a big graben structure under these continental margins, parallel to the coast, was deduced. This riftzone fully developed during the Miocene in a sedimentary deltaic sequence, that was deposited from the early Cretaceous to the middle Tertiary as a long "ribbon" on the continental margins along the coasts. The adjacent continents seem to have been elevated temporarily at the end of the Tertiary. In the emerged continental slope (the limiting faultplane on the continental side of the graben) canyons could be formed by subaerial erosion. The continents should have sunken back again during the Pliocene with almost the same vertical amount and thus the canyons got drowned. Isostatic readjustment to compensate for the erosion on the continents and sedimentation in the continental margins seems to be one of the causes for the inferred sequence of events. The continental margin along the western side of the North Atlantic Ocean is treated in some detail as an example. |
| Het vierde internationale kolenwasserijcongres | 1963 | Baerts, J.W.R. | 42(3) | |
| De slikverwerking | 1963 | Bitter, J.H. | 42(3) | |
| Note on geological developments in southeast Asia | 1963 | Valk, W. | 42(3) | |
| Boekbesprekingen | 1963 | 42(3) | ||
| Geologisch en mijnbouwkundig nieuws | 1963 | 42(3) | ||
| #REF! | 1963 | 42(3) | ||
| Geologisch begrip | 1963 | D'Arnaud Gerkens, J.C. | 42(4) | |
| Comment varient dans l'Espace les structures geologiques | 1963 | Pruvost, P. | 42(4) | |
| Een vulkanisch sediment in de ondergrond van de Betuwe | 1963 | Crommelin, R.D. | 42(4) | |
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| Some time relations of movement and metamorphism in the Scottish Highlands | 1963 | Johnson, M.R.W. | 42(5) | The paper attempts to summarise recent work on time relationships of deformation and crystallisation in the Moine and Dalradian rocks of the Caledonian orogenic belt in Scotland. Three or four deformation episodes, each accompanied by some kind of metamorphism, have been detected. Crystallisations of metamorphic minerals can be shown to have accompanied and, more especially, followed a particular episode of deformation and so the observed metamorphic fabrics result from a complex interplay of deformations and crystallisations. Rocks may contain disequilibrium assemblages, with the metastable survival of early crystallised minerals. In the Dalradians, and probably the Moines also, the earliest known movements, which caused great thickening of the sedimentary pile, were accompanied by only low-grade, dynamic, metamorphism. The main episodes of crystallisation occurred before, during and after the second deformation. The three episodes are part of a continuous, perhaps progressive, metamorphic process, which possibly embraced some local oscillations in P/T conditions. The third, final, episode of crystallization - an important and extended static period between the second and third fold movements - often marks the climax of the crystallisation and grain growth resulting in the build-up of schistose or gneissose fabrics. During this episode in the Dalradians there were regional crystallisations of kyanite-sillimanite ("Barrovian type") and andalusite-sillimanite ("Buchan type") sequences. The occurrence of these sequences at different structural levels is thought to have been controlled by orogenic P/T gradients. An account is included on current work on problems of dating the migmatites in the Scottish Highlands. A separation in time between migmatitic and regional metamorphism has been proposed at various times by different workers. Recently it has been suggested that the Dalradian migmatites and associated sillimanite have been superimposed upon the pattern of andalusite/kyanite metamorphism. The available evidence bearing on this problem is discussed. The migmatites appear to show a different, perhaps more prolonged history of crystallisation than do the non-migmatitic rocks. T/P oscillations may have played an important part in the evolution of the migmatite fabric and the climax of crystallisation in the migmatite zones may not have have been attained at the same time as elsewhere. Although the history of crystallisation in relation to deformation in the Moines follows a broadly similar pattern to that in the Dalradians it has yet to be established that the regional metamorphism Moine and Dalradian tracts are coeval. Indeed, recent geochronological work, to which brief reference is made, suggests they may not be coeval. |
| Some examples of the relations between deformation and metamorphism from the Central Pyrenees | 1963 | Zwart, H.J. | 42(5) | Four examples of relations between deformation and metamorphism are discussed. In the Bosost area a folding phase with N-S axes is accompanied by uniform rotation of minerals, indicating that the schistosity is a plane of shear and that the folds are shearfolds. Another phase of deformation consists of two sets of folds perpendicular to each other. Their shearfold character and contemporaneity cannot be proved in steeply dipping slates, but in the schists of the Hospitalet massif rotation of minerals again is demonstrative of this type of folding. A detailed scheme of the metamorphic history of the Bosost area can be established by dating the minerals with four phases of deformation. The order of crystallization shows increase in temperature during a large part of the metamorphic history. The mineral assemblages are formed under low confining pressure. Two types of gneisses occur in the Pyrenees, gneisses with regular schistosity and lineations and migmatitic gneisses with strongly folded schistosiry. The relationships between these gneisses and their metamorphic grade indicate that metamorphism of the first group took place under drier conditions. |
| Ablauf und Altersverhältnis der Postvaristischen tektonik und metamorphose im Westalpenbogen | 1963 | Wunderlich, H.G. | 42(5) | The tectonic and metamorphic processes in the western Alps are characterized, by a regular chronological sequence of activities encompassing thrusting, folding and formation of secondary fabric elements. Alpine metamorphic crystallization and magmatism; all these events occurred in course of the deformation of the geosynclinal prism. Thrusting, folding and penetrative movements set in at the innermost parts of the Alpine chain and become successively younger when proceeding to the northern and western edges of the depositional basin. Folding and penetrative movements, giving birth to schistosity and lineation (in N-S and E-W direction), are always younger than the thrusting, when considering the individual and successively deformed sectors of the mountain chain. The Alpine regional metamorphism has been found to be restricted to certain areas within the internal, most strongly deformed parts of the area, where the metamorphic crystallization goes hand-in-hand with the penetrative movements, ultimately post-dating the same. A certain time-place relationship between the metamorphism and Alpine magmatism (Traversella, Biella, Iorio, Bergell, Adamello) is obviously present, pointing to a genetic relationship between the two. The depositional basins, filled up by orogenic sediments, are shifted slowly towards the outer edge of the Alpine chain and are themselves followed by thrusting and folding movements. All these events, however, were brought to an end with the late thrustings in the external parts of the mountain and folding of the sub-Alpine chain. Thereupon the regional uplift followed. |
| A commentary on the correlation of the metamorphism and deformation in space and time | 1963 | Tex, E. den | 42(5) | |
| Some remarks concerning the scarcity of retrograde vs. progressive metamorphism | 1963 | Schuiling, R.D. | 42(5) | |
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| Aspects of the genesis of bituminous rock sequences | 1963 | Bitterli, P. | 42(6) | From the investigation of some 150 W. European, primary-bituminous rock sequences of Cambrian to younger Tertiary age, it is concluded that bituminous material occurs in a great variety of sediments (shales, carbonates, clays, siltstones, etc.), though predominantly in fine-grained and laminated rocks. Favourable situations for the formation of bituminous sequences seem to be often created at palaeogeographic turning points (orogeneses; epeirogenic or eustatic oscillations) which resulted in either transgressions or regressions and were followed by stagnation and anaerobic conditions. As regards environments of deposition of the sequences studied, a, great many occurrences are of a transitional or an alternating facies; brackish and mainly limnic deposits often show higher concentrations of organic matter and thicker beds than marine deposits. As regards the genesis of bituminous rock sequences, the interplay of various climatic, physico-chemical and other factors, governing or influencing type and amount of organic matter, inorganic components, anaerobic conditions, etc., is of great importance. Depending on whether these conditions continue more or less uniformly for a certain time, or alternate periodically, there will result: a) continuous (homogeneous) or b) cyclic (rhythmic) sequences; unsettled conditions and irregular repetitions will end in c) complex sequences. In an attempt to subdivide the many bituminous sequences studied. according to the original depositional environment, various types of basins and other aquatic realms are recognized, which can be groupel in: 1) open marine, 2) transitional, and 3) continental. |
| A peat-layer of Early Würm glacial age | 1963 | Polak, B.; Hamming, C. | 42(6) | A deposit, representing a zone of the Brørup Interstadial of the Würm glaciation is described. This deposit was found in the north-eastern part of the province of Overijssel. So far sediments of the Brørup Interstadial were only known to be present at Amersfoort and this find thus represents a second occurrence in the Netherlands. |
| Erfahrungen mit 865 V-Niederspannungsanlagen im Holländischen Grubenbetrieb | 1963 | Kempen, W.; Reyen, C. van | 42(6) | |
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| Ontwikkeling van de diepte-injectie op de mijn Julia | 1963 | Bianchi, M.; Hooijdonk, J. van | 42(7) | |
| Henry Clifton Sorby and the sedimentary structures of sands and sandstones in relation to flow conditions | 1963 | Allen, J.R.L. | 42(7) | The scheme of sandstone facies in relation to increasing intensity of fluid flow developed by Sorby is modified in the light of recent experimental studies, as follows: small scale cross-stratification + large scale cross-stratification (cosets) + flat-bedding with primary current lineation. A. cyclothem probably of fluviatile origin from the Lower Old Red Sandstone (Lower Devonian) of the Anglo-Welsh Basin is analysed to demonstrate the practical value of the scheme in the interpretation of facies. |
| Geologische bibliografie van Nederland | 1963 | 42(7) | ||
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| Some geological observations on the coast of Crete | 1963 | Boekschoten, G.J. | 42(8) | Several features of Cretan beaches are described. Some instances of the influence of recent tectonic movement are given. The advent of volcanic material from Santorini on Cretan beaches must have happened quite recently. Beachrock formation is due to mixing of calciferous fresh-water with alkaline sea-water in beach sands. Density currents create a suitable hydrological background for beach sand cementation. Solution basins of 50 cm diameter and 5 cm depth are formed in limestones within a period of 1500 years. Aquafacts and ventifacts from the Cretan coasts are described. |
| Conodonts of Upper Devonian and Lower Carboniferous age from Southern Portugal | 1963 | Boogaard, M. van den | 42(8) | Conodonts were found in samples from limestone outcrops in the Baixo Alentejo, southern Portugal; five samples from outcrops in the Pomarão region and two samples from a limestone-quarry near Carvoeiro, north of Mertola. (See maps fig. 1). The conodonts from the limestones of the Pomarão area belong to the uppermost Platyclymenia- and lowermost Gonioclymenia-stage, Upper Devonian; those from the Carvoeiro limestone to the Pericyclus-stagg Lower Carboniferous. Some new forms are described. |
| Twee zeventigjarigen en hun gedenkboek | 1963 | 42(8) | ||
| In memoriam Prof. Dr. Th. H.F. Klompé | 1963 | 42(8) | ||
| Gouden Doctoraat Dr Schurmann | 1963 | 42(8) | ||
| De losvloer van schacht IV van Staatsmijn Hendrik - Algemene richtlijnen voor het ontwerpen van losvloeren, leidende gedachten bij het ontwerp voor Staatsmijn Hendrik. Bijzonderheden over de uitvoering, speciaal wat betreft de automatisering | 1963 | Clercq, H. le | 42(9) | |
| De toepassing van gesloten radio-actieve bronnen voor bedrijfscontrole in mijnen en bovengrondse werken | 1963 | Dijkstra, H.; Steur, C. | 42(9) | A survey is given of the background-knowledge, necessary for the application of closed radio-active sources in the mining-industry. Several methods of measurement and control in use at the Staatsmijnen collieries are mentioned and shown by diagram or photograph. A suggestion is made of a method for sorting tubs, loaded with stone, loaded with coal, or empty. |
| Elektronische rekenmachines in het mijnbedrijf | 1963 | Knoester, C.J. | 42(9) | |
| In memoriam Prof Dr. Ir. C. Schouten | 1963 | Engelbert; van Bevervoorde, W.F.C. | 42(9) | |
| #REF! | 1963 | 42(9) | ||
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| Observations on sedimentology and geomorphology of the Guadalete drainage area (Cádiz, Spain) | 1963 | Mabesoone, J.M. | 42(10) | The W part of the Subbetic region in the province of Cádiz is drained by the Guadalete river. The area consists of sediments ranging in age from Triassic to Recent. The chief alpine orogenic phase which affected this region took place after the deposition of the Oligocene sediments. The Miocene shows only slight undulations, and in the younger deposits only evidence of tilting towards the W could be demonstrated. The river Guadalete flows through a mountain area as for as Puerto Serrano; from there it winds through a syncline in the Miocene deposits almost to the Loma del Torno. Finally, it flows towards the sea through a wide valley which was drowned several times during the Pleistocene transgression stages. The first river terraces begin to appear S of Puerto Serrano. Three levels (30-40, 15-20, and 2-5 m) can be distinguished. Sedimentological analysis of their deposits point to: (1) a shaping of limestone pebbles strongly influenced by a local supply of fresh material; (2) a content of rounded-brilliant quarz sand grains determined by the content of these grains in the underlying deposits; (3) a grain size of the finer part of the terrace material that also depends on the underlying sediments. The modern river-bed has the same characteristics with one exception: the grain size of the river-bed sands becomes generally finer downstream, but coarser particles are mixed with the finer type where the river passes through a gorge in the lower valley area. Furthermore, the deposits have a bi-phasic character with a fairly high silt-content. Heavy mineral distributions in the terrace as well as in the river-bed sediments show that the Guadalere supplied a characteristic association to the area. The older deposits, those of the Villafranchian included, have an EGA-distribution (epidote-garnet-andalusite) but the river deposits show an EZG-distribution (epidote-zircon-garnet). The latter association must thus be due to a supply from the source area, upstream from Puerto Serrano. The heights of the terrace remnants above river level and their situation permit the drawing of the following conclusions: (1) during its HT-time the river had a somewhat more easterly course than it has at present; (2) a slow tilting of the area caused the slipoff towards the W; (3) the length slopes of the Pleistocene river courses are steeper than the present one, causing a dipping of the terraces below the modern river plain. Some special features are also discussed, such as the gorge near Bornos, the intrenched meander of Arcos, and the cut-off meander near Jerez. The recent filling-up of the estuary is briefly explained. It appears that the Guadalete filled up the northern marsh part, that the sea filled the southern part with reworked deposits from the adjacent land, and that the environment has always been marine to brackish. |
| Permian near Wadi Araba eastern desert of Egypt | 1963 | Schürmann, H.M.E.; Burger, D.; Dijkstra, S.J. | 42(10) | |
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| Het carboon in de ondergrond van Nederland en de oorsprong van het massief van Brabant | 1963 | Patijn, R.J.H. | 42(11) | |
| De vorming van aardgas ten gevolge van nainkoling in het noordoosten van Nederland | 1963 | Patijn, R.J.H. | 42(11) | |
| A recent dicovery of Itaberite in southern Surinam | 1963 | Ornstein, M.A.M.; Haug, G.M.W. | 42(11) | |
| Convolute lamination, metadepositional ruptures and slumping in an exposure near Pobla de Segur (Spain) | 1963 | Nagtegaal, P.J.C. | 42(11) | This paper presents the results of a comparative study of convolute lamination, metadepositional rupture, and slumping. The observations concern one exposure near Pobla de Segur (Spain), where these three types of sedimentary structures are equally well developed. The exposed rocks consist of a regular alternation of Upper Cretaceous, mostly graded, carbonate-rich siltstones and shales. The type of grading and the presence of a certain percentage of allochtonous material point to deposition of the siltstones by turbidity currents. Field observations, laboratory analyses, and mutual comparison of the structures suggest that in this exposure the convolute lamination, metadepositional rupture, and slumping have a common origin. Strongly dependent on the mineralogical composition and grainsize of the sediment as well as the various states due to differences of moisture content, these structures are the diverse results of gravity-induced, Iateral movements during and shortly after deposition. Many samples from the exposure were ground in order to approximate the original sediment. Thixotropy tests of these powders support the conclusions. |
| In memoriam Prof. ir. C.L. van Nes | 1963 | Seldenrath, T.R. | 42(11) | |
| #REF! | 1963 | 42(11) | ||
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| Einleitung zur informationstagung auf dem gebiete der Grubengasbekaempfung | 1963 | Hellwig, F. | 42(12) | |
| Het ontstaan en het vrijkomen van mijngas | 1963 | Linsel, E. | 42(12) | |
| Mijngas en ventilatie | 1963 | Maas, W. | 42(12) | |
| Strahlausbreitung vor ort bei blasenden Sonderbewetterungsanlagen | 1963 | Renner, K. | 42(12) | |
| Grubengasbekaempfung durch aufspueren | 1963 | Vergeron, M. de | 42(12) | |
| Bestrijding van gasuitbarstingen | 1963 | Stassen, P.; Vandeloise, R. | 42(12) | |
| #REF! | 1963 | 42(12) | ||
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| Three examples of periglacial solifluction in the southeastern plateau Central France | 1964 | Rutten, M.G. | 43(1) | Three examples of periglacial solifluction in the Velay (France) are described. The difference between primary basaltic scoria and the same material resedimented through solifluction; the difference between phonolitic periglacial block fields and present day phonolitic block scree; and the difference between older and younger solifluction deposits at the Issarlès Maar are studied. |
| Evidence of "Late" Alpine overthrusting, in the region NW of Lijar, Sierra de Los Filabres (SE Spain) | 1964 | Voet, H.W. | 43(1) | To the north-west of Lijar "abnormal" tectonic successions are exposed, caused by relatively late thrusting. Elements of a Nevado-Filabride unit with a medium grade of alpine metamorphism are found overlying Alpuiarride elements showing a low grade of alpine metamorphism, the separating thrust planes being subhorizontal. Within a restricted area the following succession is found (from bottom to top): Nevado-Filabride mica schists and marbles – Alpujarride phyllites - Nevado-Filabride "older schists", mica schists and marbles - Alpujarride phyllites - Nevado-Filabride marbles. |
| Stichting voor isotopen-geologisch onderzoek | 1964 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Verschure, R.H. | 43(1) | |
| Ter herdenking Ir. L. W. Leyds | 1964 | Schieferdecker, A.A.G. | 43(1) | |
| In memoriam Prof. Dr. G.L. Smit Sibinga | 1964 | Simons, A.L. | 43(1) | |
| #REF! | 1964 | 43(1) | ||
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| Notulen Ledenvergadering Dec 1963 Genootschapszaken | 1964 | 43(1) | ||
| Zur tektonischen synthese der Ost- und Westalpen nach 60 jahren Ostalpiner Deckentheorie | 1964 | Wunderlich, H.G. | 43(2) | |
| The function of geology in petroleum production | 1964 | Dikkers, A.J. | 43(2) | |
| #REF! | 1964 | 43(2) | ||
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| Voorwoord, speciale uitgave professor Dr. Mr. F. Florschütz | 1964 | Vlerk, I.M. van der; Hammen, T. van der; Zagwijn, W.H.; Heyst, F.J.J. van | 43(3) | |
| Bibliografie professor Dr. Mr. F. Florschütz | 1964 | 43(3) | ||
| Un gisement du pléistocène inférieur aux environs de Bordeaux les Argilles de Bruges (Gironde) | 1964 | Balland, R. | 43(3) | |
| Étude stratigraphique et paleogéographique du gisement de Mammiferes fossiles Pléistocène moyen de Solilhac près le Puy-en-Velay (Haute-Loire), France | 1964 | Bout, P. | 43(3) | |
| Results of a pollenanalytic investigation in the untersee near Lunz in Austria | 1964 | Burger, D. | 43(3) | The Untersee pollen diagram was derived from a boring in the Untersee near Lunz. The geomorphological features of the area are briefly described. The pollen diagram pictures the vegetational history of an epoch that covers a good deal of the Lateglacial and nearly all of the Holocene. The section begins with a sterile glacial clay, that changes into stratified (varved?) clay at the beginning of what we assume to be the Bölling interstadial. During the Alleröd interstadial a brown organic calcareous mud was laid down. The boundary with the Holocene is marked by an abrupt change of the sediment into a lime gyttja. The formation of peat in the upper part of the section commenced some 3000 years ago during the Subatlantic. The Younger Dryas and possibly the lowermost part of the Holocene are missing because of a disturbance in the sedimentation. Palynologically the Holocene is developed quite traditional, and the Alleröd (established by radiocarbon dating GRN 2406) and the preceding Older Dryas are clearly discernable. The assumed Bölling oscillation shows a double-topped curve, and the corresponding part of the section exists of some 600-700 (varve) stratifications. This could point to a passage of an equal number of years, which is in agreement with the duration of the Bölling time. |
| Results of a pollenanalytic investigation in the untersee near Lunz in Austria | 1964 | Burger, D. | 43(3) | Enclosure B |
| Grèzes, litées et bancs de neige | 1964 | Guillien, Y. | 43(3) | |
| A pollen diagram from the Quaternary of the Sabana de Bogotá (Colombia) and its significance for the geology of the Northern Andes | 1964 | Hammen, T. van der; Gonzalez, E. | 43(3) | A provisional pollen diagram is presented from 200 m of lake deposits and peat from the Sabana de Bogotá (Colombia, South America), at an elevation of about 2600 m. It represents the major part of the Quaternary (fig. 3). The sedimentation must have started shortly after the upheaval of the Northern Andes. In the lower part the vegetation is poor in species, but gradually new types appear. Part of them (Alnus, Quercus etc.) entered this part of the Andes from the North (fig. 2). A clear zonation can be established (fig. 1), giving a clue for the dating and correlation of terraces in the region. A partly tentative correlation is given of the glacials and interglacials with those of Europe (fig. 1). The upheaval of this part of the Andes must have taken place at the very beginning of the Pleistocene or somewhat earlier, in the Pliocene. |
| Estudio palinológico de la turbera de estany (Olotm Gerona) | 1964 | Menéndez Amor, J.; Amorós, J.L.; Galván, J. | 43(3) | |
| A pollen diagram from equatorial Africa Cherangani, Kenya | 1964 | Zinderen Bakker, E.M. van | 43(3) | The pollen diagram of a swamp, 3.70 m deep, and situated at an altitude of 2900 m in Kenya has been studied. The swamp is at present surrounded by the uppermost montane forest. The diagram shows that the tree-line was much lower down in former times and a number of climatic zones could be inferred from the diagram. A C-14 date of 12,650 ± 100 B.P. (GRN 3048) obtained from the 2.85-3.00 m level enabled the author to calculate the age of these climatic zones. At the dated level, which is contemporaneous with the Oldest Dryas time (compare: Radiocarbon dates K-544, K-545,K-546), the climate has been cold and dry. All the zones correspond remarkably well in age and temperature characteristics with those of the European chronology from the Pleniglacial B of the Würm onward. Only the Bölling Interstadial has not yet been recognized. The close correspondence with the study of v. d. Hammen and Gonzalez in Colombia (1960 a,b) is apparent (Table I). The results prove again that the temperature fluctuations during the Quaternary were of cosmic origin. The Pluvial theory for Africa as well as the ecology of plants, animals and man will have to be studied in this continent against the background of the European temperature chronology. The Gamblian Pluvial was contemporaneous with the Würm Glacial and represented a hypothermal period in Africa. The objection that movements connected with the Rift valley could have caused the climatic changes can be ruled out as the climatic correlation with Europe is too convincing in detail to be casual. |
| #REF! | 1964 | 43(3) | ||
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| Problemen van de geotektoniek | 1964 | Sitter, L. U. de | 43(4) | |
| Uitreiking van de van Waterschoot van der Gracht Penning aan Dr. Ir. W. P. van Leckwijck | 1964 | 43(4) | ||
| Palynologial data on the age of the bauxite in British Guiana and Surinam | 1964 | Wijmstra, T.A.; Hammen, T. van der | 43(4) | |
| On the tectonics of the Sulcis area, S. Sardinia | 1964 | Poll, J.J.K.; Zwart, H.J. | 43(4) | |
| #REF! | 1964 | 43(4) | ||
| KNGMG Jaarverslag 1963 | 1964 | 43(4) | ||
| Geomorphology of the surroundings of Kuantan (Eastern Malaya) | 1964 | Nossin, J.J. | 43(5) | The area discussed is located in eastern MaIaya, bordering the China Sea (fig. 1). The morphological aspects are shown in fig. 2. Under the hot and humid climate with strong monsoonal influence, rocks undergo a deep and intense weathering. A biotite granite and an olivine basalt from the majority of the country rock. The granite weathers into an unsorted mass of sand and clay which is subjected to strong mass movements in spite of the dense vegetation. During colluviation, silt is washed out leaving the colluvium as a bimodal deposit. The granite landscape exhibits lateral planation from the base, resulting in comparatively flat piedmonts surrounding steep hills. Both carry a thick residual cover. Granitic colluvium occurs on the piedmonts as well, and also occupies large parts of the surrounding sedimentary flats. The basalt weathers into a heavy homogeneous clay which undergoes little or no mass displacement and produces a basically different landscape. It is lower and flatter than the granite zone and densely dissected by a dentritic network of insequent streams with steep valley-sides and heads. Other rocks and their weathering products are of subordinate consequence in this area. The coast is lined by a series of beach ridges which are Holocene of age. Between the higher land and these beach ridges large flats were filled in with fluvial and swamp deposits after the closure of the bars. The drainage on these flats is largely impeded and frequent shifts have occurred in the fluvial pattern. The beach ridges blocking the drainage system force rivers to converge upon common outlets; parts of the swamps have thick peat layers. The fluvial deposits have a remarkably high silt contents, much of which is supplied by washing-out from the granite colluvium. Seasonal changes in transportive capacity of the rivers cause bimodal grain size distribution in many of the fluvial sediments. Earlier workers postulated a Holocene tectonic uplift of eastern Malaya. A discussion of evidence points out that no such uplift has taken place, but that the relative fall of sea level during the Holocene has been eustatically caused. An examination of ancient maps may support the submission that the southern part of this area was only converted into land after 1800 A.D. |
| Paleomagnetic research in the Netherlands | 1964 | Rutten, M.G.; Veldkamp, J. | 43(5) | Since 1956 paleomagnetic research is carried out in co-operation between geologists of Utrecht university and geophysicists of the Royal Netherlands MeteoroIogical Institute in De Bilt. A number of studies on rock magnetism has been published on Iceland (Rutten and Wensink, 1959, 1960, a, b), Norway (van Everdingen, 1960), Germany (Nijenhuis, 1961; As and Zijderveld, in press), France (Den Boer, 1957; As and Zijderveld, 1958; Kruseman, 1962), Spain (van der Lingen, 1960; Schwarz, 1962, 1963) and Italy (Rutten, 1959; Dietzel, 1960; van Hilten, 1960, 1961, 1962b; de Boer, 1961). The position of the magnetic pole for these countries has been studied from rock samples of Paleozoic to Quarternary age. Special attention has been paid to the magnetic cleaning of the samples. A method of cleaning was developed by As and Zijderveld (As and Zijderveld, 1958; As, 1960), in which the remanent magnetization is observed after exposing the sample to alternating fields of increasing strength. This makes it possible in many cases to remove the unstable part of the magnetization, while saving a good deal of the more stable remanent magnetism which is supposed to have been induced during the geneses of the rocks. The special point in this method is that not only the intensity but also the direction of the magnetization is studied. It is found that the behaviour of the direction of the remanent magnetism during stepwise demagnetization is of greater importance than its intensity. To test the secular variation in the geologic past, Wensink and collaborators and Hantelman are studying continuous sections of lava flows in Iceland, respectively from the Plio-Pleistocene and from the earlier Tertiary. The variation is as large as in recent times; the magnetic dipole axis is found to be wandering up to 30° of the axis of rotation. In Permian ignimbrites, both from the Oslo Graben and from northern ltaly, the secular variation seems, however, to have been much smaller, a difference requiring more research. Paleomagnetism is used as a tool in many geologic field studies. In Iceland in this way a detailed stratigraphy of basalt flows and intercalated tillites has been built up. This leads to an analysis of the tectonics of the Central Graben, whilst it also proves the existence of widespread glaciation already during the Pliocene. In southern Europe the pole positions belonging to the Permian of the Alpine foldbelt are found to be consistently aberrant from those of "Meso-Europe". Large scale crustal drift must have occurred in the Tethys during the Mesozoic. Movements of up to about 5000 km have been postulated, far exceeding those needed by the most nappist of alpine tectonicians. |
| Rejuvenation of Pre-Cambrian rocks under epirogenetical conditions during old Palaeozoic times in Africa | 1964 | Schürmann, H.M.E. | 43(5) | An international team produced 30 isotope age determinations of various Pre-Cambrian rocks and minerals from the Northern part of the Eastern Desert of Egypt, surprisingly showing - With a few exceptions of about 650 m.y. - Palaeozoic ages (500-550 m.y.). Fortunately fossil-bearing Lower Cambrian has been established lying flat and unconformably over Pre-Cambrian. As two major unconformities exist between the Pre-Cambrian proper and the Lower Cambrian (firstly, Hammamat series with boulder beds composed of Pre-Cambrian igneous and secondly Lower Cambrian unconformably above Hammamat series) one had expected an isotopic age of 600-1000 m.y. for the igneous of the Pre-Cambrian. In the Red Sea area no folded Cambrian and no cambrian orogeny has been proven; only epirogenetic tectonics exist. This also holds good for East and South Africa, where no fossil-bearing Cambrian has been established as yet, but where similar yound isotope ages if igneous rocks are available. As explanation one could take into consideration the possibility of rejuvenation of young Pre-Cambrian rocks of the crust in Palaeozoic times due to rising convection currents increase in temperature, tension and epirogeny (taphrogeny), the major tectonic feature along the Red Sea and in East Africa. |
| Enkele opmerkingen over kalkzandsteenbanken in het preglaciaal van Midden-Nederland | 1964 | Crommelin, R.D. | 43(5) | |
| #REF! | 1964 | 43(5) | ||
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| Interpretation of the wandering paths of ancient magnetic poles | 1964 | Hilten, D. van | 43(6) | Polar wandering paths have been constructed for imaginary continents performing simple drifting movements. The effect of both continental drift and polar wandering upon the shape of the polar wandering paths are analysed. The results have been compiled in the final section of this paper. The often-heard assumption that polar wandering paths should coincide when the corresponding continents are replaced in their original, pre-drifting configuration is only partly correct. A method is given to determine besides the ancient latitude also the relative longitudinal positions of continents from their paleomagnetic data. |
| The method of statistical structural analysis (as applied to the crystalline basement of the Dolomites in North italy) | 1964 | Agterberg, F.P. | 43(6) | The structure of the crystalline basement of the Dolomites can be divided in (1) a more regional Hercynian structure including almost all major and minor folds, and (2) a number of local Alpine structures which are disturbing the Hercynian strucure. The Alpine deformations consist of lateral compression structures in the S. Stefano and Pusteria areas, respectively northeast and north of the Dolomites, and probably some rapid increments in thickness of the crystalline rocks in the Cima d'Asta and Gosaldo areas south of the Dolomites. The Hercynian minor folds in the S. Stefano area have been refolded into an anticlinal structure with a southeast directed Alpine axis. The limbs of this anticline have been rotated with respect to each other along the axial plane. The amount of rotation is locally as high as 63°. This large shearing movement took place during Alpine orogeny. The Alpine deformation is also found in the adjacent permian beds overlying the prepermian erosion plane. Similar conclusions can be drawn with respect to the Pusteria area. The regional schistosity of the Cima d'Asta and Gosaldo areas is probably subparallel to the prepermian erosion plane. Variations in the mean strike of this schistosity demonstrate that there are locally rapid increments in thickness in the crystalline rocks south of the Dolomites. A new explanation for this phenomenon is proposed. The regional schistosity in the Gosaldo area is generally a secondary schistosity. Distinction between primary and secondary schistosity cannot be made in many localities. However, the undefined schistosity planes show a mean attitude that, in terms of Student's t-test, cannot be distinguished from the mean attitude of the well-defined secondary S-planes in other localities. The combined groups of S-planes are thus homogeneous from a statistical point of view. This conclusion is not in disagreement with the fact that the stratification in the crystalline rocks and the enveloping contour of many Hercynian minor folds (equivalent to D'Amico's S1) make different angles with the regional schistosity. |
| Petrography and tectonics in the Agordo-Cereda region (Crystalline of the Southern Alps) | 1964 | D'Amico, C. | 43(6) | A stratigraphic series of epizonal metamorphic rocks can be recognized in the Agordo-Cereda region (crystalline of the Southern Alps); the metamorphic grade increases toward the deepest portions of this series. Tectonically, two sets of different S-surfaces are to be distinguished (S1 and S2). Agterberg's tectonic interpretation of the region is discussed and rejected. Some large changes of volume are postulated by that author as a consequence of the alpine movements: however, they are not supported by petrographic evidences. Some assumption are implicit in the statistics of the tectonic measures as considered by Agterberg i.e.: Hercynian deformation was homogeneous all over in the region; S1 and S2 are parallel; S of the metamorphic rock and S of the Permo-trias are parallel. These assumptions are not correct. The tectonic interpretation of other crystalline regions in the eastern Southern Alps, as made by Agterberg, is also called in question. |
| The Hexhlet instrument for dust determinations | 1964 | Matla, W.P.M. | 43(6) | |
| In memoriam Prof. Dr. Ir. C.H. Edelman, M.I. | 1964 | Doeglas, D.J. | 43(6) | |
| Internationale hydrologische bibliografie | 1964 | Tromp, N.W. | 43(6) | |
| #REF! | 1964 | 43(6) | ||
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| Hypothèses concernant la position des unités structurales et paléogéographiques de la transversale Jaén-Grenade (Andalousie) | 1964 | Busnardo, R. | 43(7) | |
| Sur les rapports entre les zones Prébétiques et subbétiques entre Cazorla (Prov. De Jaén) et Huéscar (Prov. De Grenade, Espagne) | 1964 | Foucault, A. | 43(7) | |
| Mise au point sur l'âge des phenomènes tectoniques majeurs dans les Cordillères Bétiques occidentales | 1964 | Chauve, P.; Didon, J.; Magne, J.; Peyre, Y. | 43(7) | |
| Problemes structuraux dans le domaine Alpujarride au sud-ouest de la Sierra Nevada | 1964 | Boulin, J. | 43(7) | |
| Ein Querschnitt durch die Betischen Kordilleren bei Ronda (SW Spanien) | 1964 | Hoeppener, R.; Hoppe, P.; Dürr, S.; Mollat, H. | 43(7) | In fünf Abschnitten wird ein Querschnitt durch die westlichen Betischen Kordilleren beschrieben2. In der "Einführung" geben wir einen Überblick über die verschiedenen Einheiten, die in diesem Raume unterschieden werden können und weisen auf ihre Beziehungen zu Einheiten der zentralen und östlichen Betischen Kordilleren en sowie zu den Einheiten des Rifs in N-Afrika hin. Im zweiten Abschnitt, "Der Norden", steht die stratigraphisch-fazielle Entwicklung im Subbetikum und im Penibetikum im Vordergrund der Betrachtung. Das gegenseitige Verhältnis dieser beiden Einheiten wird diskutiert. "Die Mitte" umfasst die Front der Betischen Decken mit ihrer Vielfalt von Einheiten z.T. filabridisch-alpujarridischen Charakters. Die Beziehungen dieser Decken zu ihrem Vorland legen die Deutung nahe, dass die Sedimentationsräume der Decken südlich an die des Vorlandes anschlossen. Der Bereich der Mittelmeerküste, "Der Süden", erfährt eine neue Aufgliederung. Die stratigraphische Stellung der z.T. hochmetamorphen Gesteine und ihr Verband mit den basisch-ultrabasischen Massiven wird untersucht. Im "Ausblick" werden die wichtigsten Ergebnisse zusammengefasst und die Deurungen diskutiert, die die geologische Situation den Bearbeitern nahelegte. |
| Speculations based upon a comparison of the stratigraphies of the different tectonic units between Vélez Rubio and Moratalla | 1964 | Gillavry, H.J.M. | 43(7) | A comparison of stratigraphic successions of different tectonic units along the meridian Vélez Rubio to Moratalla has failed to disclose obvious indications for a tectonic reversal of the original geographic arrangement. The hypothesis of deposition of Betic of Málaga upon the South flank of a Subbetic basin is considered and the logic consequences are examined. The zone of outcrops of the Betic of Málaga, from Sierra de Espuña through Vélez Rubio and perhaps to Málaga, would be subautochthonous. The proved extent of the Betic of Mãlaga nappe would be restricted. At least three major phases of movement are envisaged: 1) an early Oligo-Miocene nonhward thrust of the Alpujarrides, 2) a later Oligo-Miocene southward nappe-movement of the Betic of Málaga, and 3) a Miocene northwest thrust of northern Subbetic over Prebetic. The main axis of compression would have moved episodically northward. |
| Zur Gliederung des Jungtertiärs im Becken von Vera, Südostspanien | 1964 | Völk, H.R.; Rondeel, H.E. | 43(7) | Eine jungtertiäre Schichtfolge wird lithologisch gegliedert und kurz beschrieben. Dabei wird vor allem ein älterer und ein jüngerer Anteil unterschieden; beide sind durch Lithologie und tektonischen Stil gut charakterisiert. |
| Distinct phases of Alpine overthrusting and subsequent thrusting in the Eastern part of the Betic zone of Spain | 1964 | Egeler, C.G.; Bodenhausen, J.W.A. | 43(7) | The large scale horizontal translations in the eastern part of the Betic zone are ascribed to at least two distinct phases of overthrusting. It is emphasized that the later of these phases has been responsible for important changes in the original superposition of the major units in the deeper part of the orogene. This is illustrated by the widespread occurrence of "abnormal" tectonic successions, especially in the northern parts of the Sierra de los Filabres. The effects of subsequent folding and steep thrusting can be seen throughout the Betic zone to be superimposed on the overthrust structures. Cross-sections through the Sierra de las Estancias clearly illustrate the resulting imbricate patern. |
| On the stratigraphy of the Nevado-Filabride units as exposed in the eastern Sierra de Los Filabres (SE Spain) | 1964 | Nijhuis, H.J. | 43(7) | |
| Essai de corrélations des unités Bétique dus la transversale de Lorca - Aguilas | 1964 | Fernex, F. | 43(7) | |
| The Almagro unit: a new structural element in the betic zone? | 1964 | Simon, O.J. | 43(7) | Recent investigations in the Sierras de Almagro and de Enmedio, situated in the south-eastern part of the Betic Cordilleras, have revealed the presence of a unit - named the Almagro unit - which tectonically underlies rocks of the Alpujarride complex and the Betic of Málaga. Several hypotheses are discussed-with regard to the zone of deposition of the rocks of this Almagro unit. At this stage of investigations the author favours the view that they were deposited to the north of the Nevado-Filabride complex. According to this line of thought the Almagro unit would represent a new structural element in the Betic Zone s.s. It is stressed, however, that further detailed investigations will be necessary to check this working-hypothesis. |
| Schatting van de maximale diepte van de bron van een warmtestroomanomalie | 1964 | Collette, B.J. | 43(7) | |
| Experimentele metamorfose | 1964 | Schuiling, R.D. | 43(7) | |
| Activiteiten in 1963 van de "commission on new minerals and mineral names" van de "International mineralogical association" | 1964 | Roever, W.P. de | 43(7) | |
| #REF! | 1964 | 43(7) | ||
| #REF! | 1964 | 43(7) | ||
| De vlekken in de vlekleien van steige (Vogezen) en Vogtland (Saksen) | 1964 | Bosma, W. | 43(7) | |
| On the establishment and activity of the provisional commision on the genesis of ore deposits | 1964 | Kutina, J. | 43(7) | |
| De veiligheidscongressen Aix-les-Bains 1963 en Salzburg 1963 | 1964 | Maas, W. | 43(8) | |
| An interesting pegmatite deposit in Northeastern Surinam | 1964 | Montagne, D.G. | 43(8) | A description is given of a small complex Li-Ta-Sn pegmatite in heavily weathered prae-Cambrian rocks near the Marowijne River in Northeastern Surinam. Detailed exploration was carried out during a pilot exploitation of amblygonite and tantalite/cassiterite. The often enormous masses of amblygonite are conspicuous (up to at least 8 m). The absence of lepidolite and the great uncertainty about the presence of spodumene are also remarkable. The geological setting is mainly controlled by faulting. Heavy chemical weathering severely hampered the study of the internal structure. A two-staged genesis of the pegmatite is tentatively suggested |
| Ancient and recent turbidites | 1964 | Bouma, A.H. | 43(8) | Ancient turbidites are characterized by a single facies model which is composed of five intervals in a fixed succession. Each interval contains one dominant sedimentary structure. The intervals are from bottom to top: graded interval, Iower interval of parallel lamination, interval of current tipple lamination, upper interval of parallel lamination and pelitic interval. Most of the turbidite layers do not have this complete succession of intervals, but only part of them without changing the order of the intervals. Investigations by means of radiography in deep-sea sands from submarine canyons and adjacent troughs have been carried out so as to compare these sands with the facies model of ancient turbidites. It appears that recent turbidites containing the turbidite facies model, can only be found on the outer part of the canyon fans and in the throughs. |
| Graptolites in the "Tibetan zone" of the Nepalese Himalayas | 1964 | Strachan, I.; Bodenhausen, J.W.A.; Booy, T. de; Egeler, C.G. | 43(8) | |
| #REF! | 1964 | 43(8) | ||
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| A contribution to the sedimentary petrolohy and provenance of young Pleistocene cover sand in the Netherlands | 1964 | Crommelin, R.D. | 43(9) | The aim of the investigation was to examine the mineralogy of Young Pleistocene cover sands as related to their depositional environment and more specifically to study the interrelationship between subsurface, Older and Younger cover sand in terms of heavy mineral composition. 75 profiles over the total cover sand area of the Netherlands were sampled in pairs. Heavy mineral analysis was confined to the 210-150 micron fraction so as to minimize confounding provenance and grain size effects. The results permit a subdivision into three distinct regions, each showing a characteristic heavy mineral composition which moreover appeared to be closely related to the mineralogy of the subsurface. Hence a more or less local provenance of the cover sand formation is advocated, "local" being taken in the opposite meaning to "conveyed over a long distance" as would be the case if the North Sea Basin for example, was taken as the source area. The relation between Older and Younger coversand was tested by the two-way analysis of variance method' It was found that within the three cover sand regions there is often a very significant locality contrast, whereas the stratum contrast is usually not significant. This brings us to the concept that local reworking of Older cover sand gave rise to Younger cover sand, whereas the absence in most cases of significant mineralogical changes when passing from Older cover sand to Younger cover sand usually indicates that no systematic agents were active in this process. Finally some remarks are made on the effect of the "closed-array system" on variables of constant sum, a frequent condition in sedimentary petrology to which Chayes has recently called attention and which is indirectly connected with the present problem. |
| Secular variation of Earth magnetism in Plio-Pleistocene basalts of Eastern Iceland | 1964 | Wensink, H. | 43(9) | Oriented samples of Plio-Pleistocene basalts were collected in Eastern Iceland for a paleomagnetic investigation. Pole positions were determined for successive individual flows. These show an irregular course which can be explained as a result of the secular variation of the earth magnetism. The stratigraphical succession consists of the paleomagnetic series N2 and R1. In both series a maximum of three basalt flows is intercalated with an inverted direction of. magnetization. These flows, nearly always accompanied by tillites and also by tuff breccias and globular basalts, have a wide distribution E of the Central Icelandic Graben, but were not found at its western side. The remanent magnetization of these flows may be explained either as a result of self-reversal or of induction from older lavas. |
| Netherlands Mesozoic committee | 1964 | 43(9) | ||
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| #REF! | 1964 | 43(9) | ||
| Secundair vervoer in een kolenmijn | 1964 | Goderbauer, L. | 43(10) | In dit artikel worden behandeld de verschillende aspecten die met het ondergrondse materiaalvervoer samenhangen. - Allereerst wordt het begrip secundair materiaalvervoer omschreven, als zijnde het materiaalvervoer in de kolenafdeling. - Vervolgens wordt het belang van het secundair materiaaltransport nader toegeÌicht, waarbij blijkt dat de kosten van het totaal vervoer ondergronds op circa 8-11 gld per ton neerkomen, terwijl de kosten van het materiaalvervoer circa. 4 à 5 gld per ton bedragen. - Daarna worden enige belangrijke aspecten van het vervoer belicht, zoals de economische kant, de wijze van aanlevering der materialen en de naar de tijd geregelde voorziening van de pijlers. - De verschillende vervoersmethodieken, zoals: sleepbak, monorail, bandvervoer enz. worden bezien naar hun systematiek, de inzetcondities en de transportmogelijkheden. - De vervoersorganisatie wordt qua opzet, beoordeling en haar mogelijkheden in ogenschouw genomen. - Tenslotte worden enige resultaten en gevonden betrekkingen weergegeven die op de mijnzetel Oranje-Nassau II zijn gevonden. Als conclusie kan worden vermeld: - dat het materiaaltransport in relatie tot de kostprijs, van dusdanige importantie is, dat hieraan ruime aandacht moet worden geschonken; - dat de keuze der middelen bepalend kan zijn voor de te bereiken mogelijkheden; - dat tijdige planning en ingepaste werkvoorbereiding der ondergrondse werken eveneens van doorslaggevend belang kan zijn t.a.v. de later te bereiken resultaten; - dat de organisatie wel het belangrijkste aspect is ter bereiking van optimale resultaten; - dat een regelmatige beoordeling van de resultaten enerzijds en het beschikken over een groep arbeidsanalysten anderzijds noodzakelijk is om steeds bij te blijven. Verder zij opgemerkt dat de monorailinstallatie niet alleen als vervoermiddel, maar ook als hulpmiddel bij het verplaatsen over korte afstanden van allerlei materiaal, bij de voorbereiding en bij de winning van groot belang is en dat zij ook daar haar nut heeft bewezen. Tenslotte moet nog worden opgemerkt dat niet uit het oog mag worden verloren dat de resultaten bereikt met de invoering van het monorailtransport of een verbeterd sleepbakvervoer niet uitsluitend ziin terug te vinden in de cijfers van het vervoer als zodanig. Het hele bedrijf vormt uiteraard een harmonisch geheel, waardoor de verbeteringen op andere plaatsen ten goede komen aan het monorailvervoer, terwijl anderzijds verbeteringen die bijv. het monorailvervoer mogelijk maken, eveneens doorwerken in andere sectoren van het bedrijf. Hierdoor is het noodzakelijk dat het vervolg van de harmonisering van de rationalisatie-aanpak ook in de komende jaren met gelijke interesse, belangstelling en daadkracht wordt voortgezet ter verkrijging van een optimaal rendement ondergronds. |
| Cross-stratified units, some with silt bands, in the Folkestone beds (Lower Greensand) of Southeast England | 1964 | Allen, J.R.L.; Narayan, J. | 43(10) | Cross-stratified units in the Folkestone Beds (Lower Albian) of the English Weald have foresets, graded from fine up into coarse, showing either abrupt or tangential contacts with the bases of the units. When the contact is tangential, thin silt bands may occur between groups of sandy foresets and bottomsets. The bottomsets then commonly show small-scale asymmetrical ripples and cross-stratification indicating currents in directions opposite to those which formed the larger foresets. Studies in a laboratory flume show that these features are consistent with the interpretation of the crossstratified units in terms of the migration of large-scale ripples in a shallow sea, under tidal conditions. Those units with silt bands could represent ripples moved only during storm conditions, when the normal tidal flows were enhanced by wind-induced currents. |
| #REF! | 1964 | 43(10) | ||
| #REF! | 1964 | 43(10) | ||
| Modderkogels, mergelconcreties of askogels van Krakatau | 1964 | Faber, F.J. | 43(11) | Some volcanoes, although they are by no means "mud volcanoes", have erupted "mud balls", usually with a diameter of 0.5 to 1.5 cm, but there are specimens known of 7 cm. They are almost perfect spheres. Mud balls, found in and near the Indonesian volcanoes of Tankuban Prahu and Kawah ldjen, were described by Stehn (1932). Smaller mud pellets are also collected near many other volcanoes. The large mud balls (sometimes called ash balls) are also known as accretionary lapilli or -pellets, as they have a composition of concentric layers. The smaller pellets may have been formed by isolated raindrops on dry ash, as already Poulett Scrope (1829) pointed out, and recently again Miura (1959) in Japan, but for the bigger specimens Miura (1959) in Japan, but for the bigger specimen this explanation is not applicable. For them the hypothesis presented by Stehn (1932) is accepted, summarized in the Nomenclature (Schieferdecker, 1959), under number 4225. The spherical mud balls, composed of concenric sheils of volcanic ash are formed around a grain of sand or a lapillo and originated during prolongated rotation in whirling eruption clouds. In the literature the occurence of mud balls with a diameter of more than one or two centimeter is rarely mentioned, which indicates that they must be rather scarce. A number of them is included in the Verbeek-Collection (Museum of the Technological University at Delft). Verbeek assembled them soon after the catastrophic eruption of 1883 at the Krakatao, the island volcano situated between the islands of Java and Sumatra in Indonesia. Also Escher collected many specimens; they are at present in the Rijksmuseum in Leiden. Verbeek (1885) in his famous treatise on Krakatao pays some attention to these remarkable products, and called them calcitic "concretions". Now in Verbeek's collection, there are indeed true concretions of a more or less spheric shape, and with dimensions of more than ore centimetre, but there are also other bodies, in the present treatise called mud balls. The true concretions show a layering parallel to a flat plane. They contain much CaCO3; this was also mentioned by Verbeek, see table. It is remarkable that the other bodies from Krakatao also have a high CaCO3-content, but they have indications of a concentric shell structure, and resemble very closely' the mud balls described by Stehn. The chemical composition of the Krakatao mud balls, however, is different from other mud balls, mentioned in the literature. The high CaCO3-content of the concretions may have augmented gradually arid they may have been formed (as Verbeek and also Escher suggested) in the sedimentary basement of the volcano. The occurrence, together with the mud balls with a high CaCO3-content, is a remarkable coincidence. Originally the concentric mud balls must have been in a position of accumulating a high CaCO3-content. They were formed during an eruption prior to that of 1883. It is assumed that at this time there has been a crater below the sealevel that may have been partly filled with CaCO3 containing mud. Finally, although there is a difference in chemical composition between Krakatao mud balls and those described by Stehn, I think they have the same genesis which may be sustained by the remarkable similarity in shape of some of the balls and tectites. This also points to an origin of the shape in the air, and not as a concretion. |
| The spots in spotted slates of Steige (Vosges) and Vogtland (Saxony) | 1964 | Bosma, W. | 43(11) | New data are submitted about the genesis and the mineralogical composition of the spots in the spotted slates belonging to the well-known contact aureole in the Steiger Schiefer (Vosges). They are based on a comparative study of the spots in the spotted slates of Steige and of Vogtland (Saxony). The spots have been studied macroscopically as well as with the microscope and X-rays. The results indicate that the spots in the slates of both regions are pseudomorphs after cordierite. In the Vogtland slates relics of the characteristic twinning structure are often seen. Unaltered cordierite is generally only present in the hornfelses. The effects of contact metamorphism are discussed in relation with the theoretical temperature distribution around a cooling intrusive body. |
| De ,,Zone van Rosmalen" | 1964 | Zonneveld, J.I.S. | 43(11) | De Ridder and Zagwijn (1962) described the "Zone of Rosmalen", a mixed Rhine and Meuse sediment of Holsteinian age in Eastern North Brabant. They supposed that this zone represents a gradual transition of the Formations of Sterksel and Veghel. In the course of the Holsteinian the influence of the river Rhine should have decreased gradually, the river Meuse gaining in importance. It is shown that this reconstruction cannot be in accordance with the reality: the Rhine did not flow continuous in the region under consideration ,the "Zone of Rosmalen" is merely the lower part of the Formation of Veghel in which sediments derived from the subsoil (consisting of older augite free Rhine sand) have been contaminated. |
| Geologische bibliografie van Nederland | 1964 | 43(11) | ||
| #REF! | 1964 | 43(11) | ||
| #REF! | 1964 | 43(11) | ||
| New facts on the geology of the "Young" unconsolidated sediments of Northern Surinam | 1964 | Montagne, D.G. | 43(12) | A short synopsis is given of the most important data on the stratigraphy of the "young", unconsolidated sediments in Central Northern Surinam, as collected in recent years in and around the Billiton bauxite mines. Some information on heavy minerals, clay mineralogy and grain size distribution is added. A "standard Section" for the area is constructed and a new stratigraphical table is presented. Attention is called to the possible regional importance of some of the data presented. |
| New facts on the geology of the "Young" unconsolidated sediments of Northern Surinam | 1964 | Montagne, D.G. | 43(12) | Plate II |
| The development of successive structures in the Devonian and Carboniferous of Devon and Cornwall | 1964 | Zwart, H.J. | 43(12) | The structures in the Devonian and Carboniferous along the west coast of Devon and North Cornwall are described. The Devonian north of the Culm synclinorium contains steep cleavage-folds with E-W axes. In the northern part of the Culm measures vertical accordion folds occur. Farther south a second set, with E-W directed recumbent folds, deforms the first folds with a consistent southward overthrusting movement. South of Rusey Beach another kind of recumbent folding with N-S axes was found and on these, E-W recumbent folds are superposed. Here the first set constitutes the upper part of a metamorphic infrastructure and is accompanied by schistosity and extension in B. A possible link between the two sets of folds is proposed. |
| Gravimetrische stofgrenzen van het stofinstituut en Amerikaanse stofgrenzen | 1964 | Matla, W.P.M.; Terpstra, J. | 43(12) | The gravimetrically-determined dust-limit values of the "Stofinstituut" and the .American dust limits published at the end of 1962 are first described. Both limit values can be represented by hyperbolic functions. With the aid of 133 dust measurements by gravimetric means and also by the American method with the midget impinger, carried out by the "Institut d'Hygiène des Mines" of the Belgian mining industry, it has been possible to compare the dust-limit values. It was found that for the given dust conditions both limits are the same. |
| Relatie tussen het kwartsgehalte en het asgehalte van pijlerstof | 1964 | Matla, W.P.M.; Terpstra, J. | 43(12) | A large number of dust samples were taken in the various working operations in mining and the quartz and ash contents determined. The results of the analyses have been processed statistically. A clear relationship was found between the quartz and ash contents of the dust, so that the ash content is a good measure of the quartz content. |
| #REF! | 1964 | 43(12) | ||
| #REF! | 1964 | 43(12) | ||
| #REF! | 1964 | 43(12) | ||
| Coastal geomorphology of Eastern Nigeria: Beach ridge barrier islands and vegetated tidal flats | 1965 | Allen, J.R.L. | 44(1) | The visible portion of the Niger delta consists, in eastern Nigeria, of three geomorphological units. Behind a chain of barrier islands formed of sand ridges of two types, occurs a broad tidal flat colonised by mangroves and marked by a reticulate drainage pattern. The tidal flat is succeeded inland by a forested river floodplain. The tidal flat is also partly in contact with a low terrace formed on Late Tertiary and possibly Pleistocene sediments. The nature of the barrier islands and the tidal flat is related to the forces at work in the region. The mangrove swamp of the eastern delta is growing at the expense of the barrier islands, the floodplain, and the terrace because of erosion in tidal channels. It is suggested that the reticulate drainage pattern of the tidal flat is due to the stabilizing of deposited sediment by the mangroves and the manner in which these plants grow collectively. The Nigerian barrier complex, situated in the tropics, is compared with the temperate tidal flats of the Dutch coast. The main differences depend on the contrasted role of plants in the two areas, and thus finally on climate. |
| Value of experiments in Geology | 1965 | Kuenen, P.H. | 44(1) | |
| Palynological study of a very thick peat section in Greece, and the Würm-glacial vegetation in the Mediterranean region | 1965 | Hammen, T. van der; Wijmstra, T.A.; Molen, W.H. van der | 44(1) | A pollen diagram from Macedonia, partly dated with C14, suggests dense oak-forests during the early Holocene and a steppe-like open vegetation during the Würm-glacial. As similar conditions were found elsewhere in the northern Mediterranean, we think no proper pluvial conditions prevailed in that area during the last glacial. |
| #REF! | 1965 | 44(1) | ||
| Recente mogelijkheden voor geologische luchtverkenning | 1965 | Poley, J.T. | 44(1) | |
| #REF! | 1965 | 44(1) | ||
| The buried bauxite deposit of onverdacht, Surinam, South-America | 1965 | Aleva, G.J.J. | 44(2) | Data arc presented about the buried bauxite deposit at Onverdacht, Surinam (in the Guiana Lowlands). The upper boundary of the bauxite layer is an old topographic surface with a consequent drainage pattern. The lower boundary shows many features of a sedimentary nature, indicating the contact between two sedimentary beds of different physical composition. Statistical work on SiO2 and Fe2O3 analyses of borehole samples is reported. The bauxite layer is formed by the bauxitization of a presumably arkosic or silty sedimentary bed, with a continued bauxitization at lower levels that attacked the underlying or intercalated kaolin. After having been buried by younger sediments, silica-rich solutions partly destroyed the top part of the bauxite bed. In principle, the bauxitization here was not different from that of most other bauxite deposits, viz. the extreme weathering and leaching of a pre-existing rock, the nature of this rock (igneous, metamorphic or sedimentary) being of no genetic importance. |
| Preliminary palynological study of hydrocarbons in Israel | 1965 | Horowitz, A.; Langozky, Y. | 44(2) | |
| Thin sections for determination the composition of the light-mineral fraction of the unconsolidated sediments | 1965 | Vogel, D.E. | 44(2) | Several ways exist for determining the composition of the light-mineral fraction of unconsolidated sediments. For not mounted samples: separation by heavy liquids, x-ray analysis, and the use of different immersion liquids; and for mounted samples staining with an organic dye, etching with HF and the use of the universal stage, These methods were investigated as to their suitability for exact sedimentpetrographical work but all were found to have limitations. A technique for making thin sections of unconsolidated sediments as described by Mamourofski and Samsonof was modified slightly and adapted to our needs. In the resulting slides the distinction of quartz from oligoclaseandesine proved to be quite easy. Moreover, the carbonate content of the sample can be retained because no treatment with HCI is necessary; if needed, subdivisions in the quartz- and rock-fragment groups can be made. |
| #REF! | 1965 | 44(2) | ||
| #REF! | 1965 | 44(2) | ||
| #REF! | 1965 | Harsveldt, H.M. | 44(2) | |
| The curvature of the Antilles | 1965 | North, F.K. | 44(3) | Geosynclinal belts of mid-Mesozoic, pre-Cretaceous age form much of the western edge of the Americas from Alaska to Baja California, and from coastal Peru to a point far south in Chile. They also appear in the curvilinear belt of the Greater Antilles, and in the row of islands off the north coast of South America. It is suggested that these orogenic sectors arose out of a compound geosyncline originally more or less straight, and that the violently convolute portion, from Guatemala to Puerto Rico and thence back to the Goajira Peninsula, has undergone progressively increasing northeasterly curvatute as a consequence of tangential migration. The migration is envisaged as being due tot the tangential "squeezing out" of a segment of the crust and subcrust, between the opposed rotations of two plates of continental dimensions: that of South America (rotating clockwise), and that of the North Pacific (rotating anticlockwise). Acting as a moving agent behind the migrating orogenic arc was a prong of old rock, still recognizable at the surface. This moving agent is compared with similarly recognizable prongs behind similarly arcuate orogens in the Himalaya and in the Alps. The tangential migration reached a limit with the impingement of the migrating arc against a stable foreland. The foreland is the old crystalline platform on which the Bahama Banks and the Lesser Antilles now stand. From the time of this impingement onward, deformation has been taken up by other means, developing on the one hand large sttike-slip fauits, and on the other great arcuate or linear downtucks of the oceanic crust. It is to these latter that the famous negative gravity anomalies are due. It is concluded that the ophiolitic belts on the two sides of the Caribbean are not likely to join in an arc around the eastern end. As both belts have undergone deformation in the same sense (from the south towards the north), they are more probably the dismembered halves of a single belt originally more or less straight. |
| Carboniferous (Westphalian) foraminifera from Abu Darag eastern desert, Egypt | 1965 | Omara, S.; Vangerow, E.F. | 44(3) | Foraminifera from marine Carboniferous shales, intercalating the Nubian-type sandstones at Abu Darag, Eastern Desert, Egypt, fix the age of this section as Westphalian, viz. stratigraphically lower than the Wadi Araba section of Lower Stephanian age. The Abu Darag section occupies thus, an intermediate stratigraphic position between the Lower Carboniferous (Tournaisian-Visean) of southwestern Sinai, and the Lower Stephanian of Wadi Araba. |
| Hand-drilling tools for geological investigation | 1965 | Lammers, J. | 44(3) | ln a flat country like the Netherlands field geologists have to rely largely on data derived from borings. As nearly the whole surface of unconsolidated sediments is of Quaternary age, geologists have to work with hand-drilling tools adapted to these special circumstances. A synopsis is given of these tools, and their use by the Geological Surrey. |
| Committee Du Neogene Mediterraneen | 1965 | Rutsch, R.F. | 44(3) | |
| #REF! | 1965 | 44(3) | ||
| #REF! | 1965 | 44(3) | ||
| Metamorphic lineages of the orogenic plutonism | 1965 | Tex, E. den | 44(4) | Firstly a tripartition of the orogenic plutonites based on their geological association and on the nature of their mafic minerals is proposed. Genesis of the micaceous and hornblendic granite-syenite-diorite-lamprophyre series through anatexis of water-saturated or slightly undersarurated rocks of suitable composition is discussed in the light of melting behaviour in the haplogranitic and wet basaltic systems. A similar derivation is argued for the orthopyroxenic charnockite-anorthosite-norite-pyroxenite series found to occupy deeper levels of the older orogenes especially. Here anatexis and palingenesis are presumed to operate in virtually water-free rocks in the granulite facies. The garnetiferous. Charnockite-eclogite-"alpine-type” peridolite series is believed to have suffered less anatexis and virtually no palingenesis. It is subdivided into a peripheral, low-temperature, ophiolitic suite of glaucophane-schist facies affiliation and a hight-temperature eclogite-facies suite situated in the very root zones of mainly precambrian and caledonian orogenic terrains. Secondly an artempt is made to trace the origin of the three series of orogenic plutonites through their alleged meramorphic lineages. A high-temperature, an intermediate, and a high-pressure lineage are discerned on the basis of so-called persister-minerals characteristic of the subfacies-series concerned. The high-temperature lineage leading towards the granitic series of plutonites is defined by the quasi-isochemical pairs: andalusite-sillimanite and biotite-cordierite. Its Iimiting geothermal gradients are discussed in the light of the stability field of "wet" Mg-Cordierite. The high-pressure lineage is shown to have many characteristic "persisters", but the low-pressure boundary curves of kyanite, zoisite + kyanite, pyrope, aragonite and jadeite + quartz are approached by geothermal gradients varying from 10 to 23°C/km and an average is struck at 18°C/km. This lineage is wide enough provide for at least two subfacies-suites ending up in the eclogite facies: a low-temperature plagioclase-free sequence from glaucophane-schist to eclogite and a higher temperature greenschist/prasinite/"alpine” amphibolite/garnet-clinopyroxene granulite suite characterized by the stable association of an epidote-group mineral and an increasingly sodic plagioclase. The intermediate lineage is less well-defined but it leads via the calcic plagioclase-orthopyroxene granulite subfacies to charnockitic, anorthositic, noritic, pyroxenitic, and related plutonites. Natural metamorphic series are not necessarrily confined to the artificial boundaries of the lineages here proposed, although the latter may aid in defining the former. Thirdly the probability in terms of density requirements is shown for having the "intermediate” zone of the orogenic crust, below the Conrad discontinuity, constituted by weighted assemblages of granulite and eclogite facies rocks instead of the usually postulated homogeneous basalt of gabbro layer. Also the water economy of the various regional metamorphic lineages is speculated upon against the background of a frequency analysis of water contents in regional metamorphic rocks grouped according to facies and silica-content. |
| Beschouwingen over het economisch meest gunstige ontginningssysteem in een kolenmijn in verband met de mijngasbestrijding | 1965 | Stuffken, J. | 44(4) | The paper deals with a study undertaken to determine what combination of mining method and ventilation system will give the lowest costprice per ton of coal output under conditions where the production level of the longwall face is limited by the release of methane. In these considerations attention was given to the following three non-related factors. 1. the cost per ton of coal as a function of the rate of the daily advance of the face; 2. the volume of methane released per ton of coal produced; 3. the possibilities with regard to supplying the air volume needed and mixing the released gas. On the basis of these data a calculation programme has been developed which often permits of choosing the preferable system. The choice frequently turns out to be a combination of an advancing-and-retreating method with downcast ventilation. |
| Toekenning van de waterschoot van der gracht penning aan prof. dr. mr. F. Florschütz | 1965 | 44(4) | ||
| #REF! | 1965 | 44(4) | ||
| Jaarverslag 1964 | 1965 | 44(4) | ||
| Aandrijvingen voor kolenschaafinstallaties | 1965 | Clercq, H. le | 44(5) | |
| Directe aandrijving met draaistroommotoren voor kolenschaafinstallaties | 1965 | Zeegers, J.J. | 44(5) | |
| Hydrostatische aandrijvingen bij ondergrondse pijlerinstallaties | 1965 | Stalman, M.E. | 44(5) | |
| Aanbouwploeg met gelijkstroomaandrijving voor snelheidsregeling | 1965 | Omers, H.L. | 44(5) | |
| International assocciation for the genesis of ore deposits | 1965 | Uytenbogaardt, W.; Tex, E. den | 44(5) | |
| Geologie en bodemkunde | 1965 | Bennema, J. | 44(6) | The differences between geology and pedology may be expressed as differences in depth scale and in rime scale. Pedology is studying only the uppermost part of the earth's crust, and is in the first place interested in recent and present changes induced by environmental forces in the geologic material. It is less than geology a historic science. There is, notwithstanding these differences, a strong relationship between geology and pedology, of which the following three aspects are considered: 1) Many soils are under the influence of the soil forming processes gradually developing into more mature or senile stages till the moment they are buried by sedimentation or destructed by erosion. Other soils are found in a steady state, the soil forming processes being in equilibrium with either sedimentation or erosion. The geologic phenomena of erosion and sedimentation are thus, to a great extent, governing the distribution of the soils of different stages of development 2) These different stages may, especially in the tropics, often be expressed as differences in weathering phases of the soil material. The knowledge of weathering is an important point of contact between geology and pedology. 3) Soils are mainly formed from geologic materials. Many characteristics of the soils are directly or indirectly related to the kind of geologic materials from which they are derived. |
| Fieldwork in the Charnockitic Precambrian of Rogaland (SW Norway) | 1965 | Tobi, A.C. | 44(6) | In the "southern tip of Norway" a charnockitic type of Precambrian is found in two regions, a smaller one around Arendal in the east and a larger one in Rogaland in the west. In Rogaland, a complex of intrusive masses, chiefly consisting of anorthosites and of rocks varying from monzonites to norites, is surrounded by charnockitic migmatites. Outside of the Egersund Border Fault, which follows the boundary of the intrusive masses at some distance, the charnockitic migmatites are accompanied by garnet-rich migmatites perhaps comparable to the khondalites of peninsular India. The charnockitic character of the region is due to granulite facies conditions. Probably, we are dealing here with a sillimanite-cordierite subfacies. An interesting feature of this high-grade metamorphism is the blurring of the difference between magmatic and metamorphic phenomena. Another point for further study will be the gradual transition to rocks to amphibolite facies beIonging to the Telemark Precambrian in the east. |
| Symposium kool- en gasuitbarstingen gehouden te Nimes van 24 tot 28 november 1964 | 1965 | Maas, W. | 44(6) | |
| #REF! | 1965 | 44(6) | ||
| Composition and origin of "Pedra Canga" and related ironstones in Northeastern Brazil | 1965 | Mabesoone, J.M. | 44(7) | In tropical Brazil various types of ironstones occur. They have been sampled in the northeastern part of the country, observed in hand specimens and thin sections, and analyzed by X-ray, DTA, and chemically. From the data thus obtained two principal types of ironstones, occurring on top and in sedimentary rocks, could be distinguished. The first type, - conglomeratic ironstones crusts -, is of lateritic origin; however, the process of its formation remained unfinished. The other type, - iron-cemented conglomerates -, found in Cenozoic deposits, is a reworked and redeposited erosion product of the first type. The ironstone crusts occur in two levels. Their formation in closely related to the development of these levels. The crusts are fossil, and their age is presumed to be Middle Tertiary and Plio-Pleistocene, respectively. |
| De Krumbein-Tukey methode toegepast op de onderlinge vergelijking van Pleistocene zanden | 1965 | Crommelin, R.D. | 44(7) | A. versatile method for analysing and testing various kinds of differences in rock bodies was published by W.C. Krumbein and J.W. Tukey in 1956 but did not receive due attention outside the United States. The present paper aims at reintroducing the method in a Netherlands journal by discussing and elaborating the general trend of thought and then applying it to a current sedimentary petrological problem. The method is based on a sampling design at various areal levels (multistage or nested sampling design) by means of which the overall variability in, for instance, the mineral composition of a region studied can be split up into separate components each of which is characteristic of one of the various levels distinguished (e.g. formations, exposures within formations, samples within exposures, etc.). The variability at a certain level is expressed as an interaction-effect between the unities at that level and the mineral species which constitute the analysis. The significance of these interaction-effects is subsequently tested by analysis of variance technique. The principle of the Krumbein-Tukey method is illustrated by two imaginary examples and some concepts related to the model are discussed. The arrangement of data and computations are shown in the Appendix. The method was next applied to the problem of differentiating between several sandy deposits in the Netherlands ranging from Old Pleistocene to Middle Pleistocene which for the rest are very similar. The sampling design was planned at three levels, viz. regions, exposures within regions and samples within exposures. The 150-105 micron fraction was examined for heavy minerals. The highest level was formed by the Emmen, Sibculo and Hattem regions representing different stratigraphical formations. The fourth region, Bergen op Zoom, was shown to be so different from each of the other three regions that it could be excluded from statistical testing. It could be shown that the difference between Sibculo and Hattem and also the difference between Sibculo and Emmen was very significant, whereas the difference between Emmen and Hattem was less distinct. Differences between the exposures in the three regions were always found to be very significant. Some evidence is given that under present conditions no reliable conclusions can be expected from correlation by means of mineralogical characteristics (correlation taken in the sense of determining stratigraphic position). The opinion expressed in a previous paper that the cover sands in the northern part of the Netherlands may be derived from the underlying proglacial deposits is supported by some results of this investigation. |
| On the tectonics of the Sierra de Carrascoy (Province of Murcia, Spain) | 1965 | Bodenhausen, J.W.A.; Simon, O.J. | 44(7) | Recent reconnaissance in the Sierra de Carrascoy has revealed the presence of at least four major tectonic units. These units show strong resemblances with the four major tectonic units distinguished in the Sierra de Almagro - viz., from below to above, the Almagro, Ballabona-Cucharón, Variegato and Betic of Málaga units, - and also occur in the same tectonic order as in the last-mentioned mountain range. The presence of a counterpart of the Almago unit in the Sierra de Carrascoy in a similar position as in the Sierra de Almagro substantiates a recent view that this unit - which now has been found in various ranges a considerable distance apart - constitutes a separate structural element in the Betic Cordilleras. |
| A palynological study on the age of some borehole samples from the Amazonas Delta Area, NW Brazil | 1965 | Boer, N.P.; Hammen, T. van der; Wymstra, T.A. | 44(7) | In the first part of this paper the results of a palynological investigation of borehole samples from the Amazonas Delta Area are discussed. The samples of one of the holes showed a typical Lower to Middle Cretaceous age; the samples from the two others had a Lower Tertiary to Upper Cretaceous flora. In the second part of this paper the tectonical and stratigraphical consequences of these results are discussed and a comparison is made between the Marajó and Guiana Basins. |
| International Mineralogical Association | 1965 | 44(7) | ||
| #REF! | 1965 | 44(7) | ||
| #REF! | 1965 | 44(7) | ||
| #REF! | 1965 | 44(7) | ||
| Winning en conditionering van het aardgas van Slochteren | 1965 | Bongaerts, J.M.P. | 44(8) | After the discovery of Slochteren gasfield on 14th August, 1959 further appraisal, organisation, development and production succeeded and overlapped each other in a rather rapid succession. At this moment the field is already in production and producing ± 3,5 x 166 m3/day from one cluster. The system followed is rather simple. the permeability of the field and consequently the productivity of the wells allows withdrawal of gas in large quantities at only a few drainage points, called "clusters". At each cluster a unit is installed to treat the gas and condition it to pipeline specifications i.e. a water and hydrocarbon dewpoint of -2°C at pressures varying from 74 to 1 kg/cm2. This is necessary to prevent hydrate troubles and condensation of hydrocarbons in the pipeline system. The dehydration method followed is adiabatic expansion of the gas across a bean thereby using the Joule-Kelvin effect. This expansion results in a sharp temperature drop because of which water and heavier hydrocarbon condens and the gas gets a dewpoint of -12° C at 74 kg/cm2. This low temperature is required because of possible retrograde conditions. After this the gas is measured with the orifice method which uses as "a first" the gas density instead of static pressure, static temperature and compressibility in the flow computation. Also instead of multiple orifice meter system "one orifice meterrun" is used with a number of DP cells of a varying range. The whole plant and wells are highly automated and the complete operation is unattended, being run and watched from one central point. Numerous safety measures are incorporated one of which is the "bottom hole safety valve" in the well which again is a new development. |
| Een nieuwe methode voor de bevestiging van de schachtuitrusting aan de wand van een hoofdschacht | 1965 | Stuffken, J.; Amstel, J.A. van | 44(8) | Fixing brackets to an existing concrete wall by means of anchor bolts provides a quick and simple method of mounting in place parts of a shaft installation, for instance the cage guides. This method saves much time in that it does away with the necessity of cutting holes in which beams have to be fixed with concrete. Neither is it necessary in the case of new shafts being planned to determine beforehand the places where recesses have to be made in the shaft wall, so that the choice of a particular type of shaft equipment can be postponed to a later stage. |
| Geological sketch of Svalbard Islands (Spitsbergen) | 1965 | Escher, E.F. | 44(8) | A summary is given of the geology of the arctic archipelago of Svalbard, mainly on the base of publications. A geologically attractive feature of the Svalbard Islands, which cover in total about 64,400 km2, is the presence of a sedimentary sequence which belongs to the long time span from pre-Cambrian to Lower Tertiary inclusive; only few gaps exist. Probable pre-Cambrian basement, which is exposed in Northeast Land, is followed by the partly geosynclinal Hecla Hoek Group of formations, pre-Cambrian to Ordovician in age and up to 15,000 m thick. The lower part of the Hecla Hoek succession is metamorphosed. The sequence is strongly affected by the Caledonian orogeny and intruded by granites of which the youngest are Caledonian in age. Devonian sediments, which are developed in Old Red facies, are chiefly preserved in a downfaulted region in northern West Spitsbergen where their total thickness is estimated to be more than 5,000 m. They rest unconformably on Hecla Hoek and probably were eroded away in large areas in pre-Carboniferous time. From Carboniferous to Lower Tertiary Svalbard belonged to a shelf on which a predominantly marine sequence of clastic and, subordinate, carbonate rocks was laid down, interrupted by some intervals in freshwater or mixed facies. The principal region of exposure of post-Devonian sediments is central and southern west Spitsbergen. Formation thicknesses are variable; in the Isfjord region in West Spitsbergen approximate thicknesses are: Carboniferous-Permian 1,100-1,500 m; Mesozoic 1,300-2,000 m; Lower Tertiary 2,000 m. In Svalbard the dominant tectonic event is the Caledonian orogenetic phase already mentioned. There followed the Svalbard phase in Upper Devonian time, which mainly caused faulting. Variscan movements are proved on Bear Island, where Permian beds onlap unconformably on slightly folded older strata. Probably in Upper Cretaceous time West Spitsbergen and Northeast Land were tilted to the south. Alpine movements are assumed to have occurred in Upper Tertiary time. Their exact dating is not possible because of the absence of Upper Tertiary deposits. They resulted in the formation of a broad, flat syncline in southern West Spitsbergen and, along its western border, a zone of pronounced faulting and folding. Caledonian, Devonian and Tertiary structures and faults mostly are directed north-and-south to NNW-SSE; the younger structures obviously are influenced by the Caledonian direction, which generally is north-and-south. in Svalbard, between Upper Devonian and Lower Tertiary, coal seams were formed at various times. In recent years, in West Spitsbergen five mines exploited coal for export, one of them working Lower Carboniferous, the others Lower Tertiary seams. |
| Over de verspreiding van mammoetfossielen in noordelijk Nederland | 1965 | Boekschoten, G.J. | 44(8) | Tentative explanations are given for the almost complete absence of mammoth fossils in the sediments of Saalian and Weichselian age of the Northern Netherlands. The northeastern provenance of the older fluviatile strata is thought to account for the absence of reworked skeletal elements. The Weichselian finds are restricted to the valley of the only larger river this could be due to ecological factors. |
| #REF! | 1965 | 44(8) | ||
| #REF! | 1965 | 44(8) | ||
| Genootschapszaken | 1965 | 44(8) | ||
| Exploration for oil and gas by emanometric methods | 1965 | Thomeer, J.H.M.A. | 44(9) | Since the early twenties the occurrence was observed of hydrocarbon traces in the soil over oil and gas accumulations. These traces appear to form a halo pattern above the oil-water-boundary of the accumulation. Similar observations were made in respect to salt concentration and radioactivity. It would appear that these complex phenomena can be satisfactorily explained on the basis of rock load, subsequent fluid expulsion and capillary barrier effects. Whether, however, these halo's could satisfactorily be utilised for the explorarion and localisation of subsurface accumulations, seems rather doubtful. There are too many factors that rend to displace the halo or render its formation impossible. At best, emanometric surveys might supply supplementary information to orthodox geological and geophysical observations, and even this under locally favourable conditions only. |
| Paleomagnetic investigation in the Vänern district (Sweden) | 1965 | Mulder, F.G. | 44(9) | Orientated samples of dolerite and limestone were collected in Sweden for a paleomagnetic investigation. The limestone samples are of Ordovician age and the dolerite samples are from two sills intruded in Silurian shales. At demagnetization with the use of A.C. fields up to 900 Oe, the limestone samples show only a little decrement of magnetization. Therefore, only the magnetization of the non 'cleaned' samples is given, The average magnetic direction of the limestone samples is: decl. 198°; incl. -4°; with a cone of confidence α95=11° and a pole position of 31° N; 173° E. All the dolerite samples, also demagnetised with the use of A.C. fields up to 900 Oe, show a total loss of magnetism. Samples from the sill NW of Skövde (Billingen) gave the following results: decl. 198°; incl. -2°; with a cone of confidence α95=3° and a pole position of 31° N; 172° E. Samples from the sill E of Trollhättan (Hunneberg) gave the following results: decl. 203°; incl. with a cone of confidence α95=3° and a pole position of 38° N; 162° E. |
| De ontwikkeling van een slagwalsbreker | 1965 | Minkhorst, J.H.K.; Muysken, P.J. | 44(9) | The raw coal from a long-wall face often contains large lumps of coal and stone, which may cause spilling and stoppages in the outbye conveyorbelts and transfer points. "Beien" coal crushers, comprising a single slow-speed toothed roll mounted in a swinging frame on the stageloader, have been used for many years. Dutch State Mines have developed an impact roll for the same of a similar frame. It consists of a heavy roil with one breaking ridge, which is excentrically suspended by compound leaf springs between two circular disks carried on the horizontal shaft driven at a speed of 240 r.p.m. Mass and speed give the roll sufficient kinetic energy to break hard material without slowing down. Fitted with this impact roll the crusher has satisfactorily handled large lumps of hard stone, which used to pass unbroken. Due to low cost this small unit may also compete against hand sledging of large lumps in a small crushing plant. |
| Tectonics of the late Precambrian ignimbrites in western Rajasthan (India) | 1965 | Rutten, M.G. | 44(9) | The Late Precambrian Malani Rhyolites of western Rajasthan, India, are formed predominantly by ignimbrites. Several of the isolated outcrops of the Malani Rhyolites show extremely strong westward tilting. This is thought to be an effect accompanying transcurrent faulting inherent upon the northward drift of the Indian subcontinent. |
| Mega-undations as cause of continental drift | 1965 | Bemmelen, R.W. van | 44(9) | After a short review of newer acquisitions of our geonomic knowledge, a mechanical model is conceived for the explanation of mega- and geotectonic processes. The motor, providing the gravitational energy, is sought in the lower mantle (turbulent or laminar flowcircuits in material with a Newtonian viscosity). The outer spheres (upper mantle and crust) are elevated and depressed by these deep-seated flowsystems, forming extensive deformations of the geoid, measuring thousands of kilometers across, called megaundations. The upwarps spread under gravity and the downwarps contract by means of a composite gravity flow of matter which is largely in a crystalline state. This flow is characterized by (hot-) creep deformations (Andradean viscosity), and it is accompanied by continental drift. |
| #REF! | 1965 | 44(9) | ||
| #REF! | 1965 | 44(9) | ||
| #REF! | 1965 | 44(9) | ||
| Coccoliths and discoasters | 1965 | Cohen, C.L.D. | 44(10) | A short review is given of the principal biological characteristics of the little known group of the Coccolithophorids. The related Discoasters are shortly mentioned. Some of the technical details are described that are to be used when working with these very small forms. Their rôle as rockbuilders is briefly mentioned and some aspects are described of their use in stratigraphic paleontology. A few examples are given of their application in biostratigraphic zonation and correlation. Their advantages and disadvantages are shortly reviewed |
| Een vondst van marien icenien in de achterhoek | 1965 | Rees Vellinga, E. van; Ridder, N.A. de | 44(10) | |
| An approximation to the genetic classification of non-organic sedimentary structures | 1965 | Nagtegaal, P.J.C. | 44(10) | Non-organic sedimentary strucures are divided into three major groups according to the time and site of their formation. The three groups are: 1) syndepositional structures, 2) metadepositional structures and 3) postdepositional structures. The moment of final deposition of a sedimentary grain is taken as time reference and the depositional interface is used as spatial reference. On the basis of this threefold division a classification is developed which, to a limited degree, makes it possible to group together genetically related structures. |
| Isotopic ages of two granites on the Iberian continental margin: the Traba granite (Spain) and the Berlenga Granite (Portugal) | 1965 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Verschure, R.H.; Hebeda, E.H. | 44(10) | |
| De gravimetrische stofgrenzen van het stofinstituut | 1965 | Malta, W.P.M.; Terpstra, J. | 44(10) | The dust concentration limits I/II, Il/III and III/IV of the "stofinstituut van de Gezamenlijke Steenkolenmijnen in Limburg" approximately can be described by the hyperbolic function G=x/A+11 mg/m3, in which: G= dust concentration in mg/m3; A = ash content of the dust in % and x = respectively 1170,1750 and 2620. This holds for ash percentages between 10 and 100 %. The dust concentration limits of dust with ash percentages between 0 and 10 % ate equal to those of dust with 10 % ash. Die Staubgrenzwerte Staubstuten l/II, II/III und III/IV des "stofinstituut van de Gezamenlijke Steenkolenmijnen in Limburg" werden annähernd durch die hyperbolische Funktion G=x/A+11 mg/m3 dargestellt; hierin ist G= die Staubkonzentration in mg/m3 A = Aschegehalt des Staubes in % und x= bezw. 1170, 1750 und 2620. Diese hyperbolischen Funktionen sind annähernd gültig für Aschegehälte zwischen 10 und 100%. Die Staubgrenzwerte von Stäuben mit Aschegehälten zwischen 0 und 10 % sind deren mit einem Aschegehalt von 10 % gleich. |
| On the estimation of relative grain frequencies in heavy mineral slides | 1965 | Harten, D. van | 44(10) | Counting methods, applied in order to obtain information on grain frequency in heavy mineral residues are critically reviewed. The method of line counting is discussed in some detail from a theoretical point of view, the conclusion being that this method should not be used as a means of obtaining relative grain frequencies in instances where mineralogical character and grain size are correlated. The technique of ribbon sampling, being insensitive to particle size, is proposed instead. Line and ribbon counting methods are tested in some artificial two-component slides of known composition. Finally, the results of comparative counts in slides prepared from a natural sediment are discussed. |
| In memoriam prof. dr. mr. F. Florschütz | 1965 | Hammen, T. van der | 44(10) | |
| #REF! | 1965 | 44(10) | ||
| #REF! | 1965 | 44(10) | ||
| #REF! | 1965 | 44(10) | ||
| Hercynian and alpine orogenies in Northern Spain | 1965 | Ulbo de Sitter, L. | 44(11) | In northern Spain many different orogenes have developed since the Pre-Cambrian and lasting into the Alpine period. In the western part a N-S strike predominates, in the central and eastern part an E-W trend. The intensity of both the Hercynian and the Alpine E-W striking tectonic deformation, increases eastwards. The Pyrenees are separated from the Cantabrian Mts and the Celtiberic chain by the Ebro block. Both the basin development and the tectonic deformation is largely dependent on fundamental faults and ridges of which the North-Pyrenean fault and the León line are the most important ones. Cross folding and divergent fold trends are partly due to successive N-S and E-W stress fields, partly to the block boundaries formed by these fault lines and their splays. |
| The age of the Mondoñedo formation and the mastodon fauna of Mosquera (Sabana de Bogotá) | 1965 | Hammen, T. van der | 44(11) | The Mondoñedo Formation is found at the edges of the Sabana de Bogotá (Colombia), that was formerly a pluvial lake. The formation, known for its fossil Mastodon.fauna, is here provisionally subdivided into Upper, Middle and Lower Mondoñedo Formation, The Upper Mondoñedo Formation consists of an upper recent soil, a series of sandy loams often with angular gravel, and a lower soil-complex. This soil-complex contains charcoal which was C14-dated on two places, as resp.10,760 ± 160 and 10,840 ± 110 yrs. The charcoal from the Alleröd soil-layer of Europe has the same age. It corresponds there to the time that certain tree-species died as a result of the deterioration of the climate at the very end of the Alleröd-Interstadial, becoming an easy prey for natural forest-fires. Near the base of this soil-complex, or just below it, angular gravel is present together with fragments of "Limonitic Crust" (derived from erosion of the Lower Mondoñedo Formation). The Middle Mondoñedo Formation consists apparently mainly of the sandy "Brown Loams" and equivalents, and at its base (just on top of the "Limonitic Crust") the Mastodon-fauna is found. A molar of Mastodon was analysed for its fluorinecontent by C. J. Overweel. The percentage (0.90 %), suggests an approximate age of Early Würm-Glacial to Late Riss-Würm-Interglacial. The Lower Mondoñedo Formation consists of the "Red Loams" and equivalents, covered locally at the top by a "Limonitic Crust". This part of the formation may eventually be as old as, or perhaps even older than Riss-Würm-Interglacial |
| De kolenproductie en energievoorziening van West-Europa | 1965 | Muysken, P.J. | 44(11) | |
| Chamosite in recent sediments of the Niger and Orinoco deltas | 1965 | Porrenga, D.H. | 44(11) | The mineralised faecal pellets in Recent shallowwater sediments of the Niger and Orinoco deltas contain mainly authigenic poorly ordered chamosite with a fairly high magnesium content. Photographs, chemical- and X-ray data of these chamositic pellets are given and their origin and occurrence are discussed. |
| A dip comparator for routine geological investigations of aerial photographs | 1965 | Rondeel, H.E. | 44(11) | |
| Tilt-compensating compass | 1965 | Bouma, A.H.; Mutti, E.; Maarschalkerweerd, M.H. | 44(11) | A light weight tilt-compensating compass has been constructed, It enables the investigation to measure the pretectonic directions of linear sedimentary structures of a folded series. The compass can also be used to mark the orientation of samples before they will be collected. |
| #REF! | 1965 | 44(11) | ||
| #REF! | 1965 | 44(11) | ||
| Hot ontwerp van de nieuwe losvloer van staatsmijn Emma | 1965 | Clercq, H. le | 44(12) | The top landing mine car circuits at four "Staatsmiinen" collieries were replaced or reconstructed in the period 1955-1965. The last renovation, that of the hang bench circuit at the "Emma" colliery was finished in 1965.Its design is the most advanced as it was based on the experiences gained in the previous reconstructions. Operations on the "Emma" landing stage, serving a four cage shaft with a capacity of 340 mine cars of 2500 litres or 1000 tons gross per hour, are full automatic and supervised by two bankmen only. The track scheme was kept as simple as possible; for reversing the cars turn-tables are used. There are two tipplers, each for three products and no provision was made for a stand-by tippler. Full automation was obtained by regarding the car circuit as a whole from the functial point of view. Descriptions are given of the principle of automation as well as of some examples, |
| Zyklischer bewegungsablauf beim vorrücken orogener fronten und der mechanismus des Deckschollentransports nach dem surf riding-prinzip | 1965 | Wunderlich, H.G. | 44(12) | A characteristic of advancing orogenic fronts is a phase shift in successive movements, which expresses itself in a retardation of the movement maxima and a lateral shift in the zones of strongest movement with respect to the region in which activity takes place at present. In this connection, it is possible to consider the movements at the orogenic fronts as cycles that bear a formal resemblance to the propagation of an impulse in the form of waves. Vertical and horizontal crustal movements are interrelated like the orbital movements of point masses. The horizontal and vertical movements as well as the sum of the elevation and depression and the sum of the compression and stretching of the crust during the passage of the front can be described by curves of trigonometrical functions. The maxima and minima of these curves form clues as to the location of gravitational anomalies in the orogen, the region of most severe crustal shortening or stretching, local steepening of the temperature gradient and the paths ascending plutonics and volcanics are most likely to take. Comparing the undulatory propagation of the zone of maximum horizontal movement towards the foredeep with the motion of water waves provides a simple explanation of the long-distance transport of tabular crustal fragments: they are carried forward like surf broads. This assumption makes superfluous both the expulsion of such crustal fragments from distant steeply dipping root zones and the long slopes required by gravitational sliding. Kennzeichen vorrückender Orogenfronten ist die Phasenverschiebung der Bewegungsvorgänge, die sich in einer Verzögerung der Bewegungsmaxima und einer seitlichen Verschiebung der Zonen stärkster Effektivbewegungen gegenüber den Bereichen gegenwärtiger Aktivität äussert. Die Bewegungsvorgänge an orogenen Fronten lassen sich dabei deskriptiv als zyklische Abläufe auffassen, die eine formelle Ähnlichkeit mit der Fortpflanzung des Impulses bei Wellenbewegungen besitzen. Horizontal- und Vertikalbewegungen der Kruste greifen dabei im Sinne einer Orbitalbewegung der Massenpunkte ineinander. Als beschreibende Funktion für diesen Bewegungsablauf ergeben sich Kurven von 'Winkelfunktionen, und zwar für Horizontal- und Vertikalbewegungen sowie für die Summe der Hebung bzw. Senkung und der Einengung bzw. Dehnung der Kruste im Laufe des Frontdurchganges. Die Maxima und Minima dieser Kurven ergeben Anhaltspunkte für die Iage der Schwereanomalien im Orogen, für Bereiche stärkster Einengung oder Krustendehnung, örtliche Versteilung des Temperaturgradienten sowie für günstige Aufstiegswege der Plutonite und Vulkanite. Aus der wellenartigen Fortpflanzung des Bereiches maximaler Horizontalbewegung in Richtung zur Vortiefe ergibt sich in Parallele zum Bewegungsablauf von Wasserwellen eine einfache Erklärung für weitreichenden Horizontaltransport flacher Deckschollen ähnlich dem Vorgang beim Wellenreiten (surf-riding), welche die Annahme sowohl einer Auspressung dieser Deckschollen aus ferngelegener, steiler Wurzelzone als auch der für gravitative Freigleitung erforderlichen entsprechend langen Böschungsreege überflüssig macht. |
| De relatie tussen katteklei, pyriet en gips in de Luxemburgse Trias | 1965 | Sijperda, W.S. | 44(12) | During a field-trip the yellow parts in variegated clay lenticles in a triassic pebble deposit near Reichlingen, Luxemburg, were recognised as cat's clay, a basic ferric sulphate, comparable to the car's clay occurrences in certain holocene soils in The Netherlands. Cat's clay originates by oxidation of pyrite in the absence of calcium carbonate. If calcium carbonate is present gypsum is formed. At Reichlingen the pyrite left cubic holes after oxidation. The pebble deposit is likely to belong to the same time - stratigraphic unit as the variegated marls near Diekirch. These marls contain bands of gypsum and cubic pseudomorphs, known as halite pseudomorphs. It is argued that the pseudomorphs at Diekirch and the cubic holes at Reichlingen are similar: in both cases pyrite cubes were oxidized. This oxidation gave rise to the development of cat's clay in the near-shore facies (no presence of calcium carbonate), and to the formation of gypsum in the "normal" facies where calcium carbonate was present. The cubic pseudomorphs in the triassic marls, therefore, are not halite pseudomorphs but pyrite pseudomorphs. The gypsum did not originate by primary sedimentation but by weathering of pyrite. |
| #REF! | 1965 | 44(12) | ||
| #REF! | 1965 | 44(12) | ||
| Der meteorit von Kangean (Indonesien) (Ein olivin-bronzit-chondrit) | 1966 | Niggli, E. | 45(1) | The Meteorite of Kangean (an island of Indonesia, NE of Java) felI on September 27th, 1908; it is described here for the first time. The original weight is not known, as the meteorite was broken up by the people who found it. A mass of 1632.973 g could be recovered, certainly more than half the original stone. This meteorite is deposited in the Mineralogical-geological Museum in Delft (Technical Institute), Netherlands. The surface of the meteorite is covered with a black fusion crust; the front face of the lenticular body shows well developed piezoglypts. The structure is chondritic. The meteorite is rather strongly weathered. The mineralogical composition is: olivine (Fo80-82), bronzite (~ En82), nickel-iron, troilite, chromite, ? plagioclase, glass and secondary iron hydroxydes. The meteorite is an olivine-bronzite-chondritre. The nickel-iron bodies of the meteorite were investigated with the electron microprobe. Profile analyses were made for Fe, Ni and Co. Most of the bodies (type A) consist mainly of kamacite with few inclusions of taenite grains; we found also however bodies (type B) of which the main mass is taenite with regularly distributed small inclusions of kamacite. In the taenite grains in bodies of type A the Ni-content is higher at the borders than in the middle parts of the grains. The distribution of the cobalt in the nickel iron bodies coincides roughly with that of iron and not with that of nickel. |
| Probleemstelling bij het ontwerp van de nieuwe losvloer van staatsmijn Emma | 1966 | Antkowiak, W.A. | 45(1) | The forty years old pithead of Emma Colliery, Dutch State Mines, was designed for one type of coal only. Gradually, more types of coal had to be handled, involving a number of complications that acted as a check on the pithead capacity and stood in the way of technical developments, such as automation. Consequently technical adaptation of the excisting pithead was not a sufficient answer to the problems associated with the introduction of larger mine cars, but demanded a more fundamental approach. |
| Isotopic age determinations on Surinam rocks | 1966 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Verschure, R.H.; Hebeda, E.H. | 45(1) | |
| #REF! | 1966 | 45(1) | ||
| #REF! | 1966 | Thiadens, A.A.; Plas, L. van der; Snell, A.W. | 45(1) | |
| Depositional environment and provenance of the sediments in the Guadalete Estuary (Spain) | 1966 | Mabesoone, J.M. | 45(2) | The river Guadalete in SW. Spain has excavated a 8-10 m deep estuary of which. two thirds have been filled up with almost clayey deposits mainly in postroman times. Many samples were taken with a hand auger. The amount of material thus obtained was only small. This made some special investigation techniques necessary. The grain size of the thin sand layers was determined by a counting method in which at the same time roundness is measured. It appears that the centre of the northern estuary part was filled up by the Guadalete, whereas the lateral parts are derived from recent and subrecent beaches. The southern estuary part, however, got its few sand layers chiefly from reworked older marine deposits exposed in the valley slopes. By means of geochemical methods, furthermore the environment has been reconstructed in which the clay was deposited. The ratio calculated from exchangeable K, Na, Ca, and Mg indicates that this environment has always been marine to brackish. Only the uppermost clays at the beginning of the northern marsh part show some fresh water influence. Boron and lithium, which occur in a greater quantity in marine clays than in fresh-water clays, confirm these results. |
| The Susaća-interstadial and the subdivision of the late-glacial | 1966 | Hammen, T. van der; Vogel, J.C. | 45(2) | During a recent pollen analytical study of a Holocene and Late-Glacial section from Cienaga del Visitador (Susaća, Eastern Cordillera of Colombia; van der Hammen & Gonzalez, 1961), an "interstadial" was recognized, earlier than Allerød and Bølling s.s.. A C 14 date showed that this interstadial must be somewhat older than 12,770 + 130 B.P. (GRN 3053), a clate for the cold phase between Bølling and the above mentioned ínterstadial. This fact led us to reinvestigate a number of dated pollen diagrams from different parts of the world. Several facts seemed to confirm the existence of a pre-Bølling Late-Glacial interstadial, and we therefore think it justified to introduce a name for it: the Susaća -Interstadial. It lasted from about 13,700 to 13,100 B.P. The pertinent data from various parts of the world relevant to the dating of the interstadial are presented, as well as a more complete subdivision of Late-Glacial time resulting from this work. |
| Isotopic evidence for Upper-Cambrian or Lower-Ordovician granite emplacement in the Vigo area, North-Western Spain | 1966 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Verschure, R.H.; Hebeda, E.H.; Floor, P. | 45(2) | |
| Structural observations in the bude to tintagel area of the coast of North Cornwall, England | 1966 | Freshney, E.C.; McKeown, M.C.; Williams, M.; Dearman, W.R. | 45(2) | |
| Tectonics of the North Cornish coast England | 1966 | Mackintosh, D.M. | 45(2) | |
| Structural observations in the bude to tintagel area of the coast of North Cornwall, England and Tectonics of the North Cornish coast, England, a reply | 1966 | Zwart, H.J. | 45(2) | |
| Sedimentatie in de zuidelijke bocht van de Noordzee - Tektonische consequenties van het paleomagnetische onderzoek aan de permische porfieren van Lugano, Noord-Italië | 1966 | Houbolt, J.J.H.C.; Hilten, D. van; Zijderveld, J.D.A. | 45(2) | |
| #REF! | 1966 | 45(2) | ||
| #REF! | 1966 | 45(2) | ||
| #REF! | 1966 | Plas, L. van der | 45(2) | |
| Reversal of air flow by a fire | 1966 | Maas, W.; Sadée, C. | 45(3) | The calculations given in this paper show that the temperature of the gases in the return airways behind a fire greatly influences the chance of a reversal of the ventilating air in parallel districts. A method to predict these temperatures behind a fire is given. The temperature in the fire has to be known. Calculations give this temperature for a fully developed timber fire. Some general conclusions which are important for fire-fighting are drawn. |
| Rotated magnetite crystals from the Rocroi massif (Ardennes) | 1966 | Zwart, H.J.; Oele, J.A. | 45(3) | The rotation about the B-axis of magnetite crystals in Cambrian phyilites from the Rocroi massif is described. A possible explanation for this rotation in connection with the folds is given. |
| De mijnwetgeving op de Noordzee | 1966 | Driessen, C.F. | 45(3) | |
| Cosmos and the Evolution of Life | 1966 | 45(3) | ||
| #REF! | 1966 | 45(3) | ||
| #REF! | 1966 | 45(3) | ||
| Rationalisatie in het ondergronds bedrijf van een kolenmijn - organisatie en techniek | 1966 | Kraak, J. | 45(4) | |
| The pliocene and quarternary of the Sabana de Bogotá (the Tilatá- and Sabana formations) | 1966 | Hammen, T. van der | 45(4) | The age and the correlation of the Pliocene and Quaternary formations of the Sabana de Bogotá (Colombia) are discussed. New data of pollen analysis, C14 dating etc. lead to the differentiation of two postfolding formations: one of Pliocene age, containing a tropical pollen flora, and one representing the Quaternary, containing an upland pollen flora. It is argued that the first one probably corresponds to the type Tilatá Formation, and the second one to the Sabana Formation as basically proposed by Hubach. An attempt was made to date the morphological units distinguished by JuIivert (1961) in the Southern Sabana de Bogotá. His "high-terrace" of the Tunjuelo Valley was cut into Würm-Glacial sediments. The "cone" of the Tunjuelo Valley is most probably a fluviogiacial deposit of Riss-Glacial time. The altered, often kaolinitic, marginal sediments, found above the proper level of the flat part of the Sabana, correspond only partly to the "high-terrace". They are eroded sediments of different (Quaternary) ages, deposited when the lake-level was high, and eroded when it was low, a cyclic phenomenon that reccured at least 12 times. |
| Uitreiking van de Waterschoot van der Gracht penning aan Ir. A. Hellemans | 1966 | 45(4) | ||
| Note préliminaire sur l'âge des roches de l' "unité cucharón" dans la Sierra de Carrascoy (Province de Murcie, Espagne) | 1966 | Simon, O.J. | 45(4) | |
| #REF! | 1966 | 45(4) | ||
| Koninklijk Nederlands Geologisch Mijnbouwkundig Genootschap - Jaarverslag 1965 | 1966 | 45(4) | ||
| The Siljan ring of Paleozoic, Central Sweden: A posthumous ringcomplex of a late Precambrian Dala porphyries caldera | 1966 | Rutten, M.G. | 45(5) | The Dala Porphyries, recently mapped by Hjelmquist, from a volcanic province of late Precambrian age in central Sweden, attaining a minimum volume of volcanics of 150 km3. The Siljan ring of eaily paleozoics, distinguished from the early Paleozoic epicontinental cover of the Fennoskandian Shield by its thicker facies, with reef limestones, and by its peculiar, strong tectonization, occupies a ring 45 km in diameter and 5 km to 10 km wide, to the east of the Dala Porphyries. It is postulated that the Siljan ring structure developed as a result of posthumous movements at the site of the ring-complex surrounding a caldera from which the Dala Porphyries had erupted earlier. |
| Versterking van een gietijzeren schachtbekleding door middel van een deformeerbare manchet | 1966 | Bruens, F.P.; Moonen, J.G.D.; Weehuizen, J.M. | 45(5) | |
| De invloed van de inclinatiefout bij paleomagnetische waarnemingen op continentverschuivingen en aardexpansie | 1966 | Hilten, D. van | 45(5) | |
| Fouten in palaeomagnetische poolposities ten gevolge van systematische fouten in de palaeomagnetische inclinatie | 1966 | Hospers, J. | 45(5) | |
| Lower Cretaceous planktonic foraminifera from the subbetic of Southern Spain | 1966 | Hermes, J.J. | 45(5) | A fauna of planktonic Foraminifera from the Subbetic near Caravaca contains GIobigerineIIoides bIowi (Bolli), Globigerina graysonensis Tappan and some other species, probably including Hedbergella infracretacea (Glaessner). This association is believed to indicate an early Aptian, possibly a late Barremian, age. The succession of planktonic foraminiferal faunas of the early Cretaceous is discussed and shown to be far from settled. |
| #REF! | 1966 | 45(5) | ||
| #REF! | 1966 | 45(5) | ||
| #REF! | 1966 | 45(5) | ||
| Internationaal congres van directeuren van mijnbouwkundige veiligheidsinstituten - Sheffield 1965 | 1966 | Maas, W.; Sadée, C. | 45(6) | |
| Aspects techniques et economiques de l'energie geothermique | 1966 | Dam, A. ten | 45(6) | This paper gives a very general summary of the presently known distribution of geothermal fields; geology and mechanism of such fields, exploration methods and technical means are discussed. In the last chapter the economic aspects of geothermal energy are discussed. Geothermal exploration has much in common with petroleum prospection and should interest any country where on geological grounds this new form of energy could be present. Taking into account the risk factor involved in any exploratory operation, electricity can be generated with natural steam at lower cost than with other sources of energy. |
| Isotopic age determinations on tourmaline granite-gneisses and a metagranite in the eastern Betic Cordilleras (South-Eastern Sierra de Los Filabres), S.E. Spain | 1966 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Hebeda, E.H.; Verschure, R.H. | 45(6) | |
| isotopic age of the Quartz-diorite batholith on the island of Aruba, Netherlands Antilles | 1966 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Verschure, R.H.; Hebeda, E.H.; Lagaay, R.A. | 45(6) | |
| Isotopic age of tin granites in Rondônia, N.W. Brazil | 1966 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Hebeda, E.H.; Verschure, R.H.; Bon, E.H. | 45(6) | |
| Tectonics of Late Precambrian ignimbrites in western Rajasthan (india) - Discussion | 1966 | Mukherjee, A. | 45(6) | |
| #REF! | 1966 | 45(6) | ||
| #REF! | 1966 | 45(6) | ||
| #REF! | 1966 | 45(6) | ||
| Considérations sur la composition, la genèse et la classification de la Tourbe, du lignite et de la houille | 1966 | Kreulen, D.J.W. | 45(7) | Considerations on the composition, the origin and the classification of peat, lignite and coal. In this paper it is attempted to bring under one common denomenator certain specialized, professional views on the composition and genesis of peat. lignite and hard coal. The chemical part starts with the conception rank and ends with information about aromaticy, ringcondensation index and molecular size of the mean structural unit. The H/C versus O/C diagram (fig. 3) is noticed. Thereupon the conditions which control the formation of peat, lignite and hard coal are discussed. The objections made by W. Gothan and R. KräuseI against the swamp theory of H. Potonié are mentioned and appreciated. The transformation of plant débris is conceived as the result of biochemical transformation together with oxidation and reduction phenomenae. It is stressed that humic acids ate often improperly considered as intermediate stage during coalification. Their structure points clearly to a formation by oxidation. Consequently it is supposed that the transformation of plant débris resulted in lignite or hard coal respectively accordingly to predominance of oxidation or reduction reactions. This idea is on the root of a new classification scheme (fig. 6) in which all immature coals have an appropriate place. The author fails to see pressure as a controlling factor of rank. Experiments are mentioned (fig. 4, A and B) in which the appearance of an earthy brown coal (brown and dull) changed to black and glossy under a pressure which was equivalent to that of a normal, average, overburden. During this treatment the ultimate analysis, however, did not change. Other experiments are mentioned which demonstrate an increase in carbon content of cellulose and lignine when exposed to relatively low temperatures (130 °C) for long periods of time (up to 3200 h). It was established that the transformation under these conditions is accelerated by water. Finally reference is made to a booklet in the german language in which the subject is treated more amply. |
| Palaeomagnetism of some central European mineral deposits and its geophysical significance | 1966 | Krs, M. | 45(7) | Palaeomagnetic research conducted on several types of Central European mineral deposits (pneumatolytic, cata - to epithermal), distributed throughout metallogenic regions of various tectonic development, has fully bore out the view that under certain conditions palaeomagnetism can be used for dating epigenetic mineralization. New palaeomagnetic data, supplemented by an extensive laboratory study of palaeomagnetic stability, provide new interpretation aspects for palaeomagnetism concerning the reconstruction of tectonic development, and thermal history of mineral deposits, as compared with earlier results (V. Flanus and M. Krs, 1963a). The polar windering path derived from the palaeomagnetism of products of various mineralization processes coincides remarkably with the polar wandering path for the Eurasian continent as derived from the palaeomagnetism of biostratigraphically dated rocks (ranging from the Carboniferous to the Quaternary). A discussion is presented concerning the possibility of tentatively determining the intensity of the geomagnetic field in the geologic past, based on investigating thermoremanent magnetization of cassiterite (SnO2) with Fe-ions attached to its lattice. A study of the "thermal memory" of cassiterite yielded data strongly contradicting the regeneration of cassiterite deposits in the past. A similar conclusion was reached previously (M. Krs, 1964b) for hydrothermal deposits where haematite acts as carrier of palaeomagnetism. |
| Using quantitative methods in geology | 1966 | Kauffman, M.E. | 45(7) | |
| #REF! | 1966 | 45(7) | ||
| #REF! | 1966 | 45(7) | ||
| #REF! | 1966 | 45(7) | ||
| Contribution of the bureau of mines to the geology of the central mountains of West New Guinea | 1966 | Wegen, G. van der | 45(8) | In 1960 the Bureau of Mines in former Netherlands New Guinea took up the investigations in those areas of the southern part of the territory, where-a-private enterprise explored for alluvial gold deposits before the Second World War. The gold finds were not of largescale mining importance. The investigations, renewed by the Bureau of Mines, intended to trace the possibility of exploitation on minor scale. The problem of the origin of the alluvial gold is of academic importance, since the investigations of 1960 and 1961 led to negative results. The area in question must be sought on the south flank of the crestal part of the Central Mountains. The Bureau of Mines commenced the survey of the geologically most unknown region of the Central Mountains in 1961. The survey was restricted to several reconnaissances and ended with the transfer of the administration of West New Guinea to the United Nations Temporary Executive Authority on the first of October,1962. |
| Antidune bedding in the Namurian of Derbyshire, England | 1966 | Collinson, J.D. | 45(8) | Massive beds from a channel fill sequence in the Namurian of Derbyshire are described. From a comparison with modern, flume-produced, structures and from a hydrodynamic interpretation of the sequence of sedimentary structures, it is concluded that the massive beds were deposited in the upper part of the upper flow regime and therefore represent the first recognised antidune deposits in ancient sediments. |
| A continuous reflection profile along the Netherlands coast from Walcheren to Den Helder | 1966 | Collette, B.J.; Lagaay, R.A. | 45(8) | A reflection profile along the Netherlands coast from Walcheren to Den Helder is presented, obtained with the so-called air gun profiler. The penetration was one second. The downdipping of the layers from the Brabant massif, the extension of the Saxonic 'anticlinal' zone Rotterdam- The Hague, and the thickening of the sediments towards the North are recognized. The base Quaternary and the base Tertiary are tentatively identified. |
| Note on the formation of stylolites | 1966 | Manten, A.A. | 45(8) | Described here are a number of observations on stylolites, found in Silurian limestones in the island of Gotland (Sweden). The three current theories on stylolite formation are briefly summarized. Only the solution-pressure theory of Stockdale can satisfactorily explain the origin of the stylolites in Gotland. |
| Mineral analysis by means of thin layer chromatography using liquid iion exchangers | 1966 | Vries, G. de; Sijperda, W.S. | 45(8) | A rapid chromatographic technique using a thin layer of silica gel impregnated with liquid anion exchangers on small glass plates is introduced in mineral analysis. The principles of the ion exchange process and the practical application are outlined. |
| #REF! | 1966 | 45(8) | ||
| #REF! | 1966 | 45(8) | ||
| In memoriam - Professor Dr. Ir. Felix Andries Vening Meinesz | 1966 | Colette, B.J. | 45(9) | |
| Glaucophanitic stone implements from West New guinea (West Irian) | 1966 | Verhofstad, J. | 45(9) | A collection of hand polished stone adzes and other stone implements in use by native tribes in the Central Highlands of West New Guinea (West Irian) is described. All the specimens are glaucophanites containing epidote, glaucophane and lawsonite as principal minerals. Glaucophane-bearing rocks have not been described earlier from New Guinea. No field data are available but there is evidence that the rocks come from a zone of low-grade metamorphic and basic to ultrabasic igneous rocks existing along the northern edge of the Central Ranges. The blue to green rocks are very fine grained and many show a fine undulating banding. Mineralogical aspects include the occurrence of several members of the glaucophane-riebeckite series, of lawsonite in subradiating “sheaves” and of colourless pumpellyite; the last mineral however was not identified with certainty. It is concluded that these glaucophanitic rocks from New Guinea belong to the lawsonite-pumpellyite-epidote-glaucophane sub-facies as defined by Miyashiro and Seki (1958) from Japanese metamorphic terrains. |
| On the occurrence of oolitic limestones, intercalated in pelagic Aptian-Albian marls in the subbetic WNW of lorca (Prov. Murcia - Spain) | 1966 | Dekker, L.; Rooijen, P. van; Soediono, H. | 45(9) | Evidence has been found that layers of oolitic limestones and other calcarenites, intercalated in Aptian-Albian marls rich in Radiolaria and planktonic Foraminifera, consist largely of redeposited ooliths and rock fragments carried into the marl basin by gravitational transport. This proves the existence, during Aptian-Albian times, of an eroded area, probably within the Subbetic paleogeographic realm. As shown by the age of redeposited material in the oolites, the hiatus involved covers a sequence from Upper Dogger or Lower Malm to Aptian-Albian age |
| Diaklaasvorming in de diepte (t.g.v. de lithologische druk), als oorzaak van open trekscheuren in de hogere gesteentelagen | 1966 | Gramberg, J. | 45(9) | |
| Mineral analysis by means of thin layer chromatography using liquid ion-exchangers. Part III Data on non-sulphidic minerals. Part II: Qualitative analysis of sulphide ore minerals | 1966 | Sijperda, W.S.; Vries, G. de | 45(9) | Thirty sulphide minerals have been analysed using the rapid thin layer technique described in part I. After preparation of the test solution chromatograms were run using 2, 6 and 10 N HCI as eluants. Then the constituents were visualized with the aid of suitable reagents. Combination of Rf value and mode of detection reveals the identity of the constituents. The results are discussed. |
| Chemical procedures for the praparation of rubidium and strontium samples for isotopic age determination | 1966 | Boelrijk, N.A.I.M. | 45(9) | |
| #REF! | 1966 | 45(9) | ||
| #REF! | 1966 | 45(9) | ||
| Het aardgastransportnet in Nederland | 1966 | Walkate, H.J. | 45(10) | |
| Scour-and-fill structures from a fluvial piedmond environment | 1966 | Nagtegaal, P.J.C. | 45(10) | Conglomerate-filled scour-and-fill structures are of frequent occurrence in Eo-Oligocene fluvial piedmont deposits in the Southern Pyrenees (Spain). Many scour-and-fills occur at the erosive bases of conglomeratic sheetflood deposits which alternate with sandy siltstones; others are found both within the conglomerates and isolated in the sandy siltstones. The latter type develops out of the downstream terminations of the conglomerate sheets. Of 376 scour-and-fills eroded into sandy silt, 35% shows load deformation. The most frequently deformed structures are those having an estimated initial width/depth ratio of about 2. diagrams show that the scour-and-fills, which were locally found to occur in a braided pattern, are very nearly parallel to each other in restricted areas. The general orientation pattern is related to an underlying unconformity surface carrying a pronounced relief. The width/depth ratio of the scour-and-fills eroded into sandy silt tends to increase in the downstream direction. In the Pobla de Segur area the downstream increase of the width/depth ratio is accompanied by a decrease of the cross-sectional area of the scour-and-fills. |
| Prallhammermessungen im steinkohlenbergwerk Emma-Hendrik der Staatsmijnen in Limburg | 1966 | Beuken, H.; Absil, P. | 45(10) | Until recently, the crushing strength of rock adjacent to coal seams was measured by means of hydraulic jacks. The crushing strength of coal could not be determined underground owing to the required vertical positioning of the jack. The use of the "Betonprüfgerät Type N" (Testhammer) was known from German mining practice. This hammer has now been tested at Emma-Hendrik colliery. It was found to be a simple and handy appliance for measuring the crushing strength of rock and coal in situ. Its low weight and small dimensions, added to the circumstance that the measurements can be performed both easily and at low cost, have contributed towards making the "Testhammer" a widely used tool in mining practice. The crushing strength figures obtained with the Testhammer have proved to be very reliable. |
| #REF! | 1966 | 45(10) | ||
| #REF! | 1966 | 45(10) | ||
| #REF! | 1966 | 45(10) | ||
| interrelation of metamorphism and deformation in Central Singhbhum, Eastern India | 1966 | Baran Roy, A. | 45(11) | The metamorphic rocks in central Singhbhum show two periods of metamorphism, the earlier progressive regional metamorphism having been followed by retrogressive metamorphism in zones of shearing. The isograds of the progressive regional metamorphism are roughly parallel to the trends of the sub-horizontal fold axes and the index minerals formed during this metamorphism form a progressive series in time. The metamorphism is broadly coeval with the folding movements and predates the shearing movements which initiated the retrogressive metamorphism. No cause-and-effect relationship exists between the regional metamorphism and the granites of the region. |
| Biostratigraphy of Upper Jurassic and Cretaceous sediments near Caravaca (SE Spain) with special emphasis on Tintinnina and Nannoconus | 1966 | Geel, T. | 45(11) | The Nannoconus zones recognized by Brönnimann in Cuba and by Baldi Beke in Hungary and the Tintinnina zones found by Remane near Grenoble are reported from a section near Caravaca in southern Spain. In the same section planktonic Foraminifera and ammonites occur. The correlation and the age of the various biozones is discussed. |
| Report on the discovery of a rudist in Upper Cretaceous pelagic limestones near La Parroquia (Prov. Murcia - SE. Spain) | 1966 | Dekker, L. | 45(11) | Attention is drawn to the discovery of a rudist which surprisingly was found embedded in limestones, developed in the "Couches Rouges" facies. The "Couches Rouges" are usually assumed to have been deposited in relatively deep water, while this rudist must have been derived from a reef, and thus from relatively shallow water. Rudist and sediment are both of Late Cretaceous age. |
| Note on a Jurassic-Cretaceous section in the subbetic SW of Carvaca (Prov. Murcia, Spain) | 1966 | Veen, G.W. van | 45(11) | In the Subbetic, south-west of the town of Caravaca, a relatively undisturbed sequence of Jurassic and Cretaceous calcareous sediments has been found. A number of rock- stratigraphic units have been distinguished in this sequence. Their lithology is described and their ages are discussed. |
| Further data on oolitic limestones, intercalated in the pelagic sequence of the Subbetic, WNW of Lorca (Prov. Murcia - Spain) | 1966 | Rooijen, P. van | 45(11) | Dekker, van Rooijen and Soediono (1966) have demonstrated that during, Aptian-Albian times an area undergoing erosion existed, most probably situated in the Subbetic realm, which supplied detrital material of mainly Jurassic tocks. In the present note it is shown that this situation continued at least until late Albian or early Cenomanian times. |
| #REF! | 1966 | 45(11) | ||
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| The structural evolution of the Southern Alps | 1966 | Bemmelen, R.W. van | 45(12) | The present author has worked in the Southern Alps with students of the Geological Institute of the State University of Utrecht during the past fourteen years (1953-1966). The intent of this work was to test the author's concept of gravity tectonics by means of detailed geological studies of selected areas, statistical analyses of microtectonic elements, and paleomagnetic researches. This testing of the theoretical concept occurred by means of the scientific method of verification, called the "Prognosis-Diagnosis Method". A number of examples are presented as the diagnostic facts of observation, which all confirm the predictions (prognoses) of the concept of gravity tectonics. Therefore, this concept appears to provide an entirely satisfactory model for the mechanics of the structural deformations in this part of the Alps. |
| The Susacá - interstadial and the subdivision of the late-glacial discussion | 1966 | Dreimanis, A. | 45(12) | Late-Glacial interstadials, contemporaneous with the recently introduced Susacá-Interstadial, have been recognized for some time in the Great Lakes Region of North America (the Cary-Port Huron, or Cary-Mankato, or Bowmanville, or Arkona, ending approximately 13,000 B.P.), and in Northern Europe (the Raunis Interstadial, 13,390 ± 500 B.P., and the correlative Plyusna Interstadial). It is suggested that the name Raunis Interstadial be used for the region affected by the North European continental glaciation. |
| #REF! | 1966 | 45(12) | ||
| #REF! | 1966 | 45(12) | ||
| #REF! | 1966 | 45(12) | ||
| Zircons from some gneisses and granites in the central and eastern Pyrenees | 1967 | Kalsbeek, F.; Zwart, H.J. | 46(1) | The presence of many subrounded and irregular zircons in the leucocratic gneisses from the Aston-Hospitalet massif does not indicate a sedimentary origin of these rocks. The gneisses are probably orthogneisses, and the rounding of the zircons is the result of two phases of metamorphism which the rocks underwent. The zircons in the granites of Axles-Thermes and Lys-Caillouas resemble those of the Aston-Hospitalet gneisses, zircons in the granite of the Valle de Aran are different. |
| On the geology and tectonics of the lake Siljan area, central Sweden | 1967 | Stam, J.C. | 46(1) | The tectonic picture of Paleozoic formations, occurring in a ring-shaped structure near Lake Siljan, Central Sweden, is discussed. Evidence, based on the surface geology and the logging of the cores from a number of drillholes, points to the existence of several thrustfaults, which indicates a more complicated structure than believed thus far. |
| Isotopic age determinations on Surinam rocks | 1967 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Verschure, R.H.; Hebeda, E.H. | 46(1) | |
| #REF! | 1967 | 46(1) | ||
| #REF! | 1967 | 46(1) | ||
| Orogenfront - verlagerung in Alpen, Apennin und Dinariden und die einwurzelung strittiger deckencomplexe | 1967 | Wunderlich, H.G. | 46(2) | The movement of orogenic zones in the Alps, the northern Apennines and the Dinarides and the insertion of rootless nappes. For the Alps, the notthern Apennines and the Dinarides a gradual shift can be demonstrated of the zone of active folding toward the foreland during Cretaceous and Tertiary times. By plotting the development of facies and tectonics in space-time diagrams it is easy to establish that the orogenic fronts were moved askew from the centre to the mariginal parts of the respective orogenic systems. The earlier the start of the synorogenic facies and, accordingly of the folding processes within an orogenic zone, the more central was the position of this zone within the whole orogenic belt. By applying this method it becomes possible to determine the original position of rootless nappe complexes. |
| The Permian climate in the basin of Lodève, Hérault, France | 1967 | Kruseman, G.P. | 46(2) | South of Lodève (Dépt. Hérault) in the southern part of France Lower Permian (Rotliegendes) rocks crop out. Grey Autunian shaes are followed by red beds of the Saxonian. The latter arc generally fine sandy siltstones and claystones, however, in the western part of the region conglomerates and coarse sandstones are present. The sedimentary structures, the texture of the rocks and their mineralogical composition, as well as the remains of the Permian flora and fauna give us the clues necessary for a palaeoclimatic reconstruction. The Autunian was deposited in a swampy environment under a uniformly warm and humid, rain forest climate. The hematite, which provides the red pigmentation, and the detrital material which furthermore builds the Saxonian red beds, were formed in the erosional area under a warm and alternately wet and dry, savanne climate and deposited in the much drier depositional area of Lodève by river and, perhaps, wind action. The differences in climate between the erosional and depositional areas are due to differences in altitude which are a normal phenomenon in a continental environment. Finally, it is tentatively suggested that the wet and dry seasons of the Saxonian found their origin in a summer high pressure and a winter low pressure belt over the East European Permian sea which could have resulted in a wet eastern monsoon and a dry western monsoon, respectively. |
| Reversal of air flow by a fire - Verslag van de Viith Guiana geological conference | 1967 | Stenuit, R.; Maas, W.; Hammen, T. van der | 46(2) | |
| #REF! | 1967 | 46(2) | ||
| #REF! | 1967 | 46(2) | ||
| #REF! | 1967 | 46(2) | ||
| Stratigraphy, climatic succession and radiocarbon dating of the last glacial in the Netherlands | 1967 | Hammen, T. van der; Maarleveld, G.C.; Vogel, J.C.; Zagwijn, W.H. | 46(3) | Field-data, pollen-analysis and some 30 radiocarbon dates have been the basis for the construction of a climatic curve for the Last Glacial in the Netherlands. The coldest part, the Pleniglacial (between more than 50.000 and 13-14,000 years ago). witnessed at least two phases of a rise in temperature: about 38,000 and 30,000 years ago, the Hengelo and Denekamp Interstadials; the period is classified as Middle pleniglacial. The maximum cold. with polar desert conditions, lasted from about 26,000 to 13.000 years ago. This phase is mainly characterized by the presence of a desert pavement associated with large frost-wedges on top of an arctic soil; organic remains are completely absent. In contrast to other parts of the Last Glacial sedimentation was almost at a standstill. The sequence in Holland is compared with the loess-area of Austria. The Paudorf soil complex can be correlated with the Middle pleniglacial. There is a close resemblance of the climatic curve with palaeotemperature curves obtained from deep-sea sediments. |
| The alteration of cordierite in spotted schists from the Central Pyrenees | 1967 | Bosma, W. | 46(3) | Quantitative data are submitted about the mineral composition of the altered cordierite porphyroblasts appearing as black spots in contact rocks and regional metamorphic rocks from several places in the Central Pyrenees. These spots have pseudohexagonal forms. The combined results of quantitative microscopic and X-ray investigations indicate that the alteration products consist of roughly equal amounts of muscovite and chlorite. These minerals form micro- and cryptocrystalline aggregates, which may resemble the unaltered cordierite in optical properties. |
| Results and problems in diatom investigation at the geological survey in Haarlem | 1967 | Saar, A. du | 46(3) | |
| Note on the history of a Jurassic turtle skull in the Teyler museum | 1967 | Regteren Altena, C.O. van | 46(3) | |
| #REF! | 1967 | 46(3) | ||
| #REF! | 1967 | 46(3) | ||
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| Entwicklung des schreitenden ausbaus durch die Bergbauforschungsanstalt | 1967 | Loonen, H.E. | 46(4) | In the past five years Staatsmijnen/DSM have experimented, on the surface and underground, with two types of self-advancing support designed by their own staff. The object of the present paper is, on the one hand, to give an insight into the ideas underlying the development programme, and, on the other, to report on the experience obtained. |
| Bijdrage tot de kwartair-geologie van westelijk Noordbrabant | 1967 | Oosten, M.F. van | 46(4) | The article describes certain aspects of the Pleistocene geology of the western part of the province of Noord-Brabant. An old Pleistocene clay layer is mostly present at a depth of a few metres. The surface of the clay consists of a very humic or peaty layer of Eemian age. In a deep erosion valley in the old clay near Breda, the Eemian is represented by a thick peat layer, resting on sand of unknown origin and age. A second peat layer reflecting a cold, arctic flora, probably of Riss- glacial age, has been found in this sand. Fluviatile sands, some with cross-lamination and solifluction phenomena and with thin intercalations of peat containing a subarctic parklandscape flora, arc overlying the Eemian or the old- pleistocene clay. They date from the Pleniglacial A-stage of the Würm-glacial. In the Breda valley this stage is represented by a humic loess also with a peat layer. A highly cryoturbatic loamlayer, called ,,Wouw-Loam" and a medium to slightly coarse-textured sand containing some gravel, on top of this loam, may be of Paudorf-interstadial age or somewhat older or younger, By solifluction and/or fluviatile influence reworked material of the latter is often present as a thin layer of coarse sand with much gravel. A second loess deposit, of the same age or more probably dating from the younger Pleniglacial-B stage, can be found in the Breda-valley. During the Pleniglacial-B stage, the eolian Older coversand was deposited. A thin gravel layer, being a deflation and/or washout horizon of the coarse sand with gravel, marks the sharp boundary between this Older coversand and the underlying horizons. A strongly Loamy coversand, which in many places covets the ,,typical" Older coversand, most probably dates from the end of the Pleniglacial B and perhaps from the transition to the late Glacial (Bølling interstadial) Younger coversand from the Older and Younger Dryas time may also be encountered. The former in a thin layer on top of the Older coversand; the latter only in some places as ridges, sometimes underlain by a formation dating from the Allerød interstadial. |
| #REF! | 1967 | 46(4) | ||
| #REF! | 1967 | 46(4) | ||
| KNGMG Jaarverslag 1966 | 1967 | 46(4) | ||
| The Mahang formation: a Mid-Palaeozoic euxinic facies from Malaya - With notes on its conditions of deposition and palaeogeography | 1967 | Burton, C.K. | 46(5) | The subject of this communication is a rock-stratigraphic unit from northwest Malaya comprised essentially of highly carbonaceous, more or less siliceous, shale and mudstone, with subsidiary arenite, minor chert and very limited calcareous argillite and limestone. The name "Mahang Formation" proposed by Courtier (in manuscript) is now formally adopted for this rock unit in accordance with the American Code of Stratigraphic Nomenclature. Fossil trilobites in the Mahang Formation are considered to be Ordovician, abundant graptolìtes are clearly Lower to Middle Silurian whilst the contained tentaculites appear to be Lower to Middle Devonian in age. Of singular interest is the intimate association of Silurian graptolites with Devonian tentaculites at 15 localities. It is evident that the Mahang Formation corresponds closely to the euxinic facies of Pettijohn (1957). The Mahang basin of deposition seems to have originated upon a platform in Upper Ordovician times with the development of a geanticlinal barrier to the east on the approximate site of the modern Main Range. Shelf conditions probably persisted to the west. Initially there was free communication with the open ocean across the submerged barrier and in the Lower Silurian a graptolitic plankton flourished in the surface waters. As the orogenic cycle developed however, the geanticline was progressively raised until external connections were effectively severed. This isolation is expressed in the apparent absence of Ludlow forms in the prolific Mahang plankton. In the Lower Devonian the geanticline is believed to have collapsed in a chain of islands, whereupon a tentaculite plankton invaded the Mahang basin. Associated orogenic movements may now have caused the surface to become polluted by toxic bottom water, with consequent annihilation of tentaculites. Their shells then sank to the bottom to join a minority of older graptolite and trilobite remains which had been disturbed by the same earth movements. A regional review shows that in the mid-Palaeozoic a geosynclinal tract extended throughout most of the length of Malaya and thence northwards into Thailand. ln Malaya the black shale facies is not known to occur to any considerable extent beyond the Mahang basin, but it reappears near Fang in northwest Thailand. |
| The Denekamp- and Paudorf interstadials | 1967 | Vogel, J.C.; Hammen, T. van der | 46(5) | In this article the stratigraphical position, pollen diagrams and C 14 dates of the Denekamp Interstadial are discussed. The C 14 dates for the Paudorf Interstadial are evaluated, and the most reliable dates and data are compared with those of the Denekamp Interstadial. The conclusion is drawn, that the end of both interstadials is contemporaneous. It is possible, however, that the beginning of the Paudorf Interstadial corresponds to the beginning of the Hengelo Interstadial. |
| Over stenen-oriëntatie in het Nederlandse keileem | 1967 | Boekschoten, G.J.; Veenstra, H.J. | 46(5) | Forty-seven measurements on groups of oriented pebbles in Dutch tills of the Saale Glaciation have been carried out at four localities. The tills possess a variable composition according to their source area and the amount of fluvial gravel that has been taken up from older deposits. No distinct orientation of the erratics could be found. The enclosure of glacial rafts and sand lenses in the tills is a common phenomenon, but a preferred orientation of these enclosures is also absent. Either a primary orientation of the effects in the moraine did not occur, or the orientation disappeared by secondary causes. The latter are summarized in the following. The Dutch boulder clays have been deposited on unconsolidated sediments, chiefly sands. Some boulder clay areas are ice-pushed from various directions by glacier tongues belonging to the oscillating edge of the ice cap. Another cause is decalcification, which is a normal process in the boulder clays of the Netherlands. It must be expected that this leaching has influenced the volume and texture of the boulder clays causing settlement. Finally, the rather thin boulder clay layers were disturbed by cryoturbation, which reached a depth of 1.50 m or more. An interesting side-effect of cryoturbation is the occurrence of disintegrated, but chemically unaltered, gneisses and crystalline schists. Periodical thawing and freezing could account for these rotten stones in the boulder clay. |
| Dinoflagellates and their stratigraphic use | 1967 | Clarke, R.F.A. | 46(5) | |
| Isotopic age determinations on a biotite granodiorite and a biotite-hornblende diorite in the coastal area west of Accra, Ghana | 1967 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Hebeda, E.H. ; Verschure, R.H.; Szumlas, F. | 46(5) | |
| #REF! | 1967 | 46(5) | ||
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| Remarkable types of mega cross-stratification in the fluviatile sequence of a subrecent distributary of the Rhine. Amerongen; the Netherlands | 1967 | Boersma, J.R. | 46(6) | A fluviatile sequence probably laid down in recent times by a meandering distributary of the Rhine system was investigated in a large weir-lock excavation in the present E.-W. alluvial valley of the Rhine. It consists mainly of medium to fine grained sands on a large scale grading fine upwards. The predominant sedimentary structure is a mega cross-stratification with considerable set-length. Its analysis in differently orientated sections brought to light that the fluvial megaripples (dunes), which have given rise to this structure, had straight rather than winding crestlines. A large clayey body (width 20 m, max. height 2.5 m) consisting of silts and clays in regular alternation was found to fill an elongated, channel-like depression. Its lower boundary is convex downward and cuts into the above mentioned sands. Highly uncommon types of mega cross-stratified sets were observed in the upper part of the sandy sequence. Sets of relatively coarse-grained large scale cross-strata are seen to be underlain by, and structurally tied up with fine socalled bottomset layers of considerable thickness. These bottomset layers can have a very complex upbuilding in fact the most complete succession of structures observed in them, covers from top to bottom: 1. straight or wavy lamination, 2. small scale climbing cross-stratification with foresets dipping in a direction opposite to that of the mega foresets, 3. irregular trough-shaped sets with foresets variable in direction and steepness, 4. small scale tabular sets of cross-stratification having the same direction as the mega foresets. The structures 1-4 are considered to have been formed simultaneously in this downstream order at the lee of the megaripple (dune) front by: backflow in the vortex. area (1, 2); irregular currents in the flowimpinge area (3); and coflow downstream of the latter (4); structure 1 is found closest to the front, structure 4 occurs farther away from it. The conditions under which these structures were formed are claimed to be low current velocity together with large supply from suspension as occur on the upper pointbar. A comparison with apparently similar types of cross-stratification described for the Folkestone Beds (Lower Greensands, England) revealed fundamental differences. In fact the structures in the latter formation are now suggested to be due to reversing tidal curents of unequal strength, rather than to concommittant actions of mainflow and backflow in the lee of the megaripple crest. |
| De oriëntatie van scheve gelaagdheid, rolstenen en elkele molluskensoorten in de zanden van Kruisschans | 1967 | Michel, W.F.E. | 46(6) | To find out the relationship between a paleocurrent and the orientation of molluscshells, the Pleistocene "Zanden van Kruisschans 2" north of Antwerp were studied. Maximum dip direction of the trough-shaped cross-bedding (fig. 2, 5 and 6) and orientation of the long axis of pebbles (fig. 8 and 9) were measured to determine the paleocurrent direction. Of four mollusc species which were studied, one species showed random orientation (fig. 11), but the other species, two lamellibranchs (fig. 10 and 12) and one gasteropod (Fig. 13) showed a marked orientation to the paleocurrent that moved 260°-080°. It is even possible to find the paleocurrent direction by only using fig. 10 and 13. Of the bivalve shells, 87% lies with its convex side up because this is the most stable orientation in a current as fig. 14 and 15 clearly show. |
| Over de daling van het Noordzeegebied | 1967 | Collette, B.J. | 46(6) | |
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| Development of the North Netherlands gas discovery in Groningen | 1967 | Ruiter, H.J. de; Laan, G. van der; Udink, H.G. | 46(7) | The discovery well of the Groningen gas field was drilled in 7959. At the end of 1963, when more wells had been drilled, and a re-interpretation of seismic data had been made, the large size of the field became apparent. At present proven reserves are estimated at 1650 x 109 m3 (58 x 1012 ft3). The favourable properties of this huge sandstone reservoir (permeability 0.1 - 1 Darcy) and the results of the first production tests led to the decision to concentrate the wells in "clusters" (groups of closely spaced wells). After the first clusters of 6 to 8 wells with a capacity of 6 x 106 m3/day per cluster had come on stream, field tests and additional studies indicated that larger clusters would be possible. Future field observations may lead to further adjustments in the drainage pattern. In order to solve the complicated problem of optimization of the field's development, mathematical reservoir and economic models are being programmed for an electronic computer. |
| Depositional sequences and sand distribution in a deltaic complex | 1967 | Oomkens, E. | 46(7) | The post-glacial delta complex of the Rhône river is a sediment lens in which, volumetrically, coastal-plain deposits and marine deposits are almost equally important. An analysis of the lithological relationships shows that the deltaic sediments can be grouped in one of the following depositional sequences: 1. Regressive sequences 2. Channel-fill sequences 3. Transgressive sequences. Regressive sequences are due to a process whereby sediment-laden river water enters a basin that is filled with water of higher density (e.g. sea or lagoon). This process produces a sediment body that contains finegrained sediment at its base and dominantly coarse grained sediment at its top (upward coarsening). The topmost sand member may reach a thickness of 10 metres. The sand is deposited in sheets hundreds of square kilometres in extent. The sand has a gradational contact with the underlying marine clay. Channel-fill sequences are due to a process whereby a decrease in current velocity occurs in a channel. This process produces a sediment body that contains coarse grained sediment at its base and dominantly fine-grained sediment at its top (upward fining). The basal sand member varies widely in shape and texture. Commonly the sand member is elongate and has a width/thickness ratio of as much as 1000. Transgressive sequences are due to a process whereby the rate of subsidence exceeds that of sedimentary buildup. This process leads to deposition of a sediment body in which coastal-plain deposits are overlain by coarse grained coastal-barrier deposits (upward coarsening) what are in turn overlain by marine deposits. The sand member varies in thickness but is seldom more than 2 metres thick. It occurs in sheets. The sand commonly has a gradational contact with underlying coastal-plain clays. |
| #REF! | 1967 | 46(7) | ||
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| The duality of orogenic belts | 1967 | Zwart, H.J. | 46(8) | A twofold classification of the orogenic belts of the word is proposed, based in first instance on the facies series of the metamorphic rocks. The Hercynian and Alpine orogens of Europe are reviewed in detail and are found to differ respectively in several ways: (1) low pressure metamorphism with andalusite and cordierite vs. high pressure metamorphism with glaucophane, sodium pyroxene, lawsonite and kyanite, (2) thin vs. thick metamorphic zones, (3) abundant vs. few granites and migmatites, (4) few vs. abundant ophiolites and ultrabasites, (5) broad vs. narrow orogen, (6) small vs. large uplift, (z) scarce vs. dominant nappe structures. The Caledonian orogen of Europe is examined and found to be intermediate in nature between the "Hercynotype" and "Alpinotype" orogens. The Svecofennian- Karelian belt of the Baltic shield is found to be a typical Hercynotype orogen. The paired metamorphic belts of the Circumpacific region appear to be a new element in the earth's history and tend to emphasize the peculiar character of the Pacific Ocean. It seems probable that the thermal history of the earth has not appreciably changed during the last 2500 million years. The pressure-temperature fields of the various facies and facies series based on field and experimental work are discussed. Finally the causes of regional metamorphism are considered. |
| In Memoriam Professor Pierre Pruvost | 1967 | 46(8) | ||
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| Van de voorzitter | 1967 | Sitter, L.U. de | 46(9) | |
| In memoriam - Dr. P. Kruizinga | 1967 | Faber, F.J. | 46(9) | |
| The late Tertiary peneplain of South Limburg (The Netherlands) silifications and fossil soils; a geological and pedological investigation | 1967 | Broek, J.M.M. van den; Waals, L. van der | 46(9) | South Limburg formed the border-zone of a large West European peneplain during the Tertiary and the Late Tertiary. Thin local deposits of strongly weathered and corroded sand and gravel, strongly weathered outcrops of underlying formations, deep fossil soils and extensive surface silicifications are the characteristic features of this peneplain. Through a combined geological and pedological survey these features were found to be interrelated. They are the result of typical climatic circumstances and the associated vegetation acting on the earth surface. Such influences can leave their marks on the surface only during a period of geological calm: a period without any noticeable sedimentation or erosion. Such periods generally escape a geologist's observation; they Me of utmost importance to the soil scientist. In South Limburg the Late Tertiary peneplain is partly covered by Pleistocene Maas deposits (in the western parts); the rest of this surface is dissected and remodeled during the Pleistocene (the eastern part). From our systematic inventory a tentative description can be given of the important features of the environment during these times. In the long periods of geological calm a strong weathering developed as a result of a warm, humid climate with dry periods of several weeks. Erosion has been unimportant and restricted mainly to the strongly weathered surface material, This material has been shifted over short distances only. A thin discontinuous sheet of sediments developed on the peneplain, that has been named the Basal gravel complex. The deposits of the borders of the peneplain and of the contiguous graben are much thicker and easier to enravel stratigraphically. This fringe area has been called the accumulation region. Soil forming processes have produced rather deep soils on the peneplain as well as in the deposits of the Basal gravel complex. Mobilisation of silica produced extensive surface silicification of limestones and in well drained clayless sands; these features compare favourably with the silcrete duricrusts in other parts of the world. In South Limburg the peneplain is later transformed by erosion, furrowing, the influences of frost periods and the covering with younger sediments during the Pleistocene. In other parts of the world such fossil table lands are much better conserved because the climate became more arid. |
| The role of micro-crack systems in the spheroidal wheatering of an intrusive granite in galicia (NW Spain) | 1967 | Bisdom, E.B.A. | 46(9) | The phenomenon of spheroidal weathering is related to the development of micro-crack systems. Between the "unweathered coarse granite" of zone 1 and the boulder surface a "limonite" band can be distinguished, which can be divided into two zones (2 and 3) according to the pattern of the micro-cracks. Scales are formed in zone 1 along cracks lying roughly parallel to the boulder surface and becoming macro-cracks in zone 4, where the scales are released. The results of this study of the crack system formed during the spheroidal weathering of a coarse-grained granite throw doubt on theories that explain the spheroidal shape as being due to either magmatic cores or the release of confining pressure. Two terms are used in a special sense in this paper, viz. concentric banding, resulting from the crack system involved in spheroidal weathering, and ghost structure, which is here defined as the phenomenon seen in a regolith in situ after the boulder has completely weathered away. |
| #REF! | 1967 | 46(9) | ||
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| Seismic profiling in the North Sea Basin | 1967 | Lagaay, R.A.; Collette, B.J.; Schouten, J.A. | 46(10) | Seismic sections of the upper sedimentary layers and an isochron map of the base Tertiary in the southern part of the North Sea basin are presented. They are the result of an instrument testing program with an air gun profiler. Several structural features of the Cenozoic can be correlated with the geology of adjacent areas. An important aspect of the formation of the North Sea basin is the differential sagging, leading to the formation of subbasins that shift place in time. |
| Flat-bottomed glacial valleys, braided rivers and the beaver | 1967 | Rutten, M.G. | 46(10) | Flat-bottomed glacial valleys on the northern continents owe this feature not to aggradation by braided rivers, but to the beaver. |
| On the occurrence of the scyphomedusa in the Cambrian of the Cantabrian mountains (NW Spain) | 1967 | Meer Mohr, C.G. van der; Okulitch, V.J. | 46(10) | |
| In defense of the Orbulina datum | 1967 | Soediono, H. | 46(10) | Brandy's suggestions that Orbulina is biphyletic and the Orbulina datum diachronous are rejected |
| Isotopic age determinations on granitic rocks in Northern Portugal | 1967 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Verschure, R.H.; Hebeda, E.H. | 46(10) | |
| Seventh international sedimentological congress, Great Britain 1967 | 1967 | Jong, J.D. de | 46(10) | |
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| Das paläozoikum im gebiet zwischen San Benito und Torrecampo (Sierra Morena/Spanien) | 1967 | Puschmann, H. | 46(11) | A section published by Triguero (1961) from the area north of Torrecampo (Prov. Córdoba) was remapped. Some different stratigraphic and tectonic points of view resulted from this investigation. Bed rocks were identified as the "Armorikanische Quarzit" (deep seated Ordovician) up to the deep lying part of the Lower Carboniferous series in the area which is highly tectonically disturbed. Facies and stratigraphy correspond to those of northern Sierra Morena. A stratigraphicaI break includes the higher Siegen, Ems and Middle Devonian. (Triguero, however, suggested a stratigraphical break from Ludlow up to Siegen.) Upper Devonian (Frasnien) Iies conform on the Siegen-Quarzit (deeper seated Siegen) contrary to the former conception. |
| Sense of fault displacements | 1967 | Tjia, H.D. | 46(11) | The direction with smoother touch along a fault plane parallel to the slickensides does not invariably correspond with the direction of fault displacement. There are more fault plane features which produce coarser touch in the direction of motion than there are markings which feel smooth in that direction; therefore, the smoother touch criterion for interpreting fault movements should be discarded. Excellent directional indicators on fault planes include: Prod marks, tension fractures and associated steps, crescentic gouges, the attitude of secondary shear fractures, chattermarks, and knobbly protuberances resembling "roches moutonnées". Separately the following markings are not reliable, because similar-looking features may be caused by more than one process: Pluck marks and steps formed through stick-slip and spalling; triangular scratches and bruises; spurs and trails; drag which may have experienced elastic rebound. |
| Sur la présence d'éléments du Bétique de Málaga au sud de la Sierra Nevada, près de cherín (Espagne Méridionale) | 1967 | Bodenhausen, J.W.A.; Fontboté, J.M.; Simon, O.J. | 46(11) | |
| The relation between the Betic of Málaga and some post-eocene formations in the area near la Fuensanta-La Parroquia (Provincia de Murcia, SE Spain) | 1967 | Geel, T. | 46(11) | An interpretation of the geology of the La Yesera and El Cimbre locations near Fuensanta-La Parroquia is given, which differs from that of Fernex et al. (1965). In La Yesera evidence has been found for major tectonic movements which took place in the interval between the deposition of Bolli's (1957) Globorotalia kugleri Zone and the lower part of Bolli's (1957) Globigerinatella insueta Zone, that is probably in the upper Oligocene-lower Miocene. |
| A comparative table of recently published geological time-scales for the Phanerozoic time - explanatory notice | 1967 | 46(11) | ||
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| In memoriam - Prof. dr. B.G. Escher | 1967 | 46(12) | ||
| L'Unakite du cotentin | 1967 | Escher, B.G.; Plas, L. van der; Veen, A.H. van der | 46(12) | |
| Geometrical and time relationships for three fold systems and a subsidiary movement phase in metamorphic rocks south of Bagnères-de-Bigorre, French Pyrenees | 1967 | Read, R.A. | 46(12) | In an area of differential, regional metamorphism, the main aspects of the structural history are basically similar to those established for the eastern Pyrenees (Zwart, 1963a), and are related to at least two generations of folding and an intermediate phase of deformation. The first period of folding is associated with an axial plane slaty cleavage and has produced the most prominent structures in the region (EW trending). Two sets of small scale, asymmetric folds are associated with axial plane, strain slip cleavages (NS and EW striking) and post-date first phase structures. These later generation fold systems show differential development on all scales and although, in certain instances, they can be physically distinguished, their chronological relationship remains undecided. Andalusite and staurolite porphyroblasts grew between the first and second phases of deformation and have internal fabric configurations compatible with a period of movement occuring towards the end of the growth period of the porphyroblasts and involving renewed slip on the first phase cleavage about NS trending axes of internal rotation. This subsidiary movement phase appears to be kinematically related to the NS striking strain slip cleavage system. A concept of large scale internal rotation associated with the strain slip cleavage systems is basically consistent with derivation of flat-lying first phase cleavage orientations from initially steeper attitudes. |
| A rapid reconnaissance of the main clay mineral provinces in the Guyanas | 1967 | Brinkman, R. | 46(12) | Major differences in clay mineralogy correspond to the major landscape boundaries in the Guyanas. Two of the landscapes have a rather uniform clay mineral composition and two are more variable. Small amounts of accessory non-clay minerals occur in the clay fraction of many samples; clay-size quartz is generally present. The young coastal plain and the tidal river (estuary) alluvium belong to a rather uniform clay mineral association containing a mixture of smectite, illite and kandite with a cation exchange capacity of about 40-50 me/100 g clay. Parent material appears to be Amazon mud reworked by the sea. The old coastal plain is a complex of three clay mineral associations containing smectite, illite and kandite; illite and kandite; and kandite. The last two of these have exchange capacities of about 25-35 me/100s clay. The three associations may have a common parent material similar to that of the young coastal plain; the variability may be caused by acid destruction of part of the clays due to pyrite oxidation. The white and Brown Sands plateau appears to be part of one vast uniform clay mineral association, also occurring in Brazil and containing kandite with very low exchange capacity: 2-4 me/100g clay. The low exchange capacity may have been caused by differential transport seaward of the finest clay fraction during deposition of the sediments. The interior residual and alluvial areas consist of two clay mineral associations, containing kandite with or without illite. Exchange capacities are about 10-20 me/100g clay. |
| Vergleich des "vetschauer-kalkes" der Aachener kreide mit dem Kreide-profil von Süd-Limburg anhand von coccolithen | 1967 | Vangerow, E.F.; Schloemer, W. | 46(12) | By making use of Coccolith spectra an attempt is made to compare the "Vetschauer Kalk" of the Aachen cretaceous and the "Kunrade chalk" with the wellknown chalkprofiie of the Maas Valley. Most likely 'we may assume that the "Vetschauer Kalk" corresponds only with the lowest Maastricht Chalk, i.e. the lower part of the foraminiferal zone H, whereas the "Kunrade Chalk" belongs to the region of foraminiferal zone H - K. The Postmaastrichtian Chalk from Houthem shows a distinct floral cutting as opposed to the subjacent Maastrichtian layers. So this chalk might be attributed to the Danian. |
| Upper Cretaceous larger foraminifera in the subbetic south of Caravaca (Prov. Murcia - SE Spain) | 1967 | Veen, G.W. van | 46(12) | Fragments of larger Foraminifera have been found in sandy intercalations of an Upper Cretaceous pelagic limestone sequence of the Subbetic south of Caravaca. The author believes that these larger Foraminifera have been derived from the Prebetic in the north, and emplaced by turbidity currents. |
| De laatglaciale geschiedenis van het verwilderde riviersysteem ten zuidwesten van Nijmegen | 1967 | Teunissen, D.; Oorschot, H.G.C.M. van | 46(12) | A study was made of the peat in the beds in the central part of a fossil braided river system of Würm- (Wisconsin-) glacial age in the vicinity of Nijmegen (Guelderland province, The Netherlands). The results of these investigations point to the fact that this system was vacated by the rivers Rhine and Meuse in late glacial times. The dispersal- and gathering channels were abandoned in the beginning of the Bølling Interstadium and the main channels in the beginning of the Allerød Intersadium. After that time, the gathering channels drained away the rain and melted snow of the region, because they were situated in a faint depression in the landscape. Thus the filling material in the gathering channels remained more or less sandy until Boreal times whereas, for a long period prior to that, the mean channels had been filled with peat deposits. After the end of the Boreal all investigated channels have filled exclusively by peat until Subboreal or Subatlantic times. |
| Relation between Neogene sedimentation and late orogenic movements in the eastern Betic Cordilleras (SE Spain) | 1967 | Völk, H.R. | 46(12) | Essentially the sedimentary rock sequence of the Neogene basin of Vera in south-east Spain can be divided into an older and a younger group of formation, which are separated by an angular unconformity. Both groups are clearly distinguished by a different deformational pattern and a different detritus composition. In the Younger Neogene formations – in contrast to the Older ones - a striking domination of clastic components were found originating from higher grade metamorphic rocks of the deepest tectonic units of the Betic orogene, viz. the "Nevado-Filabrides". The almost complete lack of higher metamorphic clastic material in the Older Neogene formations together with the absence of these older formations along the western margin and the adjacent uplands of the Vera basin - as far as it is bordered by rocks of the "Nevado-Filabrides" - points to a rapid uplift of the central Betic zone in Middle Miocene times (VöIk 1967, p. 136/137. These movements are supposed to have affected large parts of the eastern Betic Cordilleras. Further arguments are advanced for a tentative correlation with the "younger phase of the later tectogenesis" (Voet), 1967)2 of the Betic orogene as working hypothesis. |
| #REF! | 1967 | 46(12) | ||
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| Change of command | 1968 | Jong, J.D. de | 47(1) | |
| On criteria for the continuance of flute marks, and their implications | 1968 | Allen, J.R.L. | 47(1) | A consideration of the structure of the region of separated flow generated at a negative step when Reynolds numbers are large, and of the mechanics of the turbulent suspension of sediment, leads to two criteria for the continued growth of flute marks fashioned on a mud bed by a current. These marks are well known from turbidites, and are not uncommon in other sedimentary facies. The criteria have the general form Ucrit=f1(Vg) = f2(D) in which Ucrit is the critical flow velocity of a current bearing sediment of physical size D or of effective falling velocity 4, Flutes continue to grow provided that U > Ucrit but when U < Ucrit become infilled with grains or completely covered over by a grain layer. Alternatively, the criteria can be expressed in terms of flow power, whence an inverse correlation emerges, in the case of turbidites bearing flutes, between the Bouma division which begins the turbidite and a characteristic value of D for that division. |
| Isotopic age determinations on Surinam rocks, 3. Proterozoic and Permo-Triassic basalt magmatism in the Guiana shield | 1968 | Priem, H.N.A.; Hebeda, E.H.; Boelrijk, N.A.I.M.; Verschure, R.H. | 47(1) | K-Ar measurements show that basalt magma has intruded the basement rocks and Roraima deposits in Surinam (Dutch Guiana) 1690 ± 100 m.y. ago (Early to Middle Proterozoic) and 221 ± 10 m.y. ago (Lower Triassic or Upper Permian). The Permo-Triassic dolerites are augite dolerites rich in iron ore and with K/Rb ratios between 267 and 309. The Proterozoic dolerites carry hypersthene in addition to augite, contain less iron ore and have K/Rb ratios between 128 and 233. |
| A new concept of the Paleotectonic set-up of a part of northern Peninsular India with special reference to the great boundary faults | 1968 | Tewari, A.P. | 47(1) | Existence of a deep/fundamental fault in parts of the Mirzapur district, Uttar Pradesh, India, which lies along the northern limits of Peninsulat India, has been examined in places by the author. The fault, which is trans-subcontinental in dimension and recurrent in activity, gives a sharp tectonic break in Peninsular India, and not only divides the Vindhyans from the Pre-Vindhyans (Flysch and Molasse Formations) but also limits the extension of the lower-Gondwanas in Peninsular India, Hence the author feels that it should be designated as a Great Boundary Fault, Westward extension of the Great Boundary Fault through the vast area covered with the Deccan Trap, leads one to believe that this fault has provided channel for the upwelling of the Deccan Trap. It is interesting to note that earlier (1938), Heron had established a similar fault over a length of 800 KM in Rajasthan. He did not, however, discuss the lateral extension of the fault towards the south when it was lost under the Trap country. The author is led to believe that the Great Boundary Fault of Rajasthan swings to the east to form the Narmada-Son valleys, now filled with Pleistocene and alluvium terraces, and extends not only in the Mirzapur District under an identical geological set up and tectonic framework but also continues eastwards to the Palamau and Gaya districts of Bihar. With this correlation the author has deciphered a new tectonic picture of northern Peninsular India, The author is also of the view that this new concept would be helpful in deciphering the continuity of the important sulphide and other mineralized belts/zones of Rajasthan in the Mirzapur district and their correlation with that of the Bihar area. The author also points out in this paper the possibility of crustal folding involving the Vindhyans and the Pre-Vindhyans together with the Great Boundary Faults along the southern fringe of the Bundelkhand massif. If this view is accepted the possible age of this Great Crustal Fold could be related to the Hercynian orogeny, which is based on the distribution of the marine Permo-Carboniferous fauna along a great regional arc (i.e. between Bap in Rajasthan, Umaria and Manendragarh in Madhya Pradesh and Daltanganj in Bihar). |
| Coal rank and lowest-grade regional metamorphism in the souther Bowen Basin, Queensland, Australia | 1968 | Kisch, H.J. | 47(1) | The mineralogy of sedimentary rocks associated with Upper Permian coals in eastern Queensland, ranging in degree of coalification or “rank” from medium-volatile bituminous to semi-anthracite, is described. Kaolinite is the predominant clay mineral associated with the lower-rank coals: chlorite is absent and siderite is the predominant carbonate. At Bluff chlorite makes its appearance in a kaolinite tonstein in coal with 89% carbon. In the shales, feldspathic wackes, and tonsteins associated with the Baralaba semi-anthracites (90-91,5% carbon), kaotinite has completely given way to chlorite and illite, and ankerite is the major carbonate. The previously described chlorite-dioctahedral 1M illite crystal tonsteins at Baralaba (Kisch, 1966a) are probably laterally equivalent to kaolinite tonsteins in medium-volatile bituminous coal at Moura. The absence of zeolites from the rocks investigated is considered to reflect the high μCO2/μH2O chemical potential ratio during burial metamorphism. The coal rank in association with which chlorite and illite formed at the expense of kaolinite at Baralaba is higher than that at which laumontite-rich assemblages appear in tuffs and volcanic sandstones in the Sydney Basin of New South Wales (Kisch, 1966b). Coal rank may be an important aid in correlating burial metamorphic assemblages in areas with and without zeolites, and other hydrous calciumaluminosilicates. |
| A geological reconnaissance in the Nassau range, West new Guinea | 1968 | Dow, D.B. | 47(1) | In 1961 an attempt to make the first climb of the Carstenz Pyramid in West New Guinea ended in failure, but during the approach to the mountains much new country on the northern side of the Nassau Range was explored. The observations made during the trip are the only geological information at present available for a large area of the Nassau Range. Remarkably clean quartz sandstone of probable Mesozoic age forms the basement on which Lower Tertiary marine sediments were deposited, probably unconformably. Faulting commenced at an early stage of the sedimentation, breaking the area into a series of horsts and grabens which had a considerable influence on sedimentation. The sedimentation was punctuated, probably in the Lower Miocene, by andesitic vulcanism. Well-preserved erosion features and moraine deposits due to a late Pleistocene glaciation are found over about 12,000 feet: there is also some evidence of an earlier glaciation. The Tertiary rocks are generally only gently folded but they are dislocated by long, slightly curved, faults of considelable vertical displacement. They show many feature characteristic of transcurrent faults, and it is possible that horizontal movement on the faults was predominant. |
| Discussion; On A geological reconnaissance in the Nassau range, West new Guinea | 1968 | Visser, W.A. | 47(1) | |
| Geomorphology and sedimentary petrology in the southern gulf of St. Lawrence | 1968 | Nota, D.J.G. | 47(1) | |
| Paleomagnetisme en aardexpansie | 1968 | Hospers, J. | 47(1) | |
| Invalidity of the billiton granite, Indonesia, for defining the Jurassic/Upper Triassic boundary in the Thai-Malayan orogen | 1968 | Strachan Hutchison, C. | 47(1) | The Billiton granite is shown both stratigraphically and radiometrically to be invalid for setting the base of the Jurassic at 180 ± 5 m.y.. A review of the nore recent stratigraphic and radiometric developments in this region shows that the evolution of the Thai-Malayan orogen and the emplacement of the “tin-belt” granite is much more complex than the model upon which the age of the Billiton granite was based. |
| Comments on: Invalidity of the billiton granite, Indonesia, for defining the Jurassic/Upper Triassic boundary in the Thai-Malayan orogen, by C.S. Hutchison | 1968 | Schürmann, H.M.E. | 47(1) | |
| #REF! | 1968 | 47(1) | ||
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| Notulen van de Buitengewone Ledenvergadering | 1968 | 47(1) | ||
| The Papuan geosyncline and the concept of geosynclines | 1968 | Hermes, J.J. | 47(2) | The geologic history of the Papuan geosyncline is shortly described. Attention is drawn to the fact that due to the collision between the Asian and the Australian continent, a segment of the size of the Papuan geosyncline was torn loose, and both bent and broken, leading to the present sinuous shape of the western part of the island (fig. 5). It is suggested that some other sinuous mountain chains may have acquired their present shape in this manner. The development of the Papuan geosyncline is compared with the model of Aubouin based on the Hellenides of Greece and that of Dietz based on his interpretation of the Atlantic CoastaI Plain geosyncline. Important differences exist between the three models. The nomenclature of geosynclines is discussed. |
| Mineralogical composition of material less than 500 micron from a red and grey boulder clay sample in the Netherlands | 1968 | Riezebos, P.A. | 47(2) | Methods devised to collect mineral data for specific purposes have sometimes been used rather indiscriminately in weathering, sedimentological and soil studies. This may partly be due to insufficient knowledge about the dispersion of mineralogical information within the sample material. As an illustration of such a distribution the results of a fractionated optical analysis of light as well heavy concentrates from two well-known glacial deposits ale here presented. At the same time the results of an ore microscopic analysis of the opaque grains in the heavy concentrates from the total 50-500 micron size range are given. |
| On the geology of San Andres islands, western Caribbean | 1968 | Milliman, J.D.; Supko, P.R. | 47(2) | San Andres Island is an uplifted limestone island in the Western Caribbean. Analogy with the surrounding islands and nearby mainland of Central America suggests San Andres to have a volcanic base, although bathymetric and magnetometer data indicate it to be deep-seated. |
| A late-glacial volcanic ash deposit in southeastern Belgium | 1968 | Hulshof, A.K.; Jungerius, P.D.; Riezebos, P.A. | 47(2) | A volcanic ash deposit was found in a peat bog in the Semois valley near Arlon, Belgium. Palynological evidence points to an Allerød age. The volcanic minerals in Belgium and Luxembourg have previously been correlated with ash deposits of the same age in central Germany which resulted from eruptions in the Laacher See area at a time of westerly winds. Although the Laacher See is not excluded as a possible source of origin, the ash in Belgium differs from known Laacher See deposits in relative importance of brown amphibole and sphene, and absence of volcanic glass and pumice ("Bims”). The ash is the product of an eruption in the Eifel region during a period of northeasterly wind. |
| Note on the formation of stylolites | 1968 | Schot, E.H.; Park, W.C. | 47(2) | |
| Pre- or post-induration formation of stylolite seams: a reply | 1968 | Manten, A.A. | 47(2) | |
| Pollen analysis at the Cueva del Toll, Catalonia: a ctritical re-appraisal | 1968 | Butzer, K.W.; Freeman, L.G. | 47(2) | The published paleo-environmental data from the Cueva del Toll are discussed. The two pollen profiles by Donner-Kurtén and by Florschütz-Menéndez refer to the same stratigraphic units although there are small but ecologically significant differences between these profiles. The faunal evidence suggests strongly that the pollen sequence covers part or most of the Last glacial, as suggested by Donner and Kurtén. However, the climatic interpretation suggested by these authors to account for the fluctuations of AP: NAP pollen ratios seems open to question. |
| Evolutie van een embryo | 1968 | Vlerk, I.M. van der | 47(2) | A worldwide correlation based on an association of genera of larger foraminifera is unreliable. It proceeds from the wrong assumption that all these genera lived in the same milieu. Instead of this method of correlation another one is introduced. It is based on the experience that the curvature of the wall between the first and second chamber of the embryo of a megalospheric Lepidocyclina increases persistently when going from older to younger strata. This parameter is called the "degree of curvature”. Investigations on both lepidocyclinas and planktonic foraminifers (by J,A. Postuma; see: Proc. Kon. Ak. Wet. Amsterdam, B,4, 1967,391-398) from a well documented section in East Java & Madura and 5 localities in Europe and America, combined with the examingation of lepidocyclinas from Chattian, Aquitanian and Burdigalian localities in Europe led to the hypothesis: “same degree of curvature’ = same age”. Starting from this hypothesis the following conclusions are drawn (see table): 1 the boundary Oligocene/Miocene should be placed in the Globorotalia Kugleri - zone. 2. the Tertiary-e5 of the Far East is to be correlated with the Chattian, the Aquitanian and part of the Burdigalian of Europe. 3. the boundary Tertiary e/f should be placed within the Burdigalian. 4. the lepidocyclinas from an Aquitanian and from a Burdigalian locality in Europe have “degree's of curvature” which do not differ significantly (Student's t-test). |
| The Lembang fault, West Java | 1968 | Tjia, H.D. | 47(2) | The Lembang fault consists of a northward faci.ng scarp, exposed over 22 kilometers, which in general strikes parallel to Java's longitudinal axis. Former investigators have attributed predominantly dip slip displacements to this fault. However, topographic, morphologic, and structural evidences indicate the western part of the Lembang fault, west of the Tjikapundung valley, during its latest development to be essentially strike slip in nature and possessing sinistral sense, The horizontal displacement ranges between 75 m and 250 m with an average of 140 m. Using the latter figure, it is found that the annual displacement amounts to at least 3 centimeters. The average ratio of strike slip to dip slip is 2 to 1, which is in agreement with the youngest recorded movement. The eastern part of the fault between Maribaja and Mount Pulusari is a dip slip fault and has exposed throws which range from 130 m to 450 m. Three important, tranverse faults caused the crestline to increase stepwise in elevation from west to east. |
| Recent sediments in the eastern part of the lake Geneva (Lac Léman) | 1968 | Houbolt, J.J.H.C.; Jonker, J.B.M. | 47(2) | The sedimentation in the eastern part of the Lake of Geneva was studied from cores and seismic profiler records, It was found that off the mouth of the Rhône river a sublacustrine channel with natural levees leads down to a depth of about 200m. The channel bottom and natural Ievees were found to be sandy, but outside the natural levees mud was encountered. Below a depth of about 200 metres the natural levees along the channel disappear and sand layers are found in the vicinity of the channel. The channel disappears completely at a depth of about 280 m. Around and below the point where the channel fades out, a fan-shaped sand body occurs, which reaches to the deepest part of the Lake, the central plain, at 309 m. The sediments on this central plain contain only a few very thin sand layers. The bottom of the sediment fill of the Lake was found to plunge to the east, The “top Molasse” reflector was lost halfway up the delta foreslope, at about 750 milliseconds. |
| Mineral assemblages in Rotliegendes | 1968 | Booy, T. de | 47(2) | |
| Surface installations and operations | 1968 | Bijl, P.C.J. | 47(2) | |
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| Edelstenen en hun dubbelgangers | 1968 | Zwaan, P.C. | 47(2) | |
| Exploration and delineation of the Groningen Gas Field | 1968 | Groen, D.M.W. te; Steenken, W.F. | 47(2) | |
| Petrophysics Groningen Gas Field | 1968 | Laan, G. van der | 47(2) | |
| Reservoir behaviour and field development Groningen Gas Field | 1968 | Udink, H.G. | 47(2) | |
| Drilling experience Groningen Gas Field | 1968 | Bor, A.M.W. | 47(2) | |
| Subsurface installations and operations Groningen Gas Field | 1968 | Willems, J.F.J. | 47(2) | |
| On the character and classification of bed forms | 1968 | Allen, J.R.L. | 47(3) | A bed form is any deviation from a flat bed, that depends for its origin on an interaction between a bed material and a fluid flow such that there occurs a spatially non-uniform transfer of material from bed to flow or between bed and flow. The occurrence of bed forms is independent of the precise nature of the fluid, whether a liquid or gas or a flow of granular matter, and also of the nature of the bed material, whether cohesionless or cohesive. In nature bed forms are generated by the wind and by sand avalanches, as well as by river, wave and tidal currents. Bed forms arise on surfaces of loose sand or gravel, on beds of mud or rock, and on surfaces of ice or hardened snow. An analysis of the more important of the determinative physical processes allows bed forms to be classified according to: 1) the orientation of the form and the directional properties of the parent flow system, 2) the character of the boundary on which the form arises, and 3) the dependence of the scale of the form on the scale of the parent flow system. By an application of these criteria, bed forms hitherto treated disparately are brought into revealing juxtapositions that suggest where general explanations of bed forms can be obtained in future. |
| Geology and Paleomagnetism of an anticlinal structure in Lower Triassic sediments near Atienza (Guadalajara, Spain) | 1968 | Voo, R. van der | 47(3) | The results of detailed geological mapping in an anticlinal structure of Lower Triassic sediments are presented. For paleomagnetic studies 60 samples were collected of fine-grained red sandstones and their magnetic behaviour is analysed. Most of the samples contained only one type of magnetization, directed along the recent local geomagnetic field, and it is assumed that these magnetizations are secondary. About 25% of the samples appeared to have stable magnetizations with directions diverging from the present-day geomagnetic field in Spain. These directions, however, proved not to be characteristic for the Triassic geomagnetic field, since after unfolding their data were inconsistent. |
| Isotopic age determinations on surinam rocks, 4 ages of basement rocks in North-Western Surinam and of the Roraima tuff at Tafelberg | 1968 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Hebeda, E.H.; Verschure, R.H.; Verdurmen, E.A.T. | 47(3) | (1) Rb-Sr measurements show that in the Avanavero region (Kabalebo River, north-western Surinam) deposition of the Dalbana and Matapi volcanics, and subsequent emplacement of the granite-quartzdiorite batholiths took place in a single orogenic period, approximately 1800-1900 million years ago. Since the Dalbana volcanics are generally correlated with the Iwokrama Formation in Guyana, this raises some doubts on the K-Ar age of (2595 ± 125) x 106yr measured on riebeckite from the Makarapan Granite intruding the Iwokrama Formation (Snelling & McConnell, 1966). (2) A (1200 ± 100) x 106yr old metamorphic event, designated as the Nickerie Metamorphic Episode, caused widespread rejuvenation of micas in north-western Surinam. Probably, a long, broad belt of overprinted age values down to (1200 ± 100) x 106yr extends from south-eastern Guyana east-to-eastnortheastward through Guyana and northeastward through Surinam to the Atlantic coast. (3) Rb-Sr and K-Ar age determinations on a tuff from the Roraima Formation at Tafelberg, central Surinam, point to an age of (1610 ± 60) x 106yr. Probably, both Roraima sedimentation and subsequent dolerite intrusions took place, approximately, 1600-1700 million years ago. |
| Mineral analysis by means of thin layer chromatography using liquid ion-exchangers. Part III Data on non-sulphidic minerals | 1968 | Sijperda, W.S.; Vries, G. de | 47(3) | Using the rapid chromatographic technique described in part I 25 minerals have been analyzed. in order to obtain data concerning detection and Rf value |
| The age of Eifel Maars as shown by the presence of Laacher See ash of Allerød age | 1968 | Jungerius, P.D.; Riezebos, P.A.; Slotboom, R.T. | 47(3) | Laacher See ash of Allerød age, with a characteristic heavy mineral assemblage of brown amphibole, pyroxene and sphene, occurs as intercalations in the peat bogs of the western Eifel. Previously this ash has been attributed to eruptions of local maars and has erroneously been used to date these maars. It is here shown that the maar volcanism of the western Eifel terminated prior to the final Laacher See eruption. |
| Das Quartärprofil von Kärlich/Neuwieder Becken | 1968 | Brunnacker, K. | 47(3) | The Quaternary deposits in the clay-pit of Kärlich near Koblenz have been re-examined. There are two gravel beds at the bottom, followed by a loam of back swamp deposits. They are followed by loess beds of some glaciation phases, the lowest of which is far more complex than the others, similar as has been found at Regensburg3Bavaria. The loess beds can be correlated with the four classical Alpine glaciations. A more detailed description is under preparation. |
| Geologische waarnemingen op de Noordzee | 1968 | Heybroek, P. | 47(3) | |
| Geologische waarnemingen op de Noordzee | 1968 | Heybroek, P. | 47(3) | Big plate F1 |
| Geologische waarnemingen op de Noordzee | 1968 | Heybroek, P. | 47(3) | Big plate F2 |
| Geologische waarnemingen op de Noordzee | 1968 | Heybroek, P. | 47(3) | Big plate F3 |
| Het boren naar olie en gas op zee | 1968 | Buskingm B.E.; B.I.P.M. | 47(3) | |
| A new coring apparatus for unconsolidated sediments | 1968 | Overzee, B. | 47(3) | |
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| Recent sediments in the southern Bight of the North Sea | 1968 | Houbolt, J.J.H.C. | 47(4) | The recent sediments of the southern bight of the North Sea were studied mainly as a possible model for the interpretation of fossil sand bodies, The area examined lies between England, Belgium and the Netherlands. It is an area of strong tidal currents. A group of ridges were found to consist of sand and to rest on an essentially flat surface which is a continuation of the surrounding sea bottom. The ridges of the Well Bank area are asymmetric in cross section and are oriented parallel to the current direction. Sand seems to be transported obliquely over the gentle southwest slope of the ridges in a northerly direction towards the crest, whence it is deposited on their steeper northeast flank. This process gives rise to an internal cross-stratification which is visible on the sparker records. The ridges of the Well Bank area seem to be moving slowly northeastwards. Sparker records of the ridges formed by sand accumulation outside the WelI Bank area revealed no internal structures and foreset directions observed in cores of them were found to be erratic and their asymmetry in cross section was found to be irregular. It is therefore impossible to deduce their internal structures from surface observations. It is certain, however, that they are all isolated sand bodies standing on a flat subsurface that is exposed outside their flanks. The fact that the flood current does not follow the same path as the ebb current gives some of these ridges very complicated forms (e.g. Flemish Banks and Haisborough Sand), In all cases, it can be stated that the sand of which these sand ridges consist is derived from the sea bottom and not directly from a river mouth. The sand in the ridges of the WeII Bank area seems to have been derived from a glacial outwash fan formed in the area during the last glaciation. The material in the Outer Gabbard and probably the other ridges in the neighbourhood is derived from Tertiary sediments outcropping in that area. The sand in the Flemish Banks, the Hinder Banks, the Sandettie and the Falls is derived from Rhine sands deposited in the area during stages of lower sea level. The Brown Ridge and the Zeeland Ridges were found to have been formed at least partly by erosion of older deposits. Mega-ripples not associated with the sand ridges were found in great abundance in the area off the Dutch coast. They were all found to have their steepest slope towards the NNE. It is suggested that sand is transported towards the NNE in this area and that the fine fraction accumulates on the Texel Spur. This Texel Spur was found to be covered with extremely well sorted fine sands, which were completely churned. There is evidence, though weak, that this Texel Spur sand is 10 meters thick. |
| 1968 | Houbolt, J.J.H.C. | 47(4) | Large enclosure E1 | |
| 1968 | Houbolt, J.J.H.C. | 47(4) | Large enclosure E2 | |
| A survey of the geohydrological and hydrological investigations in the Netherlands | 1968 | Heide, S. van der | 47(4) | In this publication a review is given of the hydrogeological investigations in the Netherlands, After incidental research by private companies for water supply the first systematical studies in hydrogeology have been carried out by the Government Institute for Water Supply, which was founded in 1913. It was also this institute which stimulated the hydrogeological investigations by the Zuyder Zee Works. These developed to one of the most extensive in the Netherlands. Modern methods of investigations were introduced in 1951 with the application of geo-electrical methods to determine the boundary between fresh and salt water in the subsoil. As a result of the success of these methods geo-electrical research was further developed in the Netherlands and is applied now in several cases. Among other modern methods the investigations on C14 and stabile isotopes by Dr. J.C. Vogel have to be mentioned. Extensive new hydrogeological investigations commenced after 1953 as a consequence of the Delta Works in the southwestern part of the Netherlands, Extremely detailed hydrogeological information was obtained by these investigations. On the other hand hydrogeological research was undertaken, mainly after the war, in connection with agricultural problems. These are now dealt with by the Institute of Land and Water Management Research in Wageningen. Studies on ground water in the coal mines in South Limburg have been made and hydrogeological mapping of South and Central Limburg has been carried out by the Geological Bureau in Heerlen. Meanwhile a new institute has been founded with the special task of making hydrogeological maps of the Netherlands. This institute, Dienst Grondwaterverkenning TNO (Ground-Water Survey), includes both the TNO Organization for Geo-electrical Research and the TNO Archives of Ground-Water Levels. |
| Planctonic foraminifera from the Seroe Mainsji formation of Curacao | 1968 | Hermes, J.J. | 47(4) | Planldonic Foraminifera from the Seroe Mainsjie Formation of Curacao cannot be fitted with certainty into one of the biostratigraphic zones recognized by Bolli in Trinidad, although there is no doubt that the fauna is restricted to the upper part of the Middle Eocene. |
| Post glacial sea-level rise in the Christchurch metropolitan area, New Zealand | 1968 | Suggate, R.P. | 47(4) | Radiocarbon-dated samples are discussed in relation to the Iocal stratigraphic sequence, which records post-glacial transgression of the sea followed by regression during progradation of the shoreline. They indicate that sea level apparently rose from -17 m (-58 ft) 8,000 years ago and was still rising when it reached its present level about 5,000 years ago; less certainly the sea was at about -22 m (-73 ft) 9,400 years ago. A sea level 5,000 years ago substantially below that of the present day has been commonly advocated in The Netherlands and elsewhere, but a single post-glacial sea-level curve may not be applicable universally. |
| De invloed van Mg++-ionen op de precipitatie van calcium carbonaat. | 1968 | Groot, K. de | 47(4) | |
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| On the stage | 1968 | Hinte, J.E. van | 47(5) | The fundamental chronostratigraphic unit is the Stage. Each Stage has its own standard, a type section or stratotype. It is irrelevant whether these sections are “complete” and whether successive stratotypes overlap or not. The stratotypes merely form “reference points” in the ideal chronostratigraphic scale. ln the future chronostratigraphic units will be defined as the rocks formed during the years a - b B.C.. Once the age is measured for beds of a known relative age, the traditional time-scale has done its service, Until then the definition of Stage boundaries mostly will be biostratigraphic and therefore cannot be but subjective and susceptible to changes with evolving paleontologic knowledge and concepts; rigid definitions lead only to fruitless discussions. |
| Phase contrast applied in the microscopic study of mineral particles in saprolites | 1968 | Riezebos, P.A. | 47(5) | Knowledge of the mineralogical composition of silt fractions in weathering material is essential, as it may contribute to understand the relationships between mineral assemblages in sand and clay fractions. The shortcomings of bright field microscopy in the identification of such mineral fragments are discussed. The principles of phase contrast are briefly reviewed, as the application of phase contrast accessories, combined with the use of dispersion staining and variable monochromatic light, considerably facilitates the optical identification of these small mineral particles. A further adventage is that mineralogical information from both sand and silt fractions is obtained in the same way, so that alteration of mineral properties and other features are similarly observed and evaluated with decreasing grain sizes, The results of some investigated samples are presented and the data indicate that the mineral constituents produced by alteration and already present in the sand fractions, increase with decreasing silt sizes and that these alteration products are of detrital nature. It is concluded that in order to characterize and to understand the weathering sequence, a mineralogical analysis of sand and silt fractions is needed. |
| Spilite-Keratophyres et ophiolites influence de la traversee dún socle sialique sur le magmatisme initial. | 1968 | Rocci, G.; Juteau, T. | 47(5) | After giving the definition of the initial magmatism, the authors insist on the typical petrographic associations without tackling the so much debated problem of spilitisation. The petrographic range of products given off during the initial magmatism goes from ultrabasic rocks to hypersiliceous acid keratophyres and includes plutonic rocks as well as true lavas. In so big a range it is difficult to know what kind of associations fits to reality. The American geologists for instance, represented by Turner and Verhoogen (1960) introduce a definite distinction between the spilite-keratophyre serie and the peridotite-serpentinegabbro association, considering the fact that the setting of these two groups appear independent. On the other hand the alpine geologists as their spokesman Vuagnat (1963) remarks, after precise field work observations, consider that the ultrabasicgabbro-diabase group cannot be dissociated and constitutes the ophiolitic suite. Therefore the authors of the present work wonder whether; 1) There are really two distinct associations, a basic and acid one i.e. spilite - keratophyre, the other one being ultrabasic and basic i.e, ultrabasites- gabbros-diabases. 2) And if so are the two associations really compatible in the same geosyncline? To answer these two questions two types of observations are made: one concerning the initial volcanism in the northern limb of the hercynian orogen, the other the geosynclinals magmatism in the alpine ranges. A brief comparison of the characteristics of these two types of phenomena leads to the following conclusion: the ultrabasic rocks are widespread in the alpine orogen but are very uncommon in the hercynian one, meanwhile the volcanic acid rocks appear in important masses only in the hercynian range. Consequently the answer to the preceding questions is possible. In fact there are two types of associations of initial volcanism: the first one, basic and acid, essentially effusive, is the spilite-keratophere association; the other one basic and ultrabasic volcano-plutonic includes the ophiolltic alpine type series. |
| Some results of profile drilling along the railroad between Onverwacht and Zanderij, Surinam | 1968 | Levelt, T.W.M.; Quakernaat, J. | 47(5) | The mineralogical composition of clay fractions in samples of a series of borings between Onverwacht and Zanderij admits a subdivision of the sediments south of the lowland bauxite excavations near Onverwacht, Surinam. Layers with kaolinite, an abundance of illite, and with or without montmorillonite are Lelydorp and Demarara sediments. Deeper layers dominant in kaolinite, with traces to moderate amounts of illite, and sometimes montmorillonite seem to be Para sediments. These beds are deposited over sediments with kaolinite clays belonging to the Onverwacht/Coesewijne series. Where borings reach the weathered bedrock the clay is mostly pure, well crystallized kaolinite. A cross section of the zones of equal clay composition show a sedimentation pattern of layers with incised and refilled gullies. A correlation with the stratigraphy in the coastal plain is given. |
| The occurrence of halloysite and gibbsite in peneplain deposits of the Belgian Condroz | 1968 | Buurman, P.; Plas, L. van der | 47(5) | In sands of the Onx and Om formations on the Belgian Condroz Peneplain both hydrated halloysite and dehydrated halloysite have beenlound in sandpits near Louveigné and Florzé. The occurrence of Florzé is accompanied with gibbsite. X-ray diffraction patterns, electronmicrographs, DTA, TGA, scanning calorimetrical analyses and chemical analyses have been made of both samples and are reported. The material may have derived from the type locality of halloysite discovered near Angleur and described in detail by Berthier. Another possible origin is reIated with the climatological history of the early Ardennes peneplain. |
| Rb-Sr age determinations of some gneisses and granites of the Aston-Hospitalet Massif (Pyremees) | 1968 | Jäger, E.; Zwart, H.J. | 47(5) | A number of radiometric Rb/Sr age determinations on muscovites, biotites and whole rock samples from various gneisses and granites of the Aston-Hospitalet massif have been executed. All apparent muscovite ages fall in the range of 255-274 m.y. dating the end of the Hercynian metamorphism. The biotites of the Aston massif give distinctly younger ages, as young as 113 m.y. This is probably due to a period of heating during a metamorphic episode in Mesozoic times. Total rock analyses were performed on eight granites and gneisses. Three of these analyses define an isochron of 475 m.y.; the other five scatter near a straight line corresponding to 300 m.y. Geological observations and Rb-Sr results suggest that these rocks were formed 475 m.y. ago and were remobilized during Hercynian metamorphism 300 m.y. ago. Because of the low initial Sr87/Sr86 combined with extremely high Rb/Sr-ratios, a formation in Precambrian time can be excluded. The high Rb/Sr-ratios point to magmatic and not sedimentary origin. we therefore explain these rocks as Ordovician granites which were metamorphosed during the Hercynian orogeny. |
| Ages of Malayan granites | 1968 | Snelling, N.J.; Bignell, J.D.; Harding, R.R. | 47(5) | The results of Rb:Sr whole rock age determinations on Malayan granites are summarised. They indicate intrusion during the Upper Carboniferous, Triassic, and Upper Cretaceous. The Triassic granites appear to have been intruded during two episodes at circa 230 m.y, and 200 m,y. Most K:Ar ages on micas from the various granites show evidence of having been disturbed by both younger intrusions and other tectonic phenomena, and the simple assumption that K:Ar ages date the intrusion of the host granite is not necessarily valid. |
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| Introduction Instrumental Analysis | 1968 | Roorda, H.J.; Eisma, E. | 47(6) | |
| Instrumental methods in the chemical analysis of minerals | 1968 | Dijkstra, G. | 47(6) | |
| The application of neutron activation analysis in geochemistry | 1968 | Das, H.A.; Sijperda, W.S. | 47(6) | ln geochemical work neutron activation analysis is rapidly gaining upon "classical” techniques such as wet analysis and emission spectrography. The main reason is that activation analysis permits the determination of both major and trace elements; it is a convenient method for the simultaneous determination of a large number of elements in small samples. Moreover, the method is very sensitive for most elements, The present paper deals with neutron activation analysis of rock samples, as performed at the Reactor Centrum Nederland, Petten (NH). The principles of activation analysis are discussed. Then, the determination of silicon, aluminium, iron, potassium, sodium, manganese, scandium, chromium, cobalt, rubidium and cesium is described in more detail, Results, obtained for rock standard G-2, are given. |
| A new automatic sample changer for the Philips X-ray difractometer PW 1050 | 1968 | Porrenga, D.H.; Versmissen, J.L. | 47(6) | |
| Aspects of automation in X-ray spectrometry | 1968 | Porrenga, D.H.; Versmissen, J.L. | 47(6) | In X-ray spectrometry, full or partial automation of the sample preparation, intensity measurement and data processing has both advantages and drawbacks. Special attention is paid to a new automatic sample changer, which has been made at the Koninklijke/Shell Exploratie en Produktie Laboratorium at Rijswijk as an accessory to a Philips vacuum X-ray spectrometer. |
| The TPD electron probe X-ray micro analyzer | 1968 | Fontijn, L.A.; Bok, A.B.; Kornet, J.G. | 47(6) | The article describes an electron probe X-ray micro-analyzer specially designed for mineralogical investigations and constructed for the Department of Mining Engineering of the Technological University, Delft. A miniature magnetic lens is used in the electron optics making it possible to employ a standard Leitz polarization microscope. The specimen can be rotated around the microscope axis and translated in two orthogonal directions. |
| Reflectance measurements on coal | 1968 | Vries, H.A.W. de; Bokhoven, C. | 47(6) | After giving a description of the reflectance-measuring equipment, the authors discuss the relation between degree of coalification (rank) and reflectance. Coal appears to become ever more anisotropic with increasing rank. The anisotropy observed in coal is reminiscent of the optical behavior of a negative mono-axial crystal. The respective merits of reflectance measurements in polarized and non-polarized light are compared; in this connection attention is given to the accuracy of the rank analysis. Further, a method of approximation is indicated for calculating the reflectance in non-polarized light from the reflectances measured parallel to the ordinary and extra-ordinary rays. In conclusion, the optical behaviour is correlated with the coal structure. |
| Microradiography and X-ray microscopy in geology | 1968 | Jongebloed, W.L.; Porrenga, D.H. | 47(6) | Photographs have been made of a specimen of Operculina with an X-ray projection microscope, a light microscope and by means of microradiography. Comparison of the pictures obtained shows that, if original unsectioned specimens are examined, the two X-ray methods are superior to the lightmicroscope technique as regards both depth of focus and penetration power, These methods are moreover non-destructive and time saving. Results obtained also show that for the rapid and routine investigation of microfossils or for detailed study, the microradiography and X-ray microscopy methods are, respectively, equal or superior to the light-microscope technique, |
| An electron luminescence microscope | 1968 | Poole, J.B. le; Bok, A.B.; Boogerd, W.J. | 47(6) | |
| Some aspects of a geochemical investigation in an area with low anomaly contrast in S. Limburg (Netherlands) | 1968 | Dijkstra, S.; Bot, A.C.W.C. | 47(6) | The present paper deals with a number of aspects of different disciplines relevant to a geochemical investigation which was carried out in the southern part of the Dutch province of Limburg, in an area just north of a former Belgian lead-zinc mining district. Some information on the local geography and geology is briefly summarized, and the structural and stratigraphical controls of ore localization at depth are outlined. From the geochemical point of view the area showed several complex features regarding soil formation and lithology. Metal contamination by human activities constituted an additional problem, Soils and stream sediments displayed low lead and zinc contrast, and metal determinations of high precision were therefore required. Under these conditions dithizone field methods proved to be unsatisfactory, whereas good results were obtained with analytical methods based on atomic-absorption spectrophotometry. The laboratory procedures, which satisfied the particular precision requirements, are described and their applicability for general use in various types of geochemical exploration surveys is discussed. A new statistical method for the grouping of spatially related data is introduced, with the aid of this method geochemical contour maps were drawn and significant differences between a number of broad geochemical patterns could be established. |
| Quantitative analysis of the available alumina content by (D.T.A.) in bauxite from "Onverdracht", Surinam | 1968 | Veen, A.H. van der | 47(6) | A linear relation is found between the available alumina content of bauxites from the mine Onverdacht in Suriname and the gibbsite-peak area as determined by d.t.a. (differential thermal analysis). Available alumina is an economic value, which can be determined by means of bomb digestion and subsequent filtration and titration procedures. These procedures are described in detail. The quantitative d.t.a. method, the apparatus applied and the procedures used, are also described and discussed in detail, Special attention is paid to reproducibility of the d.t.a. and to the systematic operator's errors in order to eliminate such errors as far as possible. |
| Gas chromatography its principles and applications in organic geochemistry | 1968 | Schenck, P.A. | 47(6) | This article is a short introduction to the theoretical and practical aspects of gas chromatography. Several applications in - mainly organic - geochemistry are presented. References are given to general and more specialised literature. |
| Mass spectrometry and some of its applications in organic geochemstry | 1968 | Engelhardt, E.D. | 47(6) | |
| Report on the second international summer school on quantitative methods in reflected-light microscopy | 1968 | Uytenbogaardt, W. | 47(6) | A review is given of the organisation of the Second lnternational Summer School on Quantitative Methods in Reflected-Light Microscopy, held in Bensheim (near Frankfurt), Western Germany, 28 August - 2 September, 1967. The lectures given at this Summer School are mentioned and summarized. |
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| Van de voorzitter aan de leden | 1968 | Krol, G.L. | 47(6) | |
| Naar een genootschap - nieuwe stijl? | 1968 | Dijkstra, S.; Weeda, J.; Hols, A.; Tobi, A.C.; Visser, W.A.; Weehuizen, J.M. | 47(6) | |
| Van de voorzitter aan de leden | 1969 | Krol, G.L. | 48(1) | |
| The paths of grain through wave-like bed forms | 1969 | Allen, J.R.L. | 48(1) | From a knowledge of the topography of skin-frictionlines, the paths of transported grains relative to the ground and to bed features are presented for different kinds of wave-Iike bed form encountered in aqueous flows. In the case of a sinusbed (antidunes), the height of the forms and their propagation velocity can be used without correction to measure the rate of downstream transport of sediment involved in the movement of the waves. The flow over a ripple or dune bed is separated' however, and within the forms there occurs a sediment stream moving backward relative to the external flow direction. The rate of downstream transport of sediment involved in movement of the waves is in these cases a net rate depending on the ratio of the thickness of the forward-moving and backwardmoving sediment streams. Thus estimates of bedload transport rate based on the full heights of ripples or dunes can be in substantial error. |
| Analysis of large scale superposed folding in a migmatite terrain | 1969 | Naha, K.; Mukherji, P. | 48(1) | In the "hook syncline" of central Rajasthan, India, the large metasedimentary bands of early Precambrian age, considered to form synclinal cores in the older basement gneisses, represent extensively migmatized palaeosomes. The curious, hook-shaped double closures in the map pattern of these palaeosomes are due to a superposition of tight upright folds with NS-striking axial planes on isoclinal reclined folds plunging westward, a feature duplicated in numerous examples in hand specimen and outcrop. The later folds, which vary in style from open in the southeast to isoclinal in the northwest, have caused a wide scattering in the orientation of the axes and axial planes of the first set of folds. Although the later folds always trend NS, they range in plunge from subhorizontal to vertical, depending on their location in the limbs and hinges of the early folds. Flexure modified by flattening and flow seems to have been the dominant mechanism in the evolution of the folds. Migmatization, which has transgressed the stratigraphic levels, is broadly synkinematic with the first deformation. The style and orientation of the folds of the two systems are mutually incompatible in any single deformation plan. The increase in the intensity of the second deformation westward near the contact of the younger Precambrian (Proterozoic) Delhi System of rocks suggests that it is connected with the Delhi orogeny, whereas the first folding on an EW trend is linked with an earlier orogeny, hitherto unrecognized in Rajasthan. |
| Late Albian foraminifera from the subbetic of Southern Spain | 1969 | Hermes, J.J. | 48(1) | A fauna of planktonic Foraminifera from the Late Albian of southern Spain is described. The genus Ticinella is discussed in some detail. The species of Hedbergella from the Albian and Cenomanian are reviewed |
| Submarine canyon and fan deposits in the Upper Cretaceous of the South-Central Pyrenees, Spain | 1969 | Hoorn, B. van | 48(1) | This preliminary study shows the existence of a submarine canyon during Upper Cretaceous time in the South-Central Pyrenees. Deposits filling up this canyon are mainly an alternation of thick limestone breccias and calcareous quartz sandstone layers in the western part of the area, grading into an alternation of limestone breccias, turbidites and blue marls in the east. A western location of the source area of breccia components is demonstrated by their stratigraphic record and measured current directions. After a short transport on a relatively steep slope in a submarine canyon, material was deposited in the canyon mouth building up submarine fans. |
| Remarks on the age of emplacement of the Betic of Málaga in the Sierra Espuña, Spain | 1969 | Hermes, J.J.; Kuhry, B. | 48(1) | Observations in the Sierra Espuña region disprove paquet’s assumption (1966a, 1966b, 1967, 1968) of the transgressive character of his "Auversian conglomerates" and thus of the emplacement of the upper tectonic units of the Betic of Málaga before the Auversian and after the Lutetian. |
| Strontium-isotopen en Rb-Sr chronometrie | 1969 | Priem, H.N.A. | 48(1) | |
| De toekomstige drinkwatervoorziening van Nederland | 1969 | Huisman, L. | 48(1) | |
| Evenwichten tussen calciumcarbonaat en phosphaationen in zoet water. | 1969 | Golterman, H.L.; Hogendijk, C.J. | 48(1) | |
| Karstverschijnselen | 1969 | Heege, J.P. ter | 48(1) | |
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| Reakties op "naar een genootschap - nieuwe stijl?" | 1969 | 48(2) | ||
| In memoriam Prof. Dr. J.P. Bakker | 1969 | Pannekoek, A.J. | 48(2) | |
| Introduction and summary of the stratigraphical and sedimentological results of boring alliance-28 in the coastal plain of Surinam (Dutch Guiana) | 1969 | Voorthuysen, J.H. van | 48(2) | |
| Boron content of core samples from alliance-28, Surinam, as an indicator of paleosalinity | 1969 | Porrenga, D.H. | 48(2) | The boron content of the clay fraction of 66 samples from the 338-m deep core hole Alliance-28 in Northern Surinam, indicates a marine palaeosalinity in the Paleocene-Eocene interval at about 295, 240 and 223 m depth, in the Pleistocene interval at about 80 m depth and also in the larger part of the Holocene interval. It furthermore suggests deposition in (almost) fresh water in the upper and lower part of the Paleocene-Eocene interval and in the Pliocene interval. Brackish water is indicated for some parts of the Paleocene-Eocene and the larger part of the Pleistocene intervals. The boron content is relatively high (60-140) ppm) in the clay fraction of calcareous and/or glauconitic sediments, markedly less (30-60 ppm) in sediments intercalated with brown coal and generally lowest (1040 ppm) in white kaolin layers. |
| The clay minerals from the boring Alliance-28, Surinam | 1969 | Hartman, P. | 48(2) | The clay mineralogical composition of about 75 samples is reported. Kaolinite and anatase are always present, and in some layers these are the only minerals in the clay fraction. In other layers kaolinite is associated with montmorillonite and/or disordered illite-montmorillonite mixed-layer minerals. In two layers illite is found, but always associated with the other clay minerals. In some samples traces of vermiculite and pyrite occur. |
| Palynology of the Alliance well, Surinam | 1969 | Wijmstra, T.A. | 48(2) | In this article the palynology of the Alliance well is discussed. From the pollenzones observed in this well the presence of Upper Cretaceous, Paleocene, Eocene, Miocene and Plio-Pleistocene strata could be proved. Also a correlation with marine micropaleontological horizons has been established. |
| 1969 | Wijmstra, T.A. | 48(2) | Large Enclosures | |
| Holocene and paleocene foraminifera of boring Alliance-28 in Surinam (Dutch Guiana) | 1969 | Voorthuysen, J.H. van | 48(2) | This paper presents a description of the Foraminifera of the marine part of the geological column of the coastal plain of Dutch Guiana (Surinam) derived from the cored waterwell Alliance 28 to a depth of 337.50 m. |
| Preliminary note on the ostracod faunas of the boring Alliance-28 in Surinam (Dutch Guiana) | 1969 | Noordermeer, E.J.; Wagner, C.W. | 48(2) | Large Enclosures |
| Preliminary note on the ostracod faunas of the boring Alliance-28 in Surinam (Dutch Guiana) | 1969 | Noordermeer, E.J.; Wagner, C.W. | 48(2) | |
| Paleocene bryozoa from a boring in Surinam | 1969 | Lagaaij, R. | 48(2) | Two species of Bryozoa, identified as belonging to the genera Nellia and "Vincularia", occur in some quantity in the Paleocene interval in the boring Alliance-28, drilled in the coastal plain of Surinam (Dutch Guiana). Both the Nellia and the "Vincularia" occur in assemblages virtually consisting of one single species. Recent assemblages in which Nettia makes up 80-100% of the total count indicate shallow inner-neritic (2-10 fathoms) conditions, coupled with slightly reduced salinities (<33‰). A similar environment is inferred for the Paleocene Nellia assemblage in the boring. |
| Mollusca from boring "Allicance-28"in Surinam (Dutch Guiana) | 1969 | Regteren Altena, C.O. van | 48(2) | Molluscan remains have been studied from depths of 12.25, 15.00 and, 16.25 m and from sixteen levels from depths between 258.85 and 311.00 m. The fauna of the first series of samples agrees with the Recent fauna of the Surinam coast and seems to have lived at moderate depth, say about ten fathoms, off the coast in and on a muddy clay bottom with occasional sand bars, but without hard rock. The fauna of the second series is supposed to be of Palaeocene age on the base of the associated Foraminifera. The molluscan remains consist mainly of fragments and young specimens, for the greater part of oysters. These remains are too poor for specific identification. About ten families or genera can be recognised, among which Vulselta is remarkable. This genus, which is rare in the Tertiaries of the New World, is represented by several hinge fragments. |
| A microproblematicum from the Paleocene of Surinam | 1969 | Hughes Clarke, M.W. | 48(2) | A problematic single-chambered microfossil is described from the Paleocene of boring Alliance 28 in Surinam (Dutch Guiana). Its possible affinities are briefly discussed. |
| Geomorphology and sediments of Western Surinam shelf; a preliminary note | 1969 | Nota, D.J.G. | 48(2) | |
| Geological and geophysical evidence for a rift valley in the Guiana Shield | 1969 | McConnell, R.B.; Masson Smith, D.; Berrange, J.P. | 48(2) | Geological and geophysical evidence points to the existence in the Guiana Shield between latitudes 3°N and 4°N of a steep-walled graben structure which is filled with a thick packet of sediments of which the uppermost is the Takutu Formation showing rare outcrops beneath a blanket of laterite and Quaternary alluvium. The Takutu Formation has been dated on palynological evidence (van der Hamm en and Burger, 1966) as Jurassic to Cretaceous. A gravity reconnaissance was carried out over the western portion of the structure and revealed anomalies which indicate a depth to basement of several km, The strike of the geological structure appears to be ENE-WSW over 160 km, with a width of 50 km, and it is suggested that it is in the nature of a rift valley: it has been considered to constitute a major structural break which divides the folded Precambrian formations of Guyana into northern and southern geological provinces. |
| The geochronology of Guyana | 1969 | Snelling, N.J.; McConnell, R.B. | 48(2) | The Precambrian rocks of Guyana occur in two geological provinces separated by a structural break followed in part by an infilled rift valley which traverses the country to the immediate south of latitude 4°N. North of this structure the folded and more or less metamorphosed sedimentary and volcanic rocks of the Barama-Mazaruni Assemblage and the gneissose granitic rocks of the Bartica Assemblage are intruded by members of the Younger Granite Group, and all are overlain with marked unconformity by the tabular, continental deposits of the Roraima Formation. Both the Roraima Formation and the pre-Roraima rocks are cut by dolerite dykes and sills which constitute the Younger Basic Intrusive Group, including the Roraima Intrusive Suite and a minor dyke suite. Age determinations indicate a younger limit to the post-Barama-Mazaruni-Bartica diastrophism of c.2000 m.y. This diastrophism is now termed the Akawaian episode and is believed to correspond closely in time to the emplacement of most of the Younger Granites. One member of the Mazaruni Group is possibly older than c.2500 m.y. A younger limit to the Roraima Formation of c.1700 m.y. is set by K-Ar and Rb-Sr age determinations on the dolerites of the Roraima Intrusive Suite and on micas of a contact hornfels in the Roraima Formation. In the southern geological province the major rock unit is the South Savanna Granite which intrudes high-grade gneisses (granulite facies) of the Kanuku Group and metasediments of the Marudi Group. A uranium-lead determination, though affected by uranium leaching, sets a maximum limit to the age of this granite of 2075 m.y., and Rb-Sr determinations indicate emplacement at c.1850 m.y. The granite shows evidence of dynamic metamorphism, and K-Ar determinations on micas suggest an age of c.1200 m.y. for this metamorphism. The Kanuku gneisses and South Savanna granites are cut by dolerite dykes, one of which has been dated at 450 m.y. |
| Pollen analysis of two sections in the young coastal plain of Surinam | 1969 | Roeleveld, W. | 48(2) | Pollen diagrams have been made of two sections in the young coastal plain of Surinam (S. America). According to C 14 dates the clayey and peaty sediments have an early Holocene age. The pollen diagrams clearly show the changes of the vegetation caused by the postglacial ingression of the sea. |
| #REF! | 1969 | 48(2) | VERSLAG VAN LEZINGEN GEHOUDEN OP DE HYDROGEOLOGISCHE DAG VAN DE KNGMG OP 24 JANUARI 1969 TE DELFT | |
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| Rede, uitgesproken door de voorzitter van het KNGMG, bij de aanbieding van de van Waterschoot van der Gracht penning aan Ir. C.E.P.M. Raedts op 15 maart 1969 | 1969 | 48(3) | ||
| Rede, uitgesproken door de voorzitter van het KNGMG, bij de aanbieding van de van Waterschoot van der Gracht penning aan Prof. Dr. L.U. de Sitter op 15 maart 1969 | 1969 | 48(3) | ||
| Afscheidscollege Prof. Dr. F.J. Faber | 1969 | 48(3) | ||
| Orogenic evolution of the Betic Zone (Betic Cordilleras, Spain), with emphasis on the nappe structures | 1969 | Egeler, C.G.; Simon, O.J. | 48(3) | The structure in the southeastern section of the Betic Zone reflects a highly complex evolution during the Alpine cycle, including several orogenic phases of different character. At least two major phases of overthrusting appear to have played a role in the formation of the nappe structures. A number of problems are briefly commented upon, including the direction and the age of the nappe movements and the amount of shortening. |
| Orogenic evolution of the Betic Zone (Betic Cordilleras, Spain), with emphasis on the nappe structures | 1969 | Egeler, C.G.; Simon, O.J. | 48(3) | Large Enclosure 1 |
| Orogenic evolution of the Betic Zone (Betic Cordilleras, Spain), with emphasis on the nappe structures | 1969 | Egeler, C.G.; Simon, O.J. | 48(3) | Large Enclosure 2 |
| Preface INQUA Subcommission on the Study of the Holocene and that on Baltic and North Sea Shorelines, held in the Netherlands in October 1968 | 1969 | Hageman, B.P. | 48(3) | |
| The cause of the holocene climate change | 1969 | Kukla, J. | 48(3) | The worldwide repeated changes of climate through the whole Quaternary era make it clear that the recent general weather conditions will not last forever, but will be substituted by a severe Glacial stage, similar to those recorded in the close geological past. It is highly important for humanity to know, at what time the climate deterioration is to be expected, which processes are ruling it and how to fight the incoming cooling trend. The first results of a new method are described, based on the calculation of the main part of the past earth's heat budget. The heat reaction of the snowline is detected as being the principal key controlling the global climate change and as strongly amplifying any slight thermal impulse of interplanetary or terrestrial origin. The perturbations of the earth's orbital elements are found to be responsible for the general long-time climatic changes including the start and the end of the Holocene interglacial. The convincing proof for this statement lies in the isotope dated geological evidence of the past 250,000 years. We are now able to date astronomically the various gross past climatic trends with a relatively high accuracy. The short-range oscillations of climate observed during Holocene, may partly reflect the short-time movements of earth's rotational axis and/or the changes of the solar constant, both up to now very poorly investigated. Strong suspection, however, exists that the Little Ice Ages of the Late Holocene and the global warming which started at around A.D. 1890 are both the results of mans activity. Further investigation in this branch is urgently needed, because the pronounced weather deterioration is expected to come in the close future. |
| An outline of the geological history of the coastal dunes in the Western Netherlands | 1969 | Jelgersma, S.; Regteren Altena, J.F. van | 48(3) | |
| The marine holocene of sylt - discussion of the age and facies | 1969 | Hoffmann, D. | 48(3) | Investigation of the marsh area of Sylt during 1965-66-67 yielded new data regarding the development of Sylt during the Holocene. Three transgressions of the sea were established. The deposits of the first belong to the Calais (according to Brand et al. 1966) and the others to the Dunkirk. The ages of the transgressions were determined by means of 14C-analysis and cultural layers. South of Westerland, the finegrained facies of the second transgression indicates that the area was well protected by the “Geestkerne" and the southern beach-barrier of the island. |
| on the Würm - Flandrian boundary in Deep-sea cores | 1969 | Olausson, E. | 48(3) | Due to the present drainage pattern the North Atlantic receives much more weathered products than the other oceans do. Dissolutions and oxidations at the bottom of the North Atlantic seem to change in time, being climatologically controlled. The dissolution of carbonates in North Atlantic has been intensified during ice ages mainly in the zone of Polar Bottom Water. During the Main (Upper) Würm the Arctic Ocean was not ice covered because of the absence of a salinity discontinuity (halocline). It is believed that an intense formation of bottom water occurred there and that this water then flushed the North Atlantic bottom and caused the increased dissolution of carbonates. At the transition Alleröd/Younger Dryas (Würm/Flandrian boundary) the Arctic Ocean was covered by a pack-ice. The developed halocline stopped the sink water formation. Then the outflow of cool bottom water to the Norwegian Sea dropped suddenly. The lack of this bottom water caused an increased carbonate deposition in the North Atlantic approximately 11,000 B.P., and somewhat later on, a decrease of it occurred in the Indian and Pacific Oceans (see fig. 1). The isotopic paleotemperature method has been found invalid. The percentages of warmwater-indicating foraminifera suggest that the North Atlantic gradually became warmer from the Alleröd up to the climatic optimum about 6000 B.P. The precipitation in the arid lands around the Gulf of Aden during the late Würm and Flandrian are given in Fig. 6. The highest precipitation during aforementioned times occurred during the Atlantic subage and the lowest one during the Preboreal subage. It is suggested that the Red Sea was dry during maximum of the Main (Upper) Würm Ice age. A marked change in the vertical circulation happened about 8000 B.P. The Eastern Mediterranean and the Cariaco Trench changed into a (quasi)stagnant phase approximately during or at the end of the Alleröd subage. The climatic deterioration during the younger Dryas stadial is explained as caused by the albedo change which occurred when the Arctic Ocean went into the pack ice phase. The duration of this stadial is about 600 yrs. Such a short interval is hard to trace in abyssal cores. The last large change in deepsea cores has probably happened at the end of the Alleröd subage. These two points suggest that the upper boundary of the Würm age is to be placed at the Earlier Dryas - Alleröd boundary. The present age is here called Flandrian since Holocene is a term of higher rank (epoch). I also suggest that Pleistocene should be considered as the only epoch in the euaternary period- "Holocene" could be discarded. |
| The pleistocene-holocene boundary: an evaluation of the various criteria used for determining it on a provincial basis, and suggestions for establishing it world-wide | 1969 | Morrison, R.B. | 48(4) | |
| Development of the western part of the Netherlands during the holocene | 1969 | Hageman, B.P. | 48(4) | |
| Eustatic and climatic changes during the last 15,000 years | 1969 | Mörner, N.A. | 48(4) | This is a short description of the results concerning shorelevel displacement, isostasy, eustasy and climatic changes obtained from a comprehensive investigation of the Late Quaternary history of the Kattegatt Sea and the Swedish West Coast (Southern Scandinavia). This investigation has been described in its entirety in a thorough monography (Mörner 1969), to which I refer for further information. |
| Zur Pleistozän/Holozän-grenze im südlichen peribaltischen raum | 1969 | Kliewe, H. | 48(4) | |
| Internal structure of some tidal mega-ripples on a shoal in the Westerschelde estuary, the Netherlands report of a preliminary investigation | 1969 | Boersma, J.R. | 48(4) | Ebb mega-ripples on a sandy shoal in the Westerschelde estuary (SW-Netherlands) were studied in crossection. The internal structure is dominated by large scale ebb-directed cross-stratification of a particular type showing flood induced erosional and/or depositional modifications. The characteristics betraying the tidal origin of the crossstratified structure are: 1.. Erosional unconformities (diastems) between the successive cross-stratal bundles that build one large scale set. 2. Regular alternations between such bundles and conformably inclined solitary trains of small scale sets containing upslope directed cross-strata. 3. The isolated occurrence of a ± 1 dm thick coset of small scale cross-strata conformably intercalated between two of the above mentioned bundles. 4. (Sub)horizontal cosets of small scale cross-stratification erosively separating vertically successive large scale ebbsets. The above mentioned features confirm the subordinate and rather erosional activity of the flood currents as compared with that of the ebb. |
| #REF! | 1969 | 48(4) | ||
| KNGMG notulen van de 57e Gewone Algemene Vergadering 1969 | 1969 | 48(4) | ||
| VERHANDELINGEN, DEEL 26, I969, rectificatie pagina 157 | 1969 | 48(5) | ||
| Ter herdenking Dr. Ir. Th. Groothoff | 1969 | Vooys, G.J. de | 48(5) | |
| The tin industry | 1969 | Jones, M.P. | 48(5) | |
| The quarternary geology of the Dutch part of the North Sea, north of the Frisian Isles | 1969 | Oele, E. | 48(5) | A geological map of the Dutch part of the North Sea, north of 53°20' lat. is presented. Fluvioglacial clays of the Elsterian glaciation are presumed to underlie the younger deposits. During the Saalian glaciation the clay was partly eroded by glaciers, which led to the formation of the central deep southeast of the Dogger Bank, the bank itself being an erosion rest. At the same time boulder clay of Scandinavian origin was deposited. Deposits of the Holsteinian and Eemian interglacials have not been found. Owing to the rapid rise of the sea level supply and sedimentation could not keep up with it. During the Early- and Late-Weichselian fluvial clays were deposited, while coversands were laid down during Weichselian Pleniglacial times. The surface of the fluvioglacial clay in the central deep remained uncovered owing to strong winds. The Holocene sequence starts with a basal peat bed, on top of which fresh-water clay settled. The transgreding sea led to the formation first of brackish to marine clayey, later of sandy deposits. (Elbow deposits). During the Atlantic and Subboreal no sediments were deposited. In the present Subatlantic a reworking and deposition of the material present led to the formation of the young seasand bed. |
| The quarternary geology of the Dutch part of the North Sea, north of the Frisian Isles | 1969 | Oele, E. | 48(5) | Large Enclosure |
| Deformation of an alpine ultramafic association in Darvel Bay, East Sabah, Malaysia | 1969 | Hutchison, C.S.; Dhonau, T.J. | 48(5) | The island-arc system of the Philippines, which includes the well-known Zambales alpine complex, continues westwards along Palawan island and along the Sulu archipelago into North Borneo. Within this arc, there is a characteristic association of ultramafic rocks, banded amphibolites of gabbroic composition, and a younger flysch sequence characterised by abundant spilites. In the Darvel Bay area of east Sabah (North Borneo), the ultramafic rocks are shown to be concordantly interfoliated with the banded amphibolites. The folding, which is predominantly along an east-west axial direction, has been accompanied by dynamothermal metamorphism characteristically to almandine-amphibolite facies. An increase in metamorphism to hornblende-granulite facies occurs in a "thermal aureole" of the syntectonic ultramafic body in central Darvel Bay. The island-arc system has been subjected to several periods of deformation, the youngest of which was accompanied by greenschist facies metamorphism, which has affected not only the ultramafic-metabasite association, but also the overlying flysch sequence and has converted many of the spilites to amphibolites. Structural data indicate that ultramafic intrusions accompanied both the older and the younger periods of deformation. Subsequent intense faulting has further obscured the earlier tectonic history of the ultramafic association. |
| Palynologie en classificatie van Perm en Trias in West-Europa | 1969 | Visscher, H. | 48(5) | |
| Palynostratigrafische problematiek van de "Lettenkohle" in Zuid-Frankrijk | 1969 | Gradstein, F.M. | 48(5) | |
| Surface protection around abandonned mine shafts | 1969 | Schilp, R. | 48(5) | |
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| Investigations in the Västervik area, southeastern Sweden - 1. Structural geology and genesis of the "younger" granites | 1969 | Westra, L.; Elbers, F.J.; Sijperda, W.S. | 48(6) | A geological map, short description and general petrological discussion is given of a small part of Svecofennian in SE-Sweden. The problems concern a relatively small sedimentary complex and surrounding granite gneisses, hybide diorites, migmatites and associated "younger" granites. Structural analysis has revealed that deformation has taken place in at least two phases. The first phase is characterized by isoclinal folding of the bedding plane with horizontal axial plane and generation of axial plane schistosity of newly formed mica. The second and dominant deformation phase is characterized by parallel, often plastic, folding with vertical axial plane. The metamorphism linked with this second phase is characterized by the crystallization of andalusite and sillimanite in sediments of appropriate composition. Moreover, this deformation is accompanied by extensive migmatization and the intrusion of granite dikes, the so-called "younger" granites, A mushroom-like interference pattern of superposed folds from both phases is extensively discussed. A new geochemical test is applied to establish the depth of intrusion of the "younger" granites. This test is based on the variation of the eutectic composition of a granitic melt at varying pressures, as determined experimentally by von Platen and Höller (1966). The results suggest a rather shallow depth of intrusion, which corresponds to the type of the broadly contemporaneous metamorphism of the associated sediments. Results of the analysis of trace elements of the "younger" granites, especially the low K/Rb-ratio, indicate an anatectic origin of these granites. |
| Investigations in the Västervik area, southeastern Sweden - 1. Structural geology and genesis of the "younger" granites | 1969 | Westra, L.; Elbers, F.J.; Sijperda, W.S. | 48(6) | Large Enclosure |
| Investigations in the Västervik area, southeastern Sweden - 2. Isotopic age determinations | 1969 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Hebeda, E.H.; Verschure, R.H.; Verdurmen, E.A.T. | 48(6) | Whole-rocks of three granites and a gneiss from the Västervik area, south-eastern Sweden, have a Rb-Sr age of 1750 ± 50 million years: (late) Svecofennian. Age measurements on three separated biotites disclose the imprints of younger, probably Gothian events, but a discordance exists between the K-Ar and Rb-Sr ages: 1465 ± 30 and 1380 ± 50 million years, respectively. A pegmatite yielded a Rb-Sr whole-rock age of 1425 ± 50 million years. |
| Mining of wide, flatly dipping reefs at Kamativi tin mines LTD., Rhodesia | 1969 | Botman, A.G. | 48(6) | A description is given here of the development of ideas and activities that have-led to the introduction of a new method of mining deep, thick, flatly dipping pegmatite reefs at Kamativi, Rhodesia. |
| Paleomagnetism of some Late Paleozoic and Triassic rocks from the eastern Lombardic Alps, Italy | 1969 | Zijderveld, J.D.A.; Jong, K.A. de | 48(6) | The directions of magnetization of five volcanic units of the Late Paleozoic rock sequence from the Eastern Lombardic Alps, each sampled at one site, display small within unit dispersion and rather large between-unit dispersion. They yield a mean direction of D = 135°, I = -21° (α95 = 20°), which is as divergent from the Late Paleozoic paleomagnetic field in the Alpine Foreland as the directions of contemporaneous rocks in other places in the Southern Alps. The characteristic magnetization direction of the Middle Triassic porphyrite of Valle di Scalve is D=161°, I=-21°. It is remarkably similar to the Late Paleozoic results and rather different from other Triassic paleomagnetic directions from the Southern AIps. Both the Late Paleozoic and the Triassic paleomagnetic directions indicate a counterclockwise rotation of the Southern AIps with respect to the Alpine Foreland (about 50°). There is no clear paleomagnetic evidence of large translational megatectonic movements between the Southern Alps and the Alpine Foreland. |
| A preliminary report on the stratigraphical position of the Matuyama-Brunhes geomagnetic field reversal in the Quaternary sediments of the Netherlands | 1969 | Montfrans, H.M. van; Hospers, J. | 48(6) | Continental sediments of Quaternary age from the Netherlands have been investigated palaeomagnetically. The evidence available at present concerning the stratigraphical position of the Matuyama-Brunhes geomagnetic field reversal (0.70 m.y. ago) places this boundary in or directly above the "Cromerian" interglacial stage. It is known that in the Netherlands the "Cromerian" interglacial stage was preceded by and followed by three glacial stages. |
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| Notulen van de Buitengewone Ledenvergadering oktober 1969 | 1969 | 48(6) | ||
| Research on ventilation and safety and its application at Dutch state mines | 1970 | Maas, W. | 49(1) | Dutch Statemines conducted until 1965 research for underground operations in the Centraal Proefstation. The present paper sketches the image formed on the occurrence of methane in the underground works, its release during mining operations, the method of safe dilution, and the removal in high concentrations. It gives measures taken to prevent ignition possibilities and finally describes how using the results of this research the Inspectorate allowed to increase the methane percentage in the general body of the air from 1.5 to 2 %. |
| The angle of initial yield of haphazard assemblages of equal spheres in bulk | 1970 | Allen, J.R.L. | 49(1) | The maximum slope angle assumed by heaped granular solids is of considerable interest in geology, geomorphology and soil mechanics, as also is the slope stability of such heaps. Representing the solids by equal spheres, we here deduce that the relationship between the maximum slope angle (angle of initial yield) and the concentration of equal spheres arranged haphazardly in bulk in the gravity field is tan Φi= k1C - k2 + A, in which Φi is the angle of initial yield, C is the fractional volume concentration, k1 and k2 are known constants depending on the properties of equal spheres in regular cubical and rhombohedral array, and A is a variable dimensionless coefficient representing frictional, electrostatic and other non-gravitational forces. This relationship is broadly confirmed by experiments using glass beads of two different narrow size ranges, though the experiments are not of a high order and accuracy. It is of interest that a natural sand, well sorted compared with other sands but still showing an approximately 1 : 4 range of sizes, also conforms to the relationship deduced for equal spheres. |
| De oudste mijnbouw in Nederland | 1970 | Engelen, F.H.C. | 49(1) | In 1881 flint-working sites were discovered in the south of the Netherlands, in the neighbourhood of Maastricht near the Belgium border. Specially Belgium archeologists from the university of Liege did field work in this site till 1953. In 1914 the first shaft and a mining gallery were found in the wall of a small ravine. During 1923-1925 Prof. Dr. v. Giffen and Dr. v.d. Sleen were the first archeologists of Dutch origin who did some succesful excavations. In 1964 Prof.Dr. Waterbolk from the Biological Archeological Institute of the Groningen University discovered a couple of shafts more than 140 meters from the ravine. So he proved that a very extended mining-activity had existed in neolithic times. At that time, twelve members of the Netherlands Geological Association planned to continue the excavations by digging a gallery from the first-discovered flintmines up to the new shaftfield. This gallery will have a total length of ± 140 m. At both sides 10 meters of the chalk-rock had to be explored on prehistorical mining activities. The members of the group, working in the week-ends during more than 4 years, made a gallery of 100 meters length already and penetrated into the prehistorical flintmines. They have dug out more than 500 meters of ancient galleries and discovered about 35 shafts. A deep insight has been obtained in the mining-system of the neolithic miners, who used the pillar and room system and made shafts of ± 10 meters deep. More than 7500 flint-picks, used during the work, have been found, some deerhornpicks, charcoal and a human skull. A radio-carbon determination of the charcoal dated the prehistorical mining activities at 3150 (± 60) before Christ. During the more than four years of excavations the working method was modernized. Starting with barrows, changing over to lorries, the group now uses a beltconveyor. Instead of steelpicks, now pneumatic hammers are used and the working-site is lighted by electric lamps. A great deal of work is still to be done by the members of the group before the gallery will be completed over its total length. The working group proved that the neolithic flintmining industry in the Netherlands is of the same rank as that of Spiennes in Belgium and of other well-known neolithic mines in Europe. |
| Grading of matrix and pebble characteristics in syntectonic pebbly mudstones and associated conglomerates with examples from the carboniferous of Northern Spain | 1970 | Loon, A.J. van | 49(1) | Pebbly mudstones are known from many syntectonic sediments. Since particles of clay size can only be deposited in very quiet water, in which pebbles cannot be transported, the occurrence of pebbles and, a clayey matrix proves that such sediments must have been transported by mass movement. If the matrix of the pebble-containing sediment consists of sand grains, the sediment could have been deposited grain after grain. But here too it may have been transported by mass movement, which can sometimes be proved if the matrix grades from sand to silt or even clay size. Three examples from the Upper Carboniferous of the Cantabrian Mountains (N. Spain) are described. Attention has been paid to the characteristics of the pebbles, from which the mechanism of deposition can be reconstructed. |
| Grading of matrix and pebble characteristics in syntectonic pebbly mudstones and associated conglomerates with examples from the carboniferous of Northern Spain | 1970 | Loon, A.J. van | 49(1) | Large Enclosure |
| Preliminary note on pleistoccene sealevel fluctuation in the southwestern parts of the Netherlands | 1970 | Voorthuysen, J.H. van | 49(1) | |
| Transgressivite de l'eocene suprieur dans les malaguides de la Sierra de Espuña (Cordilleres Betiques, Sud est de l'espagne) mise au point | 1970 | Paquet, J. | 49(1) | |
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| Genootschapszaken: AAPG zusterorganisatie | 1970 | 49(1) | ||
| Experimental marine suspension currents, competency and capacity | 1970 | Kuenen, P.H.; Sengupta, S. | 49(2) | In a circular flume (diameter 4 m) suspension currents were generated with various kinds and concentrations of clay (lutum) and sand. Starting from maximum velocity (230 or 300 cm/sec) samples were drawn off at successively lower velocities at three levels. The amount in suspension coarser than 33 microns was measured and for a number of representative cases grain size analyses of these sands were made. There is an increase in median and amount from the higher to lower levels. At curent velocity of 48 cm/sec particles smaller than 38 microns are not concentrated towards the bottom. At higher velocities there is even concentration upwards in some cases for grains smaller than 150 microns. The results demonstrate that the concepts of competency and capacity are strongly interrelated, the grain size distribution of the load in suspension depending on the original charge placed in the flume. The deposits tended to show log-normal distribution, the steepness of the cumulative curve depending on the composition of the suspension. All grain sizes in suspension were involved in the deposit forming. This was not due to current fluctuations and only partially to entrapment of fines between coarser grains. The coarser the fraction the more is abandoned relatively. For this reason the remaining suspension does show a decreasing median. The lutum greatly increases the carrying power, especially for finer grain sizes, the strongly flocculated Wadden Sea lutum having the greatest influence. The quantitative results are presumably roughly applicable to the lower part of turbidity currents. However, the exchange with higher levels is excluded in the experiments, and the paddles cause increased turbulence. Spiral flow is another drawback. For the deposition of a bed with median size of 200 microns, a velocity of 2 to 3 metres is required, for a median of 1 mm (that is to say a gravelly turbidite) something of the order of 10 m/sec, much depending on the concentration of lutum. At rippling velocity, about 50-60 cm/sec, the median of the deposit is around 80 microns. There appears to be no or only insignificant exchange between deposit and current in so far as concerns the grains that have become immobilized. No flutings or groovings develop during the process of deposition. Even while rippling is going on there is no or only slight local erosion. The climbing ripples of many turbidites with deposition on the stoss-side betoken non-erosion. No indications of the existence of a traction carpet were found or observed, a circumstance that is attributed to the absence of grains larger than those carried all the way in suspension. |
| Some data on the Holocene deposits in the Mark and Weerijs valleys (prov. Of Noord-Brabant, the Netherlands) | 1970 | Riezebos, P.A.; Slotboom, R.T. | 49(2) | Descriptions of cores from Holocene sediments in the Mark and Weerijs valleys (Province of Noord-Brabant, The Netherlands) allow the distinction of two groups of profiles. Those of the first group show humous sand at the top, underlain by peat. The sand may be more clayey at the base. In the present paper, this sand is indicated as a type I deposit. In the second group of profiles the peat contains an intercalated fine-sandy clay layer, indicated as a type II deposit. The thickness of this layer varies strongly, and the over- and underlying peat may be partially or wholly absent. Field observations point to a high-water origin of the type I deposits. Micropaleontological data from deposits of type II appear to indicate deposition in a fresh-water environment. Heavy-mineral data from type I and II deposits suggest a common source of origin. Grain size analyses, however, show a marked difference between the two types. This difference in grain-size distribution is attributed to an enrichment of type I deposits by cover sand. Palynological investigation of four complete cores showed that sediments of type I have been deposited in both valleys since the early Middle Ages. In the Mark valley, the deposition of type II started with the Atlantic and continued at least up to the Subatlantic. The formation of this type of deposit in the Weerijs valley appears to be confined to the Subboreal. The earlier sedimentation in the Mark valley is thought to be due to the post-glacial rise of the phreatic surface and to a deeper level of the Mark valley bottom. The presence of type II sediments of Atlantic and Subboreal age intercalated in peat, suggest that this relative rise of the phreatic surface was stronger during the Atlantic and Subboreal. |
| Quaternary shore lines of the Sunda land Southeast Asia | 1970 | Tjia, H.D. | 49(2) | All frequently occurring positive shore lines and a few of the submerged strand lines of the Sunda Land, i.e. comprising the Sunda Shelf, Malayan Peninsula, eastern rim of Sumatra, South and West Kalimantan (Borneo), can be correlated with the classical examples of Quaternary shore lines of the Mediterranean and elsewhere. The submarine shore lines of the Sunda Land are at depths of -82-90 m, -67 m, -60 m, -50-51 m, -45 m, -36 m, -30-33 m, - 28 m, -18-22m, -13 m, -10 m, and -7 m. Elevated beaches above the present sea level are at +10-12 m, +16-18 m, +30-33 m, and +50 m. Variable sea levels of the past 6,000 years left traces at a few meters below till about 6 meter above the present sea stand. Warping appears to be indicated along the western margin of the Sunda Land where on one side submergence amounting to 30 m and on the other side emergence of 30 m have occurred since the last glaciation. |
| A reconnaissance of deltaic environment in the Middle Eocene of the south -central Pyrenees, Spain | 1970 | Eden, J.G. van | 49(2) | A regressive sequence of Eocene sediments is exposed in an area West of Tremp (South-Central Pyrenees, Spain). The sequence forms part of deposits formed in the Upper Cretaceous-Eocene marginal basin south of the Pyrenees. Insignificant amounts of continental and littoral deposits are preserved on the north coast of this marginal basin. In the studied areas, however, on the eastern margin of the basin, a variety of continental environments is found. Three formations axe distinguished within the Eocene deposits. At the base is the Roda Formation with a regressive marine series of limestone, marl, and sandstone. Partly overlying this formation and partly laterally transitional to it is the Montaña Formation, with continental and littoral deposits. The Santa Liestra Formation, formed after a major regressive phase, is the youngest. The distribution of these formations on the geological map and their main sedimentary facies are presented in figure 1. The Montañana Formation is regarded as a deltaic association. Two major sedimentary environments are distinguished: (1) a flood-plain environment with fluvial sandstones, conglomerates and finer sediments of the inter-distributary lagoons and swamps, and (2) a transitional environment with channel mouth, bay, tidal flat, and deltafront deposits, containing marine fauna. Two types of large-scale cross-bedding, with different origins are compared. One is interpreted as river subdeltaic formations in lagoons, while the other has been formed by lateral deposition in a migrating river channel. Several small sedimentary structures occur, of which "current crescent marks" and "longitudinal furrows-and-ridges" are discussed in some detail. Excellent exposure of the Montañana Formation provided the opportunity for an almost complete paleogeographic interpretation. The paleogeographic pattern of the floodplain is not that of the ideal delta, in which one major stream forms a fan-shaped deposit. Instead there is a concentration of supply from the north and east by several small rivers, caused by the configuration of the upland area. |
| Jhr. Dr. Ir. P.J.C. de Wijckerslooth de Weerdesteijn (1904-1969) | 1970 | 49(2) | ||
| On the genesis and emplacement of the ophiolites in the Oman mountains "Geosyncline" | 1970 | Reinhardt, B.M. | 49(2) | |
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| Van de voorzitter aan de leden | 1970 | 49(3) | ||
| Rede uitgesproken door de voorziter van het genootschap bij de uitreiking van de van Waterschoot van der Gracht penning aan de Prof. Dr. Ir. R.W. van Bemmelen | 1970 | 49(3) | ||
| Ter herdenking Prof. Dr. G.J.A. Grond 1890-1970 | 1970 | Drent, S. | 49(3) | |
| Lunar rocks and minerals | 1970 | Zussman, J. | 49(3) | |
| The systematic packing of prolate spheroids with reference to concentration and dilatancy | 1970 | Allen, J.R.L. | 49(3) | The use of the sphere as the ideal sedimentary particle is criticised and the prolate spheroid (ellipsoid of revolution) is proposed as a more realistic alternative. Equal prolate spheroids identically oriented in space can be packed in six ways analogous to the six packings of equal spheres. The volume concentration of spheroids in systematic packing is identical with the concentration of spheres in the equivalent packing, except in cases of "cubic" packing in which concentration is a function of spheroid orientation and axial ratio. The dilatation angle of assemblages of prolate spheroids is a function of type and orientation of packing and of spheroid orientation relative to the direction of displacement. The maximum angle of initial yield of packings of spheroids is also dependent on type and orientation of packing and on spheroid orientation. The implications of these findings for the steepness and stability of slopes formed on loose granular materials are discussed. |
| Mikroskopische untersuchungen an gesteinshüttenprodukten und schlacken | 1970 | Trojer, F. | 49(3) | |
| Wodginite from northeastern Brazil | 1970 | Burke, E.A.J.; Kieft, C.; Felius, R.O.; Adusumilli, S.M. | 49(3) | Two varieties of wodginite, Fe-rich and Mn-rich, occur in pegmatites at Seridózinho, Paraiba State, Brazil. The mineral is monoclinic with a=9.46 Å, b=11.43 Å, c=5.12 Å, ß=91°12' (for the Mn-variety). Optical properties, micro-indentation hardness and reflectance values, and electron-microprobe analyses are presented. A discussion of previously published analyses leads to the conclusion that there seem to be two possible systems to fit the analyses of wodginite into a formula. |
| Zur genese einer stirnschuppe der Esla-decke (Kantabrisches Bebirge, Spanien) | 1970 | Ruhrmann, G. | 49(3) | A special re-mapping of the Esla region (Province of Léon) brought to light an isolated block of allochthonous limestone in the frontal area of the Esla nappe. Three interpretations are discussed: 1. The block is a squeezed out remnant of the north flank of an anticlinorium. There was no movement of a nappe. 2. The block remained attached to autochthonous material during an eastward movement of the Esla nappe. 3. The limestone was isolated during movement of the nappe and was overrun by its own nappe. We can therefore call it a "Stirnschuppe" sensu Tollmann (1967). The third interpretation is most probable. |
| Algemene' of 'Fysische' geologie | 1970 | Brouwer, A.; Fischer, M.M. | 49(3) | |
| Environmental studies concerning Upper Devonian (and Lower Carboniferous) coastal sections of the South County Cork | 1970 | Raaf, J.F.M. de | 49(3) | |
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| #REF! | 1970 | 49(3) | ||
| KNGMG jaarverslag 1969 | 1970 | 49(3) | ||
| Weichselian stratigraphy and radiocarbon dating in South Wales | 1970 | John, B.S.; Ellis-Gruffydd, I.D. | 49(4) | There are many difficulties involved in both the interpretation and correlation of Weichselian deposits in South Wales - a fact illustrated by the multiplicity of viewpoints in the literature. It is suggested that the Weichselian stage was characterised by (1) an early prolonged periglacial phase, possibly with local upland glaciation and with some climatic fluctuations; (2) a major glaciation in which Irish Sea ice and Welsh ice played different relative roles in different areas; and (3) a shorter periglacial phase with some corrie glaciation in the uplands. There are four radiocarbon dates for the Late-glacial. The dates from Port Talbot (Glam.) confirm the age of organic deposits from Swansea Bay and provide an approximate date for the onset of the Flandrian transgression; and the date from Aberaeron (Cards.) points to the existence of Zone II organic deposits beneath solifluction earth and above glacial drifts of probable Weichselian age. There are also four dates for the Middle Weichselian, supporting other evidence for an interstadial at this time and for a later extensive glaciation by the Irish Sea glacier in Cardigan Bay. There is no unequivocal age determination for the organic content of the calcareous Irish Sea till. Palaeobotanical investigations undertaken so far have revealed that a wide range of organic material exists in the glacial drifts, including a significant amount of Tertiary pollen and spores and many fragments of Tertiary lignite. It is therefore difficult to relate the palaeobotanical evidence with any confidence to either the stratigraphy or the radiocarbon dates. However, an interglacial deposit discovered in situ at West Angle (Pembs.) may provide another pointer to the true age of the South Wales drifts; and the radiocarbon date for the human skeleton from Paviland (Glam.) should also be of major significance for the establishment of a reliable Weichselian chronology. |
| Premiere mesure geochronologique en Sierra Morena | 1970 | Leutwein, F.; Saupé, F.; Sonet, J.; Bouyx, E. | 49(4) | La datation par les méthodes Rb-Sr et K-A de la roche totale et de plusieurs minéraux de deux échantillons de la granodiorite de Fontanosas (Ciudad Real, Espagne) a donné pour celle-ci un âge de 302 M.a. L'âge de ce stock tardi-ou post-tectonique, joint à des critères stratigraphiques permet d'attribuer le plissement principal de la région d'Almadén à la phase sudète. |
| An application of factor analysis to the interpretation of the genesis of magnetite in the smallwood mine, labrador | 1970 | Zodrow, E.L. | 49(4) | The Smallwood Mine at Labrador City, Newfoundland, contains two recoverable iron ore minerals: specularite and magnetite. This paper inquires specifically into the genesis of magnetite using a model that statistically relates the measured variation of four variables to ideal causes that were responsible for these variations. Through the interpretation of the results of factor analysis, a theory of magnetite genesis is proposed which tentatively indentifies the Grenville orogeny as the factor largely responsible for the formation of magnetite. However, it is proposed to enlarge the factor model to include additional chemical variables which may reduce the unexplained variance in this system of variables and more clearly specify the common factors. |
| The occurrence of crandallite in a sinkhole near Florze (Belgian Condroz) | 1970 | Buurman, P.; Plas, L. van der | 49(4) | Crandallite has been found in a sinkhole near Florzé where recently also halloysite was discovered. The mineral occurs in a pocket in a residual clay derived from Visean limestones. The clay is found on top of Om and Onx deposits and below Pleistocene solifluction material. X-ray diffraction patterns, D.T.A.-traces, specific density separation, refractive indexes, X-ray fluorescence patterns and chemical composition have been determined and are reported. The samples are rich in uranium. |
| The statistical discrimination between coversan areas in the Netherlands | 1970 | Crommelin, R.D.; Keuls, M. | 49(4) | In 1968 Maarleveld published the results of a research of the coversand area in The Netherlands, based on geomorphological evidence and on the evaluation of macroscopical characteristics of the coversands mainly in the 105-75 micron fraction, resulting in a subdivision into 29 subareas. Each subarea could be described in terms of specified amounts (per mil values) of the three characteristics: white, black and green grains. In this study the analytical results of these principal characteristics are consider ed in a mote objective way, in order to arrive at a numerical comparison for all possible pairs of subareas. For any pair this comparison may be expressed as the sample-size N required to detect a difference as large as the one stated between the respective sample means. The N-numbers - which may be considered as difference- or similarity-coefficients have a practical significance in that they provide a measure for the discrimination between any pair of areas as to the characteristic in question: large N-numbers stand for a high degree of similarity, whereas small N-numbers mean that the areas under consideration are very different and consequently may be distinguished with relative ease. The relation between the N-number and the statistical parameters of the characteristics is discussed. A way is indicated how to arrive at defining areas such that they fit classes with a maximum contrast between the analytical data. |
| A Tortonian age for sedimentary rocks directly overlying volcanics in the Western part of La Serrata, Nijar, prov. Almería, SE Spain | 1970 | Zeck, H.P.; Soediono, H. | 49(4) | A well-preserverd fauna f planktonic Foraminifera indicates a Tortonian age for a calcilutite directly overlying pyroclastic orthopyroxene-labradorite pheno-andesite. The rock series belongs to the autochthonous of the Betic Cordilleras |
| Rates of diastrophic movement during the Quaternary in Indonesia | 1970 | Tjia, H.D. | 49(4) | Quaternary folding, faulting, tilting, uplift, and subsidence for several localities in Indonesia yield the following information with regard to rates of diastrophic movement. In the mobile regions the average rate of uplift with or without attendant folding amounts to 0.5 to 1.0 mm/yr. Subsidence occurs at rates of 2.0 mm/yr. As expected, diastrophic movements in the continental areas are much slower and are measured in hundredths of a millimeter annually. Wrench faulting possesses most rapid movements; rates of strike-slip movements are at least 5 mm/yr. It was also found that observation on deformational phenomena for. shorter periods yields anomalously high values of diastrophic rates. This evidence is in accordance with the spasmodic nature of diastrophism which is also reflected by the occurrence of multiple elevated terraces. |
| Rates of diastrophic movement during the Quaternary in Indonesia | 1970 | Tjia, H.D. | 49(4) | Large Enclosure |
| Significant changes and developments in Zambian mineral industry | 1970 | Vletter, D.R. de | 49(4) | |
| Beknopt verslag van het derde international geochemical exploration symposium | 1970 | Dijkstra, S. | 49(4) | |
| Het onderzoek naar de toepassing van moderne luchtopnametechnieken | 1970 | Eckhart, D.; Bosman, E.R. | 49(4) | |
| #REF! | 1970 | 49(4) | ||
| #REF! | 1970 | 49(4) | ||
| #REF! | 1970 | 49(4) | ||
| The occurrence of low pressure metamorphism in the Precambrian of the Middle-East and North East Africa | 1970 | Shimron, A.E.; Zwart, H.J. | 49(5) | The occurrence of metamorphic minerals, like andalusite and cordierite indicating formation under low pressures, is described from the Elat area in Israel and the Sinai Precambrian. The study of the timing of metamorphism with regard to folding phases has shown that the metamorphism is progressive in time. The -possibility that the Precambrian of the Arabian shield belongs to a Hercynotype orogenic belt is discussed. |
| The occurrence of low pressure metamorphism in the Precambrian of the Middle-East and North East Africa | 1970 | Shimron, A.E.; Zwart, H.J. | 49(5) | Large Enclosure |
| On the origin of several heavy clay layers in solifluction deposits of the Belgian Condroz | 1970 | Buurman, P.; Groot, G.E. de; Winkler Prins, C.F. | 49(5) | In many places in the Belgian Çondroz heavy solifluction clays occur on top of Tertiary sands. These deposits are generally found in conjunction with fair amounts of chert and silicified fossils. In order to determine the origin of the clays, investigation of the fossils (mainly brachiopods and corals) and the granulometric and mineralogical compositions were carried out. The fauna collected in the clay deposits is typical for the upper Tournaisian and lower Viséan (Lower Carboniferous). For comparison fossils were also collected from residual clays in situ on Viséan and Tournaisian limestones. No important differences between the fossil groups could be detected. The clay mineralogical analysis also indicates that the clays in the solifluction deposits are residues of soil formation on Carboniferous limestone. |
| Pollen analyses of the Helvoirt river valley | 1970 | Buurman, P. | 49(5) | Four pollen diagrams from the Helvoirt river valley (Noordbrabant, The Netherlands) are presented and discussed. Several conclusions concerning the formation of the valley and its deposits are drawn. |
| The complex NRM of the Permocarboniferous Bademli Redbeds | 1970 | Voo, R. van der; Klein, P.H. van der | 49(5) | The analysis of the NRM of 27 Permocarboniferous samples from a nappe in the Tauride Chains revealed that in most samples three magnetic components were present. Two of the components are thought to be secondary due to remagnetization in Early Tertiary, and Recent times. The third and hardest component is assumed to be Permocarboniferous. It yielded an anomalous paleomagnetic direction, though the low inclination value indicates an equatorial position during the Permocarboniferous. |
| Stabiele isotopen van koolstof en zuurstof in water en kalk | 1970 | Mook, W.G. | 49(5) | |
| Zwavelisotopen en olie geochemie | 1970 | Aldershof, W.G. | 49(5) | |
| #REF! | 1970 | 49(5) | ||
| Les alterations des materiaux en oeuvre sous climat tropical | 1970 | Hyvert, G. | 49(5) | |
| #REF! | 1970 | 49(5) | ||
| To our readers | 1970 | Jong, J.D. de | 49(6) | |
| In memoriam Prof. Dr. M.G. Rutten | 1970 | Thiadens, A.A. | 49(6) | |
| Mafic geosynclinal volcanism in the Lower Carboniferous of South Portugal | 1970 | Schermerhorn, L.J.G. | 49(6) | Lower Carboniferous mafic volcanism in the Hercynian geosyncline of South Portugal produced spilite flows, often pillow lavas, and albite diabase intrusions. Spilites only occur in a central zone. Felsic voicanism took place at about the same time in this geosyncline: in South Portugal the mafic volcanism followed the felsic eruptions but in Southwest Spain the succession is reversed. The relationships between the mafic and the felsic activity indicate a rough juxtaposition in space and time but no genetical link. The mafic volcanics are considered to derive from the upper mantle and the felsic volcanics are thought to have been generated in Iocal magma chambers by melting in the deep crust. |
| A trace element study of terrace materials from Southern Limburg, the Netherlands | 1970 | Dijkstra, S.; Sutthitavil, S. | 49(6) | The present paper deals with a trace element study of terrace materials in southern Limburg. Uncertainties and limitations of these types of studies are discussed and special attention is paid to matters like the relation between trace element content and heavy mineral association, metal ratios in various materials, and trace element trends in gravels of different age. It is suggested that discontinuities in these trends might represent important events in the development of the river system. |
| A geohydrologic study of east Gelderland (Netherlands) | 1970 | Ernst, L.F.; Ridder, N.A. de | 49(6) | This paper deals with the results of a geohydrological investigation carried out in the eastern part of The Netherlands (province Gelderland). In this region the demand for water for domestic and industrial use is rapidly increasing. The present demand of 34 million m3 per year is entirely met by extraction of groundwater. With a view on the agricultural interests the problem arises what effect a further increase of the groundwater extraction may have on the productivity of the drought-sensitive soils. This study was made to provide basic data for the solution of this problem. The geological investigations have given a much better insight in the suitability of the aquifers for groundwater exploitation than existed. The transmissivity of the aquifers according to field pumping tests and well logs, varies from about 300 to 10,000 m2/day. This variation is chiefly due to fluvioglacial erosion and aggradation during the Saale Ice Age (buried glacial channels). Utilizing a finite differences equation, in which the available transmissivity values and water table gradients had to be substituted, a map has been prepared showing the intensity of the net subsurface inflow. This flow rate is of practical importance because adding to it the mean precipitation and evaporation values immediately yields the mean drainage intensity. Transmissivity values and values of the drainage resistance were used for the calculation of the drawdown of the water table by extraction of groundwater from deep wells. In general, the groundwater is fresh but remarkable differences in electrical conductivity, sulphate-chloride ratio, hardness and iron content were found in the region. At some places the groundwater temperature was also measured. The differences in chemical composition and in temperature of the groundwater were found to be in fairly good agreement with the occurrence of positive and negative net subsurface inflow. |
| Observation on submerged sand ripples with heights ranging from 30 to 200 cm occuring in tidal channels of S.W. Netherlands | 1970 | Terwindt, J.H.J. | 49(6) | An investigation of submerged sand ripple fields with ripple heights from 30-200 cm in the fluvial tidal and tidal channels of the S.W. Netherlands was made. Such rippled surfaces were found in fluvial tidal channels, at the confluence of tidal channels and in pronounced ebb and flood channels. However, over large areas no ripple fields of this kind were observed. Ripple areas do not distinguish themselves from non-rippled areas by a difference in general current characteristics or composition of the bottom material, although no ripple (30-200 cm) fields were found in areas where the bottom material contains more than 15% mud. The asymmetry of ripples with heights of 30-100 cm is sometimes determined by the prevailing tidal current especially in ebb and flood channels; change of the asymmetry with the turn of the tide does occur. The asymmetry of ripples with heights from 100-200 cm showed much more constancy. It mostly did not change with the turn of the tide. The dimensions of the ripples in the fields may change rather rapidly. There is no relation between ripple height and water depth. It was observed that the orientation of the ripple crests is influenced by the spiral flow in tidal channels. |
| "Engineering geology" in Nederland | 1970 | Dozy, J.J. | 49(6) | |
| #REF! | 1970 | 49(6) | ||
| #REF! | 1970 | 49(6) | ||
| #REF! | 1970 | 49(6) | ||
| Van de voorzitter aan de leden | 1971 | Krol, G.L. | 50(1) | |
| Origin of Solnhofen limestone | 1971 | Straaten, L.M.J.U. van | 50(1) | |
| The genesis of belgian and Dutch flints and cherts | 1971 | Buurman, P.; Plas, L. van der | 50(1) | Different analyses were carried out on several Dutch and Belgian flints and cherts. As a result of the observations conclusions are drawn about the properties of flint and chert and a theory on the formation of flint and silicification of limestones through a calcium silicate intermediary is presented. Calculations on the physico-chemical aspects of this theory are presented, These calculations turned out to accord with several field observations. |
| Note on chamosite in sediments of the Surinam shelf | 1971 | Hardjosoesastro, R. | 50(1) | |
| Processing of water-quality data by digital computer | 1971 | Creusot, M.R.; Geirnaert, W. | 50(1) | |
| Subdivision of the "Cromerian" in the Netherlands; pollen-analysis, palaeomagnetism and sedimentary petrology | 1971 | Zagwijn, W.H.; Montfrans, H.M. van; Zandstra, J.G. | 50(1) | A subdivision of the lower part of the Middle Pleistocene ("Cromerian") of The Netherlands is proposed. At least 3 interglacials are now recognized. The Matuyama-Brunhes boundary (0.7 M.y.) has been located within this sequence. |
| A consideration of the continuity of the Tertiary orogenic systems of Europe and Asia | 1971 | Gill, W.D.; | 50(1) | |
| #REF! | 1971 | 50(1) | ||
| #REF! | 1971 | 50(1) | ||
| #REF! | 1971 | 50(1) | ||
| Foreword Special Issue on the closure of the coal mines in the Netherlands | 1971 | Krol, G.L. | 50(2) | |
| Preface Closure Coal Mines | 1971 | Block, L. de | 50(2) | |
| The melting pot of the black gold - De smeltkroes van het zwarte goud | 1971 | Rooy, C.J.M.A. van | 50(2) | |
| De opgang en teleurgang van de Limburgse Steenkoolindustrie (een historisch overzicht) | 1971 | Raedts, C.E.P.M. | 50(2) | Since the early middle ages the northern part of the Netherlands have followed its own independent energy policy. As naturally it was paramount that the supply of raw materials for the generation of energy had to be as cheap as possible, thereby benefiting local trade and industry, this policy sometimes was of disadvantage to the national coal industry. Napoleon's Mine Law of 1st May, 1810 promoted the activity in the mining industry. Towards the end of the period of French domination and during the early years of the kingdom of the Netherlands, there was only one coal mine in southern Limburg: the Domanial Mine. After the Belgian revolution of 1830 and the resulting separation of Belgium and the Netherlands the two countries went their own individual routes of industrial developments. In the area of Liege we saw the beginning of a continental industrial revolution while the northern Netherlands placed more emphasis on trade and shipping. The Domanial Mine was followed in 1852 by another one, which, however, was stopped even before the Domanial Mine closed down in 1970. The first 2 concessions after the French domination, signifying the first real emphasis on mining in Limburg, date from the years 1860-1861. It was not until 1902 that the first coal was produced from the unified Willem Sophie Mine, which exploited these two concessions. Between 1870 and 1880 another 13 mining concessions were awarded and a great number of holes were drilled. No new mines were started, however, and between 1891 and 1892 most of these concessions were cancelled. The initiative of Sarolea who obtained a concession in 1889 as a reward for the construction of the railroad from Sittard to Herzogenrath and of the Aachen (Germany) coal producers Carl and Friedrich Honigmann (who were awarded in 1893 most of the concessions that were cancelled in 1891 and 1892) meant the beginning of the modern mining industry of Limburg. The first of the 4 Oranje Nassau mines started to produce in 1899 and in 1908 all the properties of the Honigmann family went over to the De Wendel family of Lotharingen. Affiliated in this manner with large steel mills and with owners of large experience in mining, the Oranje Nassau mines started to prosper. In the meantime Mine Laura had started in 1907 and after World War I its sister Mine Julia went into operation. Concerned about the foreign influences in the Limburg mining industry a government commission was created in the year 1899. This resulted in 1901 in a law reserving all unallocated concessions for exploitation by the nation. In 1903 the first concession was assigned to a state mine, in 1915 the fourth to state mine Maurits. Finally a concession under Vlodrop was awarded for exploitation by the nation, the shafts were dug but the mine was never produced. Worth mentioning in the history of the Dutch State Mines (DSM) is that its personnel are not considered as "staff in the normal sense of the word. In 1913 the Dutch State Mines management was instructed to run the company "as much as possible as it is customary in the large private enterprise". The entire Netherlands mining industry had to find its own anyhow between the years 1900-1914 and secure national recognition. As late as in 1913 64% of its production still had to be exported. In 1919 the first steps were taken in the creation of a chemical industry by DSM, which now forms a most important element in the industrialization of southern Limburg. After World War I a couple of prosperous years followed, the years 1923 (occupation of the Ruhr district) and 1926 (major strikes in Great Britain) were very good years for the mines. Before things turned for the worse again in the thirties, production amounted to 12.2 million tons of coal in 1930. It is, however, not until 1939 that one could speak of normal conditions, but then of course the German invasion followed and the mines were put under the control of the German forces. After World War II the mines had to step in again to alleviate the energy shortage and they were therefore highly appreciated. But soon thereafter a complete change occurred in the energy market. The penetration of cheap oil, the introduction of atomic energy and the discovery of large amounts of natural gas in the Netherlands resulted in a crisis in the coal mining industry, which reached its peak in 1958. New developments like the coal and steel community, later the EEG could not save the mines and so we witnessed the end of an industry which had been of major importance to the Netherlands for many decades. |
| De liquidatie van de kolenmijnbouw in Limburg in het licht van het Nederlandse energiebeleid | 1971 | Molkenboer, J.A.M. | 50(2) | A unique feature of the termination of Netherlands coal mining for which there is no precedence is the planned and gradual run down of a complete industry, because developments in the energy market made continued economic exploitation of coal impossible. Moreover, the liquidation is being carried out rather quickly and in an area of very limited extend and is therefore creating unique problems in the search for new employment opportunities. As the state owns the largest coal mining enterprises, involvement by the government was unavoidable, the more so as the mines had to be closed down before they were technically depleted with the timing being set by the availability of cheaper replacing fuels. The author discusses all the reasons which lead to the decision to close down the mines and wonders whether in retrospect these reasons justified the policies followed. In 1965 it became apparent that solid fuels were losing their importance in the Netherlands supply of energy. It could be assumed that our steel industry would require less domestic coal, while power generation was increasingly being taken over by oil and natural gas. The competitive position of the Netherlands industry demanded the use of the cheapest possible source of energy. Even the mines' own consumption of coal for the generation of electricity and the manufacturing of coke and coke-gas could no longer be economically justified. In the meantime a significant expansion of crude oil refining capacity in the Netherlands was noticeable. Its input is subject to a certain risk - as it does in all of western Europe – of being interrupted. Groningen gas, however, could absorb satisfactorily this risk element which previously has been absorbed by the coal mining industry. The decline in the share of solid fuels in the energy market has been more rapid than had been forecasted. However, the Netherlands balance of payment has not suffered as the export value of natural gas exceeded the former export value of coal. Oil consumption has also increased but so has the export of refined products. The social aspects of the guiding policy in the liquidation process are summarized by the author as follows: a. Supported by the general re-industrialization process the state and privately owned mines are diversifying their activities. b. The high rate of industrial growth has lead to increased employment opportunities, even without the government's involvement. In retrospect it seems that the policies followed were generally successful, but it should be kept in mind that human relations were severely affected and that a few weak spots remain which are difficult to rectify. The state accepted a burden of N.fl. 1750 million (approx. US $ 500 million) to carry out a policy which had to be socially and economically acceptable. It is expected that sometime in the future the final outcome will be considered favourable mainly as a result of the splendid co-operation in many fields which one has witnessed so far. |
| De energievoorziening van Nederland voorheen en in de toekomst | 1971 | Geertman, G.H.M. | 50(2) | This article outlines the development of primary energy demand by the various consumer categories in the Netherlands since 1950, and discusses the shifts that have taken place in the contribution by the various energy sources. In addition, an attempt is made at extrapolating energy consumption towards the year 1980. At first, solid fuels held the dominant position, but when energy prices began to drop after the first Suez crisis, Dutch coal in particular felt the impact, and began to be gradually ousted form the inland market. Up to 1965, the decrease of the coal consumption was compensated almost entirely by liquid fuels, while after that year also natural gas began to play an important role. The consumption of natural gas increased so rapidly that between 1965 and 1969 the sales of fuel oil to industry showed a decline. Also the demand for natural gas for the generation of electric power and for home heating purposes has gone up sharply. In 1969 the share of natural gas in the overall energy consumption was already as high as 25% that of oil being 59%. Between 1965 and 1969 the overall demand for energy rose more than 8% annually, to reach a level of over 60 million tons of coal equivalent. The increase estimated for the period 1969-1980 is almost 6% per annum, which means that in the latter year the overall consumption will be more than 110 million tons of coal equivalent. The consumption shift on the Dutch energy market is expected to continue. Eventually, natural gas will provide more than 40% of energy demand in the Netherlands, while the share of mineral oil will drop to below 50%.The growth of the gas consumption by the three categories referred to above will persist. Special mention should be made in this connection of the increasing use of central heating installations, which is largely due to the introduction of natural gas. Since the price of natural gas has been coupled to that of heavy fuel oil, gas will remain a very competitive fuel for large-scale consumers. Nevertheless, liquid fuels will retain an important position, not only in the transportation market and for nonenergetic purposes, but also - be it to a lower degree - as a domestic heating fuel. In industry and electric power stations oil is experiencing severe competition from gas. After 1975 nuclear energy may also become important as a power generating agent. Eventually, the use of coal will come to be restricted to the iron and steel industry. |
| Vijf jaar mijnsluiting en de gevolgen voor het personeel de periode 1965-1970 | 1971 | Jochems, D.B. | 50(2) | In this contribution the author discusses the fundamental social aspects that have prevailed during the personnel reductions amounting to 30,000 workers during the last 5 years. Individual problems have of course occurred and the transition has been more successful for some than for others. In sum total we can say that the consequences of the closing of the mines for its personnel has been less severe than one might have expected. In mid 1970 the Netherlands coal mining industry still employed some 15,000 people. By analogy with the reduction of some 30,000 workers.in the previous 5 years one might expect the remainder to be run down in another 2,5 years. Mr. Hellemans in his paper will explain why this is not so. The author of this paper limits himself to a review of experience gained so far. One is inclined to forget that the Dutch State Mines (DSM) employed 5 years ago some 10,000 workers in its chemical industry (now some 12,000), this number is not included in the highest number of workers that the mining industry had in its service since World War II of some 55,000. Programmed reductions started in July, 1965. Before, between 1958 and 1965 there had been a quiet attrition of some 1,500 men per year. In 1965 the rate of reduction was accelerated to 6,000 men per year. DSM led with reducing its personnel in the solid fuels business to 1/6th of its former number, the privately-owned mines (8 in total) to somewhat less than half. Contractors and suppliers suffered of course also, but reliable information on their position is not available. As far as coal mining is concerned, the reductions affected some 1 in 4 workers in southern Limburg and even 1 in 2 workers in the eastern area where the mines are located. Re-employment opportunities are naturally of paramount importance in the area of the mine closures. The author explains that in the past it had been too readily assumed that restructuring would succeed only if for each surplus miner an industrial position would be available. However, during the restructuring phase a number of miners moved to job opportunities outside Limburg. Furthermore, a number were withdrawn from the list of employables because they were retired on early pension. As a result of these two facts only 50% of the miners that were withdrawn from the mines had to be placed in newly created positions in southern Limburg while some 10% were placed with local social labor schemes. The remaining 40% have been retired or are receiving a financial allowance until they reach retirement age. Not 30,000 industrial jobs had to be found but only half of that amount. The article contains statistical data on the jobs vacated until the middle of 1970. As a rule those who are being released qualify for unemployment compensation or a financial allowance to bridge the gap to the lower pay which they will have to accept in their new jobs. One of the major problems concerns the adjustment of the underground miners, who have high wage scales, to the much lower wage levels that prevail in industries at the surface. It is evident, however, for reasons explained in the paper, that only 17,000 of the 33,500 personnel released have qualified for compensations under the rules explained. In principle all the mines are now following the rule that no one will be released unless there is suitable alternative employment or terms for early retirement are met. Economical and production/technical considerations now take second place to social principles. A "Council of Guidance" can be called upon for assistance by any mine. The usual procedure is that job opportunities are located and investigated and that qualified candidates are brought forward by the mines. Retraining programmes have to be designed and about 650 staff and 4,150 workers have been prepared for new employment by retraining. About 25%of available staff and about 10% of the manual workers have found employment outside the province of Limburg. People of 40 years and over form the hard core of the reduction programme as they are the most difficult to place. It is gratifying that so far employment has been developed for about 2,000 handicapped workers. |
| Het gecoördineerde personeelsafvloeiingsbeleid voor de nog resterende jaren van het mijnsluitingsproces - de periode 1970-1975 | 1971 | Hellemans, A. | 50(2) | |
| Scholingsaktiviteiten in het kader van de herstructurering in Limburg | 1971 | Loos, J. | 50(2) | Due to the closing of the coal mines a significant source of employment is disappearing. Many of the skilled professionals of the mining industry are, from the point of view of education, training and aquired skills, unit for the types of alternative employment that is being offered. Training of various types, from adding to a man's skills to complete retraining is needed and forms the subject of this paper. One of the types of training is provided by the centres of professional training for adults, another and by far the most important is the reschooling by the employers or by special job training centres, following the guidelines as laid down by the Directory General of the provincial employment office. Certain aspects of reschooling are already covered by other authors in this booklet. The favourable results obtained in the retraining and reschooling programs of the ex-miners is for a large measure due to the excellent co-operation between the provincial employment authorities, industry, the labour unions and the European Coal and Steel Community. |
| Taak van de mijnschool in het herstructureringsproces | 1971 | Haverschmidt, R. | 50(2) | In 1965 the Mining School in Heerlen was employed for the re-education of underground mining technicians in order to achieve that these staff could obtain equivalent jobs in industries outside the mines. In previous years the Mining School, an acknowledged institution for advanced technical training, had trained 2,250 mining supervisors and 150 mine surveyors. Retraining would therefore be carried out in a familiar place where the material was being modified on a routine basis to be suitable for changing employment conditions. In 1964 the Mining School occupied new premises which allowed the re-educational program to be handled in the most efficient manner. The cost of re-education could be paid out of contributions received from the Dutch Government together with allowances from the European Authority for Coal and Steel. Although initially it was assumed that only staff under 40 years of age would be re-educated, this upper limit was successfully increased in the course of the years. The paper deals with the didactics, including the various streams of re-education and the placement of those who passed the final exams, 10 different reschooling possibilities could be recognized. At present 380 people have been re-educated with over 190 still at school. Continuous contact is maintained between teacher and pupil when the latter is following practical courses in various industries, one of which may employ him eventually. Much special effort is asked the schooled staff in planning the reschooling programs and in guiding the pupils through the process. Some thought is given to the future of this school in these days of accelerated obsolescene of technical skill due to rapid technical developments. The Mining School has proven that re-orientation and the necessary re-education of staff towards other industries can successfully be achieved. |
| Omscholing en wederaanpassing van ex-mijnwerkers | 1971 | Koene, G.B.M.L. | 50(2) | The tenthousands workers who are still employed in the mining industry are very much involved in the further closing of the coal mines. For alternative employment away from the mines, a planned reschooling program is essential. When selecting candidates for each of the reschooling courses all those data are collected from superiors, personnel services, psychological and medical staff, which may be relevant to a man's reschooling program and further employment. In general terms all ex-mining staff such as technical, administrative, supervisory or subordinate adjust well to employment in unrelated industries. Results of reschooling are, so far, very favourable, and hereby we specifically include the "older" workers. The latter are personally highly motivated as society and industry were of the preconceived opinion that older people would be difficult to change over to other types of work. This last point is subject to intensive study these days, and there are indications that reality is quite different and varied and that older workers have been very much prejudiced against. Experience with miners has contributed to the studies mentioned. The closure of the mines and the re-industrialization of the mining region of Southern Limburg has not only created serious problems for thousands of workers, but has especially affected those that were handicapped, physically or mentally, which can be due to physical/psychological conditions or age. Realization of these handicaps by employers and the studies thereof can lead to results that reach further than the mere re-employment of ex-miners. Anyone providing selective and adjusted employment can benefit from what has been learned in Southern Limburg. |
| Naar de education permanente | 1971 | Heiligers, G.J. | 50(2) | The second phase of the restructuring of Southern Limburg has only just started. A redrawing of the municipal boundaries has only reached the planning stage. Yet the education of the youth and, simultaneously, the reschooling of the not-so-young are of immediate concern. The new educational system will again have to be of a very special nature and content like the existing system which is now going to be abandoned. The new system calls for: - institutes for reschooling - new technical institutes offering a wide and diversified program - institutes specializing in refresher courses. These three elements form the basis for an incipient "Permanent Education", the primary aim of which should be the personality-development of its students. Additional fresh capital will have to be invested in what is most important: the potential of our youth, which potential will shape the future of the region. The financial means which this will require will have to-be found. A first start has been made with the design of a new type of school in which technical developments will be constantly taken into account. In the future one will have to ask himself in what ways a certain educational system will influence society, as a matter of fact: modern education is entitled to play a leading role in today's society. There is no lack of professional men in Southern Limburg to give this type of education. For the time being the accommodation is also sufficient. The financial backing, however, is still lacking. It is here that the assistance of the Government is most urgently needed. The University which Limburg will have must be supplemented by "intermediate level" schools, And, last but not least, expeditious and strong action is required. |
| De sociale begeleiding der industriele herstructurering | 1971 | Lebens, P.J.C. | 50(2) | The shutdown of the mines affects the social climate in Southern Limburg to a large extent, necessitating intensive social assistance for all concerned. The author recognized 4 distinct phases in the restructuring process. Initially the Provincial Administration of Limburg studied possible social repercussions of the shutdown of mines on the miners, the other professional population, housing, municipal financial matters and mental public policies had to be developed. Thereafter a start was made to carry out the suggested plans and proposals and two management-advice committees were instituted for proper planning and execution of the projects. The third phase saw several additional measures and precautions which had not been taken into account before. For example, after it was found that some 4,500 semi-invalid workers would come out of the mines, special workshops had to be provided for, which operate satisfactorily due to the present favourable economic climate. Favourable economic conditions also are the reason for the successful placement of the other miners that became available on the labour market. Of course, much attention has been paid, in particular during the first years, to all other personnel which had to leave the mining industry. There was a definite need for advice on the legal status and assistance in legal and financial matters. In 1968 some 6,000 persons made use of a special office dealing with these matters, which was operated by the unions, but also assisted non-union members. One of the problems one had to face was the reduction of income the ex miners had to get used to when working in non-mining industries. Not only were the miners and their families suffering but so did other groups of the population in the area. The closure of the mines created initially a high rate of unemployment which, however, was rapidly reduced because people moved away from the region or started to commute to jobs outside the region. Certain difficulties remain, which are likely caused by divergencies in quality and basic education. Although on the one hand much money is needed to attract new industries, the financial position of the municipalities, on the other hand, deteriorated due to the closure of the mines. As a result the social infrastructure occasionally suffered, though about Hfl 30 million (US $ 8.4 million) was made available by the government during 1967-1970 for social projects. An important aspect of social welfare is the care of mental public health: the liquidation of an industry which provided a living for almost half of the South Limburg population inevitably has mental repercussions. Many people had to retire earlier than previously; for others the sense of security disappeared. In the framework of social welfare preventive measurements have to be taken, to be carried out by sociologists and social psychologists or psychiatrists. During the last three years much work has already been done; this, however, should also be continued. The fourth phase, which is starting today, involves the co-ordination and planning for the problems discussed above. A start had been made, appointments are carried through, the ultimate goal is not only to contain the problems but also to actively build a new society. |
| De rol van de vakbeweging bij de afbouw van de mijnindustrie | 1971 | Hubben, A.J. | 50(2) | Since 1945 the Catholic Federation, together with the Netherlands Catholic Mining Union (NKMB, 65 per cent organized personnel) and the Catholic Union of Mining Officials (KVM, 85 per cent organized) requested the Government repeatedly to define its point of view regarding the difficulties of the mining industry. The author, chairman of the KVM, describes the active influence which the Federation exerts on the restructuring of the mining region, a logical consequence of the good and positive relationship that has prevailed for years between employers and employees in the mining industry. The role of the Trade Unions was in this manner formerly recognized by the authorities. Trade Unions were involved in policy making for the mine closures, the resulting personnel reductions and the control thereof. They also contributed positively to the re-industrialization of the region. The one-sided industrialization over the Iast 70 years in Southern Limburg had brought about a mono-culture; that dislocation of the work and living environment and the end of prosperity should be avoided was a subject of much concern to the Federation' The guiding principle therefore was that the shutdown of the mines should only be organized in such a way that equivalent employment opportunities would be available. This problem both qualitatively and quantitatively is unique in the Netherlands, involving directly or indirectly some 300,000 people. The unions themselves assumed responsibility for these events and their consequences. They worked closely together with the Government and employers to achieve the best results. Much personal grief still remains, however, it is only fair to mention that at least partly due to the role of the unions, the Netherlands is the only country in the Common Market where the shutdown of mines has been organized within a framework of restructuring, embracing the whole of the industry and including a social planning for all personnel. Labor participates in these matters through its representation on the Council of Guidance which is mentioned by Mr. Hellemans in his paper. Common Market people agree that a lot of good work has been done. Special attention is given to the financial repercussions, in particular regarding pensions. The unions assist their members in finding new jobs and are in the forefront to get a new university in Maastricht and to revamp the Mining School. The author maintains that officials and miners would like to continue to be members of their weII known unions and their regional affilations. Some of the familiar working conditions and labor relations have to be maintained while the industrial climate is changing. For this the full co-operation between employers and employees is essential. |
| Wat betekenen de veranderingen in de mijnstreek voor de vrouwen en voor de gezinnen? | 1971 | Stollman, E.H.M. | 50(2) | A few years ago few housewives could believe that the mines really would be closed down, but now they are already suffering the consequences of the closures. In certain cases their husbands found employment outside the mining industry, others went on early pension. A third group was transferred to the chemical side of their employers' business, for which they were not trained, more often than not resulting in friction with their new colleagues. Many housewives have quite some trouble in containing their husbands' unhappiness with respect to the changed situation, he has to worry about different things than he was used to, the daily routine had to be changed and naturally the changed circumstances affected the peace in the family and the relationships between parents and children. It was realized that children probably need a better education than father ever had and it generally is the mother, being closer to her children, who had to bear the brunt of the problems. Not only had the housewives to adjust themselves and the children to the enormous changes in the social circumstances, she often had to go to work in order to make up part of the loss of income suffered by her husband, as most new job opportunities were less lucrative than those of underground miners. Generally, the greatest part of the burden of the changed climate will have to be carried by the housewives according to the author. It will depend mainly on her whether future living in Southern Limburg will be worthwhile. The paper ends with a discussion along the different activities underway in the different women's organizations to alleviate the problem which can be catalogued as follows: a. Activities focussed on the housewives directly; b. Co-operation with other agencies in determining restructuring policy; c. Publications and other means to recognize problem areas, |
| Mijnsluiting en mijnwetgeving | 1971 | Martens, A.H.W. | 50(2) | No one objected to the principle of closing the coal mines when oil and gas pushed coal out of the energy market. Social repercussions were successfully contained. Technically, however, there are two problems which could lead to legal complications but for which there exist no juridical precedence. There are firstly the necessity to fill up the main shafts and secondly the continued certainty that mining damage would be compensated for even after the abandonment of the mines. The mining law of 1810, dating from the days of occupation by the French, which is, at least partly, still valid in the Netherlands, has no chapter dealing with closures of mines. Only in 1964 a very general and largely incomplete regulation covering this matter was incorporated in the law. The initial requirement to have the shaft completely filled was after all not necessary. The question of the subsurface water level is dealt with in another paper. Regarding mining damages, a system was chosen in which the mines Oranje Nassau, Laura and Vereniging and Willem-Sophie quaranteed voluntarily to remain fully responsible for all possible damages, also after the shutdown of these mines. A special foundation has been established by the abovementioned private companies to ensure payment of any future claims towards damages, and particulars concerning the funding of the capital is fully described. The Dutch Government took over the Domanial Mine, for which mine, as well as for the four existing State Mines, no special regulations are thought necessary. |
| Beveiliging van het maaiveld van verlaten mijnschachten in Zuid-Limburg | 1971 | Schilp, J.P. | 50(2) | In the South Limburg coal mining district, abandoned pit shafts have to be filled up - at least in the overburden section - in view of the loose nature of the overburden, and the presence of dangerous gasses in the underground workings. In other coal basins with comparable conditions, shafts have been filled down to the bottom with clastic material, generally with special provisions near the shaft insets. In several cases this method resulted in severe subsidence of the filling material and release of firedamp at the surface. In view of this, the following methods have been applied in South Limburg, also taking into account the urbanization of the area. Method I: The supported plug In nine shafts, a concrete closing plug has been placed in the shaft, at the level of the highest loading station. The plug is supported by the floor of the station. The shaft section above the plug is filled up with clastic material. The shaft mouth is capped with concrete. This method was used where the overburden is thick (average: 210m), the shaft opening large (average: 23 sq.m), and the shaft wall smooth. Method II: The shear prop a. In five cases the shaft has been filled up with concrete from the highest loading station to the surface. This method has been followed in the case of a thin overburden (average 43 m), with a short distance from the highest level to the overburden (average: 7 m) and a small shaft opening (average: 11 sq.m). b. In four shafts a shear plug has been placed above the highest level. The section above the plug is filled with clastic material. The required length of the plug depends on the distance to the surface, the size of the shaft opening and the roughness and nature of the shaft wall' The shaft mouth is capped with concrete. The average length of the filled section is 104 m, the average shaft opening is 10 sq.m and the walls have a rough and irregularly shaped surface. c. In three shafts, which have been filled over a considerable length owing to the prevalence of special conditions, a filling of concrete and clastic material, used alternately, has been applied. The concrete sections (shear plugs) are either over or opposite the shaft insets. The topmost shear plug completely separates the surface from the highest level. The shaft mouth is capped with concrete. The fillings with one exception, have shown only slight subsidence. Costs are only 20-50 percent of the amount for filling up the whole shaft and providing barriers at the level of the shaft insets. |
| Mijnwaterproblemen in het kader van opeenvolgende mijnsluitingen | 1971 | Crasborn, J.R.P.; Heuvel, H.N. van den; Kimpe, W.F.M.; Maas, W. | 50(2) | The mine water problem is dealt with by 4 authors in 4 parts and a review. In the first part "Problem definition and preliminary studies", the study made in 1966 on the possible difficulties operating mines might expect as a result of the closing of surrounding mines, is discussed. It was evident that operating mines had to be protected from yet unforeseen water breakthroughs. In the beginning in 1968 it became known that the German Mine Gouley of the "Eschweiler Mining Co." would be closed and that in 1969 their main pumps would be shut down. The water influx of this mine was about 13 m3/minute (57 US gallons/second) with a peak of 15 m3/minute (66 US gallons/second). As there exist many underground connections between the different mines on and between both sides of the border this water was expected to flow directly across the border into the Netherlands Domanial Mine and from there, together with the water of the condemned Mines Domanial and Willem-Sophie, to other mines in the Netherlands. However, the pump capacity of the remaining Netherlands mines would be insufficient to cope with this additional water influx. After numerous discussions between the different mine owners it was recommended to proceed with the execution of project "Pump Mine Domanial". As can be seen from the drawings several water retaining dams would have to be built, to protect the mines and to collect the water of the mines Gouley, Domanial and Willem-Sophie in one basin. With the assistance of vertically submerged pumps the water level in the basin could be maintained at 310-315 metres (1030-1050 ft) below the surface level of pump shaft "Beerenbosch II". In part II the execution of project "Pump Mine Domanial" is discussed, dams were built and pumps placed. The building of one of the dams cost more than Nfl. 500,000 (US $ 140,000) due to adverse circumstances. However, had this dam not been properly built and a leak had occurred, then the drainage level to other mines would have been 100 metres (330 ft) lower, and the presently available hanging pumps would not have been able to cope with the greater depth. Furthermore additional costs for deeper pumping (Nfl. 150 000 is US $42,000) and for 5 months earlier pumping (Nfl. 250,000 is US $70,000) would have been incurred. The manner in which the dams were constructed is also discussed. Because man may never reach them again later on they had to be built as water-tight as possible. It is also explained why shaft Beerenbosch II was selected for pumping and why the vertical submersible pumps made by Ritz were chosen. The total cost for the construction of the 12 dams amounted to Nfl.2.1 million (US $600,000); for pumping equipment and auxiliaries Nn. 2.3 million (US $640,000). During the execution of project pump mine Domanial and because exploitation of Mine Willem-Sophie had to be continued, the pumping of the de activated Mines Domanial and Gouley had to be continued at a cost of Nfl. 700,000 (us $195,000). The third part discusses the geological studies of the last few years, especially the hydrogeology was intensively studied. It was concluded that as a result of the filling of the underground cavaties with water, the low pressure entry points and especially those producing brackish water, will cease to produce. It is explained why the major "Willems" fault zone could be utilized as a water barrier between the area to the south and the mines located to the north of it. In Part IV the rise of the water level in a closed mine is discussed. The rate of rise in the different mines depends on several factors, about which little is known. One had to start from assumptions, although water level measurements were carried out in one of the mines. In the review the expectation is substantiated that during the 1st quarter of 1971 a level of 170 metres (570 ft) below Amsterdam harbour level wilt be reached, with the result that "Pump Mine Domanial" will start to operate. It is concluded that it is reasonable to expect that pump mine Domanial together with the pump capacity of the still active Mine Julia will be able to protect the mines that are to be closed down in the future from water influx from the mines closed down already. It is realized, however, that there still exist 2 potential water influx locations on German territory. These are old tunnels of the mines Anna and Nordstern. How to tackle these new "discoveries" is a subject for further study. |
| Werkzaamheden van het geologisch bureau van de Rijks Geologische Dienst te Heerlen, voorheen en thans | 1971 | Kimpe, W.F.M. | 50(2) | At the end of his paper the author provides his own summary, when he states "that the character of the activities of the Geological Bureau did not essentially change as the years went by". What did change was the quantity of certain investigations which were done for third parties. The article contains a tabulation of the number of reports, publication and of papers presented during the last decade. There is an increase in recent years in the number of studies on surface minerals, and also in the number of times the Bureau's advice was sought in connection with the exploration and exploitation of potable or industrial water. This directly reflects the increasing industrialisation of Southern Limburg. The Bureau was also more frequently consulted on matters of road construction. Surprisingly in these days of mines closing down. requests for advice on their part appear to be more frequent than had been expected. As from 1st January, 1968 the two geological institutions then existing in this country were re-organized into the one Geological Survey. After 60 years the Geological Bureau for the mining area ceased to be an independent unit. Its history goes back to 1907, the year in which the mining industry became actively interested in the geology of Southern Limburg. Geological mapping was also started, and likewise the Bureau was put in charge of the study of palaeobotany, the drawing up of a stratigraphy of the Carboniferous and the correlation of the individual coal seams. Both in 1927 and 1935 as in 1951 and 1958 congresses of carboniferous stratigraphy and geology were held at Heerlen. These contributed to the reputation the Bureau enjoyed abroad. The above re-organization was primarily prompted by the direct interest which the Ministry of Economic Affairs had in the increasing exploration for and exploitation of natural gas. The present paper lists the six newly created departments, which deal for instance with the investigation of the North Sea, the geology of petroleum and natural gas reservoirs in as far as they concern the Netherlands, etc. The Bureau's staff numbers six graduates and 29 non-graduates. The Bureau's achievements in the field of Carboniferous stratigraphy and of mining geology are reported in detail. The Fossilium Catalogus, of which 76 parts have already appeared, will soon be complete. Repeatedly foreign companies called on the Bureau's expertise, mainly for the stratigraphy of the Carboniferous in coal basins or in exploration wells. The next chapter deals with the practical mining geology, and emphasizes that the new methods of investigation serve to give better and more efficient information to the mining industry. The paper reviews the activities of the Bureau in its eight different aspects, and recalls that also in behalf of the "Pumpmine Domanial" several geoÌogical and hydrogeological reports have been produced. A renewed exploration of the Netherlands, with a new set of maps show the results, is necessary. The hydrogeology, as practised by the Bureau, is gaining importance in recent years because of the increasing demand for potable and industrial water. During 1969: 57 million cubic metres of ground water were produced in Southern Limburg, or, if one includes the middle part of Limburg: 85 million m3. More research is required to substantiate the expectation that this production can be doubled. |
| De herindustrialisatie van Zuidelijk Limburg | 1971 | Bloemendal, J. | 50(2) | This article gives a brief historical outline of the decline of Holland's coal mining industry - concentrated in South-Limburg - as well as a description of what has been achieved in the field of industrial redevelopment of the region and of the future prospects. At the same time, it outlines, the steps taken by the Dutch Government and the activities displayed by DSM in this reindustrialization process. These activities are enumerated in the following items: 1. Analysis of labour potential according to quantity, quality and time of availability. 2. Stocktaking of needs of industrial sites that are offered and that are available or about to become available, and of the positive and negative qualities of these sites. 3. Promotion of cooperation with and between the bodies concerned, viz., the Ministry of Economic Affairs, the Provincial Authorities, the various municipalities united in "industrieschappen" - and the mining companies. 4. Gathering as much information and literature as possible about all subjects that may be of importance to the parties interested, so as to be able to keep parties fully informed. This information has been summarized in an attractive book entitled "Facts and Facitities; South Limburg, an excellent location in the Common Market". 5. Giving effective publicity to the possibilities offered by South Limburg. 6. Assisting entrepreneurs in the development and legalization of their plans and, in so doing, acting as their sparring partner. 7. Designing financial structures for filling the gaps in the "Grant Schemes". 8. Carrying out constructional engineering work (the only assistance for which a fee is levied). 9. In certain cases, offering participation in projects that are in need of risk-bearing capital. L0. Offering temporary accomodation in DSM buildings for projects requiring a quick start. Finally, the results obtained are presented, the present situation examined and the future prospects discussed' The conclusion is that the majority of the collieries has been closed without causing any unemployment' The situation is veiled, however, first because a number of people has retired prematurely, second, because of increasing employment of workers in Germany that travel to and from, and thirdly, owing to migration. That is why the grant schemes should continue to exist and be partly changed to meet the situation. |
| Regionaal beleid in het herstructureringsgebied | 1971 | Wilbers, J.H.M. | 50(2) | In this paper the problems related to the restructuring policy in Southern Limburg (including that part of the middle of Limburg eastward of the Meuse river) are discussed. In mid 1965 the mining industry employed 45,000 men which represented 50% of the industrial population. The total number of male employables in the area of restructuring defined above amounted to 186,000 in late 1965 and is expected to reach 190,000 by the end of 1975 and 228,500 by the end of 1985. How these figures are arrived at is discussed in detail and it is concluded that new employment opportunities to be created during the period 1960-1975 amount to 49,400 and to 39,300 for the period 1916-1985. The author claims that initially far too much attention has been given to employment opportunities in industry and not to service and other peripheral activities. Since 1965 more than 30,000 mining jobs have disappeared. From 1966 till 1971 86 new industrial projects have been created with a forecasted number of 17,000 jobs, of which 61 projects of 8,000 jobs have been realized. Already existing industry grew by 2,800 jobs. Since the end of 1969 growth has been stagnent, mainly due to emigration from Limburg, the early pensioning of miners, the employment of handicapped miners in social schemes and the commuting the highly paid employment in labour - short Germany. Furthermore the active recruiting by Belgian industries and the personnel policies followed by the mining concerns have aggravated this situation. Even during the present boom, results of restructuring have fallen off and if a mild depression were to occur, trouble on the employment side might be expected. According to the author the limited restructuring policy has to be reshaped on a much broader regional basis. With a new and more imaginative policy we should also want improved labour mediation, a systematic reschooling policy, a larger and more flexible employment potential and a more selective investment policy. Improved economical, social and fiscal policies are feasible for the benefit of Limburg. It will serve no purpose to hold the proposed new policy pending the complete integration and harmonization within the European Economic Community. With relatively minor direct Governmental involvement much can be accomplished in the outlying regions of the Netherlands. |
| De oostelijke mijnstreek als sluitpost van de herstructurering | 1971 | Smeets, J.G. | 50(2) | The chief executive of one of the largest mining communities, Kerkrade, who also is Chairman of the industrial board of the Eastern mining area, poses some critical comments on the social measures taken in connection with the mine closures and some of the favourable opinions expressed by other authors. By the 1st of January, 1970, a total of 8,000 new employment opportunities had been provided for by industry in Southern Limburg. With governmental support only 3,300 of these jobs were filled by ex-miners, although at that time 32,000 mining jobs had already disappeared. The guiding policy that no mine closures would occur without having provided for alternative employment opportunities, proved to have a theoretical value only. As a result one is at the present time feeling much less confident about coming developments in the labour market of the Eastern mining region that one felt a year ago. In reality, the situation is even worse that the figures indicate and according to the author "the real problem has been circumvented". Re-industrialisation is practically stagnant, mainly because of the competitive forces in the labour market which are aggrevated by the large scale of commuting of labour to Germany. According to the author, the statistics at the moment give a confused picture and fail to show an improved employment climate. Commuting across the border gives the impression of full employment in the area, but it would only take a small fluctuation in the economic climate across the border to create a serious problem in Limburg, for which no employment vacancies are being reserved. The consequences of the re-structuring process are most severely noticed in the Eastern mining region. It is therefore necessary that strong concerns are being created which most likely requires additional government support. The possibility of re-locating government offices over the country should also be kept in mind, and in this respect the Eastern mining region would like to have the same system of transfer allowances as has been authorized for Eastern Groningen. Mr. Smeets points out that there has been no compensation for the little understood departure to another are with employment problems of the "Industrialisation Group Dutch State Mines". In his opinion it is the duty of the government to create and maintain another such employment group in the mining region. |
| Herstructurering en ruimtelijke ordening | 1971 | Woude, J. van der | 50(2) | About 70 years ago the geological and geomorphological aspects of Southern Limburg were going to be used to advantage. The first aspect gave rise to coal mining and the exploitation of marl, sand, gravel and clay; the second aspect stimutated the tourist trade. Mining, however, had a negative influence on its environment from different points of view, such as natural beauty and living conditions for the community. In the eastern part of the mining area ten mines were opened up; in the western part only one. In addition to the development of roads, railroad and canals, accelerated and often haphazard housebuilding was the result, creating, however, an economic mono-structure with the exception of the chemical industry of the DSM. Like everywhere else in the Netherlands, environmental planning was not taken seriously until after world war II. Firstly the western mining region was tackled; the plan for the eastern mining region is at present under review. Planning for the western region appears to deal with the various villages and town separately. The north-south running highway (E-9) will be the backbone for all traffic. In addition attention should be paid to touristic attractions. The western region, however, is less of a problem as it already has a new car manufacturing plant and less workers. Planning for the eastern region, where about 40,000 out of in total 50,000 miners of Southern Limburg live, had to be approached in a completely different way when compared to the western region. Industrial areas had to be developed for suburban developments. One notices a clearly defined regional policy, for the eastern region a completely revamped road system is an essential requirement and it puts planning in the eastern and western regions on equal footing. The author stress the importance of planning on a provincial level. The new regional planning should encompass the whole of Southern Limburg and be able to co-ordinate short and long-term goals in process-planning type activities. By the time the last mine is closed down in 1975, major problems will remain in the eastern region and there is not yet a consensus of opinion how to solve them. In balance, although there is ample cause for satisfaction with the results of the restructuring program, there are still plenty of problems left. The basic information on the labor situation is often confused, how many people have left the area, or are planning to leave? How many are finding employment across the border in Germany and how many are planning early retirement? In short, how will the labor force develop in the near future? What is required for proper planning of policies and priorities must be agreed upon now, such as an overall plan encompassing all of Southern Limburg, co-ordinated with the short- and long-term plans of the province and its municipalities. A way must be found to direct municipalities and their planning so as to be in line with the long-term goals of the province. |
| De ontwikkeling van de infrastructuur i.v.m. de sluiting van de mijnen | 1971 | Horsmans, G.A.A. | 50(2) | In a first Governmental note it was concluded that some 10,000 new jobs would have to be created as a result of the closing down of the mines. The government appropriated Hfl 62.5 million (US $ 172,500) for the improvement of the infrastructure in Southern Limburg. In addition a number of public works would be carried out earlier than planned systems, which did not help to stimulate the construction of a modern road-system. Any other industry employing several tens of thousands of workers would have required better roads. With the imminent closure of all the mines in 1975 a much more extensive program for the improvement of the infrastructure is necessary. The author deals successively with the following categories of public works: 1. roads, 2. waterways, 3. railroads, 4. airport and 5. purification of sewage and industrial water 1. Ever since Roman times the north-south link (the present E-9 motorway) has been the main artery, if one excepts the road Maastricht-Aachen-Cologne. At this moment a complementary east-west road system is being developed. The mining district is bypassed by the E-3 road (Antwerp-Eindhoven-Venlo-Ruhr area) to the north, and by the E-5 road (Brussels-Liege-Aachen-Cologne) to the south. The E-39 (Antwerp-Elsloo-Heerlen-Bochholtz-Aachen), however, runs right through the mining district and the bridge crossing the Meuse will undoubtedly become inadequate. The planned road Maastricht-Heerlen (estimated costs 90 million guilders or US $ 25 million) can be linked up to the E-9 near Maastricht. The second major provincial road construction project is the completion of the north-south link Roermond-Kerkrade. Before long the province will be connected to the European road system by the E-9, E-3 and E-39 roads. Other roads have been planned to open up new industrial sites. Not only the government, but also the province and the municipalities have contributed towards improving the road system. Furthermore the municipalities are constructuring roads for the same purpose. The limited number of waterways are navigable for ships of up to 2,000 tons. The good road system is offset by poor rail connections. The author mentions several requirements: the rail connection between Maastricht and the eastern part of the mining district with Aachen needs improving. In 1971 an hourly service between Maastricht and Liege and between Maastricht and Aachen will probably be realized. The railways between Maastricht and Hasselt and between München-Gladbach and Roermond, however, will probably remain closed for passenger traffic. It is obvious that for goods traffic also Southern Limburg is insufficiently integrated into the European railway system; moreover, Limburg has voiced a protest against the closing down of too many loading and unloading facilities. 4. Southern Limburg's airport plays a distinct role in the industrialization process. In 1969 well over 100,000 air passengers passed through it. 5. The treatment of effluents requires special installations. In a few cases the government and the province have furnished together 65 per cent of the construction costs. There are plans for Hoensbroek, Sittard and Born, requiring over 51 million guilders (US $ 14 million), and a plan for Roermond in which another 8 million guilders (US $ 2.2 million) are involved. These projects will not be undertaken unless they are liberally subsidized. There remain certainly plenty of things to do. |
| Statistisch overzicht van productie, bezetting en prestaties van de Limburgse steenkolenmijnen | 1971 | Westen, J.M.J. | 50(2) | |
| Samenvatting van de eerste nota inzake de mijnindustrie en de industriële herstructurering van Zuid-Limburg | 1971 | 50(2) | ||
| Samenvatting tweede nota inzake de mijnindustrie en de industriële herstructurering van Zuid-Limburg | 1971 | 50(2) | ||
| Preface Special Issue "Research on Sedimentology and Sedimentary Geology in The Netherlands" | 1971 | Jong, J.D. de | 50(3) | |
| Some sedimentological aspects of the fluvioglacial outwash plain near Soesterberg (The Netherlands) | 1971 | Augustinus, P.G.E.F.; Riezebos, H.T. | 50(3) | The fluvioglacial outwash plain near Soesterberg (The Netherlands) is a deposit, built up during the melting of the Saalian ice, by a braiding river system on the ice-free side of the ice-pushed ridge of Amersfoort. The variation in the grain-size distribution of the sediment is great. Sorting is very poor to moderate. This indicates a high stream velocity, though fluctuating, combined with a huge supply of debris. The parallel to the principal stratification plane bedded strata alternate frequently with depressions, which are filled up laterally, showing a "festoon lamination". |
| Characteristics and regional implications of a belt of high-energy coastal deposits in the Barremian of Provence (SE France) | 1971 | Burri, P.; Masse, J.P.; Wagner, C.W. | 50(3) | In the Barremian Orgon limestone of southern Provence, a belt of high-energy coastal deposits of regional extent can be traced over approximately 90 km along an east-west axis from the border of the Massif des Maures to Martigues. In this belt, coarse-grained beach beds are closely associated with muddy protected shallow marine or intertidal deposits. Such an alternation is typical for a system of migrating carbonate spits and their protected lagoons, as observed in the Recent of the Persian Gulf. The Barremian belt of coastal deposits seems not to coincide with an ancient regional shore line. It appears to be controlled by east-west striking structural trends, which have been active in Provence since the Late Jurassic. The formation of this belt anticipates the most conspicuous tectonic event in this area during Cretaceous times - the Albian uplift, known in literature as "Isthme Durancien". |
| Carbonate facies of the Santa Lucía Formation (Emsian-Couvinian) in León and Asturias, Spain | 1971 | Coo, J.C.M. de; Deelman, J.C.; Baan, D. van der | 50(3) | Three lithofacies are distinguished in the Santa Lucía Formatíon: grainstone facies, packstone facies and birdseye facies. The lithofacies pattern suggests three depositional environments. An area of wave and current action (grainstone facies), a quiet and sometimes restricted lagoon protected by the extensive shallowness of the entire platform (packstone facies) and an intertidal to supratidal part (birdseye facies). |
| Q1MdQ3 indices showing grain-size distribution on maps | 1971 | Doeglas, D.J. | 50(3) | The use of Q1MdQ3 indices for classification and distinction of environments has been advocated by the author. He mentioned that the indices could be handled by data-processing machines used in trend-surface analysis. The present paper shows the value of Q1MdQ3 indices for presentation of the regional distribution of grain size on maps (figs. 1-3). |
| Sedimentary geology of the Holocene in lake IJssel region | 1971 | Ente, P.J. | 50(3) | Topics of the Holocene sedimentary geology based upon detailed investigations in the third polder of the Zuyderzee project are presented. They comprise distribution, composition and dating of sediments of the Calais-transgression phases, strongly bound to the evolution of the western Netherlands. Mainly after the first Duinkerke-transgression phase the development evolves towards a separate history of the Zuyderzee. Its evolution from a complex of lakes towards a brackish-saline lagoon is shown by the described sediments of different composition. The development of the delta of the river lJssel is brought into relation with that of the lagoon. The displacement of sands along the coast by wind/wave effects is shown, together with the phenomenon of numerous megaripples present at. the edges of the sand masses. |
| Prograding clastic fans and transition from a fluviatile to a marine environment in Neogene deposits of Eastern Crete | 1971 | Gradstein, F.M.; Gelder, A. van | 50(3) | In Neogene deposits of the eastern Sitia district (eastern Crete), a lateral succession from fluviatile to marine deposits has been reconstructed. Paleocurrent analysis indicates mainly southwest-directed sediment transport. The reddish deposits in the east (Kastti Formation) display braided-river characteristics. The fluviomarine deposits in the central part of the area (Toplou Formation), lie laterally of the braided-river deposits eastward. The fluviomarine deposits include thick conglomerate sheets, which display giant foresetting in sets between 5 and 30 m. high. This giant foresetting probably reflects the depositional slopes of large fans built by the discharging river below sea level. The submarine nature of deposition is confirmed by Ostrea between or on the pebbles. In the extreme southwestern part of the area marine marls occur (Akhladia Formation) with clastic intercalations, which bear evidence of mass transport, and which probably have been derived from the discharging river courses northeastward. Uniserial Uvigerina and Globorotalia in these marine marls point to a Late Miocene age of these deposits and hence of the fluviomarine and the fluviatile sediments. |
| Contents and behaviour of Mercury as compared with othe heavy metals in sediments from the rivers Rhine and Ems | 1971 | Groot, A.J. de; Goeij, J.J.M. de; Zegers, C. | 50(3) | Mercury is one of the various waste substances transported by the river Rhine across the German-Dutch border. Together with a number of other heavy metals mercury is present in large quantities. Upstream these metals are predominantly fixed to the suspended solids in the water and may be deposited on river flats and flood plains. From the fresh-water tidal area of the river onward, however, these elements are more or less solubilized during their transport as organo-metallic complexes. The mobilization of mercury is most pronounced in this respect. Leading to more normal amounts of this element in sediments from the Wadden Sea. This article deals with the behaviour of mercury through the whole Rhine estuary as compared with a number of other heavy metals. As a counterpart of the Rhine the same processes ale described for the river Ems. The latter may be regarded as a classic example of an unpolluted stream. |
| Molasse and clastic-wedge sediments of the Southern Cantabrian Mountains (NW Spain) as geomorphol;ogical and environmental indicators | 1971 | Jong, J.D. de | 50(3) | Post-orogenic sediments supplied by the Cantabrian Mountains during successive stages of uplift, were of the molasse type during the Stephanian and later of the clastic-wedge type. Sedimentological research has provided information on the source area and the environmental and climatic conditions under which these generally coarse grained sediments were deposited: warm and humid for Upper Carboniferous, warm and relatively arid for Triassic and Tertiary times. The depositional environments were in all cases torrential, alluvial fans grading into flood plains with finer grained sediments. |
| Depositional environment and weathering phenomena of the white Miocene sands of Southern Limburg (The Netherlands) | 1971 | Jong, J.D. de; Waals, L. van der | 50(3) | White Miocene sands occur in a block-faulted area near the southern limitation of the marine Miocene deposits in The Netherlands. Sedimentary structures, granulometric parameters, and the occurrence of fossil shells and burrows, point to shallow-marine tidal and littoral depositional environments. The mode of occurrence of silicifications in sand and lignite, the occurrence of red-yellow podzolic soils, and the absence of any unstable components among the heavy minerals point to a post-depositional strong chemical weathering in Tertiary times. The white colour of the sands should not be considered as an effect of bleaching by the lignites. |
| The effects of selective erosion by overland flow on the ice-pushed ridges of Uelsen (County Bentheim, Germany) | 1971 | Jungerius, P.D.; Wiggers, A.J. | 50(3) | The surface of the ice-pushed ridges of Uelsen is marked by parallel ridges of Pleistocene material rich in gravel' and intervening depressions in gravel-free Pleistocene and Tertiary deposits. This relief results from selective erosion by runoff in a humid temperate or a nivation climate. Later periglacial conditions with solifluction and wind action disrupted the drainage system and suppressed the relief. Present geomorphic processes tend to diminish the effects of the periglacial environment. |
| Tentative data on flow resistance in suspension currents | 1971 | Kuenen, P.H. | 50(3) | The efficiency with which turbidity currents have carried large volumes of sand for great distances on slight slopes of the deep-sea floor is remarkable. This seems to argue against high flow resistance by 'Jostle" viscosity and floor impacting. The grading of the deposits is inexplicable by thin, dilute currents because these would have to be fed at the origin over a period of a dozen hours or longer, to supply the observed volume of larger beds, and with decreasing grain size. High densities (over 1.16) seem more probable than great thicknesses (over 100 m). Experiments on viscosity of suspensions showed moderate values up to densities of 1.2 for clay and 1.5 for mainly sandy mixtures. Eddies large in comparison with the grain size do not meet serious obstruction by jostling. Measurements in a circular flume of bottom drag for suspension currents indicate that resistance is less than for clear water on a cohesive rough bottom of the same grain size and less than 2 X that of clear water on a smooth hard floor. These results, although of a tentative nature and without refinement by considerations of scale or of the paddle turbulence, appear to show that densities over 1.16 up to 1.5 as deduced from velocity cum thickness of the currents and from grading in the turbidites, ale not contradicted by flow resistance. True experimental turbidity currents are being studied to gain further insight. |
| Transition from fluviatile to tidal-marine sediments in the Upper Devonian of Seven Heads Peninsula (South County Cork, Ireland) | 1971 | Kuijpers, E.P. | 50(3) | Along the east coast of Seven Heads peninsula (southern Ireland) a more than 1000m thick north dipping succession of Upper Devonian strata is investigated. The lithology and sedimentary structures of the facies types are described and briefly compared with recent sediments. They indicate a gradual transition from a continental "Old Red Sandstone" facies along a coastal plain facies into overlying (tidal) marine facies. |
| Recent marine limestones from the shelf off tropical Brazil | 1971 | Mabesoone, J.M. | 50(3) | Samples of recent limestones and calcareous sandstones dredged from the continental shelf off northern and northeastern Brazil have been studied. Three types of rock can be distinguished: (1) calcarenites composed of many organisms and fragments, classified as biomicrites in thin section; (2) algal accretionary limestones, showing almost entirely algal structures, named algal biomicrites; (3) calcareous sandstones, lime-cemented shelf sands of fluvial origin. Besides these, one sample was collected from the continental slope, determined as a foraminiferal intrabiosparite. Study of fauna and mineralogical composition revealed a recent age for all types, confirmed by the faunal assemblage and the dominance of aragonite and high-Mg calcite. The lithification of calcarenites and calcareous sandstones occurred by cementation of the loose bottom sediment under favourable conditions, in a marine open shelf environment, up to depths of about 100 m. The algal limestones are growth structures of calcareous algae, chiefly Lithothamnium. |
| The quaternary geology of the southern area of the Dutch part of the North Sea | 1971 | Oele, E. | 50(3) | A map of the southern area of the Dutch part of the North Sea is presented. The geological history of the Quaternary can be summarized as follows. During the Late Tertiary and Early Pleistocene sedimentation of fìne sands and clays took place in a marine environment. Gradually the westwards progradation of the "Rhine-Meuse" delta caused these sediments to be covered by a veneer of fluviatile sediments of about the same grain size. In the Middle Pleistocene the sediments became coarser, but were still of fluviatile origin. Meltwater clay of the Elsterian glaciation, present in the north, marks the first observed interruption of the fluviatile sequence. After the Holsteinian interglacial, the Saalian glaciation reshaped the topography, creating ice-pushed and morainic ridges. During the Eemian interglacial a marine environment persisted, whilst the marine sedimentary series was closed by the deposition of a fresh water clay in the Early Weichselian. 3) Later during this cold phase the coversands were formed in the north, the Kreftenheye Formation being deposited by the Rhine in the south. The Holocene sea level rise resulted in the deposition of the Lower Peat Bed and a cover of tidal flat sands on top of which, after a period of non-deposition, the young seasand was deposited. |
| The quaternary geology of the southern area of the Dutch part of the North Sea | 1971 | Oele, E. | 50(3) | Large Enclosure |
| The frequency distribution of the current speed at the Netherlands lightvessels and its possible influence on the composition of sediments in the Southern North Sea | 1971 | Otto, L. | 50(3) | Frequency distributions of current velocities were determined from the Netherlands lightvessels in the North Sea. Near the lightvessel "Texel" the frequency distribution shows a considerable degree of symmetry. By means of a simple model for transport of sediment the consequences of such a frequency distribution for the transport of particles of different sizes are investigated. There appears to be a distinct maximum in the transporting velocity near the lightvessel "Texel" for a certain particle size. This particle size is estimated to be about 300 μ, a value that corresponds with a relative poverty of particles between 200μ and 300μ "downstream" of the position of the lightvessel. |
| Tidal deposits and their sedimentary structures (Seven examples from Western Europe) | 1971 | Raaf, J.F.M. de; Boersma, J.R. | 50(3) | Seven examples of tidal sedimentation ranging between modern and Devonian age are illustrated and briefly discussed. They cover known (modern intertidal and subtidal) and mostly undetermined ancient tidal subenvironments, and have been taken from: 1. The estuarine reach of a tidal river, subtidal, Holocene, Barendrecht excavation, The Netherlands. 2. An estuarine channel, subtidal, Holocene, Haringvliet excavation, The Netherlands. 3. A Lower Pleistocene (Tiglian), possibly subtidal estuarine succession, Hattem (Veluwe), The Netherlands. 4. A dune-bearing estuarine sand-bank, intertidal, modern Western Scheldt, The Netherlands. 5. The Lower Cretaceous (Lower Greensand) Woburn sands ± 50 km NW of London, England, being probably deposited in an open marine tidal environment. 6. The Oligocene (Tongrian) Kerkom- and Neerrepen sands SE of Brussels, Belgium, representing an as yet uncertain type of tidal subenvironment. 7. An Upper Devonian tidal succession belonging to the transgressive complex (Cork beds) overlying the Old Red, W. of Cork, Eire. The following features were considered to be diagnostic for these (and other?) tidal deposits (a) vectorial bimodality of the cross-stratification, (b) common joint occurrence at different proportions of largescale and smallscale structured units in super- of juxtaposition. (c) Usually poorly developed sequential regularity with occasional occurrence of fining upward sequences. (d) Unidirectional cross-stratified sets displaying several kinds of features resulting from the intermittent and bidirectional character of the currents (discontinuity planes). (e) Fairly common occurrence of flaser- and/or lenticular bedding respectively consanguineous mud-sand interlaminations in smallscale-structured units. (f) Slight to intense bioturbation in several types of sandy and/or muddy units. At the present state of knowledge a reliable determination of the tidal sub-environment (e.g inshore, offshore, intertidal, subtidal) seems to be virtually impossible for ancient clastic deposits, except for a few cases. Establishment of detailed paleocurrent patterns may help in distinguishing open-sea tidal deposits from inshore ones. |
| A contribution to the sedimentary-petrological description of the Maas deposits in Southern Limburg (The Netherlands) | 1971 | Riezebos, P.A. | 50(3) | From the Plio-Pleistocene series of sediments deposited by the river Maas on the Late Tertiary peneplain of southern Limburg.(The Netherlands) three samples, one of Pliocene and two of Pleistocene age have been taken. From these samples the grains between 500 and 2 micron have been subjected to microscopic investigations. The acquired mineralogical data confirming in broad outline previous investigations, reveal that the Pleistocene materials deviate from the Pliocene especially on account of a very great content of goethite particles. It is suggested that the great amount of goethite may be of use to discern the Quaternary Maas deposits from other contemporary fluviatile sediments. |
| Litho-facies of inshore estuarine and tidal-inlet deposits | 1971 | Terwindt, J.H.J. | 50(3) | Three litho-facies may be distinguished in inshore estuarine and tidal-inlet deposits. In general these litho-facies are related to the intensity of the current action over the bottom. The current action shows rapid variations in time due to alternating spring and neap tides and/or wind influences and to shifts of the channel axis. As a result fining and coarsening upward sequences of the sediment types are found. The frequency of occurrence of the litho-facies varied with depth in the estuary studied, but not in the tidal inlets. |
| Depositional environments of the Eocene Mirador and Misoa Formations Maracaibo Basin, Venezuela | 1971 | Veen, F.R. van | 50(3) | Outcrops and cored sections of the Lower-Middle Eocene Mirador and Misoa formations in and around Lake Maracaibo have been analysed sedimentologically and palacontologically in order to establish depositional environments. Three genetically distinct sandstone units could be recognised: the fluviatile point bar, the deltaic distributary channel-fill and the offshore bar or barrier beach. Each of these units is characterised by a specific vertical grain-size trend and sequence of bedding types. A fluviatile environment is typical for the Mirador Formation, whereas deltaic plain and delta-fringe environments obtained during deposition of the Misoa. The Misoa constitutes overall a transgressive sequence interrupted by several phases of delta-building which become less important upwards. The Mirador and Misoa sediments are thought to form parts of one alluvial deltaic complex of Mississippi size. A deltaic source for the basinal turbidites of the Trujillo Formation, which is the lateral equivalent of the lower part of the Misoa, is likely. The Misoa grades vertically and laterally into the holo-marine shales of the Pauji Formation. |
| Directional trends in Dutch coversands | 1971 | Veenstra, H.J.; Winkelmolen, A.M. | 50(3) | The article presents a general survey of the coversands in The Netherlands and northern Belgium. About 50 samples were taken mainly in a N-S run and in 15 localities oriented cores were taken with plexiglas tubes. Of all the samples a grain-size analysis was made by sieving and all the sieve fractions were tested for rollability, a functional shape parameter. After impregnation, the cores were inspected with X-rays and the directions of the oblique bedding planes measured. Of selected parts thin-sections were cut and the grain orientation was measured under a microscope. The directional features of foreset dips and fabric anisotropy both pointed towards transport from mainly northern directions. Also the grain-size and shape-sorting studies revealed a N-S trend. This trend, however, was not continuous but showed a repetition south of the rivers Rhine and Meuse. The coversands showed strong receiving shape characteristics and the coarser grains are of low sphericity. Although the infiuence of local sources is probable, the impression was gained that the main source of the Dutch coversands must be looked for in the region north and northwest to Holland, in the present North Sea. This fits well with the former observation of the pronounced sphericity of the sands in this area, which is explained as a lag characteristic obtained during the blowing out of the coversands. |
| Sedimentological aspects of oil fields in the Niger Delta | 1971 | Weber, K.J. | 50(3) | One of the most conspicuous geological features of the Niger Delta is its growth fault pattern. Almost all the oil reserves are contained in rollover structures which are associated with growth faults. These structural features are thought to have been formed by the force of gravity acting on a thick body of sediments supplied mainly by the Niger River. These sediments form a typical deltaic offlap sequence consisting of a wedge of continental sands grading downwards into marine clayey sediments which, at a greater depth, are in a state of undercompaction. Stratigraphically most of the known oil accumulations occur in the paratic sequence, i.e. the transition zone between the continental and fully marine sediments. The paralic sequence consists of a large number of sedimentary offlap cycles, each cycle starting with a marine clay, generally less than 150 feet thick and changing upwards progressively into proximal fluviomarine interlaminated silt, sand and clay which are usually followed by various types of more sandy barrier-bar and coastal-plain deposits. The cycles are terminated by transgressions which erode away part of the offlap sequence and which are generally represented by a thin, very fossiliferous gravelly sand. In this paper the relationship between sedimentation and growth faults is discussed. Examples are given of depositional cycles and of the associated types of reservoir rock. Attention is given to the influence of the depositional environment on the petrophysical properties of the rock, reservoir continuity and reservoir imhomogeneities. |
| #REF! | 1971 | 50(3) | ||
| #REF! | 1971 | 50(3) | ||
| De huidige problematiek omtrent investering door of met het buitenlands bedrijfsleven in mijnbouwkundige objecten in ontwikkelingslanden | 1971 | Stikker, D.U. | 50(4) | |
| Isotopic dating in the Kamativi Tin Belt, Southern Rhodesia | 1971 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Hebeda, E.H.; Verdurmen, E.A.T.; Verschure, R.H. | 50(4) | Rb-Sr measurements point to an Eburnian age (around 2150 million years) for the granites and tourmaline pegmatites in the Kamativi area, southern Rhodesia. From Rb-Sr and K-Ar mineral dates it is evident that a tectonothermal event affected the area in Kibaran time, about 970 million years ago; the emplacement of the tin-bearing pegmatites was probably connected with this event |
| Eustatic drop of two meters since babylonian times? | 1971 | Vanderzee, T.J. | 50(4) | |
| #REF! | 1971 | 50(4) | ||
| #REF! | 1971 | 50(4) | ||
| KNGMG Jaarverlag 1970 | 1971 | 50(4) | ||
| A new find of the ichnofossil Phagophytichnus Ekowskii van Amerom | 1971 | Amerom, H.W.J. van; Boersma, M. | 50(5) | The ichnofossil Phagophytichnus ekowskii Van Amerom, known to occur in the Upper Carboniferous of Spain and in the Permo-Carboniferous of South Africa, is described for the first time from the Westphalian C of Northern France |
| Current vector dispersion in a river of fluctuating discharge | 1971 | Collinson, J.D. | 50(5) | As water stage falls over a bedform covered sediment surface, local flow directions are increasingly controlled by the topography and if the bed material is still mobile, smaller surface features will reflect the control. Dispersion will increase as water stage falls. A bank in the bed of the Tana River, Norway, is used to illustrate this. Pebble features record high stage directions while sand features reflect falling stage modifications in direction of flow. Consideration of this effect might be important in using palaeocurrent distributions to specify channel type in fluviatile sandstones. |
| Buried tunnel valleys off the Northumberland coast, Western North Sea | 1971 | Dingle, R.V. | 50(5) | A series of deep, steep-sided, probably linear erosion hollows is described from the East Bank area on the northwestern side of the Dogger Bank, off the Northumberland coast of England. These hollows are infilled with bedded sediments and the whole sequence overlain by thick surface sediments with large linear banks. It is concluded, after a comparison with similar features from the western North Sea, that the East Bank hollows are buried tunnel valleys, which were excavated by sub-glacial streams near the edge of the Weichsel ice sheet, which deposited the Dogger Bank terminal moraine. |
| Late Cretaceous age based on K/Ar dates of granitic rock from the Tambelan and Bunguran islands, Sunda Shelf, Indonesia | 1971 | Haile, N.S.; Bignell, J.D. | 50(5) | K/Ar determination on two adamellites from the Tambelan and Bunguran Islands, on the Sunda Shelf between the Malay Peninsula and Borneo, indicate that these are pre-Tertiary, probably Late Cretaceous' Rb-Sr determinations on the rock from Bunguran Island' and a third granitic rock from Tambelan Island, are not definitive, but are consistent with a Late Cretaceous age for the intrusion of the granitic rocks. These determinations, the first age indications from the Tambelan and Bunguran Islands, throw doubt on the supposed "pre-Upper Triassic" age of the acid batholiths in the Anambas Zone of the Sunda Shelf and its extension into West Borneo. |
| Stratigraphic position of the limestones and conglomerates around the Marimana granodiorite, Central Pyrenees, Spain | 1971 | Hartevelt, J.J.A. | 50(5) | Limestones bounding the Marimaña granodiorite, in the Central Pyrenees, which have until recently been correlated with the Cambro-Ordovician 'Calcaire métallifère" or "Calcaire de Bentaillou", have been proved to be of Devonian age. Conglomerates occurring at some distance below should be correlated with the main conglomerate level of the Cambro- Ordovician of the Pyrenees. |
| The Holocene eustatic sea level problem | 1971 | Mörner, N.A. | 50(5) | |
| Postglacial changes in level of land and sea | 1971 | Ward, W.T. | 50(5) | Four postglacial high sea levels, separated by intervals of low water, are recognized at 7.5 ft, 4,5 ft, 3.0 ft and 1 ft above present mean sea level in East Gippsland, Victoria, Australia. Direct estimation of shoreline age is made impracticable by an absence of datable material in the stranded beach sediments, but a few dates are available for lagoonal beds. These dates, and correlations with New Zealand made possible by the common occurrence of similar sequences of coastal dunes resulting from changes in postglacial climate, suggest that the four stages of high sea level occurred about 4,700, 3,000, 1,500 and 750 calendar years ago. In particular the East Gippsland shoreline sequence is similar to that observed in the Firth of Thames, New Zealand. The stranded shorelines are believed to result from combination of long-term land uplift with real changes in sea level. This conclusion follows comparison of the Firth of Thames data with observations reported for 15 other localities in New Zealand, western Europe, North America, Africa and Oceania. Contradictory theses concerning postglacial sea-level changes in these localities are reconciled if it is assumed that each locality has been affected by earth movements. Such movements are already recognized in some areas affected by isostatic rebound or by mountain-building, and are presumed in other where shorelines appear excessively high or excessively low. To facilitate comparison, two simple models that relate shoreline elevation to implied rate of uplift are used. These models are based on the supposition that the earth movements actually experienced were continuous, or can be reasonably represented as small fluctuations about a regular long-term trend. It is not yet possible to decide whether any of the localities studied has been stable in postglacial time. Earth movements may not have affected the Cook Islands, South Pacific, however. If this is so, it would seem that the sea g:ained its present level several thousand years ago. Subsequent fluctuations have been in response to global climatic changes. The highest level actually attained by the sea (5.5 ft) was reached briefly in Sub-boreal time. |
| #REF! | 1971 | 50(5) | ||
| A three dimentional vector method as an aid to continuous-dipmeter interpretation | 1971 | Nederlof, M.H.; Weber, K.J. | 50(6) | Means of dipmeter readings derived by a three dimensional vector method have proven to be useful in deriving structural dip and azimuth from a collection of widely scattered dips. A computer program to calculate 3-D vector means and related statistics has been developed. Dip distributions are comparable to the spherical normal distribution so that for practical purposes a measure of reliability of the vector means can be calculated. The 95% confidence cone around the vector mean is chosen as the most convenient yard-stick. Confidence angles for the mean dip angle and mean azimuth are derived separately from this confidence cone. Preferably, study and correlation of well logs should precede the averaging procedure. This enables the selection of intervals, which contain readings mote-or-less conforming to the structural dip and azimuth. The calculated average dips can be displayed on a tadpole plot, or other plots against depth. The average dips are much easier to interpret than the original data, especially when using a condensed depth scale. The difference between successive vector means is a measure of the rate of change of dip with depth and can reveal the presence of discontinuities, such as faults and unconformities which might otherwise remain undetected in the "raw" data. The approach is applicable to both 3-arm dipmeter logs and the mote modern 4-arm dipmeter logs for which the digitized curves are correlated by the computer. |
| Tubular fossils in the bauxites and the underlying sediments of Surinam and Guyana | 1971 | Valeton, I. | 50(6) | This paper presents a description of the possible plant fossils and burrows in the bauxite belt which extends through Surinam and Guyana. The possible plant fossils are defined as roots, treetrunks, and branches forming horizontal layers of roots in the underlying sediments and the basal part of the bauxites. The plant fossils show external textures, and internal structures which may be taken to be cuticulae. Within the bauxites burrows of various diameters may be seen. Internally, they either show the typical "Stopfgefüge" or lack structure entirely. The presence of plant roots and burrows proves that a large proportion of the bauxite in the bauxite belts of Surinam and Guyana originates from sediments formed in either a mangrove environment, a fresh-water marsh environment, or a brackish swamp environment. |
| Overconsolidation in some fine-grained sediments; its nature, genesis and value in interpreting the history of certain English Quaternary deposits | 1971 | Greensmith, J.T.; Tucker, E.V. | 50(6) | Soil mechanics parameters, such as apparent cohesion, natural moisture content and liquid limit, are useful additional factors in determining depositional and erosional events within non- and partially-lithified sedimentary successions. Overconsolidated beds, caused by desiccation, occur in the marine Quaternary succession of the Essex coast and they indicate at least two important periods of prolonged desiccation during lowered sea levels. The older phase reflects, in part, the late- Devensian - Holocene (Flandrian) interIude of depressed base-level and extended over at least 10,000 years. The younger and shorter phase is intra-Holocene c. 4,500 B.P. |
| Radiometric evidence for a Precambrian metamorphic event in N.W. Spain | 1971 | Vogel, D.E.; Abdel-Monem, A.A. | 50(6) | |
| Solifluction and colluviation on the ice-pushed ridges of Uelsen, Kreis Grafschaft Bentheim, Germany | 1971 | Bos, R.H.G.; Jungerius, P.D.; Wiggers, A.J. | 50(6) | The erosional history of the ice-pushed ridges of Uelsen is reflected in correlative slope deposits. Würmian processes lowered the gravelly summits of the hills and produced the characteristically unsorted solifluction deposits. These include remnants of an Eemian (?) soil. In contrast, Holocene erosion only affected the fine-grained soils on the flanks of the hills. It acted so slowly that well-developed humus podzols could be preserved on the eroded slopes, as well as on sites of colluvial deposition. The colluvium is strongly sorted because many small mineral grains were transported in humic aggregates of modal size. |
| Brief account of the symposium on geochemical exploration in Delft - March 5th, 1971 | 1971 | Botman, A.C. | 50(6) | |
| Present status and future prospects in exploration geochemistry | 1971 | Webb, J.S. | 50(6) | |
| Global distribution of tin abundances | 1971 | Oosterom, M.G.; Schuiling, R.D. | 50(6) | |
| The regional geochemical landscape of the Moresnet metallogenic district | 1971 | Dijkstra, S. | 50(6) | |
| Geochemical patterns and structural alignments in relation to antimony-mercury-tungsten mineralisations in the Nidge area, Turkey | 1971 | Kleyn, P.H. van der | 50(6) | |
| Use of mercury in geochemical exploration | 1971 | Friedrich, G. | 50(6) | |
| Application of automatic data processing to problems of exploration geochemistry | 1971 | Bosman, E.R.; Eckhart, D.; Kubik, K. | 50(6) | |
| Geobotanical exploration | 1971 | Cole, M.M. | 50(6) | |
| Marine geochemical exploration | 1971 | Tooms, J.S. | 50(6) | |
| Indrukken van het IMA-IAGOD congres, Tokio-Kyoto 1970 | 1971 | Uytenbogaardt, W. | 50(6) | |
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| Review of geohydrological activities in the Netherlands since World War II, in particular of the government institute for water supply | 1972 | Romijn, E. | 51(1) | Geohydrological activities in The Netherlands have undergone some remarkable developments since World War II. Besides the Government Institute for Water Supply many other agencies and institutes have contributed to this progress. Scientific achievements in geohydrology have largely run parallel with the rapid social and economic development of the Netherlands since the war. |
| Hydrogeological maps of the Netherlands | 1972 | Jelgersma, S.; Visser, W.A. | 51(1) | Two hydrogeological maps, in scale 1 : 1,500,000, have been compiled, based on the principles laid down for the International Hydrogeological Map of Europe. Map I is representative for shallow conditions; map II is representative for the sequence of sediments ranging from Pliocene to Holocene. |
| Hydrogeological maps of the Netherlands | 1972 | Jelgersma, S.; Visser, W.A. | 51(1) | Large Enclosure |
| Geohydrological investigations with a view to groundwater catchment, a case history | 1972 | Damme, J.M.G. van | 51(1) | With the intention to give an impression of the usually applied geohydrological procedures for the foundation of a pumping station in the Netherlands, the investigations for the well field at Beerschoten (provincie of Utrecht, The Netherlands) are reviewed. The area concerned is located on the western slope of ice pushed hills forming the Utrecht Ridge. The subsoil consists predominantly of Pleistocene sandy deposits of fluviatile origin, with local loam layers. The groundwater has a suitable quality for the preparation of drinking water and requires only a simple treatment. From a pumping test it appeared that the studied area is situated in the transition zone between a recharge and a discharge area and that loam layers delay the propagation of drawdowns from the pumped aquifer to the phreatic surface. The transmissivity of the aquifer from which the water will be withdrawn amounts to 3500 m2/day. On the base of subsequent studies carried out by means of a mathematical method and electrical model tests a prediction of the consequences of the withdrawal for the groundwater table has been given. Several relatively simple statistical methods are described, from which it appears that in spite of a certain lack of appropriate data. The prediction given was reasonably reliable and also that after adjustments for several external influences the actual consequences of the withdrawal could be very well determined. As in many other cases, the practical sustained yield in this area depends merely on the drawdowns due to the withdrawal and on the decrease of underground flow to ditches. From the point of view of water resources management the survey forms an example of a case where a series of multi-purpose investigations should serve to arrive at an optimum exploitation of the groundwater. |
| Fresh water winning and salt water encroachment in the Amsterdam dune water catchment area | 1972 | Roebert, A.J. | 51(1) | In the Amsterdam dune-water catchment area, a freshwater lens of some 40 to 90 m thickness is resting on salt water in the lower aquifer, located at a depth of 20 m to 160 m - O.D. Waterextraction from the lower aquifer has disturbed the fresh-water/salt-water interface, extending it into a zone of dispersed, brackish water. For many years, the extraction area has been overdrawn. This article will discuss salinity conditions in the Amsterdam catchment area, and draw up a comparison between its current stock of fresh water and the original volume present before the start of waterwinning in the area. With the introduction, in 1957, of artificial recharge through infiltration of Rhine-water into the upper aquifer above 15 m - O.D., water extraction from the lower aquifer, which had been hampered by increasing salt-water contamination of the wells owing to the upconing of brackish water, was virtually stopped. The lower aquifer, however, still holds a vast stock of fresh water, which, if developed by a system of intermittent extraction, could substantially contribute to the water supply of the greater Amsterdam area. |
| Fresh water winning and salt water encroachment in the Amsterdam dune water catchment area | 1972 | Roebert, A.J. | 51(1) | Large Enclosure |
| Buried channel aquifers and present open drainage system of East Gelderland, the Netherlands | 1972 | Vries, J.J. de; Rees Vellinga, E. van | 51(1) | In the eastern part of the province of Gelderland, two buried valley systems have been traced. One system is filled with fluvioglacial deposits dating from the Saalian Ice Age, the other with preglacial fluvial sediments which are remarkable rich in vulcanic minerals. Both systems have a course which is almost perpendicular to the present drainage system. This change in stream direction is explained by postglacial replacement of the main drainage channel in the area, tectonic movement perpendicular to the old channels, and postglacial filling of the old channels with wind blown sand. |
| Permeability distribution in a holocene distributary channel-fill near Leerdam, (The Netherlands) | 1972 | Weber, K.J.; Eijpe, R.; Leijnse, D.; Moens, C. | 51(1) | In order to understand and predict the production performance of a reservoir it may be important to know its permeability distribution in detail. The internal structure of Iayered sand bodies, such as those that result from the deposition of sands in channels, could for instance cause an overall permeability anisotropy. We have developed a method of deriving the permeability distribution in such a sand body from measurements on core samples. This method has been checked by comparing the permeability distribution deduced from measurements on samples from an actual channel-fill with that derived from flow tests in the same sand body. Our experimental data on unconsolidated distributary channel-fills show that permeability anisotropy is negligible in such sand bodies. |
| Contribution to the geochemistry of groundwater in Northern Germany | 1972 | Löhnert, E.P. | 51(1) | Moderately saline groundwaters, which are still usable for drinking and industrial purposes, occur in Northern Germany until depths of approximately 500 meters below the surface. Apart from local saline water intrusions along the North Sea coast and rivers, the saline components of groundwater are derived from deep groundwaters, which can be related to salt bodies mainly of Zechstein age. Sulfate waters are found in the immediate vicinity of salt domes. In contrast chloride salt waters and brines are also found further away from the salt bodies, and show indications of reduction and base-exchange. The relationships of the groundwater types toward each other should be clarified by means of isotope research. A chemical classification of groundwater has been proposed, which bears in mind the absolute as well as the relative contents of main ions (fig. 2). |
| The use of geohydrology in solving water management problems in agriculture | 1972 | Wesseling, J.; Colenbrander, H.J. | 51(1) | For the study of water management problems in agriculture often the same hydrologic parameters and calculation techniques are applicable as for civil engineering studies (e.g. foundations) and drinkwater supply studies (e.g. extraction and recharge of water). Therefore, arbitrary subdivision of hydrology as agro-hydrology, geohydrology etc. does not always make much sense. In this paper the use of some hydrologic calculation techniques in solving water management problems in agriculture is elucidated. |
| Application of models in geohydrological investigations | 1972 | Ouwerkerk, J.H. van; Zeilmaker, D.A. | 51(1) | The application of models in geohydrological investigations is closely related to the use of quantitative methods in groundwater hydrology. To help determine which type of model should be chosen an analysis of the following aspects is required: nature of the problems, structure of the hydrological system, types of models and general conditions. The large number of factors involved in this analysis, and the small number of results of alternative methods of investigations, preclude the formulation of a generally applicable rule of selecting a model. |
| The use of computers in water resources development and water supply planning | 1972 | Ridder, N.A. de | 51(1) | There is an urgent need for a new approach and the application of modern techniques in solving the problems of future water supply. More than is the case at present, proper planning must relate the physical, environmental, economical and social factors involved. But integration of the various elements encounters some major difficulties of which insufficient data and lack of an exact and comprehensive methodology are the most serious. In the last few years there have been a series of important developments in, total water resources management methods and water supply optimization techniques. Basic to these developments in total water resources management methods ciplines as Operations-Research and Systems Analysis, and the availability of high-speed electronic computers. Planning techniques based on the computer's ability to process vast amounts of information enables the engineer to check a certain solution by arbitrary variation of the given or assumed parameters of his model. The water demands of an area can be met either by delivering surface water, or groundwater, or by an almost infinite number of possible combinations of these two resources. But water should be supplied economically without causing harmful effects within the area or its surroundings. To achieve this objective the technique of linear programming can be applied, as it allows to find for each plan an optimum solution of water supply under the given constraints. Then, using a digital computer model of the groundwater basin, which is capable of simulating the extraction and replenishment flows, the consequences of future water engineering works can be determined. The unique feature of these two models is that the output of the linear programming model can be used directly on the groundwater basin model to test the physical validity of the economic solution. |
| Recent developments of physical investigations in boreholes and wells | 1972 | Walter, F. | 51(1) | Well logging methods and physical borehole investigations have come into use for geohydrological reconnaissance in The NetherIands in recent years. In open uncased boreholes the following features are logged: spontaneous potential, resistivity, natural gamma radiation and diameter; interpretation methods are given in short. Reference is made to investigation methods in observation and discharging wells. Permanent electrode systems can be used for monitoring ground-water salinity. |
| Application of natural isotopes in ground water hydrology | 1972 | Mook, W.G. | 51(1) | 18O, deuterium and tritium may serve as tracers and be used to determine the origin of groundwater. The radioactive isotopes 14C and T can be used to date water. Deuterium and 13C may give information about evaporation and processes in the unsaturated zone |
| An electronic groundwater-level detector with automatic output registration | 1972 | Rijn, W.P. van | 51(1) | A simple, robust, electronic groundwater-level detector has been constructed which measures the water level in piezometers with an accuracy of better than ± 1mm. A series of these instruments can be connected to an automatic digital recording system. Measurements can be performed according to a selected programme of measuring times. The reference level at each level-detector location is indicated by gauging glasses attached to a system of interconnected liquid-filled tubes. |
| #REF! | 1972 | 51(1) | ||
| KNGMG Ledenvergadering 1971 | 1972 | 51(1) | ||
| Aan de leden | 1972 | Krol, G.L. | 51(1) | |
| Preface Special Issue "Geohydrology - Hydrology" | 1972 | Smoor, P.B. | 51(1) | |
| Aan de leden | 1972 | Krol, G.L. | 51(2) | |
| Zestig jaren KNGMG | 1972 | Brueren, J.W.R. | 51(2) | |
| Complete lijst van de verhandelingen van het Koninklijk Nederlands Geologisch Mijnbouwkundig genootschap | 1972 | Helleman, G. | 51(2) | |
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| Preface special issue "Zambia" | 1972 | Mulaisho, D.C. | 51(3) | |
| Introduction Special Issue "Zambia" | 1972 | Vletter, D.R. de; Dijkstra, S.; Bruggen, J.W. ter | 51(3) | |
| Zambia's mineral industry and its position amongst world's major copper producers | 1972 | Vletter, D.R. de | 51(3) | Tonnages and values of the chief minerals at present mined in Zambia are included in a survey which also touches on other mineral resources, e.g, nickel. Zambia's position amongst other major copper producers is described in terms of production, average grades mined, ore reserves and costs. Estimates of copper production for the next few years are given and some events affecting the copper industry in the past decade considered, especially as they relate to the position of the developing vis à vis the developed countries. The extent to which copper dominates Zambia's economy is noted and its contribution to the Gross Domestic Product, to exports, Government revenues and employment is compared with that of its sister industries in the CIPEC countries (namely Chile, Peru and Zaire). The corporate structure of Zambia's copper mining industry is described and the terms of the agreement by which the Government of Zambia acquired a 51 per cent interest in the industry in 1970 are set out. Important implications of recent mining legislation including the Mineral Tax Act 1970 and the Income Tax (Amendment) Act,1970, are also considered. |
| Outline of the geology of Zambia | 1972 | Drysdall, A.R.; Johnson, R.L.; Moore, T.A.; Thieme, J.G. | 51(3) | The structural-stratigraphic provinces of Zambia are described with special reference to recent work by the Geo logical Survey. The Tumbide and lrumide deformations are redefined as episodes of the Kibaran Orogeny, and attention is drawn to Kibaran foreland folding within the Bangweulu Block. The Lufilian Arc is shown to be a polyphase structure, and is contrasted with the Mozambique Belt which is believed to be polyorogenic. The continental Karroo sediments preserved in the partly fault-bounded, riftlike structures of the mid-Zambezi, Luangwa and Kafue troughs are briefly described. The presence of Cretaceous beds in Western Zambia and a marine horizon beneath the continental succession are noted. |
| Outline of the geology of Zambia | 1972 | Drysdall, A.R.; Johnson, R.L.; Moore, T.A.; Thieme, J.G. | 51(3) | Large Enclosure |
| Sedimentary environment of Zambian copper deposition | 1972 | Garlick, W.G. | 51(3) | Superseding of the hydrothermal origin by syngenesis subsequent to 1928 is recorded historically. Granites claimed to be intrusive were in 1940 found to be overlain unconformably by Katanga sediments. The bulging intrusive granites became bulging paleo-hills, avoided by copper mineralization. Discovery that ore grade in the deformed and shattered orebeds of a dragfold was no richer than in the unfolded sections, proved that the mineralization was prefolding. Two decades later dolomitic facies over some granite bulges proved to be algal bioherms. By the syngenetic theory the zonal sequence, from copper-rich to iron-rich sulphide, was interpreted as representing depth zones parallel to shoreline controlled by the activity of anaerobic bacteria. Recognition of anhydrite explained mysterious cavities in veins, conditions of sedimentation, and the source of the sulphur to form the sulphides and, by its solubility, explained the high porosity of the Katanga sediments to depths of 600 m. Features of the ore shale deposits such as dissemination instead of selective replacement, mineral zoning, association with basins flanking paleo-hills, barren gaps over bioherms, apply also to mineralization in arenites. Pyritic disseminations in sediments over granite hills and sulphide concretions are confined to orebodies in arenite, explainable by its greater original permeability. Evidence for syngenesis derives from interpretation of the depositional environment, although many of the processes are still being elucidated. Prior to formation of the major ore deposits, in marine waters, evaporation of playa lakes gave high concentrations of sulphates, borates, and, under anoxic conditions, sulphide precipitation. Drying out of such lakes exposed mud flats on which efflorescences of gypsum, borates, and iron and cobalt sulphates presumably formed. Wind erosion at Mufulira produced dunes containing high proportions of gypsum later converted to anhydrite. At Chibuluma floods dissolved iron and cobalt sulphate from desiccated mud flats and on entering the saline lake precipitated hydroxides of these two metals as a heavy red mud with suspended sand grains and pebbles. The hydroxides were then converted to sulphide, whilst copper and iron were precipitated as sulphide in the overlying waters. Borates diffused into the underlying sand and combined with muddy coatings and matrix of the sand grains, to form tourmaline. Copper and cobalt were precipitated in greatest quantity at convergence of currents in the playa. Sulphide in sediment became sufficiently indurated to be eroded and redeposited as detrital grains, concentrated on foresets and truncation planes with tourmaline, sphene, epidote, and zircon grains. Compaction folding over Basement hills and even over biohermal and aeolian accumulations were controls for ore deposition. |
| Coppper orebodies in the basal lower Roan meta-sediments of the Chingola open pit area Zambian Copperbelt | 1972 | Voet, H.W.; Freeman, P.V. | 51(3) | Lenticular copper concentrations in basal atenaceous and rudaceous members of the Katanga System occur in basins in Basement gneiss and schist in an area of rugged palaeotopography at the Chingola Open Pit sector of Nchanga Mine on the Zambían Copperbelt. The gneisses and schists, as well as the unconformably overlying Katanga meta-sediments with their stratiform orebodies, have been folded into-overturned to recumbent structures .in which the westerly to northwesterly trend of anticlinal and synclinal axes is closely controlled by the old ridges and valleys, respectively. The overfolding is in turn the result of the incompetent behavior of the gneisses and schists which rode over the rigid buttress formed by the massive Nchanga Granite during orogenesis. Secondary redistribution of copper is believed to have taken place during the folding at one of the orebodies, which is located in the most intensely deformed area. Otherwise the present copper concentrations are still in their original stratigraphic positions. The close spatial relationship between the palaeoridges, the meta-sediments and the associated copper concentrations, suggests a common origin of both sediment and copper from the old ridges. Pre-existing copper lodes in the Basement gneiss and schist are invoked as the source of the copper, which was reconcentrated, either by detrital or chemical means or a combination of these processes, into the sediments at no great distance from the original lodes some of which are still preserved directly under the cupriferous sediments. |
| Suphide mineral zoning in the Baluba ore body, Zambia | 1972 | Vink, B.W. | 51(3) | This paper describes the sulphide mineral zoning through the stratigraphic column in the Baluba copper-cobalt mine in the Zambian Copperbelt. This zoning is explained by changing Eh and pH conditions with time, due to fresh river and rain waters, entering a saline basin. |
| Preliminary observations on the palynology of the Precambrian Katanga Sequence, Zambia | 1972 | Binda, P.L. | 51(3) | This is the first record of microfossils found in palynological preparations of Precambrian metasediments from the Zambian Copperbelt. Argillites and carbonates of the Lower Roan contain clusters of spherical forms, chains of cells, and filaments of algal affinity, which are similar to Precambrian microfossils reported from Australia and Europe. The Mwashia and the Kundelungu groups contain mainly isolated Sphaeromorphida. |
| Scope of stratigraphic and sedimentologic analysis of the Katanga Sequence, Zambia | 1972 | Eden, J.G. van; Binda, P.L. | 51(3) | It is speculated that the Katanga Sequence of the Zambian Copperbelt may have been deposited in a large basin which extended to the southwest into South West Africa. This concept calls for improved regional correlation, particularly since many economic strata-bound deposits in these areas are found in identical stratigraphic sequences of similar age. The Great Conglomerate, partially glacial in origin, can be considered a deposit of the widespread Late Precambrian glaciation and can, therefore, provide a much needed time-stratigraphic marker. The association of the Copperbelt orebodies to particular sedimentary facies may help to delineate trends of mineralization on a local as well as on a more regional scale. The lowermost part of the Katanga Sequence is interpreted as deposited during a regional transgression of the sea which created similar environments along a northwest-southeast belt. Though much of the Copperbelt ore is considered syn-sedimentary in origin, some occurrences are better explained by secondary processes. |
| Recent contributions to copperbelt geochemistry | 1972 | Jolly, J.L.W. | 51(3) | Short abstracts are given of some recently completed investigations bearing on the geochemistry of Copperbelt ore deposits. Three detailed investigations were carried out on veins and altered barren zones in the ore-bearing argillites and footwall quartzites at Chambishi, Luanshya and Muliashi. At all three places, hot fluids have locally altered the host rock, formed veins, leached and remobilized sulphides, and in one case, formed breccia. Comparison of samples from selected parts of the orebody and barren rock at Chambishi has shown interesting mineral and chemical trends that may have important bearing on the origin of the ore. An investigation into the use of mercury in prospecting was also undertaken with some positive results |
| Ore minerals of the Zambian copperbelt | 1972 | Notebaart, C.W.; Vink, B.W. | 51(3) | In this paper, major and minor copper and cobalt ore minerals, presently known to occur in Copperbelt ores, are described briefly. |
| The geology of the Zambia Broken Hill mine, Kabwe | 1972 | Kortman, C.R. | 51(3) | The Zambia Broken Hill ore deposits occur within a belt of dolomitic rocks of Katanga age (Upper Precambrian), which strikes NW and is flanked by shale and phyllite. The main pipe-Iike orebodies, striking WSW, and plunging to the ENE, have a massive sulphide core, consisting of sphalerite, galena and pyrite, surrounded by an oxidised zone containing willemite, smithsonite and cerrussite. An antipathetic relationship exists between lead and iron in the sulphide ore. The wall rock, a pure massive dolomite, was brecciated during oxidation. The breccia matrix consists of jasper-like lithified mud with erratic fragments of oxidised ore. A similar lithified mud is common along the outer margins of the oxidised ore, where it was emplaced through late infilling of cavities. |
| Summary - Geophysics in the Zambian environment | 1972 | Ellis, M.W. | 51(3) | |
| Introduction into mining an d metallurgy on the Zambian Copperbelt | 1972 | Bruggen, J.W. ter | 51(3) | This article gives a general review of technical practices in use at the Zambian copper industry from mining to refining. Some statistics concerning ore reserves and production for 1970 are included. |
| Open pit planning with the aid of a computer design system | 1972 | Pronk van Hoogeveen, L.A.J. | 51(3) | Computer techniques have become increasingly important in planning open pit mines. This article describes a computer system for the design of open pits to mine stratiform orebodies. The system incorporates a modified version of the Open Pit Design Program developed by Rio Tinto Zinc Consultants Ltd. The particular requirements of such a system, for example, the accuracy of representation of geological detail and the ability to follow footwalls, are described in this paper together with the methods that have been adopted to satisfy them. A description of how the computer design program was used to develop the medium and long term mining plans for the Nchanga Open Pit is included. |
| Underground mining mechanisation at roan consolidated mines since 1965 | 1972 | Collinson, B.M. | 51(3) | A brief description of the ore deposits at RCM's two large underground mines at Luanshya and Mufulira is followed by details of the main mining methods used immediately prior to mechanisation and at the present time. The objectives of mechanisation are listed together with additional benefits that have accrued. Experience with various types of mechanized mining equipment, loaders, trucks, drill rigs and raiseborers is described as are the steps taken to speed up ground support. The article concludes with a description of ventilation, underground maintenance, tyre usage and training. |
| The water problem in relation to mining at konkola division, Nchanga consolidated copper mines limited | 1972 | Rijken, J.H.A.; Clutten, J.M. | 51(3) | Nchanga Consolidated Copper Mines Limited, Konkola Division (formerly Bancroft Mines Limited) is the wettest mine on the Zambian Copperbelt and probably the second wettest in the world. The stratigraphic position of the orebody, between the Hangingwall and Footwall Aquifers, results in large quantities of controllable and uncontrollable water flowing into the workings during mining operations. In 1970 an average of 340 000 cubic metres (75 million gallons) pet day were pumped to surface, equivalent to 64 tonnes of water per tonne of ore hoisted. Sufficient pumping capacity has to be installed to lower the water table in the various aquifers in time to meet production commitments. The sustained capacity for 1972 wiII be in the region of600 000 cubic metres (130 million gallons) per day. The mining method of sub-level open stoping requires dewatering of the Footwall Aquifer during development operations and dewatering of the Hangingwall Aquifers prior to stoping. Water is, therefore, a major consideration in mine planning. A clear understanding of the geological features of the Konkola mining area is essential to develop a successful and efficient dewatering scheme. Dewatering of the various aquifers is achieved by drilling boreholes and by driving mining headings into the aquifers. The problem of recharge is not yet solved and research in this field is in progress, including colour and infrared aerial photographic surveys, chemical and neutron activation analyses of waters, regional water balance studies, and age determinations of waters by natural isotope analysis. |
| New developments at the leach plant at Nchanga consolidated copper mines limited chingola division | 1972 | Bosse, P.J.W. | 51(3) | |
| Summary - The research and development department of Nchanga consolidated copper mines limited | 1972 | Tumilty, J.A.J.; Timmers, J. | 51(3) | |
| Metallurgical practice at the broken hill division of Nchanga consolidated copper mines limited | 1972 | Barlin, B. | 51(3) | A detailed description is given of the metallurgical complex comprising a concentrator, electrolytic zinc plant, sinter plant, Imperial Smelting Furnace and lead refinery used to produce refined lead and two grades of zinc at the Broken Hill mine in Kabwe, Zambia. Flow sheets and 1970 production details are included. |
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| The evolution of petroleum engineering in the last 40 years | 1972 | Arps, J.J. | 51(4) | |
| Stufenweise durchführung von Lagerstättenuntersuchungen unter dem Gesichtspunkt der Wirtschaftlichkeit am beispiel der eisenerzlagerstätte Mano river, Liberia, Westafrika | 1972 | Theurkauf, E. | 51(4) | |
| A new find of a cave hyaena from the Netherlands | 1972 | Erdbrink, D.P. | 51(4) | Description of a mandibular fragment of the right side of a Cave Hyaena, found in 1971 near Deventer as the seventh recorded find of this species in the Netherlands, probably from an Eemian deposit. |
| Das Karbonische alter der Tiefbohrung Wanneperveen I, eine revision | 1972 | Amerom, H.W.J. van | 51(4) | A revision of the samples from the borehole Wanneperveen I, The Netherlands, leads to the following conclusions: a) Taeniopteris parva Jongmans nov. sp., published and figured in Jongmans&VanderHeide (1953) can be identified as single pinnules of Neuralethopteris schlehani forma rectinervis (Kidston). b) The non-marine shell described as "Carbonicola" carbonaria in the same above mentioned publication, is now determined as Carbonicola cf. circinata Pastiels 1960. Consequently the age of the fossil baring sediments in the borehole Wanneperveen I must be lowered from the Autunian to the Westfalian A. |
| Letter to the editor | 1972 | Wagner, R.H. | 51(4) | |
| Samenvattingen van de lezingen symposium "Enkele nieuwe aspecten van Delfstoffen in Nederland" | 1972 | 51(4) | ||
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| KNGMG Jaarverslag 1971 | 1972 | 51(4) | ||
| The Tyrrhenian sea - an introduction | 1972 | Ritsema, L. | 51(5) | |
| Deep earthquakes of the Tyrrhenian sea | 1972 | Ritsema, A.R. | 51(5) | |
| Oceanization - geothermal models | 1972 | Schuiling, R.D. | 51(5) | |
| Driving forces of Mediterranean orogeny | 1972 | Bemmelen, R.W. van | 51(5) | A critical review of newer data on the Tyrrhenian area (marine geology, land geology, paleomagnetism and seismicity) leads to a formulation of some general aspects of its evolution in Cenozoic time. A solution is suggested for the geodynamic puzzle of Corsica and Sardinia, based on a relativistic structural analysis of the apparent rotations and translations of these islands with respect to a deforming continental frame. During the Cenozoic the central Tyrrhenian area was subjected to pulses of doming and intervening periods of subsidence. The youngest uplift occurred in Mid-Pliocene time and thereafter it collapsed to bathyal depths at a rate of 1 mm/yr. This diastrophic evolution was accompanied by a geochemical transformation of the original continental type of crust (formed during the Hercynian orogeny) into an intermediary type of sialic crust (about 11 to 12 km thick). Meanwhile an orogenic crustal wave migrated radially outward from the Tyrrhenian centre of diastrophism, accompanied by radially outward directed overthrusts, imbrications, and other compressive tectonic features. The driving forces of this orogeny are evidently acting from the concave side of the orogenic arc. The expectations of three geodynamic models of interpretation, advanced for the Tyrrhenian test-case, are compared with the observed aspects of its evolution. These models are (I) plate tectonics, (II) radiogenic heating by the continental crust, and (III) active mantle diapirism. It appears that only the third model provides an explanation which is consistent with the available geonomic evidence. |
| Über einige molluskenfunde im Wellenkalk von Winterswijk (Niederlande) | 1972 | Boekschoten, G.J. | 51(5) | |
| Nieuw Zeeland en "Plate tectonics" | 1972 | Lingen, G.J. van der | 51(5) | |
| Enkele aspecten van (geo)mechanische modellenbouw | 1972 | Jong, L.N.J. de | 51(5) | |
| International soil museum | 1972 | 51(5) | ||
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| Landsliding in the Crati basin, Calabria, italy | 1972 | Nossin, J.J. | 51(6) | The Crati basin is flanked on either side by crystalline metamorphic rocks that have been subjected to intensive folding, shearing and crushing, and have hence lost much of their resistance. The basin is filled with Neogene alternations of sand, clay and conglomerates, in a (sub)horizontal position. It is a tectonic depression separated from the metamorphic surroundings by major faults. Post-Calabrían uplift of around 1000 metres, with differential movements superposed, accounts for rapid erosive incision that undercuts the slopes at the foot. Slopes have a further reduced stabitity on account of the loss of coherence in the metamorphics, of frequent faulting and of exposure of water in the slope face, often trapped by Tertiary clay layers and exposed after erosive incision. The main fault-scarp zones separating the basin from the surrounding metamorphics are zones of increased weakness. AII this accounts for an accumulated potential slope instability. Unstable slope zones are identified on air photos, whether they are presently moving or not. Zones in actual movement invariably make part of such larger zones of instability. This movement is mostly triggered off by cutting in the slope for purposes of road construction, frequent in this area under rapid development. Nine characteristic landslides are discussed. The recognition at an early stage in the planning phase, of potentially unstable slope zones from air photos - followed by field verification - allows the foreseeing of difficulties of construction and maintainance of communication lines. This may thus contribute to prevent disasters. |
| Paleomagnetic reconnaissance study of the Flamanville Granite, with special reference to the anisotropy of its susceptibility | 1972 | Voo, R. van der; Klootwijk, C.T. | 51(6) | For a preliminary paleomagnetic investigation of the Flamanville granite (Normandy, France), ten samples were studied. The granite samples had a weak remanent magnetization and a high magnetic susceptibility. The direction of the characteristic remanent magnetization was consistent with other Carboniferous paleomagnetic results from Stable Europe. The high magnetic susceptibility was distinctly anisotropic. The shape and orientation of the susceptibility ellipsoids were determined with the Utrecht astatic magnetometers, according to the method of As (1967). This method has been extended and its practical use is discussed. The orientation of the susceptibility ellipsoids could be interpreted in terms of the mode of emplacement of the granite. |
| Post-Archeozoic large-scale convection in the earth's mantle | 1972 | Vanderzee, T.J. | 51(6) | Static models of the lower mantle do not easily accommodate a cooling of the core on a terrestrial time scale. Moreover, merely shallow flows do not readily explain the present distribution of sial. Therefore, a still active, overall and occasionally reversing mantle convection is proposed that is consistent with the spasmodic character of orogenesis. This convection is compatible with modern estimates of pertinent parameters in a hydrodynamic theory of convection within spherical shells. It bears on the geomagnetic dynamo and helps to explain a correlation that has been suggested between changes in earthquake activity and in the earth's rotation. Apart from tidal dissipation within the mantle, a cooling of a radio-inactive core, on the order of 600°C during the last two and a half to three billion years, seems to be required to complete about a dozen successive mantle overturns. |
| The Plio-Pleistocene boundary in the North Sea Basin revision of its position in the marine beds | 1972 | Voorthuysen, J.H. van; Toering, K.; Zagwijn, W.H. | 51(6) | A revision is given for the definition of the Plio-Pleistocene boundary in marine beds of the North Sea Basin. It has appeared that Elphidium oregonense Cushman & Grant (an arctic species at present living in the Bering Street) characterizes a narrow faunal zone, which falls into the lower part of the first glacial stage of the Pleistocene, the Praetiglian, as defined by means of pollen-analysis. The Elphidium oregonense-zone is presently considered to mark the Plio-Pleistocene boundary. Beds hitherto assumed to belong to the Pleistocene i.e. Merksem beds, "Amstelian", are classified now within the Upper Pliocene. |
| Changes in vegetation and climate in the Amazon basin and surrounding areas during the Pleistocene | 1972 | Hammen, T. van der | 51(6) | |
| The presence of Nypa palms in Europe: a solved problem | 1972 | Haseldonckx, P. | 51(6) | Some new evidences for the autochthony of Nypa palms were found during a palynologìcal study of Eocene sediments in the Spanish Pyrenees. percentages of Spinizonocolpites Muller 1968 of nearly 40 per cent, a possible phylogenetic relationship between Spinizonocolpites baculatus and Spinizonocolpites echinatus and the appearance of fossil pollen and fruits of Nypa, restricted to the Eocene, make it unlikely that Nypa should be transported along the shores of the Tethys Sea. |
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| Holocene Sea Level changes, Cumberland Coast, Northwest England: Eustatic and glacio-isostatic movements | 1973 | Andrews, J.T.; King, C.A.M.; Stuiver, M. | 52(1) | Radiocarbon dates on materials from storm-eroded coastal sections plus other dates from peats and wood now below current high tide level are used to construct a preliminary history of relative sea level movement and to derive isostatic and eustatic components of the sea-level changes. Sea-level rose 22 m, relative to the land between 9,200 and 6,000 BP. No information is available for sea level between 6,000 and 3,600 BP but it was probably slightly higher than present. The main Postglacial Beach along this stretch of coast, and the highest evidence of marine action, is ca 5m above average high spring tide level. Shells in this beach date from 2,300±BP which suggests that at least storm waves were reaching these elevations 3,000 years or so after the usually accepted age for the feature. Relative sea-level changes after 3,600 BP were complex and there is at least one soil forming interval recorded. The high coastal sand dunes backing this stretch of coast date from between 1.200 and 1.500 BP. The estimated glacio-isostatic recovery is ca. 18m over the last 13,000 years. Computed eustatic curves indicate fluctuations in world sea-level in the last 5,000 years but these fluctuations could be caused by variations in storminess. |
| The gravity field of the Papuan Peninsula | 1973 | Milsom, J. | 52(1) | Large gravity anomalies on the Papuan Peninsula (the eastern part of the island of New Guinea) are associated with the Papuan Ultramafic Belt, an overthrust ophiolitic complex which may once have formed the frontal zone of an island arc. Very low fields occur over outcrop of the underthrust sialic metamorphics. The extreme east of the peninsula is built up of basaltic lava over which moderately high gravity fields are observed; the structure of this latter area is most simply explained in terms of Recent extensional movements |
| Displacement patterns of strike-slip faults in Malaysia-Indonesia-Philippines | 1973 | Tjia, H.D. | 52(1) | Detailed field studies seven important strike-slip faults in East and West Malaysia, West Sumatra, Java, and Central Sulawesi, used reliable, minor fault-plane markings (bruised step riser, spall, crescentic gouge, lunate fracture, chatter mark, pluck mark, slickenside prod mark) to determine the sense of displacement. The sense of movement on about ten other major transcurrent faults in the region was derived from the literature. A common direction of horizontal compression for each of three tectonic domains that subdivide the region between the Asian and Australian continents is indicated by consistent displacements along the wrench faults. For two of the currently active tectonic domains the directions of regional compression are 10°-190° (for Sumatra and Java) and approximately east-west (for the Philippines and the Indonesian islands east of Strait Makassar). These directions of regional compressions are parallel to compressive stress directions computed from sea-floor spreading rates by Le Pichon (1968) and to earthquake-slip vectors interpreted by Isacks et al. (1968) for the margins of the region under discussion. |
| De stichting van een mijnmuseum, een urgente zaak | 1973 | Raedts, C.E.P.M. | 52(1) | |
| Evidences of Post-Pleistocene desiccation in South West Ecuador and Northern Peru | 1973 | Sarma, A.V.N. | 52(1) | |
| Verslag kontaktgroep kristalgroei | 1973 | Lieth, R.M.A. | 52(1) | |
| Mineralogical analysis of the "Brown Rain" of February 7th, 1972 | 1973 | Schoorl, R. | 52(1) | |
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| Facies relationships in a tidally influenced environment: A study from the Eocene of the London Basin | 1973 | Bosence, D.W.J. | 52(2) | The sedimentology and burrow associations of a lower Tertiary (Lutetian and Cuisian) section in south-east England are described and compared with bedding types described from the Wadden Sea and Rhine estuary. In the lower part two facies are distinguished representing channel and bank deposits. Their relationship, bed forms, fauna and general lack of bioturbation suggest deposition in an inshore tidally influenced region. The sequence is truncated by bioturbated glauconitic sediments of the transgressive Bracklesham Beds. |
| Sand movement in the in- and offshore tidal area of the S.W. part of the Netherlands | 1973 | Terwindt, J.H.J. | 52(2) | This paper deals with the resultant sand movement over the offshore underwater delta along the tidal inlets of the S.W. part of the Dutch coast and with the sediment exchange between the North Sea and the underwater delta. It appears that a complicated circulation of sediments occurs in the whole channel system in the area, mostly directed perpendicular to the general coastline. On the shoals the sand transports by currents are almost negligible. The picture of sand movement by waves suggests a net northeastern sand transport over the shoals. Also the data derived from sediment balances and grain-size differences point to a net northeastern movement of fine sand over the underwater delta. The direction of the sand transport by currents and grain-size data reveal that there is an appreciable sediment exchange between the underwater delta and the North Sea in the Haringvliet area and apparently also along the southwestern part of the underwater delta. |
| Aspects of the historical and physical geology of the Sunda Shelf essential to the exploration of submarine tin placers | 1973 | Aleva, G.J.J. | 52(2) | After a short summary of the geology of the region, mainly based on observations on the tin islands, the original exploration concept is explained: the off-shore area is the drowned continuation of the land area, as studied and explored on the islands, only covered by a relatively thin layer of Recent to Holocene marine mud. The formation of cassiterite placers mainly depends on four genetic factors: primary tin occurences in the basement rocks, chemical weathering of these primary occurences, elutriation or washing out, and the presence of traps. Submarine acoustic profiling has greatly helped in identifying the depositional and erosional sequences, which would not have been possible with the aid of drilling samples only. Contrary to the situation on land, there are at least three sedimentation cycles and one erosion cycle (with a total sediment thickness of up to at least 60 m), covering the Permian basement. In the last chapter the new stratigraphical data are linked up with the principles of tin placer formation, thus leading to a new, considerably less simple, exploration concept. |
| New results from continuous gasometric determinations of carbonate in cuttings and cores from drill holes | 1973 | Schettler, H. | 52(2) | Continuous gasometric determination of carbonate in cuttings has been succesfully used by the Mobil Oil AG in the Weser-Ems area since 1954. It is used to check changes in rock composition (facies development) during drilling and to compare the results with those of adjacent drillings. Cuttings are taken at intervals of 1 to 2 m at the site of drilling; they are washed, dried, and ground. The amount of CO2 is determined with the "Scheibler- asometer" (described in MüIlet,1967) by treating 1/2 gr of the sample with HCl. Absolute carbonate content and the approximate calcite/dolomite ratio can be estimated if the first reading is taken after 30 seconds, the second after 1 minute (sometimes after 5 minutes) and the final reading after the gas development is completed (to 21 minutes). The resulting "carbonate-log" can be compared with those of adjacent drill holes during drilling operation. Such logs are very useful for exploring carbonate reservoirs and for stratigraphic correlation of sections strongly influenced by tectonics and of rocks lacking fossils. |
| New results from continuous gasometric determinations of carbonate in cuttings and cores from drill holes | 1973 | Schettler, H. | 52(2) | Large Enclosure |
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| Stratigraphy, sedimentology and palaeogeography of Eifelian, Givetian and Frasnian strata between the river Porma and the Embalse de la Luna, Cantabrian Mountains, Spain | 1973 | Reijers, T.J.A. | 52(3) | The chronostratigraphy of the Middle-Upper Devonian Portilla Limestone Formation is discussed in three stratigraphic sections. Deposition of limestones occurred in a diachronous way. A discussion in four sections, of the sedimentology of the Huergas Formation, the Portilla Limestone Formation and the Nocedo Formation leads to a palaeogeographic picture of two shallow platforms in the west and in the east, resp., on which open marine subtidal to intertidal limestone sediments were deposited. The platforms were separated by a slightly deeper depositional environment into which a delta protruded, eventually filling up the basin. This delta was covered with limestones, similar to those present on the platforms but patchy, irregularly distributed and in smaller thicknesses. The limestone deposition ended with a new, strong pulse of siliciclastic sediments, presumably coming from the NE and spreading out gradually over the whole area. In these sediments, Lower Devonian ferrugenous San Pedro pebbles are present, indicating a deep erosion in the Northern Leonides |
| A new trace fossil from non-marine upper Palaeozoic red beds in county Wexford and county Kerry, Ireland | 1973 | Horne, R.R.; Gardiner, P.R.R. | 52(3) | Previously unrecorded radially symmetrical, apparently cylindrical or downward tapering structures in red, non-marine siltstones and sandstones of Devonian to early Carboniferous age are described from south-west County Wexford and the Dingle Peninsula, County Kerry, Ireland. These structures are interpreted as biogenic trace fossils rather than inorganic features. They are most probably dwelling burrows, possibly of a fresh-water coelenterate. The most comparable known forms are LaevicycIus Quenstedt, 1879, Kulindrichnus Hallam, 1960 and Bergaueria Prantl,1946. |
| Sedimentary structures in the Southern and Central portions of the waterberg area, Northwestern transvaal | 1973 | Vries, W.C.P. de | 52(3) | Sedimentary structures in the Waterberg System comprise transverse current ripple marks, linguoid ripple marks, cross-bedding, ripple marks on foresets of cross bedding, normal type of convolute structures and so-called convolute lump structures which occur on the upper bedding plane of a convoluted bed. |
| The type Campanian and the Campanian-Maastrichtian Boundary in Europe | 1973 | Gorsel, J.T. van | 52(3) | In his description of the type Campanian Coquand mentioned two localities in which his Campanian unit occurs. Later investigations showed that the two sections are not exact time equivalents. As a result controversies arose whether the one or the other unit should be the type Campanian. The simplest solution is to consider both units as Campanian stratotypes, one representative for the lower part and the other for the upper part, the more so as this agrees quite well with usage outside France. Between the top of the upper Campanian type section and the base of the Maastrichtian type section a time gap exists. In this time gap the boundary between the geochronologic units Campanian and Maastrichtian has to be drawn. It is suggested to adopt the boundary of Seitz (1952) because this boundary is commonly used and because its use is in accordance with the priority principle |
| The Thal interfluve, Pakistan. Geomorphology and depositional history | 1973 | Higgins, G.M.; Ahmad, M.; Brinkman, R. | 52(3) | Landforms and depositional history of the semi-arid and arid Thal desert and the adjoining Indus floodplain in Pakistan are described and discussed. Climate and sand relief are controlled by three wind regimes: southern monsoon from the Arabian Sea and eastern monsoon from the Bay of Bengal in summer, and northern winds in winter. Present vegetation ranges from wooded steppe to (arid) desert steppe. The sands deposited by the Pleistocene Indus river were reworked into longitudinal and transverse ridges, alveolar (honeycomb-pattern) sands and locally barchan dunes, depending upon wind directions and forces. Abandoned Pleistocene Indus channels containing narrow clayey strips occur in this area, the eastern ones mostly obscured by wind resorting. The Holocene Indus floodplain shows four depositional stages: the sandy base of a braided river system; two stages of a thin finetextured cover; and recent moderately coarse sediments |
| Jamaica's Pleistocene reef terraces | 1973 | Cant, R.V. | 52(3) | |
| Highlights of Zambia's mineral industry in 1972 | 1973 | 52(3) | ||
| Verslag van het "international colloquium on Messinian events in the Mediterranean" | 1973 | 52(3) | ||
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| Politieke en ethische aspecten van de grondstoffenvoorziening | 1973 | Uytenbogaardt, W. | 52(4) | |
| Gravitational gliding in the Northern Sierra de Los Filabres (SE Spain) | 1973 | Langenberg, C.W. | 52(4) | Evidence is given for rotatory movements of klippes in the northern Sierra de los Filabres. Use has been made of difference in the orientation of linear structural elements in the klippes compared with that of equivalent structures in the underlying 'basal succession'. The rotations indicate gravitational gliding, probably resulting from updoming of the mountain-range in a late stage of the orogenic history. |
| Holocene transgressions and regressions on the Essex coast outer Thames estuary | 1973 | Greensmith, J.T.; Tucker, E.V. | 52(4) | Faunal and lithological changes within the 34 m of Holocene sediments of the chenier plain suggest six episodes (l-VI) of marine transgression interspersed with five episodes of regression. Evidence presented for recognising transgressions includes chenier formation, marsh retreat and vertical changes in fauna, involving brackish water and intertidal molluscs. Regressions are interpreted chiefly from geosols and peat seams. Radiocarbon dates indicate that the transgressive episodes lI, lll and V first affected the region at about 7500, 4000 and 1400 B.P. respectively. The most recent one (VI) probably commenced about 300 B.P. The dates of episodes I and IV can only be conjectured. Comparison with similar events globally as well as in the Low Countries suggests that eustatic changes in sea level have played a significant ¡ole in the Holocene history of the Outer Thames estuary. |
| The sedimentary environments of Tropical African estuaries: Freetown Peninsula, Sierra Leone | 1973 | Tucker, M.E. | 52(4) | Four main environments are described from tropical estuaries of the Freetown Peninsula, Sierra Leone: A) sand bats, B) channels, C) intertidal flats and D) mangrove swamps. The sand bars are predominantly well-sorted medium sands, with dunes as the main bed form. The channel sediments vary in grain size and bed form up the estuaries, but generally contain lag deposits (mostly of shell debris and laterite pebbles) coarser than the adjacent intertidal sediments. The intertidal flats are mostly muddy sands, commonly with scour pits and current lineation. The sedimentary structures are obliterated by infaunal bivalves and burrowing crustaceans. The mangroves, developed peripherally around the estuaries, are important in trapping and binding the finer grades of sediment. Sierra Leone has an extreme two-season climate, considerably affecting the estuarine sediments. During the dry season, a period of accretion, much sediment (mainly bed load) is taken into the estuaries from offshore. Crustaceans and bivalves increase in numbers and occupy a larger area of the intertidal flats. During the wet season, mud and plant debris are brought down by the rivers and some bed load is moved down or out of the estuaries. With rising sea level, the estuarine deposits are prograding landward, over fluviatile sediments and soils (laterite in this case), producing a coarsening upward sequence from rootlet beds through bioturbated muddy sands to well-sorted cross-bedded medium sands. |
| Influence of crystallographic habit and aggregate structure of authigenic clay minerals on sandstone permeability | 1973 | Stalder, P.J. | 52(4) | Our studies have shown that shifts in the trend of the permeability/porosity relationship for sandstones may be explained in terms of the crystallographic habit and aggregate structure of authigenic clay minerals. It is also suggested that the specific surface (surface/volume ratio) of the clay minerals (either authigenic or detrital in sandstones) could account quantitatively for the different permeability/porosity relationships and might represent a parameter that could be introduced into conventional permeability/porosity plots. It is assumed that a high specific surface of the interstitial clay minerals will induce tortuosity and therefore turbulence at higher flow rates and will also cause pore-space reduction by favouring water adsorption on the large available clay-mineral surface. The thread-like habit often observed for authigenic illite will also cause a division of pore space into a large number of tiny holes, through which fluid flow is much more difficult. |
| On the presumed dimorphism within halysites colonies | 1973 | Boer, P.L. | 52(4) | Dimorphism does not exist in Halysitidae. The mesocorallites as defined by Buehler (1955) and the microcorallites and mesocorallites as defined by Hamada (1958) are considered filling structures; the author prefers the more descriptive term tubules for these skeletal features. The taxonomic importance of the distribution of these tubules in the corallum is questioned. |
| Use of Berek compensator made still easier | 1973 | Jagadiswara Rao, R. | 52(4) | |
| "Symposium kristalgroei" Noordwijkerhout Mei 1973 | 1973 | Carpay, F.M.A. | 52(4) | |
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| KNGMG Jaarverslag 1972 | 1973 | 52(4) | ||
| In memoriam - Prof. Dr. Ir. H.A. Brouwer | 1973 | Egeler, C.G. | 52(5) | |
| Significant relations between textural and structural features of the rocks in the Churchbay-, Templebreedy members of the uppermost Old Red Sandstone complex, South of Cork, Ireland | 1973 | Leflef, D. | 52(5) | The alluvial rocks in the lower part of the uppermost Old Red Sandstone Complex show a significant relationship between their structural and textural features. In the area presently dealt with the encountered rocks are of sandstone, "intermediate", and mudstone facies which together allow a further subdivision into 7 rocktypes according to the above relationship. Each rocktype is characterized by its own association of structures and its own grainsize range. Two types of structures were found to exist: namely those which vary upon grainsize variations and those which do not. The latter category embraces horizontal lamination and low-angle cross-lamination. The category, the structures of which vary upon grainsize variations, comprises mostly high-angle cross-lamination. The distinguished rocktypes are regularly organized in vertical sequences, as well as in down-current developments, reflecting the changing flow conditions during time of deposition. |
| Lássociation spilites-quartz Keratophyres du Sud-Ouest de la Peninsule Iberique | 1973 | Soler, E. | 52(5) | Submarine volcanics were emplaced along tension faults developed along a pre-orogenic flexure zone in the southwestern Iberian peninsula. The age of these extrusions is placed between the Famennian and upper Visean. The lavas belong to the spilite-quartz kelatophyre association, with the latter strongly prevailing. Investigation of these rocks indicates two different series (a very acid one and a basic one) but without gradations. This is explained through mobilization of sialic crustal material by basic injections. The primary basic magma could have been basaltic; it may have been contaminated by sialic material and, to a greater extent, by the thick sedimentary pile which still contained connate waters and which the basaltic magma had to penetrate before reaching the sea bottom. Hybridization did not occur but rather contamination |
| On the tectonics of an area near Laujar, Sierra de Gador, Spain | 1973 | Rutter, E.H.; Gibbons, M.J. | 52(5) | A small area exhibiting contact relationships between schists of the Sierra Nevada, rocks of the Mischungzone and rocks of the Alpujarride complex, in the Betic zone of Southern Spain, has been studied. It is shown from field observations that the rocks of the Alpujarride complex suffered at least one early deformation coeval with low grade regional metamorphism, and involving tectonic transport from south to north. This was followed by gravity sliding from north to south. Fault surfaces associated with these later movements provide the most obvious evidence of tectonic disturbance in the area. The results of a petrofabric study of twin lamellae in a Mischungzone marble are consistent with the hypothesis of a late phase of gravity induced sliding. |
| Lijst van lopende tijdschriften in het bezit van het genootschap, door ruilverkeer verkregen aanwezig in de bibliotheek van de afdeling mijnbouwkunde, T.H. Delft | 1973 | Dozy, J.J. | 52(5) | |
| #REF! | 1973 | 52(5) | ||
| Pre-Bauxite red sediments and sedimentary relicts in Surinam Bauxites | 1973 | Valeton, I.; Jürgens, U.; Khoo, F. | 52(6) | In Surinam, in the northern Guiana foreland, two sections of pre-bauxite sediments and two sections of bauxites were studied for origin and composition of the primary material and the pre-bauxite diagenesis, These sections are composed of "red sediments" of the clastic hematite-kaolinite-quartz association from pre-bauxite time; These sediments are erosion products of deeply weathered laterite and were formed in shallow water around basement plateaus. The base of the sequence indicate very turbulent sedimentation; in between we find periodic occurrence of plant roots; on top (today bauxite) there is evidence for new transgression and quiet sedimentations (burrows). The diagenesis of the underlying sediment (here pre-bauxite) is characterized by kaolinization of the lower and gibbsitization of the upper sequence. The type of these red sediments, as characterized by mainly detritic hematite and kaolinite and lack of feldspars, is very uncommon. |
| A change in rocktypes associated with the approaching shoreline of the Old Red continent, South of Cork, Ireland | 1973 | Leflef, D. | 52(6) | The alluvial rocks in the upper part of the Upper Old Red Sandstone (Fennelsbay member) show a less stringent relationship between the structural and textural features than those of the lower part (Churchbay-Templebreedy members). Though this phenomenon is not readily explainable by a paleogeoglaphical development, it is concomitant with well-known changes betraying an approach of the shoreline - such as improved sorting and maturity of sandstones, gradual disappearance of red coloured rocks, and first occurrence of heterotithic rocks – characteristics which are even more strongly in evidence in the overlying Ballinluska member which is of proven (fossils) marine character. |
| Two fragmentary mandibles of archidiskodont elephants from the Netherlands | 1973 | Erdbrink, D.P.; Augustinus, P.G.E.F. | 52(6) | Description of two incomplete mandibulae or Mammuthus (A.) meridionalis dredged up in the Netherlands at Appeltern on the Meuse and at Lathum on the lJssel. Each belonged to a very old and probably male individual. A Cromerian age and a provenance from the Lower Rhine terraces in Germany is considered possible in each case, but heavy minerals analysis does not lead to conclusive evidence. |
| A simple method for accurate alignment of X-ray diffraction goniometers | 1973 | Jansen, J.H.F.; Gaast, S. van der | 52(6) | Accurate alignment of an X-ray diffraction goniometer can easily be obtained if direct scanning of the X-ray beam is used to adjust both the dial of the goniometer and the specimenholder. |
| #REF! | 1973 | 52(6) | ||
| #REF! | 1973 | 52(6) | ||
| Quelques aspects de la concentration des minerais et de son evolution | 1973 | Formanek, V. | 53(1) | La concentration des minerais est un sujet très vaste; c'est pourquoi je me limiterai à parler suelement de certains procédés de concentration en m'appesantissant un peu plus sur l'évolution du procédé de flottation |
| An aragonite-cemented volcanic beach rock near Bilbao, Spain | 1973 | Knox, G.J. | 53(1) | An unusual beach rock occurs near Bilbao. The beach is aragonite-cemented and contains melilites/volcanic glass fragments for which there is no apparent source. Man-made bricks and fresh bone fragments suggest that the beach is very young |
| Hinge movements influencing deposition during the Upper Devonian in the Esla area of the Cantabrian Mountains, Spain | 1973 | Reijers, T.J.A. | 53(1) | In the Upper Devonian succession the presence of allochthonous lithological elements and replaced fossils, a regular vertical alternation of layers of coral rubble and biostromes, and abundant indications of erosion and subareal exposure can be explained by application of a regional epeirogenetic model. Epeirogenetic movements governed sedimentation and led to a regressive and a transgressive depositional phase. The Portilla Limestone Formation and the Nocedo Formation have been mainly deposited during the regressive phase; the deposits of the Ermita Formation reflect the transgressive phase. |
| Analysis of geological information on computer files | 1973 | Bär, C.B. | 53(1) | |
| Storage and retrieval of geological data | 1973 | Mentink, H.G. | 53(1) | |
| A future for induced geothermal energy? | 1973 | Schuiling, R.D. | 53(1) | The possibility of using geothermal energy in non-volcanic, normal areas is discussed. An attempt is made to apply this concept to the Netherlands, where the geothermal gradient is in general above the world's average. If geothermal heat production from non-volcanic areas will ever be feasible, technologically or economically, is still very uncertain. |
| #REF! | 1973 | 53(1) | ||
| #REF! | 1973 | 53(1) | ||
| In memoriam - Prof. Dr. D.J. Doeglas | 1974 | Nota, D.J.G.; Plas, L. van der | 53(2) | |
| Explanation to tectonic maps of the Netherlands | 1974 | NAM; Heybroek, P. | 53(2) | Three structural contour maps and three geological maps at different levels covering the Netherlands are presented and discussed. The levels depicted are the top Carboniferous, the base Cretaceous-Upper Jurassic and the base Tertiary. The maps are discussed in relation to the tectonic history of the Netherlands. The deformation is classed as intracratonic, epeirogenetic. Three successive patterns of movement are recognized: the Permo-Triassic, the Jurassic-Lower Cretaceous, and the Cenozoic. They are basically different from each other but relatively constant in themselves. The Jurassic-Lower Cretaceous pattern and its inversion in the Upper Cretaceous receives special attention. |
| Explanation to tectonic maps of the Netherlands | 1974 | NAM; Heybroek, P. | 53(2) | Large Enclosure 1 |
| Explanation to tectonic maps of the Netherlands | 1974 | NAM; Heybroek, P. | 53(2) | Large Enclosure 2 |
| A practical method for optical spectroscopy of crystals | 1974 | Lagerwey, A.A.F. | 53(2) | In this article a recently developed method for optical spectroscopic analysis of crystallized substances is introduced. The practical method proposed is non-destructive, and the apparatus required is relatively simple and inexpensive. Principles of optical spectroscopy for the analysis of trace elements in complex crystals are reviewed; essential aspects of this method and other routine methods are compared. Next, the nature, scope, and limitations of the new practical method are discussed, and the information, which can be obtained, is summed up. In essence, the procedure consists of the sequential registration of absorption- and luminescence spectra of the substance to be examined, and the subsequent analysis of both spectra. Details of the apparatus required, and of the analysis procedure are treated in the following section; different methods for obtaining good quality absorption- and luminescence spectrograms are reviewed here. An important feature of the method is the excitation of luminescence with blue radiation; the advantages of its use are critically discussed. Facultative refinements of apparatus and method, making possible polarisation spectrography and topographical spectrography of macrocrystals, are indicated. Requirements for preparations for the purpose of calibration are mentioned. The practical value of the new method is demonstrated by results, obtained in the process of determination of some definite typochemical varieties of the crystallized minerals scheelite, apatite, zircon, spinel and topaz; these varieties are described. Finally, possible applications in the fields of mineralogy, gemmology and geochemistry, chemistry and physics, and even in industry, are reviewed. It is expected, that the proposed method will develop into a practical tool for routine researches in these branches of science. |
| Reactivering van de Nederlandse steenkolenmijnbouw bij de huidige oliecrisis? | 1974 | Weehuizen, J.M. | 53(2) | |
| Holocene sea-level changes: a discussion | 1974 | Shepard, F.P. | 53(2) | The sea-level curve by Greensmith and Tucker, based on coastal work in southeastern England, is said to conform with other worldwide evidence of Holocene sea-level changes, notably that of Fairbridge and Mörner. However, the curve shows little relation to that of any previous investigators, and contrasts greatly with that of Fairbridge because it shows a lack of appreciable sea level higher than that of the present day. |
| Holocene sea-level changes: a reply | 1974 | Greensmith, J.T.; Tucker, E.V. | 53(2) | |
| #REF! | 1974 | 53(2) | ||
| #REF! | 1974 | 53(2) | ||
| Outline of the Precambrian geology of Southern West Greenland | 1974 | Allaart, J.H.; Escher, A.; Kalsbeek, F. | 53(3) | The Archaean gneiss block of West Greenland is made up of gneisses, amphibolites and anorthositic rocks and contains the oldest crustal rocks yet known on earth. The Archaean block is bordered to the south by the Ketilidian mobile belt, largely consisting of younger granitic intrusions and to the north by the Naggsugtoqidian mobile belt which mainly consists of reworked Archaean rocks. |
| Some aspects of the definition of iron ore | 1974 | Kramer, G.M. | 53(3) | Several aspects of the definition of iron ore, as presented in the "Survey of World Iron Ore Resources" of the United Nations, are reviewed. Due to the variety of iron ore formations no general cut-off grade can be indicated. Some outside factors can be of decisive importance for an ironbearing formation reaching the "ore" status. |
| Scanning electron microscopical observations on weakly cemented Miocene sands | 1974 | Riezebos, P.A. | 53(3) | The cementation that has led to the local formation of slightly indurated layers in the white Miocene sand deposits, is due to authigenic quartz growth. Scanning electron microscopical information reveals that the secondary quartz is not only found at the grain contacts. A rather unexpected finding is its presence all around very small as well as large grains. The former ones show the most advanced idiomorphic habit and seem to play an actual part in the cementation. Presolved surfaces could not be found, so that the used silica does not appear to be produced by pressure solution. It is concluded that the grain surfaces must have been clean and highly disturbed before cementation started. This is, because only such surfaces seem to provide numerous suitable sites for nucleation, which may result in a comparatively rapid and full-scale overgrowing. However, since silica under certain conditions also dissolves very readily from disturbed surfaces, it is still possible that a part of the crystallized silica has come from the deposit itself. This particular type of early stage of cementation suggests strongly that the nature of the detrital quartz grain surfaces may be a very important factor in the kind of silica cement being formed. It is suggested that the origin of these weakly indurated layers must have been associated with seasonally rising and falling silica-bearing groundwater |
| A discussion of new results from continuous gasometric determinations of carbonate in cuttings and cores from drill holes, by Schettler, Vol. 52(2) p. 93-99 | 1974 | Abbott, B.M. | 53(3) | |
| "Swlling clay minerals in sediment-petrographical analysis" | 1974 | Quakernaat, J. | 53(3) | |
| #REF! | 1974 | 53(3) | ||
| in de greep van tijd | 1974 | Priem, H.N.A. | 53(4) | |
| Van Waterschoot van der Gracht penning | 1974 | 53(4) | ||
| Spoorelementen in het grondwater | 1974 | 53(4) | ||
| Trace elements in the waters of the dune water catchment area with artificial recharge of Amsterdam | 1974 | Engelen, G.B. | 53(4) | |
| Heavy metals as trace constituents in natural groundwaters and polluted | 1974 | Matthess, G. | 53(4) | The natural and man-made concentrations of heavy metals are discussed concerning their abundance, geochemical mobility and their physiological effects on man. The many gaps of geochemical information concerning abundance and behaviour of heavy elements in the ground should be filled especially for those elements which are important to human health. |
| Inventory of trace elements in groundwaters of the Netherlands | 1974 | Brinkmann, F.J. | 53(4) | An investigation of the Dutch groundwaters as for trace elements has been started. A sampling method has been developed. The results of the first measurements are given. They concern groundwaters from the East of the country as well as from the dune region. The investigation is handicapped by the fact that observation pits may be contaminated by rests of drilling fluid. Contrary to the first intention, production pits are also sampled now. The measurements will be extended to a complete sampling network. |
| The contamination of Dutch soils with mercury and a few other heavy metals | 1974 | Frissel, M.J.; Poelstra, P.; Klucht, N. | 53(4) | As a result of his history the average dutchman knows the various soil types in his country quite well, the chemical structure is usually unknown. The paper describes the typical aspects of the soil constituents as there arc clay minerals, sands and organic materials, Specially the properties, which control the adsorption of traces of heavy metals and pesticides got attention. An important part of the paper is devoted to the behaviour of mercury in dutch and other western european soils. Because part of the drinking water companies in the western part of Holland produce their drinking water from the River Rhine by filtration through dunes, the migration of mercury in soils got serious attention. Most mercury compounds (Hg, HgCl2, HgCICH3) do not migrate in soil, the volatile Hg (CH3)2 migtates fast. The contamination of soils is partly caused by agricultural measures' partly by flooding with water from the Rhine. An analysis of the available data indicated, however, that the main mercury source stems from the wash out of the atmosphere. The contamination of soils in areas with a high population density and much industry is considerably higher than in other areas. A similation model was developed to describe the mercury fall out drain rate. |
| Reflections on groundwaterpollution by tipping of solid wastes | 1974 | Mesu, E.J. | 53(4) | In the following paper is stated that groundwater-pollution caused by waste-tips is of very little significance. That is when is token that the waste is never dumped in open surface-water nor below the groundwater-table and that the subsoil does not contain gravel-layers nor bear ('karst"-phenomena or open fissures. Besides it appears that the leachate from a tip contains most pollution during the first years after tipping and that after two or these years this pollution diminishes gradually. The microbial breakdown of the waste and the herewith formed products play a big role in the purification-processes in the soil. Organic material is needed for the development of this microflora. This induces to the opinion to combine the tipping of certain types anorganic (chemical) waste with urban waste (high organic content) rather than to tip it separately. |
| Government revenues per barrel in the OPEC-countries 1957-1973 | 1974 | Tamboezer, R.G. | 53(4) | This paper covers the evolution of government-revenues per barrel of exported crude oil in the OPEC-countries from 1957, when the major oil-companies lowered their posted prices and thus the government revenues, through September 1973, when the ¡elation between the oil-companies and the governments had so drastically changed that the recent enormous posted-price-increases could virtually be decreed by the OPEC-governments without any recognizable influence from the company-side. Also an indication will be given of the evolution of the realized prices of crude oil over that period. In appendices, tables and figures government revenues per barrel of exported crude, volumes of exported crude and total government revenues will be given for three representative OPEC-countries (Saudi Arabia, Libya and Venezuela) and for the total Middle-East, both in current dollars and in constant dollars (1957 $). |
| Kyanite in the Hercynian metamorphic rocks of the Oporto-Viseu belt, North Portugal | 1974 | Atherton, M.P.; Atkin, B.P.; Naggar, M.H. | 53(4) | Kyanite and garnet have been found in some metamorphosed rocks of the so-called low-pressure Oporto-Viseu belt of the Older Hercynian granites, Portugal. Reassessment of the nature of the metamorphism is therefore necessary, as well as its relation to the higher pressure, Barovian metamorphic belt to the west (Oliveira de Azemeis). |
| A note on lower pressure and higher pressure metamorphic belts in North Portugal | 1974 | Oen, I.S. | 53(4) | In north portugal a lower pressure metamorphism occuring in belts associated with Older Hercynian Granites includes low and intermediate pressure facies types. A higher pressure metamorphism occurring in belts outside the main granite area includes intermediate to high pressure facies types. |
| De natuurlijke erosie als basisniveau voor het transport van elementen | 1974 | Schuiling, R.D. | 53(4) | |
| Koper en zink in de Waddenzee | 1974 | Duinker, J.C.; Eck, G.T.M. van; Nolting, R.F. | 53(4) | |
| Zware metalen in riviersedimenten | 1974 | Driel, W. van; Groot, A.J. de | 53(4) | |
| Natuurlijke en versnelde mobiliteit van fosfaat | 1974 | Golterman, H.L. | 53(4) | |
| De mobiliteit van fluor op mondiale schaal | 1974 | Aronds, C.A. | 53(4) | |
| Verblijfstijden van Zn en Cd | 1974 | Weyden, C.H. van der | 53(4) | |
| KNGMG Jaarverslag 1973 | 1974 | 53(4) | ||
| #REF! | 1974 | 53(4) | ||
| #REF! | 1974 | 53(4) | ||
| In memoriam - Prof. dr. I.M. van der Vlerk | 1974 | Hammen, T. van der | 53(5) | |
| The hercynian diastrophism in the Betic of Málaga, SE Spain: a discussion | 1974 | Roep, T.B. | 53(5) | Arguments for and against a hercynian diastrophism in the Betic of Málaga (especially of the Vélez Rubio region) are briefly discussed. It is concluded that the transition in facies, from Paleozoic turbidites to a Permo-Triassic alluvial fan, and the contrast in detritus of the Paleozoic and Permo-Triassic sediments favour the hypothesis of a hercynian diastrophism. |
| Waste disposal and underground waters | 1974 | Visser, W.A. | 53(5) | Underground waste management, environmental ìmplications and artificial recharge were the subjects discussed in two symposia, respectively in Houston, Texas, in 1971 and in New Orleans, Louisiana, in 1973. In the present paper the author summarizes aspects of the injection of liquid wastes into reservoir rocks by deep wells in the U.S.A. These aspects concern legislation and policy, statistics and actual conditions in some regionally important disposal Zones. Attention is given to the protection of useful subsurface waters Ground waters, i.e, those waters that take part in the present hydrologic cycle, and formation waters, i.e. those that are isolated from the present cycle, are distinguished. Disposal in the former constitutes a potential hazard to the environment, in the latter under certain precautions disposal may be considered safe. In The Netherlands conditions are such, that aquifers that are properly isolated from the present hydrologic cycle occur at depths greater than between approximately 500 and 1000 m. Below these depths disposal prospects are present in sandstone/ claystone alternations of upper Palaeozic to Tertiary age and possibly in upper Cretaceous limestones. In the northern and eastern parts of the country solid or liquid (including radioactive) wastes could be disposed of in artificial caverns in rock-salt deposits. |
| Enige technieken en markteconomische aspecten met betrekking tot de fabrieksmatige verwerking van steenkool tot gasvormige of vloeibare energiedragers | 1974 | Geertman, G.H.M.; Steeman, J.W.M.; Wetzels, F.J. | 53(5) | First a review is given of the existing techniques and current development in the application of coal as an energy carrier, when the disadvantages attached to the use of coal is avoided. This technical part deals mainly with the process technology of manufacturing SNG and/or crude from coal and the generation of electricity from coal respectively. Secondly, the (future) commercial proposition of these techniques is valuated by determining the unit costs of the product (depending on conversion costs and the upset-price for the coal) and comparing this with the price development of alternative energy. For USA conditions it is expected that, in spite of the relatively high costs of conversion, a competitive SNG market price can be realised, being the result of a low cost price for coal ex mine. A competitive SNG price on the basis of European coal does not seem attainable. However, in Europe a competitive production of SNG may be achieved, provided that the price of imported coal does not appreciably exceed the technical cost price. If on the other hand the price of imported coal is based on a calorific equivalence with heavy fuel oil, SNG prices do not seem competitive with natural gas prices, unless this SNG will be used for 'heavy' premium markets (non-industrial public use). Conversion of coal into liquid fractions is much more expensive than conversion into SNG and therefore probably will nog be initiated very soon under the existing European conditions. For, SNG may serve as a substitute for heavy oil fractions and middle destillates (e.g. in industrial and domestic applications); the latter in their turn may be converted into light fractions via "cracking" at relatively low conversion costs. |
| De problematiek van de ondergrondse vergassing van steenkolen | 1974 | Stuffken, J.; Wetzels, F.J. | 53(5) | Underground gasification on an industrial basis seems not applicable to European coalreserves. This conclusion is based on considerations of a technical, environmental and - especially – commercial nature. The main technical problems for European conditions are described: combustion process control, roof control, joining boreholes, control and elimination of leakage (incl. short circuit and leakage of combustion gas to the banking level), water influx into the gasification area, geological features, etc. Past experiments are very disappointing and indicate that no solution whatsoever was found for the numerous and complex technical problems. From an environmental point of view, a number of drawbacks are presented. In commercial respect underground gasification of European coal is not competitive at all because the calorific cost price of the gas produced is quite at variance with current and future prices for energy. This price discrepancy is of such a magnitude that there is serious doubt about the commercial viability of this energy source even on the very long range. Finally, no serious argument can be put forward from a strategic point of view, because of the minute share in European energy supply even in case of a large scale underground gasification program. |
| On the evolution of structure and metamorphism during the alpine orogeny in the eastern and central Betic Zone (Betic Cordilleras, Spain) | 1974 | Egeler, C.G. | 53(5) | The relationships between Alpine overthrusting, folding and regional metamorphism in the eastern and central Betic Zone are discussed, in the light of recent studies. It is substantiated that two major episodes of metamorphism had occurred, related to distinct stages of the orogenic evolution. In this there is a marked analogy with the evolutionary trend of the internal zone of the Alps. The conspicuous difference between the two belts lies in the time relationship between the final emplacement of the nappes and the 'main' episode of crystallization. In the Betic Zone it is the early episode that has determined the overall 'picture' of the metamorphism. |
| #REF! | 1974 | 53(5) | ||
| #REF! | 1974 | 53(5) | ||
| The Westphalian of the Netherlands with special reference to microspore assemblages | 1974 | Wijhe, D.H. van; Bless, M.J.M.; Dijkstra, S. | 53(6) | The Westphalian in The Netherlands can be subdivided into six biostratigraphical miospore zones. Each zone is distinguished by an assemblage of several characteristic species, which individually are not restricted to a particular zone with the exception of Radiizonates aligerens. Top and base of each zone are characterized by the first or last (regular) occurrence of a particular diagnostic species. In the Upper Westphalian A and Lower Westphalian C a distinct correlation exists between the microfloral and major lithological changes, which suggests that the Westphalian floras have been at least partly influenced by paleoecological factors. |
| Aspects of Permian, Triassic and Early Jurassic palynology of Western Europe - A research project | 1974 | Clement-Westerhof, J.A.; Eem, J.G.L.A. van der; Erve, A.W. van; Klasen, J.J.; Schuurman, W.M.L.; Visscher, H. | 53(6) | A palynological research project in the Permain, Triassic and Lower Jurassic of western Europe is briefly outlined. The project is aimed at the development and promotion of palynology as a primary tool in regional stratigraphical classification and correlation. A number of examples of specific topics currently under investigation are briefly discussed, viz. (1) a Cordaitina-assemblage from the Permian Collio Formation of northern Italy, (2) Late Permian megaspores from the Vicentinian Alps, Italy, (3) palynological assemblages from the Muschelkalk and Lettenkohle of Luxemburg, (4) a palynological reconnaissance study in the Keuper of Spain, (5) palynological assemblages from the uppermost Rhaetian of the Northern Limestone Alps in Germany, and (6) palynological assemblages from the Lower Jurassic of the Vicentinian Alps, Italy. It is emphasized that regional palynological studies should be integrated in international multidisciplinary stratigraphical projects. |
| Palynology of Rhaetian, Liassic and Dogger strata in the Eastern Netherlands | 1974 | Herngreen, G.F.W.; Boer, K.F. de | 53(6) | Rhaetian, Liassic and Dogger sediments have been examined palynologically from boreholes, mainly located in the Achterhoek area, eastern Netherlands. The results are presented in seven pollen diagrams and a distribution chart; seven pollen zones have been recognized and illustrated (6 photoplates). A range chart of selected palynomorph types has been designated, covering the uppermost Triassic-Dogger strata. Some concluding remarks concerning Liassic tectonic movements are made. |
| The palaeogeographic evolution of the Netherlands during the Quaternary | 1974 | Zagwijn, W.H. | 53(6) | An outline of the palaeogeographic evolution of the quaternary sedimentary basin of The Netherlands is given, based on a discussion of 12 maps, figured in the enclosure. In the second part of the paper a documentation of the sources used is given. |
| The palaeogeographic evolution of the Netherlands during the Quaternary | 1974 | Zagwijn, W.H. | 53(6) | Large Enclosure |
| The last interglacial-glacial cycle: state of affairs of correlation between data obtained from the land and from the ocean | 1974 | Wijmstra, T.A.; Hammen, T. van der | 53(6) | An attempt is made to evaluate the state of affairs of correlation of deep sea curves, long palynological sequences in terrestrial deposits and the stratigraphical sequence in NW Europe. There seems to be little doubt about the correlation within the reach of normal 14C dating (approximately covering the last 50,000 years), corresponding with oxygen isotope stages 1, 2 and, at least partly, with 3. If the indirect dating of the temperature minimum of stage 4 as approx. 70,000 B.P. is correct, a correlation with the Lower Pleniglacial becomes less probable and a correlation with one of the cold phases in the Early Weichselian much more likely. In that case, at least as the Macedonian region is concerned, a correlation of stage 4 with the dry phase between the Drama and Elevtheroupolis intervals seems to be the most probable. |
| Eine Interstadiale Torfschicht bei Nijmegen (Niederlande) und deren Bedeutung für die Erklärung der dortigen landschaftsmorphology | 1974 | Teunissen, D.; Teunissen van Oorschot, H. | 53(6) | An interstadial peat layer near Nijmegen (The Netherlands) and the meaning of this layer for the explanation of the surrounding landscape morphology. The Geological Map of The Netherlands (1935,1947) defines the sandy plain west of the glacial push moraine of Nijmegen as a fluvioglacial drift plain. Pons (1957) has noticed, that this plain is divided into two steps. These steps are separated by a low landscarp. We suggest that the Würm glacial dry valleys of the upper step terminate at the landscarp and that the lower step does not consist of Riss glacial sandr material as was thought previously, but that it is composed of the laterally fused, very flat alluvial cones of the dry valleys of the upper step. We base this opinion mainly on the presence of a moershoofd-interstadial (ca.45.000 years old) peat layer in the sediments of the lower step. |
| Implications of a pollen diagram from the Adriatic Sea | 1974 | Bottema, S. | 53(6) | A pollen diagram from the shelf of the Adriatic is presented and compared with diagrams from the adjoining mainland and with pollen spectra from Mediterranean deep sea samples. This comparison may give information on local pollen production on the mainland as well as on the influence of secondary pollen in deep sea sediments. Next to palynological dating, volcanic ash layers may provide more precise dates. It seems that for palynological investigations cores from shallow water are preferable to those from deeper water. |
| Palynological and paleoecological investigations in the Vosges (France): a research project | 1974 | Janssen, C.R.; Kalis, A.J.; Tamboer van den Heuvel, G.; Valk, E.J. de | 53(6) | In order to reconstruct the Late- and Post-glacial vegetation development of a west-eastern belt in the Vosges (France) palynological and paleo-ecological investigations were made. One map and five simplified diagrams are shown and will be discussed. The map shows the area in study. On basis of differences in geology and relief the area has been divided into five regions. In this paper the central region receives most interest. A diagram of surface samples taken on a mountain summit, shows the local and/or regional deposition of several pollentypes. These results are used for the interpretation of pollendiagrams and it is possible to base a zonation on regional pollentypes as far as late Post-glacial pollendiagrams are concerned. In two diagrams the trends in the curves of some regional pollentypes have been correlated to historical events and it also seems possible to reconstruct fluctuations of the upper forest limit. Figure 6 shows differences in pollen percentages in profiles of two bogs, which may be due to the existence of a vegetation zonation in the older Post-glacial. |
| Palynological and paleoecological investigations in the Vosges (France): a research project | 1974 | Janssen, C.R.; Kalis, A.J.; Tamboer van den Heuvel, G.; Valk, E.J. de | 53(6) | Large Enclosure |
| Niederwil, a palaeobotanical study of a swiss neolithic lake shore settlement | 1974 | Zeist, W. van; Casparie, W.A. | 53(6) | In 1962 and 1963, excavations were carried out in the Neolithic lake shore settlement of Niederwil, in northeastern Switzerland. The site, which is dated from ca. 3700 to ca.3625 B.C. (bristlecone pine calibrated 14C dates), was founded on gyttja and overgrown by peat. In the settlement remains the conditions were favourable for the preservation of organic material. Information on the vegetation in the vicinity of Neolithic Niederwil is based upon the results of the examination of plant macrofossils, mainly wood, seeds, and fruits, recovered from the site, and upon the palynological study of sediment cores from outside the settlement. At the time the natural vegetation of the uplands consisted of Carpinion betuli forests, in which, in addition to oak and beech, various other trees and a larger number of shrubs were found (table 1). In the river valleys Alno-Padion forests with poplar, ash and elm would have been present. In consequence of cutting and grazing, open vegetations came into existence (table 2), while Prunetalia shrub vegetations expanded considerably along forest edges. The main crop plants of the Niederwil farmers were bread wheat (Triticum aestivum), naked barley (Hordeum vulgare var. nudum), flax (Linum usitatissímum), and opium poppy (Papaver somniferum). Further, wild plants would have played a more or less important part in the diet of the Neolithic inhabitants. |
| Pollen and diatom analysis of a shore section of the former lake Wervershoof | 1974 | Voorrips, A.; Jansma, M.J. | 53(6) | A pollen- and diatom analysis of a shore section of the former Lake Wervershoof was carried out to investigate the history of occupation and vegetation in the region. The section is dated to between 1800 BC and 850 AD; a dating near the end of this period is probable. The presence of human occupation near the lake shore is shown. At this time the lake contained fresh water. The occupation changed its agricultural emphasis from the growing of wheat and barley to the growing of rye. The occupation is ended by a marine transgression. During a break in this transgression there is a renewed inhabitation. |
| Pollen and diatom analysis of a shore section of the former lake Wervershoof | 1974 | Voorrips, A.; Jansma, M.J. | 53(6) | Large Enclosure |
| Palynology in the study of present-day hillslope development | 1974 | Riezebos, P.A.; Slotboom, R.T. | 53(6) | It is pointed out that in measuring current geomorphological processes, which in general act either extremely slowly or, if more catastrophic in nature, at long intervals, knowledge of the recent geomorphological history is essential. This is particularly necessary, if the outcome of the measurements have to serve as a basis for prognosis, because an extrapolation of measurements alone is subject to a high degree of uncertainty. In the area near Bavigne (Luxembourg), where present day displacements of slope material are measured, loamy materials covering the slopes appear often to contain pollen in appreciable amounts. Pollen diagrams constructed from this sort of material show a considerable agreement with the corresponding sections of reference diagrams prepared from alluvial deposits. The disturbance of the pollen stratification by the decay of included contemporaneous pollen combined with a supply of younger pollen, which is considered to be common in sandy soils, apparently has been equally effective in the alluvial fills and in the soils developed in the slope-covering materials. Hence, the disturbance must have been of a similar order of magnitude in the alluvial as well as in the slope materials. The present authors therefore consider the palynological analysis under certain circumstances as an appropriate technique for collecting the necessary information in regolithic materials. The data obtained suggest that pollen analysis of these materials, in conjunction with lithological and pedological field evidence, not only may be used to date events, to which slope materials have been subjected in the recent past, but also to contribute to their reconstruction. |
| Palynology in the study of present-day hillslope development | 1974 | Riezebos, P.A.; Slotboom, R.T. | 53(6) | Large Enclosure |
| Problems in the interpretation of pollen diagrams of mineral soils | 1974 | Havinga, A.J. | 53(6) | The theories of pollen homogenization and of differential decay of Quercus pollen in Pleistocene cover sand soils now showing a podzol profile, adduced in earlier papers, are disputed by some palynologists. In the present article they are supported by various palynological, ecological, pedological and experimental arguments. Two examples from published evidence, relating to a loess and a cover sand soil respectively, are given to demonstrate that pollen analysis of mineral deposits with a minute pollen concentration may easily lead to the wrong conclusions. |
| The data bank of palynological species descriptions at Leiden | 1974 | Gemeraad, J.H. | 53(6) | The present state of the palynological data bank at Leiden is described, the problems, as yet partly unsolved, are explained and suggestions are given to improve the input procedure. |
| The Northwest European pollen flora, a new project | 1974 | Janssen, C.R.; Punt, W.; Reitsma, T.J. | 53(6) | |
| Committee "Geoscience and man" | 1974 | 53(6) | ||
| #REF! | 1974 | 53(6) | ||
| The Calais deposits in the vicinity of Wieringen and the geogenesis of Northern North Holland | 1975 | Ente, P.J.; Zagwijn, W.H.; Mook, W.G. | 54(1-2) | Based upon lithologic data and radiocarbon datings the lithostratigraphy of the Calais IV phase and existing subphases A and B is discussed. A subdivision of the Calais IV A subphase into two subunits 1 and, 2 is introduced. The new subdivision solves the incompatibility between statements of various previous authors on the subject. The data obtained are utilized to elucidate the genesis of northern North Holland. |
| Continental and coastal plain deposits of the uppermost Old Red Sandstone complex of Southern Ireland | 1975 | Kuijpers, E.P. | 54(1-2) | A description is given of an Old Red Sandstone sequence of Upper Devonian age occurring along the south coast of Ireland. This sequence shows a gradual transition from continental deposits to overlying tidal marine sediments via a transition zone. The most characteristic changes occurring upward in the transition-zone between the underlying continental (interior alluvial plain) deposits and the marine tidal sediments are: 1) The increasing mineralogical maturity of the sandstones. 2) The appearance of "heterolithic beds". 3) The increasing frequency of occurrence of thick fluviatile sandstones. 4) The change in rock colours from reddish via greenish to greyish hues. |
| Spilites, regional metamorphism and subduction in the Iberian Pyrite Belt: some somments | 1975 | Schermerhorn, L.J.G. | 54(1-2) | The Devonian-Lower Carboniferous eugeosynclinal succession of the lberian Pyrite Belt was deformed and regionally metamorphosed during the Hercynian orogeny. Metamorphic grade decreases from lower greenschist facies in the north to pumpellyite facies in the south. The volcanics comprise a felsic and a mafic-intermediate suite, the latter including spilite lavas and tuffs with intrusive diabases. Spilites precede, follow, and are contemporaneous with felsic eruptions. The parent magma of the spilites and albite diabases was not altered notably by contamination and assimilation. The felsic volcanics are sodic to potassic quartz keratophyres, mostly tuffs. Rio Tinto stratigraphy is reviewed. The possibility that the compositional bimodality of the volcanics might be related to subduction seems remote. |
| Allophane and its initial crystallization products as concretions in the south Limburg Chalk | 1975 | Buurman, P.; Boekschoten, G.J.; Koster, Y. | 54(1-2) | Silicon-alumina concretions with about equal amounts of both components and ranging in crystallinity between allophane and initial crystallization toward halloysite or gibbsite were found in and on Upper Cretaceous limestones. These concretions were probably the result of accumulation of Late Tertiary and Early Pleistocene weathering products, accumulated by stagnation of percolating waters. Crystallization might have been inhibited by the electrolyte concentrations in the limestone pore waters. pure allophane material was much like the allophane originally described in 1816. |
| De Nederlandse Aardwetenschappen in de spiegel van oraties en openbare lessen | 1975 | Engelen, G.B. | 54(1-2) | |
| Roraima, Tabelberg and Uatumã Formations of the Guiana Shield: a correlation | 1975 | Kloosterman, J.B. | 54(1-2) | On the western and central parts of the Guiana Shield, South America, tabular sedimentary sequences are found, consisting of sandstones, shales and conglomerates and of tuffs, tuffites and graywackes. In Venezuela, Guyana, Roraima and Surinam they have been designated the Roraima Formation; on the southern margin of the Guiana Shield in Brazil they are called the Uatumã Formation. The writer argues that they are similar in origin and probably are roughly coeval in the several parts of the Shield. Summaries and a selection of quotations are presented, in part taken from not easily available papers, and in part translated for the benefit of students who read English but not Portuguese. |
| Isotope geochronology in the Indonesian Tin Belt | 1975 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Bon, E.H.; Hebeda, E.H.; Verdurmen, E.A.T.; Verschure, R.H. | 54(1-2) | Granitic rocks on Belitung (Billiton), Bangka and the Tuju islands (Pulau Tudjuh) have a Rb-Sr isochron age of 217 ± 5 Ma with initial 87/Sr86Sr = 0.7152 ± 0.0029 (15 whole-rocks and 4 biotites). K-Ar ages of four hornblendes and two biotites average 214 ± 4 Ma. The granitic complex on Karimata has a Rb-Sr isochron age of 74 ± 2 Ma with initial 87Sr/86Sr = 0.7101 ± 0.0025 (8 whole-rocks), while an associated amphibolite has a K-Ar age of 78 ± 5 Ma. (Rb-Sr ages based upon d = 1.39 x 10-11/a; errors at 95% confidence level.) The granites have intruded into flysch-type sediments containing Norian fossils, while the regional stratigraphic and tectonic relationships strongly suggest that they are overlain by fossiliferous sediments of probably Rhaetian age. The age of 217 ± 5 Ma can thus be taken as the minimum age of the Norian, probably as representing the Norian/Rhaetian boundary. Cassiterite mineralisation is associated with both Upper Cretaceous and Upper Triassic granitic masses, but major tin deposits are related only to Upper Triassic plutons. |
| Kritik zur plattentektonik | 1975 | Bemmelen, R.W. van | 54(1-2) | For an all-round interpretation of the Earth's history geodynamic as well as geochemical processes should be taken into account. The anthropomorphic character of the jargon used by plate-tectonicists is an impediment to achieve this aim. The driving forces of the geodynamic evolution as viewed by the current model of plate tectonics are too much restricted to mechanical processes, whereas their intertwining with physico-chemical processes should also be realized. |
| Ice-pushed ridges in the Eastern part on the Netherlands river area | 1975 | Verbraeck, A. | 54(1-2) | |
| The Pre-Tertiary rocks of SW Cyprus | 1975 | Ealey, P.J.; Knox, G.J. | 54(1-2) | The pre-Tertiary rocks of SW Cyprus consist of an autochthonous unit, composed of Campanian sediments, and an allochthonous assemblage containing igneous and sedimentary rocks of Triassic to Lower Cretaceous age, and some undated metamorphic rocks. The complex rests on a basement of Cenonanian to Campanian basic pillow lavas, which form the youngest unit of the Troodos Igneous Complex. The basal autochthonous sediments (Perapedhi Formation) consist of thin (less than 10 m) iron-rich shales (umbers), locally associated with cherts and manganese nodules. The overlying autochthonous sediments (Kannaviou Formation) comprise 500 m or more of abyssal mudstones and marls intercalated with tuffaceous sandstones containing also lithoclasts similar in lithology to the large allochthonous rock units that are now referred to as "Mamonia Allochthonous Complex" The volcanic elements in the Kannaviou Formation have been derived from an andesitic-dacitic source, extraneous to Troodos, and probably reflect the crustal instability that culminated in the emplacement of the Mamonia Allochthonous Complex. During this time the Troodos Massif was probably a submarine high, undergoing submarine weathering and local brecciation. The Mamonia Allochthonous Complex comprises Triassic alkali lavas associated with reef and pelagic limestones, metamorphic schists, serpentinites, peridotites, gabbros, Triassic turbiditic sandstones and packstones intercalated with shales, Jurassic cherts, shales and packstones, and Lower Cretaceous quartz sandstones intercalated in shales. The total sedimentary thickness is not more than a few hundred metres. The association is interpreted to be of deep-marine origin in general, but including also shallower, probably continental-margin related elements at its base and top. The allochthonous units were probably emplaced on southern Cyprus as olistolithic blocks or smallscale sheets, and as debris in Campanian-pre-Upper Maastrichtian times. Their regional distribution in Cyprus makes a proveance north of Troodos unlikely |
| in vitro weathering products of pyrite | 1975 | Buurman, P. | 54(1-2) | Fine grained natural pyrite concretions oxidize spontaneously under laboratory conditions. A solution of oxidation products in distilled water yields the following crystallization products upon evaporation (in order of formation): melanterite, rozenite, szomolnokite, rhomboclase, coquimbite, roemerite, a slightly basic ferric sulphate, and voltaite. The crystallization sequence is comparable to that found in natural environments where pyrite ores are oxidizing. |
| #REF! | 1975 | 54(1-2) | ||
| In memoriam prof. Dr. Ir.F.A. van Baren | 1975 | Reynders, J.J.; Mouthaan, W.L.P.J. | 54(3-4) | |
| Jaarrede | 1975 | Eek, W.N. van | 54(3-4) | |
| Late Quaternary history of the Skagerrak; an interpretation of acoustical profiles | 1975 | Weering, T.C.E. van | 54(3-4) | In the Skagerrak several sedimentary units are present that were found previously in the Norwegian Channel. The thickness and distribution of late-postglacial sediments is measured and mapped. The origin of the sediments are discussed and a model for the late-Quaternary sedimentary history of the area is suggested. The occurrence of shadow zones is related to gasbubbles or coarse materials in the subsoil. Sedimentary structures such as large scale foresets and giant sand waves are found along the southern border of the Skagerrak. The sand waves are considered as relict structures. The bottom relief in the Skagerrak is closely related to the sedimentary history; along the southern border ice grounding has probably played an important role. |
| Fossil coleoptera from Weichselian deposits at Voorthuizen, the Netherlands | 1975 | Angus, R.B. | 54(3-4) | An account is given of fossil from two organic layers in Weischelian deposits at Voorthuizen, The Netherlands. On radiocarbon and stratigraphic evidence these beds apparently date from between the Brorup and Upton Warren interstadials. Although the samples analysed were small and gave meagre fossil assemblages, the lower bed clearly represents tundra conditions, with average July temperatures below 10°C. The upper bed gave a climatically nondescript fauna from which no firm inferences can be made. However, it is considered that had this bed been deposited under conditions as cold as those represented by the lower bed, the fossils would have given some indication of this, and it therefore seems likely that it reflects somewhat warmer conditions, with average July temperatures of about 10°C |
| Cementation of pliocene-Quaternary fluviatile clastic deposits in and along the Oman mountains | 1975 | Stalder, P.J. | 54(3-4) | Huge masses of coarse clastics were deposited and cemented during and shortly after the last uplift phases of the Oman Mountains; the environment was fluviatile and the climate was alternatively humid and semi-arid. The cement includes mainly calcite, high-magnesium calcite and dolomite; their genesis and relation to the area of water run off are discussed. The cement textures indicate both vadose and phreatic cementation. The absence of cement cathode-luminescence seems to be characteristic of this fresh-water environment of cementation. |
| Correlation of Indonesian active volcanic geochemistry with Benioff Zone Depth | 1975 | Hutchison, C.S. | 54(3-4) | The active volcanic arc of Indonesia extends almost continuously over 6000 km from north Sumatra to the Molucca Sea. Chemical analyses of 196 rocks from 33 volcanoes have been processed to give molecular norms and multiple linear correlation analyses between various chemical parameters and silicon content or differentiation index (D.I.) and vertical depth of the underlying Benioff Zone, which ranges from 140 to 300 km. The great majority of the volcanic products is of augite-hypersthene andesite or basalt, sometimes with olivine and hornblende, and occasionally with biotite, quartz and tridymite. Leucite occurs in volcanoes overlying the deepest seismic contours. Most rocks are quartz-normative, but many are olivine- and even nepheline-normative where the volcanoes overlie the greatest seismic depths. Significant relationships exist between each of potassium %, alkalis % and the ratio of potassium to alkalis and both silicon content (or D.I.) and depth to the underlying Benioff Zone. The relationship with silicon or D.I. is petrologically controlled and the relationship with Benioff Zone depth may suggest that the magmas are produced at and rise from the Benioff Zone and that some of the chemical variation is controlled by the depth of magma production. However the best correlation obtained cannot explain more than 50 to 60% of the chemical variation in terms of depth of magma production. Future refinement of the measurement of the seismic contours and improvement of the chemical analyses may lead to a closer correlation, but on the basis of the present data it is necessary to conclude that, in addition to seismic depth, other unknown factors play an important role in controlling the chemical variation of the volcanic rocks. |
| The Triassic Kodiang limestone formation in Kedah, W. Malaysia | 1975 | Coo, J.C.M. de; Smit, O.E. | 54(3-4) | The Triassic Kodiang Limestone Formation is formally described as a new lithostratigraphic unit in the Malay Peninsula. The thickness of the stratotype measured is more than 125 m. The carbonate sediments, consisting of algal stromatolites, intraformational breccias, limestone conglomerates with sedimentary slumps, black mudstones with radiolarian chert, and limestone turbidites, were deposited in a shelf, slope, and basinal environment. The paleoslope was dipping to the east. |
| An interpretation of Groningen subsurface temperature data | 1975 | Engen, H. van | 54(3-4) | Temperature surveys have been carried out by NAM in gas wells in and around the Groningen field, From these surveys subsurface temperatures at datum level (= 2,875 m S.S.) between 88 and 1 14° C have been obtained, which have been used to construct a subsurface temperature map. This map is used for volumetric gas in place calculations and the prediction of producing wellhead temperatures. On the map a number of areas with low datum depth temperatures can be seen, which appear to correspond with overlying salt domes and ridges. In these areas the heat flow rate to the surface is found to be above average. |
| An interpretation of South-Limburg subsurface temperature data | 1975 | Sadée, C.P.M. | 54(3-4) | Staatsmijnen in Limburg (now named Naamloze Vennootschap DSM at Heerlen) has conducted temperature measurements in the Carboniferous rocks of the South-Limburg coalmining area. From the measuring results the temperature gradients for both the overburden and the Carboniferous are derived. The temperature gradient of the Carboniferous averages δc = 3.0 °C/100 m, whilst, that of the overburden, depending on the composition and the water content, appears to range between δd = 5.5 and δd = 2,4 °C/100 m, according to 5 separate regional groups of measurements in the South-Limburg mining area. With the aid of the data obtained a map has been compiled of subsurface temperature at datum level, (-749 m. Amsterdam Zero Level), which chart is to serve in making predictions regarding climatic conditions in underground workings. |
| The relation between the tropical planktonic foraminiferal zoantion and the Tertiary far East letter classification | 1975 | Haak, R.; Postuma, J.A. | 54(3-4) | A correlation between the tropical planktonic foraminiferal zonation and the Tertiary Far East Letter Classification is presented. Their relationships with world-wide time stratigraphical units and classic European stages are tabulated. The datum planes of the most important planktonic and larger Foraminifera are also shown. |
| The sheeted intrusive complex of Troodos, Cyprus | 1975 | Boorder, H. de | 54(3-4) | Geological observations during a mineral exploration programme in the western part of the Troodos Igneous Complex, Cyprus, have led to the formulation of a hypothesis concerning the origin of the Sheeted Intrusive Complex in connection with the development of the Troodos dome. The hypothesis suggests an originally horizontal attitude of the "Diabase" sheets in a large part of the Sheeted Complex. Some related aspects of sulphide mineralisation are discussed. |
| Isotopic dating of glauconites from the Upper Cretaceous in the Netherlands and Belgian Limburg, 1 | 1975 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Hebeda, E.H.; Romein, B.J.; Verdurmen, E.A.T.; Verschure, R.H. | 54(3-4) | K-Ar dates of seven glauconites from Campanian and Maastrichtian horizons in Netherlands and Belgian Limburg are ionsistent with their stratigraphical position. |
| Structural evolution of the Neogene salt basins in the Eastern Mediterranean and the Red Sea | 1975 | Mulder, C.J.; Lehner, P.; Allen, D.C.K. | 54(3-4) | This paper attempts to describe the Neogene evaporite basins in the Eastern Mediterranean and the Red Sea Rift in the context of the regional tectonic framework and the regional tectonic phases of the Alpine-Mediterranean region. It is mainly based on airgun seismic surveys in the Mediterranean and Red Sea carried out in the time span between 1971 and 1973. The Neogene basins of the Eastern Mediterranean as well as the Red Sea began to form after the main Oligocene - Lower Miocene Alpine orogenic phase. The morphological conditions for evaporite deposition in the Mediterranean basins, during a short period of time were provided by late Miocene - early Pliocene tectonic movements in the basin peripheries, which caused a temporary restricted connection with the open sea. It was followed by open marine conditions during the Pliocene. Graben subsidence in the Red Sea Rift began during Oligocene - early Miocene. Initial terrestrial sedimentation was followed by widespread evaporite deposition, which lasted throughout a considerable part of the Miocene period. The late Miocene - early Pliocene tectonic phase caused a final disruption of the connection with the Mediterranean. Open marine conditions were established in the Pliocene through a connection with the Indian Ocean. Regional doming of the Arabian-Nubian shield and axial collapse, first of the main graben and later of the axial trough, is thought to represent the dominant mechanism for the origin of the Red Sea Rift. |
| A pollendiagram from the Weichselian deposits near Apeldoorn, the Netherlands | 1975 | Ruiter, G. de | 54(3-4) | Pollen analysis of a 20 m long core of peat, sand and silt deposits near Apeldoorn, the Netherlands shows that these sediments were laid down in the Late Eemian, the Early Weichselian and the Middle Weichselian. Only the most upper Eemian is present- In the Early Weichselian one zone with interstadial character and represented by a peat layer is particularly well developped, showing succesive maxima in the pollen values of Alnus, Picea and Pinus. Pollen of Betula however remains dominant. The Middle Weichselian is strongly glacial in character. It includes an oscillation with Salix, Potamogeton, Pediastrum and SeIaginella selaginoïdes pointing to more favourable conditions. |
| A pollendiagram from the Weichselian deposits near Apeldoorn, the Netherlands | 1975 | Ruiter, G. de | 54(3-4) | Large Enclosure |
| #REF! | 1975 | 54(3-4) | ||
| In memoriam William van Leckwijck (1902-1975) | 1976 | 55(1-2) | ||
| Commentaires sur la datation des glauconies du Cretace superieur du Limbourg | 1976 | Odin, G.S. | 55(1-2) | |
| Isotopic dating of glauconites from the Upper Cretaceous in the Netherlands and Belgian Limburg, 1: reply to the comments by G.S. Odin. | 1976 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Hebeda, E.H.; Romein, B.J.; Verdurmen, E.A.T.; Verschure, R.H. | 55(1-2) | |
| On the origin of submarine canyons | 1976 | Berckel, F.L. van | 55(1-2) | It is suggested that the origin of submarine canyons depends on two factors: 1. a drop of the ocean level below the shelf/slope rim as a consequence of the formation of enormous ice masses during a glaciation. 2. the presence of powerful streams, created by the melting of ice masses; these streams carried large amounts of glacial debris across the shelf and deposited them on the continental slope. Continuous overloading of these debris piles resulted in debris avalanches downslope, which excavated canyons and ultimately formed large submarine fans. |
| Marine transgressions as a factor in the formation of sandwave complexes | 1976 | Swie-Djin, N. | 55(1-2) | The genetic relation between the onset of a marine transgression and the consequent upbuilding of three ancient sandwave complexes is discussed and illustrated. These are: a. The Lower Tertiary Roda sandwave complex of the southern Pyrenean basin. b. The Lower Greensand sandwave complex of the Isle of Wight. c. The Miocene sandwave complex of the swiss Molasse. Based on these examples, a model for the formation of a sandwave complex in relation to a marine transgression and tidal action is developed. Finally, based on geological arguments derived from the sequential and structural analysis of these ancient sandwave complexes, the genesis of the modern sandwaves of the North Sea is ¡elated to the Holocene transgression. |
| Thermal anisotropy - a factor contributing to the distribution of Caledonian metamorphic zones in the SW Scottish Highlands? | 1976 | Borradaile, G.J. | 55(1-2) | The distribution of metamorphic zones in the SW Scottish Highlands may have been influenced by the bulk thermal anisotropy of the regional structure |
| Models for the estimation of world ore reserves | 1976 | Wijs, H.J. de | 55(1-2) | Although mineral resources are non-renewable, mineral reserves can be created by new discoveries and from already identified sub-economic resources. A probabilistic model is presented to adjust reserve estimates to changes in minimum workable grade. This model is based upon a rational frequency distribution for the dependence of tonnage on cut-off and average grade. For this purpose the straight lognormal transformation is rejected, and replaced by a logarithmic, three-parameter transformation of wider applicability, including negatively skewed distributions of iron, bauxite, and phosphate deposits. The estimation of ore reserves occasionally serves the restricted purpose of the commercial evaluation of mining property. Yet, more often such estimates have a wider scope: up to forecasts of the adequacy to supply the future needs of a country or the world. |
| An inexpensive infinite flume | 1976 | Winkelmolen, A.M. | 55(1-2) | A new design is presented of an infinite flume. This flume has been specially developed to study equilibrium processes during transport and deposition of sand and the influence of time on these processes. The flume-plan is oblong rectangular, the channel is 60 cm deep and 45 cm wide. In each corner reflexion blades are mounted, which are specially shaped to compensate for the increase in width in the bends. The water drive is performed by means of paddles, hanging from two parallel chains which run over cog-wheels. The paddles move in a vertical position through the water. Due to a downcurrent inclination of the chains, the paddles are gradually lifted out of the water and are free of the surface whilst flipping round the cog-wheels, thus producing no extra turbulence. Flow characteristic are shown for different discharge rates and peculiars of the flume are discussed |
| Lineament analysis from ERTS (Landsat) images of the Netherlands | 1976 | Sesören, A. | 55(1-2) | A lineament map from ERTS (Landsat) images of The Netherlands is presented. The directions of these lineaments have been compared to fault patterns in the Carboniferous, the base of the Cretaceous and the uppermost Tertiary and Quaternary. The known fault patterns are essentially similar to the Landsat lineament patterns |
| Preliminary observations on the origin and sedimentological nature of sarsen stones | 1976 | Whalley, W.B.; Chartres, C.J. | 55(1-2) | The type of orthoquartzite known as sarsen stone is found over wide areas above the Chalk of south-east England. Scanning electron microscope and thin section studies indicate that sarsens are composed of quartz grains with syntaxial overgrowths of secondary quartz. They contain relatively little inter-particle siliceous cement. Their strength appears to be derived from the interlocking structure of the quartz grains produced by the syntaxial overgrowths. |
| Eolian "sandy lignite" and associated sediments from the Miocene of the Lower Rhine Basin Western Germany | 1976 | Clemmensen, L.B. | 55(1-2) | Eolian flats are often encountered along modern shorelines in association with wash-over fans, storm inlets and swamps. A possible ancient analogy to this environmental situation has been confronted in the Miocene sediments in the Garsdorf Quarry, Western Germany. These sediments consist of several facies associations, the uppermost of which is notable due to the occurrence of sandy lignite. The sandy lignite displays several sedimentary structures of presumably eolian origin and is interpreted as an eolian sediment formed during humid conditions on eolian flats. Deposits associated with the sandy lignite include stratified channel-sand, most probably representing storm inlets filled by eolian and ephemeral stream deposits, sheets of faintly laminated sand of wash-over fan origin, and lignite formed in coastal swamps. |
| Practical applicability of a zonation with benthonic foraminifera in the worldwide Lower Cretaceous | 1976 | Bartenstein, H. | 55(1-2) | Presentation of a new zonation chart with benthonic foraminifera, valid for the worldwide Lower Cretaceous, Berriasian to Albian, in the temperate and tethyan facies realms. Divisions, sections and zones comprise 22 foraminifera columns with 36 species of different stratigraphic value. |
| Size, shape and density sorting around two barrier islands along the north coast of Holland | 1976 | Veenstra, H.J.; Winkelmolen, A.M. | 55(1-2) | The sand movement on and around two barrier islands flanking the tidal flat area north of The Netherlands is studied by means of size, shape and density sorting. Since there is mainly fine sand in the area, the competency of the transporting media is seldom reached and selection mainly occurs on shape and density. In the deeper off-shore, a coarse grain-population shows inherited characteristics from a higher energy early transgressive phase, whereas a finer population is consistent with the present-day hydrodynamic situation. Tidal channels in between the islands form outer tidal deltas. These deltas protect the islands against the waves produced by N-W gales and they form a "shadow" for the W-E longshore currents. The coastline of the islands is still retreating. The removal of sand mainly occurs during storm surges. The eroded material is redeposited in sorted zones parallel to the coast. Only the susceptible material, that is deposited farthest from the beach, can be transported by the longshore currents. The coarsest, most spherical and densest grains remain closest to the beach and can re-enter the beach as prograding bars during more quiet conditions. This process gives rise to a stepwise diminishing grain-size from island to island towards the east. The eastern island is situated on top of older river and/or tidal channel deposits, which are easy to erode. This gives the tidal inlet, and hence the tidal delta, a great lateral mobility. The eastern island is therefore very mobile. The western island is bordered by a deep tidal channel, which cuts into more resistent glacial deposits. This keeps the channel and hence its outer tidal delta in the same site. The western island therefore did not change longitude and constantly retired over its own deposits. This resulted into completely different sand properties for both islands, which mainly shows in the garnet percentages and the high rollability values for the western island. |
| Simple uses of covariograms in geology | 1976 | Dijkstra, S. | 55(1-2) | The paper presents an elementary introduction into the theory of random functions and demonstrates the usefulness of covariograms in the analysis of geological data. Most examples refer to experiences in exploration geochemistry. |
| Clay diapirism in the Lower Emsian La Vid shales near Colle, Cantabrian mountains, NW-Spain | 1976 | Stel, J.H. | 55(1-2) | Faults, tension-rupture, slumplike- and load-and-flamelike structures in thin carbonate intercalations in the Upper La Vid (Lower Emsian) shales NW of Colle are described. They are argued to have been caused or accentuated by clay diapirism. The paleoslope probably had no influence on this deformation process. |
| #REF! | 1976 | 55(1-2) | ||
| Major Flandrian transgressive cycles, sedimentation and palaeogeography in the coastal zone of Essex, England | 1976 | Greensmith, J.T.; Tucker, E.V. | 55(3-4) | The 36 m thick succession rests discordantly on sub-aerially weathered Pleistocene and older strata arid comprises 3 major marine transgressive cycles. The lower 2 are confined to the vicinity of deep Pleistocene channels whereas the 3rd, possibly initiated c. 7500 B.P. extends across the whole coastal zone. Each cycle consists of a lower division of clays and silts with thin coarser deposits towards the base and an upper division of sands and sandy gravels. The contact between the two divisions is often erosional or sharp. Landward displacement of the plain lithofacies is most pronounced during episodes of relatively rapid rise in sea level, as in the U.S.A. and Holland. At certain levels reached by the rising sea extensive bodies of relict Pleistocene sediment becamte available for marine reworking. The persistence of lagoon, marsh, beach, chenier, barrier, tidal flat and channel lithotopes through the succession in conjunction with 12 radiocarbon dates allow general palaeogeographic deductions to be drawn, more especially for c. 7500, c.4000 and c. 1350 B.P. |
| Morphogenetic trend of Lepidocyclina and its application in time stratigraphy | 1976 | Kiam Fui, H. | 55(3-4) | The morphogenetic trend of Lepidocyclina in Miocene sediments from Sarawak, East Malaysia, has been studied. A correlation has been established between the degree of curvature of Lepidocyclina and the planktonic foraminiferal zonation in the area. The results prove that this evolutionary trend of Lepidocyclina is a practical tool for chronostratigraphy. |
| The distribution of Laacher See ash west of the Eifel region | 1976 | Jungerius, P.D.; Riezebos, P.A. | 55(3-4) | Volcanic grain percentages in heavy-mineral concentrates of local colluvial deposits in Luxembourg and surrounding areas have been used to trace the dispersal of an ash deposit of Allerød age characterized by an association of brown anphibole, pyroxene and sphene. Remnants of the ash fall were detected at distances of more than 300 km southwest of the Laacher See eruption centre. As Allerød ashes previously have been found at similar distances east of this centre, it is evident that the dominant wind direction during this geological interstade cannot be reconstructed from the distribution of ashes produced by short-lived eruptions. |
| On the solenid growth habit of Paleofavosites | 1976 | Stel, J.H.; Oekentorp, K. | 55(3-4) | Serial sections of Paleofavosites specimen presents proof to the contention that Desmidopora = Multisolenia is only a growth habit of Paleofavosites. The socalled solenia are funnel-shaped parts of the paleofavosited wall around quite ordinary corner pores. The former are arranged in dumb-bell pairs among any tour adjoining corallites. Such dumb-bells are arranged crosslike, when seen in the direction of growth of the corallites. This growth habit is found in the type species of Paleofavosites as well as in other undisputed members of that genus. The present authors accordingly consider Priscosolenia as a junior synonym of Paleofavosites. Desmidopora (= Multisolenia + Mesosolenia) could serve as a subgeneric heading for paleofavositids with this peculiar growth habit. |
| Implications of the occurrence of large gravity gradients in Northern Timor | 1976 | Milsom, J.; Richardson, A. | 55(3-4) | Recent gravity measurements in eastern Timor have shown that steep gradients occur in the northern part of the island, and that the maximum Bouguer Anomaly values attained are greater than those on the inner volcanic arc immediately to the north. The observations can be explained only by supposing that the dense source rocks rise very close to the surface, and analogies can be drawn with the large anomalies associated with ophiolitic thrusts in New Guinea and New Caledonia. The pattern of volcanic activity north of Timor also resembles that of eastern New Guinea, suggesting, again by analogy, that a thrust slice is wedged in the subduction zone south of the inner Banda arc. If correct, this hypothesis provides some support for the concept of Timor as built up of a series of thrust slices resting ultimately on continental basement. |
| Cretaceous oceanic anoxic events: causes and consequences | 1976 | Schlanger, S.O.; Jenkyns, H.C. | 55(3-4) | Organic carbon-rich sediments ate globally developed in pelagic sedimentary sequences of Aptian-Albian and Cenomanian-Turonian age. They formed in a variety of paleo-bathymetric settings including oceanic plateaus and basins, continental margins and shelf seas. The widespread nature of these deposits suggests that they were not strictly controlled by local basin geometry but were a product of "Oceanic Anoxic Events". We interpret these events as the result of the interplay of two major geologic and climatic factors: firstly the Late Cretaceous transgression which increased the area and volume of shallow epicontinental and marginal seas and was accompanied by an increase in the production of organic carbon; and secondly the existence of an equable global climate which reduced the supply of cold oxygenated bottom water to the world ocean. This combination of climatic and hypsographic conditions favoured the formation of an expanded oxygen-minimum layer and where this intersected the sediment-water interface, organic carbon-rich deposits could be formed, these being records of "Oceanic Anoxic Events". |
| Critical parameters for the production depletion and substitution of mineral resources | 1976 | Brinck, J.W. | 55(3-4) | From the mining history of different mineral commodities it is indicated that the average annual growth of production can be used as an indicator for their economic and industrial maturity. Calculations show the growth rate to be determined by the size of the remaining reserves as function of the annual production. Its value at all times tends to remain directly proportional to the number of times that a mineral industry could double its annual production before depleting its remaining reserves. The observations indicate logistic growth of mineral production toward a moving ceiling which is determined by both natural- (Clarke and specific mineralisability) and technico-economic- (price and current state of mining technology) parameters. If confirmed, this will enable the prediction of ultimate production levels and possible rates of substitution of scarce commodities by more abundant ones. Furthermore, it would increase the physical base for the viability of our technological society by a factor greater than 10; increasing its predictable lifetime from less than a century to well over a thousand years. Using this relation to predict the size of the inferred reserves of a metal from its current annual production and average growth rate, close confirmation of independent estimates with the Mimic model is obtained for the major metals iron, aluminum, copper, gold, zinc and lead, each with a value of annual production in excess of one billion US$. Somewhat less convincing results are obtained for the almost equally well established industries of nickel, tin, mercury and antimony. They show lower growth rates than allowed by the theory. Still lower rates are found for the metals chromium, manganese and tungsten. The nonconforming metals all are commodities for which the USA territory shows marked deficiencies. Their less than normal growth seems to stress the importance of geographic and geo-political factors for the industrial development of mineral commodities, as well as their rather great substitutability. |
| Fan-delta sedimentation: An example from the Late Jurassic - Early Cretaceous of Milne land, Central East Greenland | 1976 | Sykes, R.M.; Brand, R.P. | 55(3-4) | The Hartz Fjeld Formation (Middle Volgian - Ryazanian) is interpreted as a synorogenic fan-delta complex. The lower part of the formation is characterised by coarsening upwards fan-delta sequences with marine delta destructive units. A thick lagoonal unit separates these sequences from the upper part of the formation in which fan-delta deposition resumed in a lateral position and fan plain sands are intercalated within bay muds. A distinction is made between fan-delta deposition, dominated by sheetflood and streamflood processes, and short-headed stream delta deposition in which flow is confined in stable channels. |
| Volcanism and metallogenesis | 1976 | Schermerhorn, L.J.G. | 55(3-4) | |
| Zum alter des "Karbons vom Christophberg", Kärnten, Österreich | 1976 | Amerom, H.W.J. van; Boersma, M.; Riehl-Herwirsch, G. | 55(3-4) | In 1961 during fieldwork plant remains were found at the "Christophberg" near St. Filippen (Carinthia, Austria). The flora was believed to be indicative of a Westphalian age. However, during the summers of 1974 and 1975 additional material has been collected, among which Callipteris conferta could be determined. Due to the discovery this flora at the base of the postvariscian transgression series at the Christophberg is at present considered to be of Rotliegend age. |
| Charles Lyell and Charles Darwin | 1976 | Brouwer, A. | 55(3-4) | Lyell's main work, The principles of geology (1830-1833), left a deep impression on Darwin. This is not only evident from the three geological books Darwin published after his return from the voyage of the Beagle, but also from his main work, The origin of species (1859). The latter can be considered as an application of Lyell's principle of uniformitarianism to the history of the living world. Lyell on the other hand never became a fully convinced Darwinian. It is suggested that this was mainly due to a fundamental difference between Lyell's steady-state model of the Earth's history, and Darwin's view of the history of life as a progressive process. Increased knowledge of the Earth's early Cryptozoic history shows that progressive changes also occurred in the history of the Earth. This, however, does not invalidate the general applicability of the principle of uniformitarianism throughout the whole of geological time. |
| Notes on the sedimentology and paleobotany of the Werfener schichten in the Western Gailtaler Alps near Kötschach (Carinthia, Austria) | 1976 | Amerom, H.W.J. van; Boersma, M.; Niedermayr, G. | 55(3-4) | During fieldwork near Kötschach in Carinthia (Austria) in the summer of 1975 plant remains in the "Werfener Schichten" (Trias) were discovered for the first time, Pleuromeia cf. sternbergii (Muenster) Corda, Voltzia sp., "roots", "seeds" and some leave fragments of uncertain identity could be recognized. The plant-bearing beds are situated in between a series of red and gray coloured, mainly coarse-grained clastics, from which important indications could be obtained on the lithological development of the triassic basal layers in the western Drauzug. |
| Inflatie in de stratigrafie? | 1976 | Brouwer, A. | 55(3-4) | It is questioned whether the complete system of lithostratigraphic terms introduced in the explanation of a (beautiful) new geological map of the Netherlands, scale 1:600000 (Zagwijn & van Staalduinen, 1975) serves a useful purpose. Some definitions seem to be in defiance of the recommendations by the International subcommission on stratigraphic classification, some terms seem to be superfluous. |
| #REF! | 1976 | 55(3-4) | ||
| In memoriam Ph.H. Kuenen | 1977 | Straaten, L.M.J.U. van | 56(1) | |
| Features of Middle Pleistocene sandur deposits in the Netherlands | 1977 | Ruegg, G.H.J. | 56(1) | The sandur deposits discussed below appear to be much similar to alluvial fan deposits. Only minor differences may occur which are related to the nature of the source area (slopes, availability of non-consolidated material) and to climatic conditions. In the introduction a synopsis is given concerning river types and their deposits in general, represented in the deposits of this part of the North Sea Basin; subsequently, Neogene and Quaternary fluvial deposits (including sandur deposits) in The Netherlands are classified based on the type of deposition. |
| Depositional environment of the Oligocene Rupel Clay in well Grashoek-l, Peel region, The Netherlands. | 1977 | Brouwer, J. | 56(1) | A continuously cored marine Oligocene Rupel Clay of the N.A.M. well Grashoek-1 (Peel region, the Netherlands) yielded a benthonic foraminiferal fauna indicative of a bathyal environment with a seadepth below 300-500 m. |
| Depositional environment of the Oligocene Rupel Clay in well Grashoek-l, Peel region, The Netherlands. | 1977 | Brouwer, J. | 56(1) | Large Enclosure |
| A volumetric model to estimate the amount of gas in a newly discovered rock reservoir. | 1977 | Prins, S. | 56(1) | A volumetric calculation of the amount of gas in a rock reservoir requires in practice numerical integration of a volume integral. The distributions of porosity- and gassaturation values throughout the reservoir have then to be known: Since in all practical cases these distributions are only partially known, the calculatiorì of the amount of gas in the reservoir can only be made using a model of the reservoir from which the overall distributions are derived. The model is based on premises that have to be specified separately. The problem of finding suitable distributions is most urgent for a newly discovered reservoir. Therefore an example of such a case has been picked out and general geological and physical considerations have been used as the principal premises in order to arrive at a starting model, named the Continuous Conformal Model (CCM). The construction and computational procedures are illustrated by a numerical example. |
| Biostratigraphy of Cretaceous calcareous nannoplankton | 1977 | Sissingh, W. | 56(1) | The stratigraphical distribution of selected species of calcareous nannoplankton from sections of Cretaceous deposits in Tunisia, France, The Netherlands, West Germany, Great Britain, Denmark, Turkey, Oman and New Jersey was studied. A number of Late Cretaceous lineages was recognised, on which a proposal for a revised zonation is based. Twenty-six zones are distinguished for the Cretaceous interval. First-order correlations between zones and Cretaceous stage-stratotypes are discussed briefly. The Upper Cretaceous part of the proposed zonation has also been correlated with planktonic foraminiferal zones. One new genus and two new species are described. |
| Biostratigraphy of Cretaceous calcareous nannoplankton | 1977 | Sissingh, W. | 56(1) | Large Enclosure |
| The geology of Cyprus and its place in the East-Mediterranean framework | 1977 | Cleintuar, M.R.; Knox, G.J.; Ealey, P.J. | 56(1) | New datings and sedimentological observations seem to confirm the Cretaceous age and submarine origin of the Troodos igneous complex in central Cyprus. Troodos rocks, of marked calc-alkali character, form the basement to an Upper Maastrichtian-Tertiary sequence, 500-1800m thick, of bathyal-shallow abyssal marls and chalks. In N Cyprus these relatively undisturbed sediments are in contact with southward thrusted flysch deposits (2000-3000 m) of prevailing Miocene age, indicating a tectonic weld of major order. Allochthonous Permian-Lower Cretaceous shelf limestones are exposed in what seems to be the core (Kyrenia Range) of the N Cyprus thrust belt. In SW and S Cyprus a thin, exotic rock complex (Mamonia) wedges in between the Upper Maastrichtian-Tertiary sediments and Troodos basement. The Mamonia comprises a Triassic- Lower Cretaceous allochthonous, mainly deep marine assemblage that rests on Campanian dated andesitic pyroclastics. The geological evolution of Cyprus is conceived by the authors as follows: The Troodos igneous complex formed part of an ocean rise in a Cretaceous sea bordered by continental margins. In about Campanian time Troodos was underthrust by the southern (Afro-Arabian) margin. Some of the continental margin rocks (the allochthonous Mamonia), preceded by pyroclastic slope deposits, came to rest on the leading edge of Troodos. The andesitic source of the pyroclastics was probably in the former margin. Quartz sandstone blocks of Lower cretaceous age, included in the allochthonous assemblage, are possibly Nubian sandstones derived from the southern continent. Continued underthrusting forced Troodos to rise without disturbing its sedimentary cover. Eventually, in the upper Miocene and Pliocene, slope deposits and detached shelf limestones from a northern(? ) source were thrust on the Troodos north flank. The tectonic setting of Cyprus is analogous to that of other peri-Arabian thrust belts in that ophiolite/deep-sea sediment associations appear thrown on the southern continent. The Troodos "ophiolite", however, seems unique because of its enormous size and relative rigidity. |
| A note on the isotopic age of Beryl pegmatites near Rama, Suriname | 1977 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Hebeda, E.H.; Verdurmen, E.A.T.; Verschure, R.H. | 56(1) | |
| A palynological investigation of the Moershoofd, Hengelo, and Denekamp interstadials in the Netherlands | 1977 | Kolstrup, E.; Wijmstra, T.A. | 56(2) | A palynological study has been made of some organic deposits from The Netherlands dated between ca. 50,000 and 30,000 B.P. From the recent ecology and distribution of plants found as fossils in the Moershoofd lnterstadial complex, the Hengelo Interstadial and the Denekamp Interstadial, it was concluded that the average July temperatures were 13°, 13-15° and 10°C, respectively. Furthermore a decrease of at least 5°C was found within a time span of 1,500 years during the Moershoofd Interstadial complex. |
| A palynological investigation of the Moershoofd, Hengelo, and Denekamp interstadials in the Netherlands | 1977 | Kolstrup, E.; Wijmstra, T.A. | 56(2) | Large Enclosure E1 |
| A palynological investigation of the Moershoofd, Hengelo, and Denekamp interstadials in the Netherlands | 1977 | Kolstrup, E.; Wijmstra, T.A. | 56(2) | Large Enclosure E2 |
| A palynological investigation of the Moershoofd, Hengelo, and Denekamp interstadials in the Netherlands | 1977 | Kolstrup, E.; Wijmstra, T.A. | 56(2) | Large Enclosure E3 |
| A palynological investigation of the Moershoofd, Hengelo, and Denekamp interstadials in the Netherlands | 1977 | Kolstrup, E.; Wijmstra, T.A. | 56(2) | Large Enclosure E4 |
| A palynological investigation of the Moershoofd, Hengelo, and Denekamp interstadials in the Netherlands | 1977 | Kolstrup, E.; Wijmstra, T.A. | 56(2) | Large Enclosure E5 |
| A palynological investigation of the Moershoofd, Hengelo, and Denekamp interstadials in the Netherlands | 1977 | Kolstrup, E.; Wijmstra, T.A. | 56(2) | Large Enclosure E6 |
| The stream network in the Netherlands as a groundwater discharge phenomenon | 1977 | Vries, J.J. de | 56(2) | The stream network in the higher, Pleistocene part of The Netherlands is genetically coupled with groundwater discharge systems of various extents. Streams of a given order can be described as the outcrops of groundwater flow systems of a corresponding order. The drainage system is controlled by the precipitation surplus (climate), by the resistance of the subsurface to groundwater flow (geology) and by the previous relief and the depth of incision (topography). This concept is defined as the Groundwater Outcrop-Erosion Model (GOEM). On the basis of this model stream nets can be synthesized theoretically. In this context use is made of data on geology, geomorphology and climate applying groundwater flow formulae and Horton's law of stream order versus stream density. Comparison of the actual and "synthetic" stream-net characteristics shows reasonable agreement. |
| Contribution to the stratigraphy of the Weichsel Pleniglacial in the Belgian Coversand area | 1977 | Vandenberghe, J.; Gullentops, F. | 56(2) | Earlier stratigraphical studies of the upper Quaternary in N.W. Belgium have been supplemented with some recently obtained dates, which allowed to make a new approach to construct a more detailed stratigraphical table of the Weichsel Pleniglacial in this region. Between a series of "laminated sands and silts" (undermost part) and a series of "coversands', (uppermost part) an important peat bed was found (Assebroek peat). The pollen spectrum indicates relative warm conditions. A 14 C-date of 30,700 BP was obtained and therefore the peat is correlated with the Arcy-Kesselt interstadial. The overlying "coversands" are characterized by three levels of ice wedges and frost cracks and by one pebble string. The formation of the lowermost level of large deep ice wedges is dated between 26,220 BP and 24,760 BP. It is shown that the severest climatic conditions during the Weichselian started very soon after the Arcy-Kesselt interstadial. |
| Late Cretaceous and Cenozoic history of Northeastern Brazil | 1977 | Mabesoone, J.M.; Rolim, J.L.; Castro, C. de | 56(2) | The late Cretaceous-Cenozoic history of northeastern Brazil is characterized by relief development, correlative sediments and paleosoil profiles. Between Albian and Miocene the so-called Sulamericana Surface developed on a slowly epirogenetic doming area, with the formation of kaolinic and arenaceous soils. During the Miocene the uplift became stronger with consequent deposition of the correlative Serra do Martins Formation and basaltic volcanism. During the more quiet Pliocene a lateritic soil developed on these sediments (Cuité Soil). The early Quaternary glaciations again caused rupture of the equilibrium, resulting in the removal of most of the sedimentary cover of the region, depositing the detritus along the coast. Erosion halted on the reappearing Jurassic planation surface elaborated in crystalline basement rocks (Sertaneja and Tabuleiros Surface). During the interglacial periods soil formation took place on the correlative deposits (Guararapes Formation, Riacho Morno Soil). The last two glaciations which apparently were of stronger intensity, caused the formation of pediments with bornhardts, and river and coastel terraces (polyphase Paraguaçu Cycle). Correlative deposits were laid down in grabens caused by tectonic reactivation (Macaiba Formation). The covering Potengi Soil was formed during the last interglacials. Recent deposition of white sands suggests a new rupture of climatic equiliblium. Paleontological evidence of this history is scarce. |
| Estimation of the tectonic strain ratio from the mean shape of deformed elliptical markers | 1977 | Lisle, R.J. | 56(2) | By considering computer models representing suites of passive elliptical markers subjected to homogeneous deformation, the relationship between the strain ellipse shape (Rs = 1+e1/1+e2) and mean final axial-ratio of the markers is investigated. Random and uniform models in terms of the choice of pre-tectonic initial axial-ratios (Ri) and marker-orientation are considered. The arithmetic mean (R), geometric mean (G) and harmonic mean (H) of the final axial-ratios (Rf = long/short axis) are calculated and it is found that R departs the most from Rs. The closest of the means to the value of Rs is given by H. Using H as an estimate of Rs always gives rise to an error when the markers had a non-circular original shape. However this error diminishes relatively with increase in Rs and decrease in Ri. For the initial clast shapes present in coarse-grained detrital sedimentary rocks and Rs equal or greater than 2.5, H allows an estimation of Rs within 10% error. |
| A structural study in the Belgian Ardennes with sections constructed using computer based methods | 1977 | Langenberg, C.W.; Rondeel, H.E.; Charlesworth, H.A.K. | 56(2) | A 50 km2 area in the eastern part of the Hercynian Dinant synclinorium of the Belgian Ardennes containing sandstones, carbonates and shales is macroscopically folded and cut by several faults. Using numerical procedures the area was divided into five domains within which the folding is statistically cylindrical. The domains were examined with the aid of structural cross-sections. Each section was .constructed using a computer-plot showing the positions of outcrops projected parallel to the fold-axis onto the plane of section, together with the traces of bedding. A composite plot was obtained for all five domains by first rotating four domains separately so that their fold-axes became parallel to the fold-axis in the fifth domain. Such rotations, which affect the coordinates of outcrops as well as the direction cosines of bedding-poles, can be accomplished by matrix multiplication. Sections constructed in this way, particularly the composite section, display the structure to considerable depths. The competent rock-units within the map area have been deformed into rounded parallel folds. The intervening incompetent units appear to be zones of disharmony especially in the south. Several southdipping listric thrust-faults can be discerned in the sections. |
| Isotopic ages in the high-grade metamorphic Coeroeni group, Southwestern Suriname | 1977 | Priem, H.N.A.; Boelrijk, N.A.I.M.; Hebeda, E.H.; Kroonenberg, S.B.; Verdurmen, E.A.T.; Verschure, R.H. | 56(2) | Six whole-rock samples from the high-grade metamorphic Coeroeni Group in southwestern Suriname define a Rb-Sr isochron age of 2042 ± 97 Ma with initial 87Sr/86Sr = 0.7027 ± 0.0039 (λ87 Rb = 1.39 x 10-11 a-1; errors at 95% confidence level).This isochron relationship dates the event of high-grade metamorphism during the Trans-Amazonian Orogenic Cycle. The initial 87Sr/86Sr value does not record a substantial pre-metamorphic crustal history. K-Ar and Rb-Sr analyses of separated minerals (4 hornblendes, 2 muscovites and 6 biotites) yield a highly discordant age pattern, ranging from about 2000 to 1200 Ma (omitting one hornblende containing excess radiogenic argon). This pattern is interpreted as reflecting various degrees of resetting of Trans-Amazonian ages due to a low-grade metamorphic event 1200 ± 100 Ma ago (the Nickerie Metamorphic Episode). The order of mineral dates fits into the common order of radiogenic nuclide retentivities, corresponding to a temperature of about 350°C during the low-grade metamorphism. |
| Engineering geology - past, present and future | 1977 | Price, D.G. | 56(2) | Engineering geology forms the bridge between geology and engineering. It is taught and practised throughout the world and fulfills all the criteria that serve to identify a separate discipline. Its strength lies in the wide range of earth sciences it encompasses while remaining firmly rooted in geology, but its diversity of interest gives rise to uncertainty over its purpose and limitations. The author briefly traces the development of the subject, attempts to define its present state relative to purpose, scope, training and practice and speculates as to further developments. |
| Boring sponges (Clionidae) and their trace fossils from the coast near Rovinj (Yugoslavia) | 1977 | Groot, R.A. de | 56(2) | Boring sponges of the genus Cliona were sampled by SCUBA-diving in the Adriatic Sea near Rovinj, Yugoslavia. Boulders of limestone and shells of molluscs, infested by clionids were collected. The sponges were identified and polyester casts were made of their bore-holes. A description is presented of the spiculae of the sponges as well as their bore-holes. It appears that sponges with different spiculae excavate different borings. The borings in limestone are larger than those in shells. |
| #REF! | 1977 | 56(2) | ||
| Morphodynamic development and preservation of physical sedimentary structures in two prograding recent ridge and runnel beaches along the Dutch coast | 1977 | Berg, J.H. van den | 56(3) | The two studied beaches both form part of the coastal barrier system which extends along the eastern margin of the southern North Sea. One of them (at Schouwen) is bordered by the coalescing ebb deltas of two major tidal inlets; the other one (at Zandvoort) lies beyond the in influence of inlets. The ridge and runnel beach environment is divided into areas lying relatively sheltered from wave action behind ridge or berm crests and seaward dipping surfaces exposed to the influence of swash and backwash during the tidal cycle. Both of the areas are characterized by a set of sedimentary bedforms and structures, which produce distinctive associations in preserved sediments. Comparison of data on sampled structures from buried sediment layers with information from repeated measurement of beach variation, permitted reconstruction of the location of these associations as preserved during the last few years in sections perpendicular to the coastline. Major differences in the morphodynamics of the two beaches as well as in the location of associated sedimentary structures preserved in these sections, are related to the degree to which the beaches are sheltered from storm waves and to rates of progradation. |
| Mud in the Dutch Delta Area | 1977 | Terwindt, J.H.J. | 56(3) | Mud is transported to the Dutch delta area from the Rhine, Waal, Maas and Scheldt rivers (resp. 0,6; 2,5; 0,7 and 0,7 million tons/year). Above, in the Rotterdam Waterway about 3,5 million tons of mud per year are brought in from the sea. The mud of the underwater delta comes from the Channel, the Haringvliet, from biological formation, from erosion of older clay and mud deposits and from mud that is dumped in this area from the Rotterdam harbours. In recent years the last mentioned quantities amount to approximately 4 million tons per year. The mud content in the water varies greatly over the area, as illustrated in figure 2. |
| The effect of gas bubble formation on the physical and engineering properties of recently deposited fine-grained sediments | 1977 | Faas, R.W.; Wartel, S. | 56(3) | Sediments in the anoxic reaches of the Veerse Meer, a tideless basin in the southwest Netherlands, possess certain physical properties which are directly dependent upon the geochemical environment in which they are accumulating. High values of water content and correspondingly low values of bulk density (unit weight) and shear strength were observed in sediments deposited in low oxygen to anoxic waters (-12 m to -20 m depth). Plasticity increased regularly with depth with highest plasticity found in the most highly reduced sediments at -20 m. One-dimensional consolidation analyses showed rapid consolidation and almost complete lack of rebound. Stress-strain diagrams show little or no reloading curves and are typical of underconsolidated or remolded sediments in which interparticle bonding is minimal. Gas generation and bubble ebullition with swelling is believed to retard normal gravitational consolidation and inhibit fabric development through continual agitation and physical manipulation of sediment particles. Both conditions (i.e., underconsolidation and remolding) exist as a direct result of methanogenesis. |
| Composition, transport and origin of sediments in the Schelde estuary | 1977 | Wartel, S. | 56(3) | The grain-size characteristics (grain-size distribution, comparison of one percent value (C) of a given grain-size distribution with the median value (M) in so-called CM-patterns, silt/clay ratio's) of the Schelde estuary are distributed in relation to the existence of a turbidity maximum. Fine sand, silt and clay are deposited, while fluid mud occurs. Towards the North Sea, as well as in an upstream direction, the sediments become much coarser. Silt, clay and part of the sand are derived from the river drainage basin. Sands are also brought into the estuary from the North Sea. Flocculation is important as a depositional agent. However, deflocculation in a seawards direction, favouring seawards transport of silt and clay particles, is assumed. Movement of fluid mud deposits in relation to river discharge has not been observed. This can be explained by narrowing of the channel and the corresponding increase in stream power, where the river crosses the Boom clay (Oligiocene). |
| Vegetational and climatic developments during the Late Glacial and the Early Holocene and aeolian sedimentation as recorded in the Uteringsveen (Drente, The Netherlands) | 1977 | Cleveringa, P.; Gans, W. de; Kolstrup, E.; Paris, F.P. | 56(3) | A lithological and palynological investigation has been made of the Late Glacial and early Holocene filling of a pingo remnant in Drente (The Netherlands). It was found that the deposition of aeolian sands, although of varying nature, was uninterupted from the beginning of the Late Glacial until the end of the Boreal. From the pollen records a vegetational development was reconstructed and its dependance on temperatures, moisture conditions, and soil development is discussed. It was concluded that the mean July temperatures were at least 10° C - possibly 13° C - in the Bølling, probably 12° - 13° C in the Earlier Dryas, around 14°C at the beginning of the Allerød, and at least 12° C in the Late Dryas time. |
| Vegetational and climatic developments during the Late Glacial and the Early Holocene and aeolian sedimentation as recorded in the Uteringsveen (Drente, The Netherlands) | 1977 | Cleveringa, P.; Gans, W. de; Kolstrup, E.; Paris, F.P. | 56(3) | Large Enclosure 1 |
| Vegetational and climatic developments during the Late Glacial and the Early Holocene and aeolian sedimentation as recorded in the Uteringsveen (Drente, The Netherlands) | 1977 | Cleveringa, P.; Gans, W. de; Kolstrup, E.; Paris, F.P. | 56(3) | Large Enclosure 2 |
| Basement tectonics from LANDSAT imagery in mining exploration | 1977 | Ramos, V.A. | 56(3) | The mineral potentials of basement cratonic areas are evaluated on the basis of mechanical analyses of their tectonic framework, obtained from LANDSAT imagery, Tensional release targets are selected through the application of different deformational models and the identification of the stage and type of deformation. Correlation between tensional release zones and epigenetic hypogenic mineralization in different cratonic areas of South America has been successful in several mining exploration programmes. |
| The influence of pore water on the compaction behaviour of carbonate sand | 1977 | Boer, R.B. de; Lagrand, J. | 56(3) | Maastrichtian Carbonate Sand collected from the Pietersberg near Maastricht (Netherlands) was compressed at room temperature, in order to detect pressure-solution phenomena. Compaction took place at slowly rising loads (10 atm/day) as well as under constant loading. The maximum loads to which the different samples were subjected varied from 15 to 280 atmospheres. The influence of the following factors on the compaction behaviour of the sand was studied: 1. presence or absence of pore water; 2. partial CO2-pressure of pore water; 3. inhibition of calcite precipitation; 4. saturation of pore water with respect to calcite; 5. circulation of pore water. At room temperature applied microscopically detectable pressure-solution phenomena were not produced. The influence of the presence of pore water on compaction was clearly demonstrated, but the pore-water composition appeared not to be a dominant factor. |
| A fast procedure for sampling sedimentary structures down to 1,1m in unconsolidated wet sands | 1977 | Berg, J.H. van den | 56(3) | An inexpensive, simple and efficient method has been developed for sampling sedimentary structures, down to 1.1 m. below the sediment surface, in unconsolidated wet sands. The method can be used on land and in quiet water to a depth of at least 4 metres. The procedure makes possible the study of sedimentary structures in the form of lacquer peels measuring 1.1 m. high and 0.1 m. wide within one hour after coring has been started. |
| The undation theory | 1977 | Bemmelen, R.W. van | 56(3) | |
| #REF! | 1977 | 56(3) | ||
| Preface - Fault tectonics in N.W. Europe | 1977 | Frost, R.T.C.; Dikkers, A.J. | 56(4) | |
| Sketch of a possible lineament pattern in Northwest Europe | 1977 | Dikkers, A.J. | 56(4) | Regional linear fracture zones, or "lineaments", are known to be elements of fundamental importance in the structure of the Variscan (Hercynian) and older basement in NW Europe. Several lineaments have shown periodic tectonic activity until very recent times; movements in different directions at different times are common. Based on data from various sources - especially aeromagnetics and Landsat images the existence of several lineaments in the North Sea area is postulated. The known and the postulated lineaments can be loosely grouped into three recognisable, but not sharply defined, directional sets: around NW-SE, NE-SW, N-S. The effect of the lineaments on the structure of the Permian and younger cover is well expressed in the segmentation of the Mesozoic-Tertiary graben systems, in particular the Central Graben-Viking Graben. |
| Sketch of a possible lineament pattern in Northwest Europe | 1977 | Dikkers, A.J. | 56(4) | Large Enclosure |
| Fault and lineament patterns in the southern highlands of Scotland | 1977 | Johnson, M.R.W.; Frost, R.T.C. | 56(4) | This paper discusses the mapped faults and photolineaments (observed on Landsat images) in part of the Scottish Caledonides. The prominent NNE-SSW to NE-SW trending wrench faults, including the Great Glen Fault, were active in the Upper Palaeozoic. In addition, recent studies have suggested Mesozoic/Tertiary activity along the Great Glen Fault. The Highland Boundary Fault, which forms the southeastern margin of the metamorphic Caledonides was an active reverse fault in Devonian times, and later transcurrent movements along it have been postulated. Another conspicuous fault set trends NW-SE; some of these faults were active in Mesozoic/Tertiary times. A minority of the faults trend roughly N-S or E-W. A map of lineaments from Landsat images has been constructed. The lineament pattern is shown to correspond closely to the fault pattern. Although by no means all mapped faults were observed on the satellite imagery, it is considered that some previously undescribed fractures and extensions to known faults were detected. |
| Fault and lineament patterns in the southern highlands of Scotland | 1977 | Johnson, M.R.W.; Frost, R.T.C. | 56(4) | Large Enclosure 1 |
| Fault and lineament patterns in the southern highlands of Scotland | 1977 | Johnson, M.R.W.; Frost, R.T.C. | 56(4) | Large Enclosure 2 |
| Analysis of fracture patterns in southern Norway | 1977 | Ramberg, I.B.; Gabrielsen, R.H.; Larsen, B.T.; Solli, A. | 56(4) | Linear features (believed to represent fractures of some kind) seen on Landsat satellite images, topographic maps and geological maps have been mapped for the area of southern Norway (roughly the region south of the 65° parallel). Special attention is given to the area of the Oslo Graben. The results of the analysis are related to the main geological and geophysical features of the region, of which a brief description is given. A system of NW-SE and NE-SW sets of lineaments is present over most of the region and predominates in the Precambrian area; it is thought to be the oldest structural element. In the Caledonian belt the NE-SW set is predominant, in accordance with the general strike. A roughly N-S trending set is obviously associated with the Oslo Graben but extends well to the north of the latter; a similar pattern is also present near the west coast. An E-W set is locally associated with Devonian movements. The coastlines of southern Norway conform closely to the directions of the dominant fracture pattern in the vicinity. |
| Analysis of fracture patterns in southern Norway | 1977 | Ramberg, I.B.; Gabrielsen, R.H.; Larsen, B.T.; Solli, A. | 56(4) | Large Enclosure 1 |
| Analysis of fracture patterns in southern Norway | 1977 | Ramberg, I.B.; Gabrielsen, R.H.; Larsen, B.T.; Solli, A. | 56(4) | Large Enclosure 2 |
| Analysis of fracture patterns in southern Norway | 1977 | Ramberg, I.B.; Gabrielsen, R.H.; Larsen, B.T.; Solli, A. | 56(4) | Large Enclosure 3 |
| Analysis of fracture patterns in southern Norway | 1977 | Ramberg, I.B.; Gabrielsen, R.H.; Larsen, B.T.; Solli, A. | 56(4) | Large Enclosure 4 |
| Analysis of fracture patterns in southern Norway | 1977 | Ramberg, I.B.; Gabrielsen, R.H.; Larsen, B.T.; Solli, A. | 56(4) | Large Enclosure 5 |
| Analysis of fracture patterns in southern Norway | 1977 | Ramberg, I.B.; Gabrielsen, R.H.; Larsen, B.T.; Solli, A. | 56(4) | Large Enclosure 6 |
| Mesozoic faulting in East Greenland | 1977 | Surlyk, F. | 56(4) | Mesozoic faulting in the East Greenland Basin is interpreted as the result of graben formation extending from a postulated "trilete junction" south of Scoresby Sund. Faults appear slightly curved in plan, but can be divided into straight sections 2 - 10 km long (up to 20° between adjacent segments). They are normal types only, dipping 60° - 80°, with throws up to 4 km partly resulting from block rotation. Although this rotation implies faults curved in section, they can usually be assumed flat with such large radii of curvature. Major faults are often complex zones (0.5 - 4 km wide) of narrow blocks and slivers. Faulting was partly synsedimentary. Comparisons of pre-Mesozoic and Mesozoic fault directions show fairly similar dominant trends (335°, 355°, 015° - 025°,035° - 050° & 085° - 090°) in all areas, indicating that pre-existing basement anisotropies controlled directions of Mesozoic-Cenozoic faulting. Basin formation was accomplished by roughly N-S boundary faults in east and west and major NW-SE faults, which together defined a series of fault blocks (subsiding successively from south to north). In Volgian- Valanginian times, the basin was further split into N-S trending antithetic blocks by faults 10 - 30 km apart (crustal extension about 6%). |
| Mesozoic faulting in East Greenland | 1977 | Surlyk, F. | 56(4) | Large Enclosure |
| Ancient and recent rifting in the Rhinegraben | 1977 | Illies, J.H. | 56(4) | The Rhinegraben is part of a western European rift system. Although of different ages and trend, these rifts are situated on pre-existing basement weakness zones. Signs of Rhinegraben subsidence occur in mid-Jurassic, but true rifting began in mid-Eocene. Boundary faults are complex systems of normal faults, dipping about 65°, perhaps flattening with depth. "Horizontal stylolite" orientations indicate an Eocene palaeostress field (related to Alpine plate collision) with its minimum component normal to the graben, i.e. ideal for rifting on the basement weakness zone. Rifting continued until Lower Miocene, but the depocentre shifted north with continued development of a mantle bulge in the south. Then, although crustal upwarping and volcanism continued, graben formation ceased - the stress field was no longer appropriately oriented. Graben activity restarted in Upper Pliocene and continues today. In-situ stress measurements indicate a sinistral shear component parallel to the graben, producing different tectonic reactions in the three slightly differently oriented graben segments. This shear motion is ascribed to continuing Alpine uplift and extension pushing northwestward the block east of the graben. The Rhinegraben and Lower Rhine Embayment are connected by a continuous seismotectonic belt where rifting is controlled by pre-existent basement fractures and regional stress, |
| Tectonic patterns in the Danish region (as deduced from a comparative analysis of magnetic, landsat, bathymetric and gravity lineaments | 1977 | Frost, R.T.C. | 56(4) | Lineament maps of the Danish region have been produced from three different data sources: magnetic anomaly maps, surface data (Landsat satellite images and bathymetric maps) and Bouguer gravity maps. The directional patterns produced, represented by rose diagrams, show several prominent and statistically significant directions. Three directions (WNW-ESE to NW-SE, NNE-SSW and NE-SW to ENE-WSW) are well defined by all three data sources, and are parallel to the principal structural trends in older exposed rocks framing the region studied; however, the other less prominent directions may also be of import. The close correspondence between patterns produced by surface data and by magnetic data (presumably mainly representative of the basement) is regarded as strong evidence that these patterns are tectonically significant and are probably present throughout the sedimentary cover. Systematic pattern differences are observed between three sub-areas of the region; these may reflect variations in the basement, different tectonic histories and/or different thicknesses of sediment. |
| An experimental approach to basement-controlled faulting | 1977 | Horsfield, W.T. | 56(4) | To assist in the interpretation of fault structures in the North Sea, a programme of scaled-model experiments was run in a specially-built sandbox. Faults were produced in the sand overburden in response to normal displacement along faults in the underlying basement. Variations in overburden fault geometry were studied in relation to the attitude of basement faults and variations in sand properties. A stereoscopic method was used to analyse successive stages of development. In the experiments, two stages were observed. Initially, curved precursor faults formed, particularly over high-angle basement faults. These were followed by planar normal faults. Over low-angle basement faults, antithetic as well as synthetic normal faults were prominent. |
| #REF! | 1977 | 56(4) | ||
| Early subsurface temperature measurements in the Netherlands | 1978 | Visser, W.A. | 57(1) | The earliest known subsurface temperatures were obtained in 1879 in a borehole (to in the a depth of 365 m) centre of the city of Utrecht. During the years 1912 - 1914 temperatures were measured to depths as great as 1400 m in a number of wells in structurally high areas in Tertiary, Senonian, Triassic, Upper Permian and Carboniferous rocks. In 1952 additional data were obtained (Peel horst), followed in 1956 by a few measurements in the South Limburg mining district. The various thermometers used are briefly described. The temperatures are related to lithology and stratigraphy and to the salinities of the interstitial waters. very low geothermal gradients are present in Quaternary to uppermost Tertiary due to percolating waters of meteoric origin. In the post-carboniferous overburden and, where shallow, in the higher parts of the Westphalian the waters are either fresh, or, if saline, do not reach sea-water concentrations. In such areas the geothermal gradients are lower than 3°C/100 m. In the Carboniferous, due to the low thermal conductivity of coal, gradients tend to be high: over 4, and reaching 5.2 to 5.6°C/100 m. In contrast, the high conductivities of anhydrite and rock salt cause low gradients (2.5 in the Buntsandstein and Zechstein formations). |
| Geological thinking and mapping in the Netherlands before and during Staring's lifetime | 1978 | Thiadens, A.A. | 57(1) | This paper deals with geological thinking and mapping in The Netherlands before and during the life of W.C.H. Staring (1808-1877). During the last two centuries there have been two centres of geological activity, viz. Groningen and Haarlem. Some outstanding pre-staring geological achievements are mentioned. As typical items, which may give an idea of the geological thinking in The Netherlands in the past, special attention is paid to theories about the origin of peat, the provenance of erratic boulders, and the mapping of Quaternary The first geological map of the Netherlands (scale 1:200,000) was made by Staring, who is considered the father of Netherlands geology. |
| Phylogenetic sequences of Lower Cretaceous benthic foraminifera and their use in biostratipgraphy | 1978 | Bartenstein, H. | 57(1) | Ten stratigraphically important phylogenetic sequences of benthic index foraminifera in the Lower Cretaceous are described. Their distribution is examined in North West Germany, which belongs to the north temperate facies realm, and they are also found to be, in part, of stratigraphic importance in the Lower Cretaceous throughout the world, including the tethyan facies realm. The development and importance of such phylogenetic sequences for biostratigraphic determinations is emphasized; the paper concludes with a supplementary note about the validity of statistical analyses as applied to phylogenetic Iineages. |
| New data on Early Dinantian (Early Carboniferous) stratigraphy and sedimentation in South Cork, Ireland | 1978 | Gelder, A. van; Clayton, G. | 57(1) | The sedimentology and stratigraphy of the Dinantian (Lower Carboniferous) Kinsale Formation are described from ten major coastal sections in south Cork, Republic of Ireland. Palynological correlations between the sections are outlined, and subdivision of the Kinsale Formation into three members is proposed. Members I and 3 are dominated by mudrocks, and are separated by the more sandy member 2. Sediments assigned to member 1 were deposited in a deep-water, marine environment below wave base, whereas members 2 and 3 were deposited on a shallow marine, muddy platform, where sandy shoals built up. The latter are especially well developed in member 2. |
| The palaeoenvironment of the Kempenland clay deposits (Lower Quaternary, N. Belgium) | 1978 | Geys, J.F. | 57(1) | Grain-size analyses show that the Kempenland deposits (Lower Quaternary, N. Belgium) were deposited in an environment of rather quiet water with a low flow energy and no tidal influence. Electron microscopical investigations indicate that the water contained few salts. The sedimentary structures are the result of an unidirectional current towards the northwest, in a river with a mainly meandering character. No evidence could be found for a marine, littoral or perimarine genesis. Most probably the Kempenland deposits can be placed within the Kedichem and Tegelen Formations of Dutch authors. |
| Sand and gravel from shallow seas | 1978 | Oele, E. | 57(1) | Various factors which influence the economic feasibility of offshore mining are discussed. The mined sands and gravels are used for constructional purposes. Therefore, some specifications of the grainsize distribution of the exploitable product are mentioned. A gravel exploration by the Netherlands Geological Survey in an area off the Norfolk coast is mentioned. Some special samplers, used for this purpose, are described. Sand and gravel on the shelves have been transported and supplied by rivers, glaciers, wind and locally by longshore currents. Marine erosion may contribute as well. The North Sea and English Channel are good examples of an aggregate-bearing shelf, since shells, sands and gravels are all present. The availability is at least as important as the transporting agents. Controlling include a.o. climate, tectonic instability and distance from the source area. Even in the Pleistocene the weathering processes in the tropical zones resulted in only small amounts of sand and gravel reaching the present-day shelf areas. In the subtropical zone the humidity and tectonic instability are a prerequisite for their presence) whereas in the temperate zones various mechanisms have led to mineable deposits. From a combination of prospective areas and densely populated regions it follows that only very restricted parts of the shelf are of interest as far as mining is concerned. |
| Theoretical stress conditions in the matrix around a rigid circular inclusion and their geological implications | 1978 | Hossain, K.M. | 57(1) | Equations are derived which describe the stress condition in the matrix around a rigid circular inclusion subjected to uniaxial stress. The values of the principal stresses and their orientations are obtained using a computer. The orientation of potential fractures around an inclusion is determined from the stress trajectories and the development of pressure shadows and pressure fringes are predicted by assuming that mineral migration occurs in response to gradients in the mean stress. The type of structures (whether pressure shadows or pressure fringes) that develop in the low mean stress zone adjacent to the inclusions is controlled by the magnitude of applied stress. |
| Contrasts across the shear zone in the Precambrian rocks of Western Singhbhum | 1978 | Bhattacharyya, D.S. | 57(1) | A prominent shear zone runs E-W across Singhbhum. Structural analysis indicates three phases of folding, all with E-W axial planes dipping northerly or subvertically to the north of the shear zone. South of this shear zone there are two phases of folding consisting of earlier folds with NNE striking axial planes, overprinted by later E-W folds. This marked structural contrast, along with other contrasting characteristics, indicates a large horizontal displacement that juxtaposed the two separate orogenic belts. Kinematic patterns indicate that such a large horizontal displacement could have been brought about by a sinistral transcurrent shear during the second phase of deformation seen in the north. The changes in kinematic patterns from N-S compression to transcurrent movement to N-S compression again during the same Singhbhum orogeny are of great interest. |
| Diagenetic and metamorphic evolution of Cambro-Ordovician siliclastic sediments in Northwestern Spain | 1978 | Gietelink, G. | 57(1) | The diagenetic and metamorphic evolutions of the Cambro-Ordovician silicictastic sediments of the Luna area, which formed part of the Lower Palaeozoic stable shelf, and of the Sil area, which was situated in the adjacent geosyncline, were determined and compared. The overburden in the Luna area reached 2500-3500 m, based on stratigraphic evidence. This is in agreement with the mineral association occurring in the sediments (authigenic illite with minor amounts of detrital kaolinite and authigenic muscovite and chlorite), indicating a depth of burial of 2000-3000 m. The sediments were subject to diagenetic changes, which occurred shortly after deposition before lithification (syndiagenetic phase), in the lithified rocks (anadiagenetic phase) and after uplifting and erosion of the area (epidiagenetic phase). Based on stratigraphic evidence, the overburden of the sediments studied in the Sil area ranged from 5000 to 14000 m. The mineral associations observed in the sediments (illite-muscovite-chlorite in the upper part and muscovite-chlorite-biotite in the lower part of the succession) are not in agreement with the estimated depth of burial. The sediments of the Sil area underwent diagenetic alterations similar to those of the sediments in the Luna area, but the effects are obscured by metamorphic recrystallization, which occurred during the Hercynian orogeny. During this period the area was affected by regional metamorphism. |
| Structure of the Northeastern plateau of the Bahariya oasis, Western desert, Egypt | 1978 | Elbassyony, A.A. | 57(1) | The structural studies of the northeastern plateau concern two fold axes trending NE-SW. The first fold axis runs through the ElHarra and ElGedida areas. The second fold axis runs through the Gebel Ghorabi and Dumbell's Hill areas. Between these two fold axes lies the plunge of the northeast anticline (Ghorabi anticline) of the Bahariya high. Two periods of deformation have affected the investigated area. The first one is considered to be a part of the Syrian arc system (of the Laramide cycle) that extends in post-cenomanian - pre-Campanian time from Bahariya to Abu Rawash near Cairo. The second one is considered to be a part of the Alpine cycle. It affects the Eocene and Oligocene sediments. Faulting accompanied both periods of deformation. The fault systems: NE-SW (aualitic), E-W (Tethyan) and NW-SE (African) are recognized. |
| Tentative explanation of the late glacial and Early Holocene climatic changes in North-Western Europe | 1978 | Geel, B. van; Kolstrup, E. | 57(1) | |
| A recently discovered nickeliferous serpentinite from Uda Walawe, Sri Lanka | 1978 | Dissanayake, C.B.; Riel, B.J. van | 57(1) | |
| #REF! | 1978 | 57(1) | ||
| Preface THE 8th CARIBBEAN GEOLOGICAL CONFERENCE (WILLEMSTAD, 1977) | 1978 | Gillavry, H.J.M.; Beets, D.J. | 57(2) | |
| Polyphasic Tertiary Tectonics of the interior range in the Central Part of the Western Caribbean chain, Guarico state, Northern Venezuela. | 1978 | Beck, C.M. | 57(2) | The southern -non metamorphic- belt of the Western Caribbean Chain is composed of the superposition of several tectonic units with an upper Cretaceous-Palaeocene content. The whole –called 'Piemontine Nappe'- was detached from an Albian and pre-Albian substratum and suffered two major compressive tectonic phases with southward displacements. The first phase Lower Middle Eocene- produced the allochthony of the previously tectonized Villa de Cura Nappe, which was strongly shortened. During the Oligocene (?) -Miocene period, a wide subsiding furrow appeared along the southern margin of the palaeorelief formed before in relation with a NNW-SSE distension. The second tangential phase -Middle-Upper Miocene- produced a partial overthrusting of the Piemontine Nappe on the Miocene terrains and a new shortening of the latter. An earlier phase may have affected the northern part of the Piemontine dominion in the lower Senonian. This hypothesis and the preceding conclusions are in opposition with the theory -generally held- of a displacement of the Villa de Cura Nappe as due to a continuous sliding occurring during Maastrichtian and Palaeocene time and followed by a continuous sliding of the Piemontine Nappe from Upper Eocene to Miocene time. The hypothesis of tectonisation by gravity sliding is discussed and discarded. |
| Seismic investigations in the Colombia, Venezuela and Grenada Basins, and on the Barbados ridge for future IPOD drilling | 1978 | Biju-Duval, B.; Mascle, A.; Montadert, L.; Wanneson, J. | 57(2) | The geological setting of five sites for future IPOD drilling in the Caribbean is described. These sites were surveyed in 1976 by IFN-CNEXO with 2800 km of multichannel seismic records. The first two sites straddle the lesser Antilles island arc where the oceanic Atlantic plate is subducted westwards under the Caribbean plate. The main objectives of these sites are to investigate the frontal overthrust of the Barbados Ridge (accretionary prism) on the Barracuda abyssal plain, and the age and nature of sediments and crust of the back a¡c basin, e.g. the Grenada Basin. The three other sites are located in the Venezuela and Colombia Basins in order to understand their composite structure better and to compare their geological history with the geological evolution of their surrounding margins. |
| Anomalous crust in the Eastern Venezuela Basin and the Bouguer gravity anomaly field of northern Venezuela and the Caribbean borderland. | 1978 | Bonini, W.E. | 57(2) | A new Bouguer gravity anomaly map is presented for the southern Caribbean borderland and northern South America. Major features are; the Lake Maracaibo-Venezuela Andes minimum (-160 mgal); gravity maxima in the Venezuelan offshore area and on the Netherland Antilles; a steep gradient (- 4.7 mgal/km) south across the Western Caribbean Mountains; the termination on Margarita ultra-mafic rocks of the minimum trend of the Lesser Antilles; and the broad gravity minimum (-200 mgal) to the east and anomalous maxima (+10 mgal) to the west associated with the Eastern Venezuela Basin. Gravity models have been calculated for two sections over this basin. The broad gravity minimum in the east can be explained by up to 15 km of sediment and crustal downwarping to a depth of 47 km. The maxima suggest an anomalous crust, possibly caused by a higher-density basement, a crustal upwarp, or both. The trend of the gravity maxima parallels those of the Eastern Venezuela Basin minimum and the Antillean trends as they enter Venezuela. In addition they are parallel to the ENE structural trends of the Precambrian south of the Orinoco River. Thus, the anomalous sub-sediment rocks could be related to Mesozoic tectonics, or Precambrian basement features. |
| Paleogeografía del Paleógeno de Cuba oriental | 1978 | Brezsnyanszky, K.; Iturralde-Vinent, M.A. | 57(2) | The changes in the tectono-sedimentary regimen between the volcanic arc stage and the platformlike stage in eastern Cuba are studied. During the Palaeocene and Lower Eocene volcano-sedimentary deposits predominated in the territory, derived from volcanic centres in the present Sierra Maestra. Transgressive carbonate sedimentation in the Middle Eocene succeeded the extinction of the volcanic activity. In the Upper Eocene a new tectono-sedimentary regimen started. Terrigenous and carbonate-terrigenous deposits played the fundamental role, and a regression started, which continued into the Middle Oligocene. At that time two islands, separated by a mediterranean channel, developed between the Golfo de Guacanayabo and the Bahía de Nipe. During the Upper Oligocene a new marine transgression started, which reached its maximum development in the Lower Miocene. The change from a volcanic arc regimen to the platform-like stage was marked by a great relief inversion. The Nipe-Guacanayabo fault need not have been a sinistral transcurrent fault; if it is, then it did not have a great displacement in the Palaeogene. The territory of eastern Cuba during the Palaeogene can be divided into a northern more stable part, and a southern unstable part. The characteristics are related to a progressive continentalization from Cretaceous to Palaeogene, and from north to south. |
| The dispersion of Na, K, Ca and Mg along the footwall of a Pb-Zn ore body, Hope Mine, Jamaica. | 1978 | Carby, B.E. | 57(2) | The Hope Mine lead-zinc deposit is located near the western margin of the Wagwater Belt, Jamaica. The galena-sphalerite mineralisation is associated with an andesite body of (?) Eocene age and was deposited from hydrothermal emanations. The dispersion patterns of Na, K, Ca and Mg in two adits of the mine are briefly described and the results are presented. The ratios MgO/CaO and K2O/Na2O are calculated. It is found that this ratio might be useful in locating ore bodies of this type. |
| Aspects of the attitude of mafic sheets in the Western Cordillera of Colombia | 1978 | Boorder, H. de | 57(2) | Changes in the attitude of sheet-like bodies of mafic rocks ('diabase') are discussed in relation to changes in the attitude of the bedding of intercalated and otherwise associated sedimentary rocks. Examples are presented in photographs of outcrops along the main road between Buga and Buenaventura, W. Colombia. The mafic sheets of the Colombian Western Cordillera and their mode of emplacement are compared with the sheets of the Sheeted Intrusive Complex of Cyprus, with reference to the sheet swarms of Iceland. Horizontal emplacement of sheets, never questioned in the Western Cordillera of Colombia, is considered as an alternative to vertical emplacement of sheets, previously suggested for the Sheeted Intrusive Complex of Cyprus. The subject matter is thought to be of importance in the (geophysical) study of the framework of the ocean floors. Further field investigation of the volcanic-sedimentary complex of the Western Cordillera of Colombia should be encouraged. |
| New data on rudist assemblages in Cuba | 1978 | Torre, A. de la; Jakus, P.; Albear, J.F. de | 57(2) | A review of the most important publications about the rudist assemblages in Cuba is offered. A faunal assemblage from the eastern part, belonging to the Maastrichtian (Titanosarcolites fauna), is studied. It includes both Titanosarcolites and Barrettia. Four faunal assemblages are recognized in the Cuban Upper Cretaceous: (1) Tepeyacia fauna, probably Cenomanian-Turonian age; (2) Durania fauna, probably of a Santonian or Coniacian age; (3) Barrettia fauna; and (4) Títanosarcolites fatna. The last two are of a (probably Upper) Maastrichtian age and are corresponding to either two different stratigraphic horizons or two different facies in that age. The relationship between these two assemblages must, however, still be investigated, although the Barrettia fauna probably is somewhat older than the Titanosarcolítes fauna, according to the work of Chubb (1956, 1961). Some evidence about the occasional association of Titanosarcolites and Barrettia at some Cuban and West Indian localities is mentioned. |
| The distribution of igneous rock suites throughout the Caribbean | 1978 | Donnelly, T.W.; Rogers, J.J.W. | 57(2) | New analytical determinations for more than one hundred igneous samples enable us to place several circum-Caribbean igneous series into a tentative tectonic perspective. We consider that the basaltic rocks from Curaçao, Aruba, Tiara (Venezuela), and the mafic intrusives of the Paraguaná Peninsula (Venezuela) belong to a MORB association of possible early Late Cretaceous age, which is correlative with basinal basalts from the Caribbean, and which has been tectonically emplaced after eruption on to the continental border. Some stratigraphically early volcanic complexes from Jamaica, Dominican Republic, Désirade, Tobago, and Bonaire are placed in the primitive group, along with the early volcanics of Puerto Rico and the Virgin Islands. Plutonic rocks from Haiti and the Pedro Bank are somewhat high in K but not broadly different from those of Puerto Rico. The young volcanics of the central Dominican Republic are of the shoshonite (high-K) group. The plutonics of the southern Caribbean continental borderland are probably all calcalkaline, including those of Tobago. Several are notably high in cobalt, which further demonstrates that the southern Aves Ridge plutonics belong here and are not part of some other series. |
| Marine lithification of reef rock and rhodolites at a fore-reef slope locality (-50m) off Bermuda | 1978 | Focke, J.W.; Gebelein, C.D. | 57(2) | At a depth of 50 meters the fore-reef slope at the northern margin of the Bermuda platform consists of solid reef rock interspersed with sand patches and channels. Coralline algae are the predominant framebuilders, the only common coral being Montastrea cavernosa. On the rippled sand abundant red algal nodules (rhodolites) occur with diameters up to 12 cm. Both reef and rhodolites show various stages of alteration and lithification by repetitive boring, secondary framebuilding, internal sedimentation and cementation. All processes are marine. Aragonite cement occurs only within the in situ deposited primary framework, and is probably a very early, post mortem precipitate. Magnesian calcite is the only common cement on all other substrates. Practically all porosity and permeability is destroyed within approximately 1500 years. Net accretion rates in the rhodolites are in the order of 0.05 mm/year. With local current patterns providing a suitable pumping mechanism, the very slow accretion rates are thought to be the main reason for the pervasive nature of diagenetic alteration on this fore-reef locality. Rhodolites of this type may be useful palaeo- environmental indicators for deep (more than 50 m) tropical waters. |
| Development of the coral facies from the Oligocene to the Recent in Eastern Cuba). | 1978 | Franco, G.L.; Nagy, E.; Radocz, G. | 57(2) | Coral formations of eastern Cuba occur around two anticlinoria in zones progressively further from the axis and nearer to the present coast. A lagoonal facies prevails. The oldest fauna, found in the Guantánamo Basin, is of Oligo-miocene age; it correlates with faunas of Antigua and the Panama Canal Zone. The fauna is of Indopacific type and grew on a gravel bottom in quiet water (Corallinacea-Lepidocyclina community). The temperature favoured true reefal growth. An abrupt change occurred at the boundary Early/Middle Miocene, possibly because of an interoceanic influx of cooler water. The development is mostly biostromic. More favourable conditions reappear in the Upper Pliocene. Pleistocene coral zonation resembles that of the Netherlands Antilles, but is less well outlined. Fifty percent of the fossil species listed occurs in Recent reefs and lagoons. |
| Late Pleistocene depositional and denudational history of Aruba, bonaire and Curaçao (Netherlands Antilles) | 1978 | Herweijer, J.P.; Focke, J.W. | 57(2) | A sequence of subaerial denudation benches, which are recognized as remnants of planation surfaces, has been found in the drainage basins of Aruba, Bonaire and Curaçao. The benches were formed during periods of relatively stable sea-level. This denudational sequence has been correlated with the late Pleistocene marine limestones of the islands. These limestone deposits represent eustatic sea-level maxima. The correlation led to a revised stratigraphy of the marine strata. At least ten units, each representing an individual sealevel event, have been recognized. One of the units (presently + 10 m above sea-level) is correlated with the 125,000 B.P. highstand. The rate of tectonic uplift is estimated to be in the order of 0.05 m/1000 year. |
| Notes on the Tertiary stratigraphy of Margarita Island | 1978 | Hunter, V.F. | 57(2) | Micropalaeontological evidence is presented for a further refinement of the Tertiary stratigraphy of Margarita Island, Venezuela. The writer supports Bermudez & Gamez (1966) and Butterlin (1970) in determining the uppermost beds of the Punta Mosquito Formation as no younger than the Truncorotaloides rohri zone of the Middle Eocene. Caudri's (1974) evidence for possible deposition of Upper Eocene sediments is challenged. Micropalaeontological studies and field observations indicate the La Guica Formation to be a middle clay member of the Mio-Pliocene Cubagua Formation. Rich planktonic foraminiferal faunas from this horizon are identified as representing the Late Miocene Neogloboquadrina dutertrei zone of Bo[i & Bermudez (1965). The Los Bagres limestone is interpreted as allochthonous blocks of Paleocene or Early Eocene age within the conglomeratic facies of the Lower Eocene Las Bermudez Formation. The time gap represented by the Miocene-Eocene unconformity on the island can be demonstrated to extend through Late Eocene to Late Miocene time. |
| Foraminiferal correlation of Tertiary mollusc horizons of the soutern Caribbean area | 1978 | Hunter, V.F. | 57(2) | Correlations of conspicuous Tertiary mollusc horizons described from the southern Caribbean area are attempted on associated micropalaeontological evidence. By this method the rich mollusk horizons characteristic of the Springvale Formation of Trinidad, the Punta Gavilán Formation of Venezuela, and the Tubará Formation of Colombia are considered time-correlatable at the Early Pliocene level. The Cantaure mollusc horizon of the Paraguaná Peninsula of northern Venezuela contains an Early Miocene (Burdigalian) microfauna and is correlatable with that of the basal part of the Castilletes Formation of the Guajira Peninsula of northern Colombia and the Quiroz horizon of the La Rosa Formation of the Maracaibo Basin. The 'Raetomya Shales' of the Jarillal Formation of western Venezuela correlate with similar macrofaunas found in the Caus Formation and other transitional facies units associated with the contact of the Middle Eocene Misoa and Pauji Formations of the Maracaibo Basin, and those of the Ceru Mainsji Formation of the island of Curaçao. These horizons can be clearly calibrated with the Truncorotaloides rohri and Orbulinoides beckmanni zones of Bolli's (1966) planktonic foraminiferal zonation. There is also micropalaeontological evidence to suggest that the Hannatoma horizon of western Venezuela can be associated with the final regressive depositional phase of the Middle Eocene throughout northwestern South America. |
| Tectonic movements during the oscillating development of the Cuban platform | 1978 | Iturralde-Vinent, M.A. | 57(2) | The geological development of Cuba has been of the platform type since the Late Eocene. A mosaic of blocks was formed, comprising five grabens, six horsts and four semigrabens, delimited by faults and flexures. The platform as a whole oscillated with a median period and amplitude. The blocks themselves oscillated with three superimposed waves: (1) oscillations with a period of the order of hundreds of millions of years and an amplitude of thousands of metres; (2) oscillations of a million to tens of millions of years, and amplitudes of hundreds to thousands of metres; and (3) oscillations of short periods of thousands of years and an amplitude of tens of metres. These movements are conditioned by a tensional regime and the external manifestations of processes in the subcrustal mantle. |
| Metasomatism in the Tertiary volcanics of the Wagwater Belt, Jamaica, W.I. | 1978 | Jackson, T.A.; Smith, T.E. | 57(2) | The Wagwater Belt represents part of a former inter-arc basin in which approximately 5,000 m of Tertiary sediments and volcanics accumulated. The volcanics are made up of minor amounts of submarine mafic flows and their sedimentary derivatives, and extensive silicic flows, volcanic breccia, conglomerates and tuffs. The mafic flows have been identified as basalts and spilites, and the silicics as dacites and quartz keratophyres. The stable-element geochemistry of the spilites is similar to that of the basalts. Ti, Zr and Y indicate that these mafic rocks were erupted in an intra-plate tectonic setting and are comparable to plateautype tholeiitic basalts. The levels of concentration of the stable elements in the quartz keratophyres are comparable to those of the dacites. The rare-earth elements of these silicic rocks confirm that they belong to the calc-alkaline series. Mineralogical, textural and geochemical data support the view that most of the basalts and dacites in the Wagwater Belt were metasomatized to spilites and quartz keratophyres respectively. |
| Reproduction and life cycle of Sorites orbiculus (Forskål), Foraminifer | 1978 | Kloos, D.; Gillavry, H.J.M. | 57(2) | A sample of megalospheric Sorites orbiculus from lagoon Awa di Oostpunt, Curaçao, contains a surprisingly large percentage of adults with brood in the reproduction chambers. Measurements of the initial chambers of a parent do not differ significantly from those of the offspring. This suggests a paratrimorphic life cycle. Two specimens contain undeveloped embryos consisting of protoconch only or of protoconch with incipient flexostyle. It is concluded that protoconch and flexostyle are separate chambers, and that brood formation proceeds with considerable but not perfect synchronism. These protoconchs have thin walls and are perfectly circular in outline; they will be somewhat deformed by the formation of the flexostyle around them after which the wall will be thickened. The question is raised whether Leutenegger's two plurinucleate specimens with micronuclei could not be diploid megalospheric schizont/gamonts in which case the haploid generation would be reduced to the micronuclei and gametes. The diploidy of such a parent can be tested if the gametes produced by it can fuse inter se into viable zygotes. |
| Unconformity between Cretaceous and Eocene rocks in Central-Western Puerto Rico: A concept rejected | 1978 | Krushensky, R.D. | 57(2) | A major unconformity between rocks of Late Cretaceous and Eocene age in central-western Puerto Rico was previously reported. Recent work suggests that the evidence cited is invalid: (1) because sediments which were interpreted as a basal conglomerate appear to be a fault breccia related (in all areas but one) to gravity sliding; (2) because more extensive mapping has shown that the lithologically distinct Anón Formation, known locally to contain fossils of early Tertiary age, interfingers conformably with formations which contain fossils of Late Cretaceous age. The evidence indicates that deposition in central-western Puerto Rico has been continuous from Late Cretaceous to at least Middle Eocene. |
| Pseudorbitoids from the Parguera Limestone, Puerto Rico, and from the Back Rio Grande Limestone, Jamaica, with remarks on the pseudorbitoidal evolutionary pattern | 1978 | Krijnen, J.P. | 57(2) | Pseudorbitoides curacaoensis and P. israelskyi are described from two localities near Parguera, SW Puerto Rico, and P. trechmanni trechmanni and P. ?rutteni rutteni from respectively the Back Rio Grande and Rio Grande (Blue Mountain inlier, Jamaica). The evolutionary pattern of the pseudorbitoids is discussed on the basis of the present material and of samples described previously from Curaçao and from western Jamaica. |
| Geology of the northern, central and south-eastern Blue Mountains, Jamaica, with a provisional compilation map of the entire inlier | 1978 | Krijnen, J.P.; Lee Chin, A.C. | 57(2) | An interpretation of successive geological events is proposed, based on lithological and palaeontological evidence encountered in the northern, central and south-eastern Blue Mountains, Jamaica. A provisional geological map of the entire inlier is given. An interpretation of a number of structural features includes some remarks regarding a plate tectonic model of the northern Caribbean plate margin. |
| Seismic risk and earthquake insurance in south and Central Amerika | 1978 | Kulhánek, O.; Båth, M. | 57(2) | A method is developed for the calculation of earthquake insurance coefficients, defined as annual premiums normalized by the value of the insured property, taking account of the extent of damage, time element and building type. The method is applied to the seismic histories of capital areas in South and Central America. |
| Active margin structures within the North slope of the Muertos trench | 1978 | Ladd, J.W.; Watkins, J.S. | 57(2) | Seismic reflection records from the north slope (landward slope) of the Muertos Trench south of Hispaniola reveal features similar to those seen on reflection records from Pacific active margins. Tectonically rotated sediment ponds characterize the slope; landward-dipping reflection horizons within the wedge of sediments underlying the slope suggest possible fault planes. Oceanic crust can be traced landward of the trench axis for tens of kilometers beneath the sediment wedge. Seismic refraction velocities are similar to velocity profiles found in Pacific inner trench slopes. The above similarities between the Muertos Trench inner slope and the inner slopes of Pacific trenches suggest similarities in tectonic origins. Although the Muertos Trench, unlike Pacific trenches, is not associated with a belt of active volcanism or a well-defined Benioff zone, models that explain the structure of Pacific trench inner slopes in terms of imbricate thrusting may also apply to the north slope of the Muertos Trench |
| Active margin structures within the North slope of the Muertos trench | 1978 | Ladd, J.W.; Watkins, J.S. | 57(2) | Large Enclosure |
| The central Falcon igneous suite, Venezuela: alkaline basaltic intrusions of oligocene-Miocene age | 1978 | Muessig, K.W. | 57(2) | Basaltic igneous rocks crop out in a 50 km belt within Oligocene sedimentary rocks in the central Falcon Basin of northwestern Venezuela. Outcrop patterns, structural orientations, chilled margins, baked contacts, sedimentary inclusions, igneous breccias and uniformly alkaline compositions suggest these bodies are shallow intrusives and extrusives. Potassium-Argon determinations on a sill yield a 22.9 ± 0.9 Ma age which is 5 Ma younger than paleontologic ages of surrounding sedimentary rocks. A span of igneous activity from 28 to 23 Ma is inferred from stratigraphic constraints. Locally, normal NNW-SSE growth faults are present in Oligocene units. Features of similar regional trend and evidence of growth faulting offshore imply a tensional tectonic regime during Oligocene-Miocene time. The tensional regime, silica undersaturated, alkaline nature of the igneous rocks, and rapid basin subsidence rates suggest a pull-apart basin model for the Falcon Basin – Bonaire Trough area. This resulted from commencement of Caribbean - South American transform motion over a wide zone of offset transform faults. |
| Caribbean dresge haul compilation: Summary and implications | 1978 | Nagle, F.; Erlich, R.N.; Canovi, C.J. | 57(2) | The locations of 400 dredge hauls from the Caribbean have been compiled from published and unpublished sources. The following information on them is listed: location, depth, rock types recovered and age, and a literature reference or institution to contact for further information. The rocks recovered provide information about the Caribbean crust along the northern border of the Caribbean from Central America to Guadeloupe; and under the Beata and Aves Ridges. They also provide evidence for extensive vertical motion (up to several thousand meters) in the Neogene throughout the northern and eastern Caribbean. Many of the dredge hauls already collected have been examined in a selective fashion only. We could significantly increase our knowledge of the Caribbean crust and Neotectonics through more systematic team investigations. There are no dredge hauls from the southern and southwestern Caribbean margins. Suggestions for five localities are made. |
| Retrograde cataclastic gneiss north of Motagua fault zone, East Central Guatemala | 1978 | Newcomb, W.E. | 57(2) | An areally extensive quartz-monzonitic gneiss, characterized by a variety of cataclastic textures, has been mapped as the structurally lowest member of the Chuacus Group in east-central Guatemala. This apparent orthogneiss is separated from overlying Chuacus Group metasediments (phyllite and marble) by a south-dipping, low-angle thrust. The appearances of the gneiss is variable, ranging in texture from ultramylonite to blastomylonite gneiss. Retrograde mineral assemblages characteristic of the upper-greenschist facies (quartz-microclineoligoclase-biotite-chlorite) developed in response to cataclastic deformation adjacent to the Motagua fault zone, and do not represent regional metamorphism in the classic sense. The areal extent of the gneiss suggests that it may be a fundamental basement unit north of the Motagua fault zone in Guatemala's Cordillera Central. It has not been recognized south of the fault zone. |
| Hydrocarbon potentian of the Trinidad area - 1977 | 1978 | Persad, K.M. | 57(2) | It is now recognized that deltaic and associated sands, together with porous marine limestones, form the vast majority of the reservoirs in the major accumulations of hydrocarbons throughout the world. The source of the hydrocarbons is now thought to be kerogen which is generated from the organic content of principally marine shales which are formed in or near the continental shelves. The Trinidad area contains several sedimentary sub-basins, most of which consist largely of deltaic and associated sediments. These sediments, like most of the ancient deltas of the world, contain major reserves of oil and gas. Other less important reserves should occur in sporadic (time-wise) porous Iimestones. The total proven and probable reserves of the Trinidad area are around 5 billion barrels of oil, of which 1.6 billion barrels have already been produced, and over 47 trillion cubic feet of gas |
| Morphology and sediments of the shelf around Martinique Island | 1978 | Pons, J.C.; Julius, C.; Klingebiel, A.; Pujos, M. | 57(2) | The oceanic cruise called 'GUYANTE' was aimed at the shelf of Martinique Island. It has been possible to re-establish and to state precisely the structural dissymmetry which opposes the Caribbean slope to the Atlantic. The four large sedimentary areas developed here are also different because of structural features. |
| Rb-Sr evidence for episodic intrusion of the late Cretaceous tonalitic batholith of Aruba, Netherlands Antilles | 1978 | Priem, H.N.A.; Beets, D.J.; Boelrijk, N.A.I.M.; Hebeda, E.H.; Verdurmen, E.A.T.; Verschure, R.H. | 57(2) | Rb-Sr investigations revealed an age of 85.1 ± 0.5 Ma (Coniacian-Santonian) for the northwestern part of the tonalitic batholith on Aruba, and an age of 70.4 ± 2.0 Ma (Maastrichtian) for the remaining part. The dates are interpreted in terms of an episodic intrusion of the batholith. It is discussed that the two episodes of tonalitic magmatism belong to two different tectonic-magmatic phases in the geologic evolution of the Caribbean region. |
| Possible use of tropical peats as fuel: an example from Jamaica | 1978 | Robinson, E. | 57(2) | Preliminary examinations of two Holocene coastal peat deposits in Jamaica have indicated more than 150 million wet tons of peat, exceeding 10 m depth in places. Most of the peat is of the sedge marsh type, bordered on the seaward side by mangrove peats. It overlies clays, resting in turn on faulted Tertiary limestone blocks. Although ash contents are comparatively high (usually more than 10%, dry weight basis), peats of this type could be attractive as sources of energy in developing countries, such as Jamaica, which have no indigenous supplies of fossil fuel. Deposits similar to those in Jamaica are probably widespread, but few studies appear to have been carried out on peats for fuel in tropical areas. |
| Relationship between plate tectonics and geothermal heat flows in Sucre Central, Venezuela | 1978 | Rodriguez, S.E. | 57(2) | The geothermic zone of Sucre Central, which extends from Cariaco to El Pilar, lies in a strongly tectonized area, in which the El Pilar fault is an important feature. These faults of supracontinental character form one of the southern boundaries of the Caribbean Plate. As a result of this tectonic setting, the northern part of the country (and specially Sucre Central) shows much evidence of geothermal activity, abnormal heat flows, constant seismic activity, and a continuous rejuvenation of the local structures. The presence in Sucre Central of Tertiary dacites, which affect strongly tectonized metamorphic sequences, and which are situated in a zone with enrichment of Pb and Zn, indicates the presence of deep-seated heat chambers which are associated with the deep plate tectonics of northern South America. |
| Baritization in the Villa de Cura complex, state of Aragua, northern Venezuela | 1978 | Rodriguez, S.E. | 57(2) | Along the northern coast of Venezuela a metallogenic zone has been discovered, which is characterized by masses of barite in metamorphic volcanics and sediments of the Villa de Cura Group. This zone is situated at 25 km SE of the city of Villa de Cura, in the industrial centre of the country. The minerals occur in lenses and masses within a sequence of strongly tectonized phyllites and meta-andesites of the El Chino Formation. Most probably these deposits are associated with the numerous occurrences of metals along the Villa de Cura complex in the states of Guárico and Aragua. |
| Stratigraphy of the Chuacús group on the south side of the Sierra de las Minas range, Guatemala | 1978 | Roper, P.J. | 57(2) | The Chuacús Group is a complex of metamorphic rocks in an east-west belt along the Central America Cordillera between the Chixoy-Philochic fault zone to the north and the Motagua fault zone to the south. Newcomb (1975) proposed a stratigraphy for the middle and eastern portions of the Sierra de las Minas range. This investigation attempts to extend that stratigraphy to the western end of the range. To achieve this, some of the formations proposed by Newcomb must be modified, and at least one new formation is introduced. Newcomb's San Augustín Formation is the lowest unit of the Chuacús Group and has not been recognized in the western end of the Sierra de las Minas range. In El Progreso quadrangle several major modifications are needed for the overlying Jones Formation. The mafic composition of this unit may in part be due to metasomatism during Mesozoic to Tertiary serpentinite emplacement. A hornblende gneiss occurs in the lower part of this sequence. |
| Geochemistry and age of the Tobago igneous rocks | 1978 | Rowley, K.C.; Roobol, J.M. | 57(2) | The island of Tobago, situated at the SE corner of the Caribbean plate, is made up of groups of volcanic, plutonic and metamorphic rocks. Thc volcanics are mainly calc-alkaline island-arc rocks which range from basalts to rhyotlacites. They have been affected by metamorphism of the lower zeolite zone facies. The plutonic rocks, which intrude the volcanics range from high-Al gabbros to biotite granodiorites, are much fresher. The metamorphics arc of the greenschist facies and are overlain by the volcanics. All these rocks were hitherto believed to be of Cretaceous age, but new K-Ar dates from the freshest available samples, including a mineral determination, show a Lower Cretaceous age for the pluton. It therefore indlicates that the overlying volcanics are at least of Lower Cretaceous age. Upper Cretaceous ages obtained for the volcanics appear to be artificially young due to the effects of metasomitic alterations on these rocks. It also appears that the Tobago metamorphic rocks may be of a Jurassic age, similar to that of equivalent rocks in neighbouring Trinidad. |
| Plate tectonics of the Northeastern Caribbean sea region | 1978 | Schell, B.A.; Tarr, A.C. | 57(2) | Previous geologic literature and the results of the Puerto Rico Seismic Network are synthesized into a plate tectonic model of the northeastern Caribbean Sea region. The Puerto Rico Seismic Network has detected earthquakes which form a well defined zone of seismicity dipping 45 to 50 degrees from the Puerto Rico Trench to a depth of about 150 km under Puerto Rico. This inclined zone of seismicity is interpreted to represent a lithospheric plate. However, focal mechanism solutions have shown that plate motion along the Puerto Rico Trench is directed in an east-to-west sense similar to that expected in a transform fault zone. A plate tectonic model is developed which shows that a portion of the North American plate, originally subducted under the northern Lesser Antilles, underrides the northern edge of the Caribbean plate. When this underriding plate reaches the Hispaniola subduction zone it sinks deeper taking on a plow-shaped configuration. The Puerto Rico type of 'transform' trench is not unique to the Caribbean, but also occurs in the western Aleutian Trench, Puysegur Trench, northern Sunda Trench, and possibly the Scotia Sea region. |
| Uranium-series ages of Pleistocene marine deposits on the Islands of Curaçao and La Blanquilla, Caribbean Sea | 1978 | Schubert, C.; Szabo, B.J. | 57(2) | Sequences of 3, resp. 5 Pleistocene limestone terraces crop out on La Blanquilla and Curaçao. All represent Pleistocene reefs which have been uplifted. Diagenesis of the corals shows a sequence of increasing alteration with elevation (or age) of the terraces. Samples of corals in growth position were collected for dating of the Lower and Middle Terraces of Curaçao, and of the Limestone Terraces 1 and 2 of La Blanquilla. 230Th age determinations indicate that the Lower Terrace of Curaçao (10 m above sea level) and the Limestone Terrace 1 at La Blanquilla (7-10 m above sea level) formed contemporaneously at about 130,000 years ago, and are time-equivalent to Terrace III of Barbados and to the main limestone terrace of La Orchila island, all deposited during the last interglacial. No equivalents of Barbados I and II Terraces were found; they are probably below sea level, indicating that the Netherlands Leeward Islands and La Blanquilla were less uplifted than Barbados. The age of the higher terraces of Curaçao and La Blanquilla is uncertain because of diagenetic changes, but may be estimated as about 325,000 years for the Limestone Terrace 2 of La Blanquilla and about 570,000 years for the Middle Terrace of Curaçao. |
| Geochemistry of a meromictic brine lake | 1978 | Sonnenfeld, P.; Hudec, P.P. | 57(2) | A meromictic lake on the island of Gran Roque, Venezuela, is both thermally and chemically stratified. The density stratification is largely chlorine-controlled, but concentration of major cations is more variable. A statistical evaluation of chemical analyses serves to indicate that differences in concentration between a central depression and a seaward one suggest seepage of seawater into the latter. Additional cations are supplied by drainage, albeit small, from nearby hills composed of basic intrusives. |
| On two species of Titanosarcolites (Rudistids) from St. James' Parish, NW Jamaica | 1978 | Wal, R.J.F. van der | 57(2) | Specimens of Titanosarcolites from St. James' Parish, NW Jamaica, are described. It is shown that in Titanosarcolites new tubes are formed by a process of subdivision of older tubes. The presence of the ligament in the right valve of Titanosarcolites giganteus is established. The internal structures of Titanosarcolites alatus (Chubb, 1967,1971) are described; the species may be intermediate between Antillocaprina and Titanosarcolites giganteus. The genus Titanosarcolites was already known from the Barettia Limestone of Sunderland. |
| Structural geology of the southeastern blue mountains, Jamaica | 1978 | Wadge, G.; Draper, G. | 57(2) | The structural geology of over 100 km of Cretaceous rocks in the southeastern Blue Mountains is described for the first time. Full stratigraphic details have yet to be resolved, but it is apparent that the structural evolution was controlled by different responses to deformation of the two dominant rock types. These are a thick massive unit of basaltic volcanics and a thinly bedded sandstone/siltstone/ mudstone sequence, separated by thin limestones. Synsedimentary deformation is recognized at the boundary of well-bedded argillaceous and thick arenaceous units. Tectonic folds have a dominant NW-SE trend, but variations exist within a mosaic of structural domains. Three fault trends are recognized with modes at 040°, 100° and 155°. |
| Longshore transport of mud by waves: Northeastern coast of South America | 1978 | Wells, J.T.; Coleman, J.M. | 57(2) | Time series measurements of waves and wave/mud interactions along the Surinam coast indicate that waves may play a greater role than previously thought in the suspension and transport of fine-grained sediment on the northeastern coast of South America. Accumulations of fluid mud or slingmud that occur on western flanks of migrating mudbanks affect incoming swell by changing their form from sinusoidal to solitary-like and by preventing wave breaking except for occasional spilling. As solitary like waves propagate over the soft-mud bottom, fluid mud is suspended, resulting in surface suspensate concentrations that exceed 3.103 mg/I. The presence of solitary waves, high suspended-sediment concentrations, and a relatively uniform angle of wave approach throughout the year may lead to extraordinarily high sediment transport rates. If waves are assumed to have a net drift as given by solitary wave theory, then, in taking angle of wave approach and actual measured concentration of sediment in suspension, enough sediment can be transported by waves alone to explain the propagation of mudbanks by fluidmud transport. On the basis of reasonable wave and sediment conditions, it is estimated that up to 70.106 m3 of mud can be transported alongshore each year. |
| Ammonites from the Curaçao lava formation, Curaçao, Caribbean | 1978 | Wiedmann, J. | 57(2) | Ammonites have been discovered for the first time in some thin pelagic intercalations in the Curaçao Lava Formation. Since this is the oldest rock unit which occurs on the island, its dating is of extreme interest. The rather poorly preserved and partly baked ammonites can be attributed to the genera Beudanticeras, Cleoniceras (Grycia), Gastroplites, ?Dipoloceras, Hysteroceras and ?Pervinquieria. The Curaçao Lava Formation is, thus, of upper Middle Albian age. This is consistent with the available equivalent K/Ar-data of 118 ± 10 and126 ± 12 M.A.b.p. (Santamaría & Schubert, 1974), since submarine extruded basalts dated by this method generally give ages somewhat too high. Paleobiogeographic relationships point to the Western Interior and Pacific faunal provinces of North America, and, to a minor degree, to the European Tethys. Moreover, this is exactly the time when Northern and Southern Atlantic became connected for the first time (WIEDMANN & NEUGEBAUER, 1978). |
| Preliminary report on the occurrence of Tertiary gold-bearing gravels in Surinam | 1978 | Wong, T.E.; Lissa, R.V. van | 57(2) | As a result of the recently commenced exploration programme of the Geological and Mining Service of Surinam, gold was discovered in gravels of the Tertiary Coesewijne Formation near Jorka Kreek and Loksie Hatti. These gravels form the base of isolated plateaus along the southern margin of the Coesewijne Formation in the vicinity of major rivers. The gravels were deposited in braided river and alluvial fan systems under semi-arid conditions. It is assumed that at Jorka Kreek both gold and rounded clasts were derived from the Precambrian Rosebel Formation, whereas at Loksie Hatti the gold is derived from local quartz veins. Further evaluation of these placers, now in progress, should reveal whether or not they are economically exploitable. |
| Some notes on the geomorphology of the shelf of St. Eustatius (Netherlands Antilles) | 1978 | Zonneveld, J.I.S. | 57(2) | During the year 1972 H.Ms. "Luymes" of the Royal Netherlands Navy made a hydrographical survey in a part of the N. E. Caribbean. The resulting echograms and maps allowed a more detailed impression of the topography of the sea bottom in this area to be made. In this paper the relief of the shelf of St. Eustatius, with its submarine terraces and ridges, is discussed. |
| Supplement to the volume of abstracts 8th Caribean Conference Willemstad | 1978 | 57(2) | ||
| Foraminifera and parallel evolution - How ofrwhy? | 1978 | Gillavry, H.J.M. | 57(3) | Directional changes are distinguished from yes-or-no changes. The latter lack the quality of direction; in the evolution of larger foraminifera they manifest themselves at first at a late ontogenetic stage as individual monstrosities, but lead, by the deuterogenetic mode, to new genera or families. Further evolution within a lineage is characterized by the directional gradualism of neptonic reduction. Various hypotheses why this complex evolution could have been of selective advantage are reviewed; complicating factors are discussed; there is still a large unexplained residue. Gradualism is considered to be rare and to be associated with faunas of low diversity, consisting of related but genetically isolated subunits which react to extra-group factors as one population, but which may evolve through intra-group competition; hence the frequent coexistence of related lineages. Still unexplained is the following of the same evolutionary pathway by forms of no near relationship. This may be due to severe structural limitation of possibilities; one pathway is followed by forms derived from planispiral ancestors, another by forms derived from trochoid ancestors. Three appendices give details on the phylomorphogenesis of Cycloclypeus, notes on lndonesian larger foraminifera, and notes on the stratigraphy of South Sumatra. |
| Rocks, life and time - an international guide through the stratigraphical labyrinth | 1978 | Brouwer, A. | 57(3) | |
| The interglacial of Frechen I/Rheinland - A section of the Tiglian A-type | 1978 | Urban, B. | 57(3) | Palynological investigations of earliest Pleistocene deposits at Frechen, some ten kilometers west of Cologne permit the dating of these sediments in terms of the Dutch biostratigraphic scale. Of special interest is a newly discovered interglacial period, termed the 'Frechen I Interglacial', which indicates a more complicated development of vegetation during the early Tiglian than was hitherto thought. |
| The interglacial of Frechen I/Rheinland - A section of the Tiglian A-type | 1978 | Urban, B. | 57(3) | Large Enclosure |
| Composite grains in heavy-mineral concentrates and their significance in the differentiation of surface deposits at the confluence of the Maas (Meuse) and Roer (Rur) rivers. | 1978 | Bisdom, E.B.A.; Gerlofsma, A.; Poelman, J.N.B.; Riezebos, P.A. | 57(3) | The varying content of composite grains in heavy-mineral concentrates was used for the differentiation of surface sediments in a geomorphologically and pedologically complicate landscape at the confluence of the Maas (Meuse) and the Roer (Rur). West of the Maas valley, these deposits contain quantities of minor importance (<10%), while to the east surface sediments with percentages ranging from 4 to 59 occur. In this latter area a decrease in an easterly direction is suggested from the data. The characteristic high composite content is also found in sediments from the present flood plain of the Maas as well as in an old fluvial deposit of this river (Caberg terrace). It is suggested that the flood plain of the Maas is the source of the surface deposits being found to the east, and that similar deposits west of the Maas valley come from another source area. Finally the possible use of composites as provenance indicators is discussed briefly. |
| Composite grains in Maas (Meuse) sediments: a survey and a discussion of their opaque components | 1978 | Riezebos, P.A.; Bisdom, E.B.A.; Boersma, O. | 57(3) | The opaque mineralogy of composite grains in acid-treated heavy-mineral concentrates from sediments of the river Maas (Meuse) was studied in reflected light and by SEM-EDXRA analysis. Secondary rutile, secondary ilmenite and hematite constitute the subtranslucent to opaque matter in these composites, which principally represent actual rock fragments. This suggests that the sediments investigated contain products of rather freshly disintegrated rocks. The opaque components enable two important groups of rock fragments to be distinguished: a major group characterized by secondary rutile, secondary ilmenite and their intergrowths; and a minor group with exclusively hematite. |
| Microfossil biostratigraphy and stage-stratotypes of the Cretaceous | 1978 | Sissingh, W. | 57(3) | Correlation of the most recent Cretaceous zonations based on calcareous nannoplankton, planktonic foraminifera and calpionellids allows more precise determination of the relative position of some Cretaceous stage-stratotypes in the standard chronostratigraphical scale. In particular, those of the Santonian, Campanian and Maastrichtian stratotypes seem to be very limited in time-span. It is possible to overcome these limitations and to some extent also the problems concerning their recognition and traceability by a pragmatic extension of the type-sections and by the introduction of auxiliary hypostratotypes in the type areas. However, it is concluded that designation of one or more independent reference sections for Upper Cretaceous stages is a preferable alternative which should receive more attention. In this way also a more useful section could be proposed for the Cenomanian, Turonian and Coniacian stages. |
| Isotopic evidence for a Middle to Late Pliocene age of the cordierite granite on Ambon, Indonesia | 1978 | Priem, H.N.A.; Andriessen, P.A.M.; Boelrijk, N.A.I.M.; Hebeda, E.H.; Hutchison, C.S.; Verdurmen, E.A.T.; Verschure, R.H. | 57(3) | Rb-Sr dating of the pair whole-rock/biotite from the cordierite-bearing granite on Ambon (Moluccas, E. Indonesia) yields an age of 3.3 ± 0. 1 Ma with initial 87Sr/86Sr = 0.7221. The K-Ar age of the biotite is 3.8 ± 0.2 Ma (ages based upon the constants recommended by Steiger & Jäger, 1977). A Middle to Late Pliocene age can thus be assigned to the granitic magmatism |
| Precambrian palaeosols at the base of the Roraima formation in Surinam | 1978 | Kroonenberg, S.B. | 57(3) | A red transition zone with granitic fragments between the Roraima sandstones and the underlying granite at Kappelsavanna, Tafelberg and Emma Range is argued to represent a pre-Roraima palaeosol. The mineralogical and micromorphological characteristics of the palaeosol indicate an origin in an arid or semi-arid climate. |
| Late Cenozoic history of Eastern Crete and implications for the geology and geodynamics of the southern Aegean area | 1978 | Fortuin, A.R. | 57(3) | An interpretation is given of the structural setting and the sedimentary history of the Middle Miocene - Quaternary deposits in eastern Crete (Ierapetra region). The present tectonic structure, characterized by normal faults in W-E and NE-SW directions, is dominated by a central NE-SW graben, which seems to mark a dislocation in the curvature of the Aegean Arc. In Late Serravallian – Early Tortonian times deposition drastically changed from terrestrial to open marine, with turbidites, filling in a graben that extended over the southern half of the region. The sources of sediment supply then shifted from east to west and slices of sediments (in part of pre-Neogene age) slid from the uplifted blocks in the north to the central parts of the region, where a submarine valley was formed. A seismic reflection profile south of Crete may show analogous gravity sliding in the Neogene. From the Late Tortonian till the Pliocene carbonate sedimentation took place. A gradual shallowing followed, which ended with deposition of the well known Messinian facies. Unstable tectonic conditions controlled the sedimentation until the Early Pliocene, when quiet open marine sedimentation returned. In the early Late Pliocene tectonic uplift started to separate Crete as a horst from the surrounding seas. Although strong, this general uplift was periodically interrupted. |
| Bioerosion by polydora (Polychaeta, sedentaria, vermes) off Helgoland, Germany | 1978 | Pers, J.N.C. van der | 57(3) | The boring activities of Polydora BOSC. 1802, are an important agent in bioerosion. Trace fossils attributed to this worm are very common. From data collected on Recent representatives of Polydora ciliata JOHNSTON 1838, it is evident that the boring mechanism of this worm is to be interpreted as a combination of mechanical and chemical processes. Dodecaceria, another genus of polychaete worms, is considered to be able to bore chemically in lime-rich substrata. |
| #REF! | 1978 | 57(3) | ||
| Preface - Key-notes of the MEGS-II | 1978 | Loon, A.J. van | 57(4) | |
| Opening adress | 1978 | Tieleman, W.H.J. | 57(4) | |
| Magnesium-salt exploration in the northeastern Netherlands | 1978 | Coelewij, P.A.J.; Haug, G.M.W.; Kuijk, H. van | 57(4) | Magnesium-bearing salts occur in the Zechstein Basin in the northeastern Netherlands at a depth of 1500 to 2500 m. Exploration has resulted in the discovery of significant amounts of this salt which will be exploited by solution mining for the production of refractory grade magnesiumoxide. Of the four main evaporite cycles, Zechstein III (the ore-bearing cycle) is fully developed and contains the magnesium salts carnallite (MgCl2.KCI.6H2O), bischofite (MgCl2.6H2O) and kieserite (MgSO4.H2O). The salt sequence has been affected by halokinesis, resulting in salt domes and other structures. The magnesium-bearing layers were thickened towards the top of the structures, thus forming prime targets for exploration. Exploration techniques comprise seismic surveys and rotary drilling. Conventional seismic methods adequately define depth and structural configuration, whilst high-resolution seismic wavelet processing is used for the identification of the magnesium-salt layers on the seismic section and determination of thickness. Seismic sections are converted into acoustic impedance sections which are calibrated from acoustic impedance logs. These in turn are derived from velocity and density measurements in bore holes. The mineral composition, ore grade, and thickness can be accurately determined by petrophysical well-logging: in particular formation density, gamma ray, and sonic logs. Results are calibrated by chemical analysis of drillcores. |
| Exploration for gas in the Irish area | 1978 | Colter, V.S. | 57(4) | Exploration for gas between the Isle of Man and the mainland has confirmed the presence of a Permo-Triassic basin, with sediment thicknesses in excess of 3,000 m. The section can be correlated with the onshore succession and consists of the following: 'Keuper' Marl + Saliferous series (eroded), 'Keuper' Waterstones, 'Keuper' Sandstone, St. Bees Sandstone Manchester Marl and equivalent halite Collyhurst Sandstone and equivalent shales. Drilling and seismic work have shown abrupt thickness changes across some faults, which may show reversals of throw at different times. Sonic velocities in shales at the base of the 'Keuper' Marl suggest depths of burial of more than 4000 m, pointing to the possibility that a thick younger Mesozoic section was once present. Diagenesis of the sandstones includes calcite and quartz cementation and the development of platy illite. Gas has been found by Hydrocarbons Great Britain Limited, a subsidiary of British Gas Corporation, in sandstones of the 'Keuper' Waterstones, 'Keuper' sandstone and top part of the St. Bees Sandstone. |
| Exploration for gas in the Irish area | 1978 | Colter, V.S. | 57(4) | Large Enclosure |
| On brown coal resources in the Lower Rhine embayment (West Germany) | 1978 | Gliese, J. | 57(4) | The Tertiary brown coal resources in the Lower Rhine Embayment amount to 55,000 million tons. The open-cast mining operations under way or at the planning stage ensure an annual production of 115-120 million tons over a period of the next 75 years. The brown coal mainly serves to generate electrical energy. At present about 150-250 m of overburden have to be removed to get at the brown coal. In future this may increase up to 500 m. The maximum thickness of the brown coal is about 100 m. The brown coal beds provide data about: - a basin-shaped subsidence of the embayment during the Miocene. No major block faulting occurred during the main period of peat accumulation. - peat compaction. 100 m of brown coal (under an overburden of 500 m) might correspond to 250 m of peat. - a Pre-Rhine river system during the main period of peat accumulation. - the perennial effectiveness of some Palaeozoic structural elements. |
| Geoscientific maps of the environment as an essential tool in planning | 1978 | Lüttig, G. | 57(4) | Without support by the geosciences it will not be possible to develop regulations for the future of mankind which provide good chances for survival. This is due to the fact that the environmental potential is being steadily restricted, as is obvious from the growing scarcity of mineral resources, energy sources, groundwater, and farming land. Thus, the author has pointed out in several publications that part of our geoscientific research capability needs to be reoriented towards the future. This includes a transformation and translation of our geocartographic material into maps that can be easily understood by the planner. The Geoscientific Map of the Natural Environment Potential (GMNEP) meets the requirements mentioned above. The individual maps are presented here and explained in detail. At the same time, the reader is informed about the plans agreed upon by the IUGS Commission on the International Geological Map. All colleagues interested in this important task are invited to cooperate with the subcommission in charge, the Subcommission on Maps of Environmental Geology (SC-MEG). |
| Évolution paléogéographique et structurale du basin de paris, de Précambrien a l'actuel, en relation avec les régions avoisinantes | 1978 | Pomerol, C. | 57(4) | The Paris Basin was born in a late Proterozoic palaeorift, obliterated in the Brioverian by detritic sediments and in the Carboniferous by granitic batholiths. After the Variscan orogenesis and the Permo-Triassic peneplanation, the Paris Basin became, during the Jurassic and Cretaceous, the intersection of three seas where the influences of the Mesogean, the North Sea, and the Protoatlantic met. Subsidence persisted in the Palaeogene where the mobility of the palaeogeography is a structural detector of the Pyrenean and Alpine tectonic phases. At the same time, a north-south undulation developed,200 meters in amplitude and 200 kilometers in wave length, which displaced the pole of negative epirogenesis from the region of Compiegne to south of Orleans. After the stabilization at the end of the Miocene and the strong positive Plio-Pleistocene epirogenesis, some neotectonic indications are the first signs of a Holocene reactivation of the subsidence in the center of the basin. |
| On the Polish Trough | 1978 | Pożaryski, W.; Brochwicz-Lewiński, W. | 57(4) | The Polish trough represents the main part of a huge synsedimentary structure stretching from the Carpathians to the North Sea, mainly in a zone of weakness at the contact of the East-European Precambrian and Palaeozoic platforms. It was active from the Early Permian to the Early Cretaceous as a graben, and in the Late Cretaceous as a downwarp. A SW corner of the Baltic Shield acted as the threshold responsible for the division of the structure into Danish and Polish parts and limiting the zone of inversion. A connection with the Carpathian geosyncline is traced. |
| Turbidite dispersal in a Miocene Deep-sea plain: The Marnoso-Arenacea of the Northern Apennines | 1978 | Ricci Lucchi, F. | 57(4) | Deposition in a typical 'flysch trough' (Marnoso-arenacea or Inner Basin of 'the Periadriatic Apenninès) was interpreted in terms of the depositional system (slope-deep-sea fan-deep-sea plain)' The basin fill is wedge-shaped and shows vertical and lateral grading; in its proximal portion, it forms a progradational turbidite 'suite' with upward increase in grain size, sand content and bed thickness indicating a transition from deep-sea plain via outer-fan to inner-fan environment. The outcropping part of the plain is 175 km long. Detailed studies of lateral variations of single beds show that:(1) sandy lobes from outer fans prograded into the plain over a distance of 25-50 km; (2) 30-40% of basin plain turbidites are more than 40 cm thick, and 15 out of 100 can be correlated axially over a distance of more than 125 km; (3) these single, huge turbidites (called Contessa-like beds) were introduced from different, lateral and axial sources but their dominant dispersal was axial. |
| Upper Cenozoic of the Southern North Sea Basin: Palaeoclimatic and palaeogeographic evolution | 1978 | Zagwijn, W.H.; Doppert, J.W.C. | 57(4) | An outline is presented of Neogene and Quaternary biozonation and lithostratigraphy of the southern North Sea Basin. The maps showing the thickness distribution of the Upper Miocene deposits and the depth contours of the base of the Quaternary depict the basin evolution. The pattern of basin development in the Quaternary differs distinctly from that in Neogene times; resemblance with the pattern in Mesozoic times is ascribed to reactivated downwarping in areas of much earlier, namely Mesozoic, basin development. Considerably greater amounts of sediments were accumulated per time unit in the southern North Sea Basin during the Quaternary as compared to the Neogene. |
| North-Western Europe: Tectonics and basin development | 1978 | Ziegler, P.A. | 57(4) | This paper discusses the geologic evolution of North-Western Europe from Late Silurian to Cainozoic times on the base of 13 palaeogeographic and 6 palaeotectonic maps. Furthermore a pre-Permian and a pre-Tertiary subcrop map as well as an isopach map of Upper Permian to Cainozoic sediments is presented. This synthesis is based to a large extent on geophysical and subsurface data acquired by the oil industry during its exploration efforts in the various on-shore and offshore sedimentary basins of North-Western Europe. A more comprehensive summary is given at the end of the paper. |
| North-Western Europe: Tectonics and basin development | 1978 | Ziegler, P.A. | 57(4) | Large Enclosure 1 |
| North-Western Europe: Tectonics and basin development | 1978 | Ziegler, P.A. | 57(4) | Large Enclosure 2 |
| North-Western Europe: Tectonics and basin development | 1978 | Ziegler, P.A. | 57(4) | Large Enclosure 3 |
| North-Western Europe: Tectonics and basin development | 1978 | Ziegler, P.A. | 57(4) | Large Enclosure 4 |
| The tectonic framework of Central and Western Europe | 1978 | Zwart, H.J.; Dornsiepen, U.F. | 57(4) | The complexity of the structure of Central and Western Europe is for a large part due to the rapid succession of four important orogenic events each belonging to a major orogenic period: the Cadomian, Caledonian, Variscan and Alpine orogenies. The four successive mountain chains have partly occupied the same space, resulting in an intricate pattern of rocks formed or deformed during each orogeny. Due to this multiple orogenesis the presence of older Precambrian rocks is difficult to demonstrate. Low grade Proterozoic sediments and volcanics are known from the Armorican and Bohemian Massifs and from the Iberian peninsula. Crystalline basement rocks predating these supracrustals have been reported only from the Armorican and Bohemian Massifs. Other signs of Precambrian events are zircon ages of more than 2000 Ma. The Cadomian orogeny has been demonstrated in England, the Armorican Massif, the Bohemian Massif, the Pyrenees and in the Iberian peninsula either by the unconformity of Cambrian on folded basement, or by geochronological methods. The folding is accompanied by regional metamorphism of varying grade up to granulite facies. Postorogenic Cadomian granitic magmatism occurs in the Armorican and Bohemian Massifs. The Caledonian orogeny occurs besides the main belt in Scandinavia, Scotland, Ireland and Wales, in the Ardennes and a zone from northern Germany towards Poland and Rumania. South of this zone no Caledonian folding based on geological evidence as unconformities can be ascertained, although numerous radiometric dates on metamorphic and igneous rocks indicate a thermal event during the period corresponding to the Caledonian orogeny. The Variscan orogeny is much better known although many problems still remain unsolved. Folding, metamorphism and granitic activity started in the Devonian, but the most widespread and intense folding, low P/T type metamorphism and granitic intrusion is of Late Carboniferous age. The pre-Cadomian basement and the Caledonian event are discussed in some detail. A pre-Mesozoic drift reconstruction shows the relationships of the Cadomian, Caledonian and Variscan belt on either side of the Atlantic Ocean. A large Y-shaped pattern of orogenic belts appears, where intermittent folding, metamorphism and granite intrusion has taken place at least from the end of the Precambrian to Permian times. Central and Western Europe lying on the intersection of these belts has been a high heatflow region during that time, for which a mantle origin is proposed. Spreading and contracting movements at different places and different times are thought to be responsible for the orogenies. However, the presence of oceans other than the Proto-Atlantic or Iapetus is as yet to be proved. It is suggested that they were of minor size or that spreading did not go beyond the rift stage. |
| #REF! | 1978 | 57(4) | ||
| Discontinuously rising Late Cainozoic eustatic reference to Sundaland, Southeast Asia | 1979 | Batchelor, B.C. | 58(1) | A Late Cainozoic global eustatic sea-level rise, of greater magnitude and opposite trend to previous schemes, is indicated, with important consequences on climates, sedimentation, pedogenesis, oceanographic features and biological distributions, especially for Sundaland and other equatorial regions. An abrupt sealevel depression during the late Middle Miocene to around 1000 m below present, is correlated with an emergent Sundaland continent. Increased land/sea area ratio resulted in more seasonal semi-arid climates facilitating savanna expansion and laterite clevelopment. A major Miocene discontinuity in sundaland is paralleled worldwide by contemporaneous unconformities or facies changes on continental terraces, reduced oceanic sedimentation and truncation and pedogenesis on Pacific reefs. Sea levels have since risen discontinuously at around 10 cm/103 a with maximum transgression in the late Quaternary. Sea-level curves are constructed assuming that eustasy is mainly due to superposition of glacio-eustatic fluctuations on a linear tectono-eustatic trend, adjusted to fit Sundaland data. Before the Middle Pleistocene Sundaland coastlines changed very little. once since then did seas rise above the shelf-break causing major coastline shifts, dramatically affecting sedimentation climates' and Extinctions of savanna-adapted mammals resulted from their geographical isolation and unsuitability of increasingly homogeneous rain-forest habitats. Intervening glacials temporarily restored former continental environments. |
| The Holocene development of the young coastal plain of Suriname | 1979 | Roeleveld, W.; Loon, A.J. van | 58(1) | A new series of 19 radiocarbon dates from the Holocene picture Young coastal plain in Suriname fits into the of a rapid sea-level rise in this area until about 6000 B.P. From 6000 B.P. onward the sealevel remained essentially at its present position. Indications for a higher position of the sea-level at about 6500 B.P. are inconclusive. From about 6500 B.P. onward the marine influence in the interior part of the young coastal plain diminished, but some marine oscillations were registered. The available evidence is too limited to permit pertinent conclusions about the regional occurence of marine fluctuations. F.om an analysis of the younger Holocene development in the Hertentits area it is concluded that a new subdivision has to be established for understanding of these marine oscillations. |
| Evidence and problems of interglacial marine deposits in Tasmania | 1979 | Geer, G. van de; Colhoun, E.A.; Bowden, A. | 58(1) | The paper outlines the distribution, height and origin of extensive pre-Holocene marine deposits from various localities in Tasmania. The marine deposits occur up to 20-30 m above present sea-level. The stratigraphic relationships of the deposits are discussed in relation to associated glacial, freshwater, Aeolian and slope deposits. 14C dating of some of these deposits strongly suggests that most of the marine deposits are of Last Interglacial age. other Australian studies suggest that the maximum sea level attained in southeastern Australia during the Last Interglacial was 5-10m. The higher marine levels in Tasmania, inferred to be of Last Interglacial age, suggest that differential tectonic and hydroisostatic deformation may have occurred during the late Quaternary. |
| The Stokersdobbe: Geology and palynology of a deep pingo remnant in Friesland (the Netherlands) | 1979 | Paris, F.P.; Cleveringa, P.; Gans, W. de | 58(1) | This paper describes the results of geological and palynological investigations of a pingo remnant in Friesland. The remnant is situated in a smal, former tributary valley of the Boorne river. As contrasted with other pingo remnants in The Netherlands, the Stokersdobbe is at its base filled with sand and gravel overlaid by a loam deposit of Bølling age. The decay of the pingo could be dated between 13,000 (Bølling) and 18,000 radiocarbon years B.P. The period of growth of the pingo is correlated with the Brandenburger Phase and the Upper Pleniglacial level of ice wedge casts. An attempt is made to correlate the Friesland and Rammelbeek phases at the transition of Weichselian to Holocene with local changes in the hydrological situation. |
| The Stokersdobbe: Geology and palynology of a deep pingo remnant in Friesland (the Netherlands) | 1979 | Paris, F.P.; Cleveringa, P.; Gans, W. de | 58(1) | Large Enclosure 1 |
| The Stokersdobbe: Geology and palynology of a deep pingo remnant in Friesland (the Netherlands) | 1979 | Paris, F.P.; Cleveringa, P.; Gans, W. de | 58(1) | Large Enclosure 2 |
| The Stokersdobbe: Geology and palynology of a deep pingo remnant in Friesland (the Netherlands) | 1979 | Paris, F.P.; Cleveringa, P.; Gans, W. de | 58(1) | Large Enclosure 3 |
| An early carboniferous river-dominated regressive facies in southern Ireland | 1979 | Maccarthy, I.A.J. | 58(1) | The Early Carboniferous Kinsale Formation contains a distinctive sand dominant unit in western County Waterford known as the Crows Point Member. This is built up by epsilon cross-stratified grey sandstones with minor thin claystone and heterolithic intercalations. Six rhythmically diminishing lithofacies, organised-into four sequential facies associations, are distinguished. Facies analysis shows it to be the record of high-energy pulses of fluvial sediment influx via distributary channels from the ESE. These were modelled by fluctuations in river stage; an overall allocyclic mechanism may have been responsible for the interpreted progressive shallowing of the distributaries. through time, accompanied by an increased tidal influence in response to a north-easterly regional transgression. The member provides additional support for a positive source area lying off the southeastern margin of the Munster Basin during the Early carboniferous. This together with its relationship to adjacent facies, indicates a NE-SW axial drainage pattern within-this basin at this time. |
| On the classification of tectonic units in the Nevado-Filabride complex of the Northern Sierra de los Filabres, Betic Cordilleras, SE Spain. | 1979 | Linthout, K.; Vissers, R.L.M. | 58(1) | A layer of calcareous cataclasites, formerly considered to be interstratified in permo-Mesozoic rocks in the lowest Nevado-Filabride tectonic unit - the Nevado-Lubrín unit - locally contains fragments of pre-Permian black schist. It is argued that the cataclasite represents a fault-rock formed in association with an important overthrust. This leads to a revision of the lithostratigraphy of the Nevado-Lubrín unit, with the cataclasitc forming the uppermost rock-body. The cataclasite is tectonically overlain by the Secano unit (composed of pre-Permian black schist and quartzite) and - where this unit is absent - by the Umbria de las Cantèras unit (consisting of a sequence of marble and calcschist). This latter thrust-mass was hitherto misinterpreted as the stratigraphic upper part of the Nevado-Lubrín unit. which led to a seemingly enigmatic position of the Secano-unit within the Nevado-Filabride rock-pile. The present interpretation solves this 'Secano-problem', as thrusting of the Umbria de las Canteras unit over the Secano unit is recognized. |
| Essay on the coalification and hydrocarbon potential of the northwest European palaeozoic | 1979 | Bartenstein, H. | 58(1) | The palaeogeographic knowledge of the European Palaeozoic (Lower Permian, Carboniferous and Devonian) is closely connected with the search for hydrocarbon deposits, because the biggest deposits of natural gas have been found so far in the Rotliegendes (Lower Permian). An extension of these reservoirs into geologically older formations, especially into Upper Carboniferous and uppermost Devonian is expected and systematic exploration investigations are being proposed. An important tool for this is the research on coalification, which has already resulted internationally in much success and is now used intensively in the European palaeozoic. this regional-geologic survey points out the current state of knowledge in the palaeogeographic as well as geochemical and coal-petrographic studies. |
| An interpretation model of semi-circular Bouguer anomalies found over the peripheral belt of the Ordenes complex (NW Spain) | 1979 | Keasberry, E.J. | 58(1) | A gravity survey of the peripheral belt of the Ordenes comprex in Galicia (NW Spain) has been combined with a little used, although known, interpretation method. From the results of the survey and geological evidence, support was found for the hypothesis that the peripheral belt could be subdivided into separate units of shallow buried, but deep-reaching bodies of high-grade ultramafic material, which appear to have their-origin in diapiric movements of upper-mantle material into a crystalline lower crust of continental type. The depth of the western body, projected underneath the high-grade metamorphic complex of Santiago de Compostela, is computed at a depth of 780 metres, while the bodies of the complexes of Sobrado-Teijeiro and Mellid are computed at a depth of 550 metres and 150 metres, respectively. The semi-circular outline of all three Bouguer anomalies suggested diapiric structures comparative to salt-domes, which have been interpreted using a three-dimensional method. |
| Upraised Caribbean sea floor below acoustic reflector B" at the southern peninsula of Haiti | 1979 | Maurasse, F.; Husler, J.; Georges, G.; Schmitt, R.; Damond, P. | 58(1) | The Dumisseau Formation, is described-as a complex of intercalated mafic and pelagic rocks of Cretaceous age exposed at the southern Peninsula of Haiti. This formation includes a lower member of possibly Early cretaceous age, and the St. Dominique Member of Late cretaceous age. Their thickness exceeds 1,5 km, and the igneous rocks show geochemical affinities for abyssal and island arc tholeiites, which accumulated in a deep eupelagic environment. The formation is here equated to an ophiolite complex described earlier by Miyashiro, and to crustal layers (2A and 2B) described by Houtz & Ewing. Correlations between the Dumisseau Formation and geophysical data concerning the crustal structure and composition of both the Caribbean crust and oceanic crust provide corroborative evidence to suggest that the analog of crustal materials below acoustic reflector B". The Dumisseau Formation thus represents a portion of the Caribbean crust uplifted through block faulting tectonism much similar to the adjacent Beata Ridge. |
| Trace fossils from the Nanka Formation, Southeastern Nigeria | 1979 | Nwajide, C.S.; Hoque, M. | 58(1) | The Eocene Nanka Formation of the Anambra Basin of southeastern Nigeria is a thick, abundantly cross-stratified, flaser and lenticular bedded unfossiliferous unit; it is composed dominantly of medium to coarse grained quartz sand with shale and claystone at several horizons. Various kinds of burrows, confined to the sand beds, are the only evidence of past organic activity within the otherwise unfossiliferous formation. These burrows have been identified to be of the ichnogenera Ophiomorpha and Skolithos. The former occurs as both isolated and randomly oriented tubes and as dichotomously branching burrows possessing tuberculate ornamentation. The latter is seen as short and narrow vertical to steeply inclined straight to curvilinear burrows. A third unidentified burrrow type occurs as horizontally oriented, unlined tubes probably constructed by sediment ingesting worms. Trace fossils have proved to be reliable environmental indicators. Both Ophiomorpha and Skolithos have been known to occur mainly in a marginal marine environment. Their presence in the Nanka Formation is, therefore, indicative of the deposition of Nanka sands in an intertidal to shallow sublittoral zone. This interpretation, based on trace fossil study, finds support on other evidences independently obtained from the lithostratigraphic and sedimentologic features of the formation. It appears then that the presence of trace fossils in otherwise unfossilliferous strata could provide a reliable basis for environmental diagnosis. |
| Exchange of publications | 1979 | 58(1) | ||
| #REF! | 1979 | 58(1) | ||
| Preface FIXISM, MOBILISM OR RELATIVISM: VAN BEMMELEN'S SEARCH FOR HARMONY | 1979 | Linden, W.J.M. van der | 58(2) | |
| Crustal convergence or diverge in the Banda Sea region of Indonesia | 1979 | Bemmelen, R.W. van | 58(2) | |
| Van Bemmelen's contributions to the growth of geotectonics and the present state of earth-science research in Indonesia | 1979 | Katili, J.A.; Hartono, H.M.S. | 58(2) | The undation theory launched more than half a century ago in Indonesia by Van Bemmelen had a tremendous impact on the development of earth sciences. An attempt is made to trace Van Bemmelen's scientific activities prior to the birth of the undation theory. First envisaged as a fixistic concept, the theory was later developed into a mobilistic one which accommodates continental drift and sea-floor spreading hypothesis. However, instead of accepting the theory of extensive rigid plates it utilised a rheological approach in dealing with island arcs. A geotectonic evolution of Indonesia is presented in this paper. Recent marine geophysical findings which appear to contradict the results of prior geological investigations are also discussed. Problems and present status of geoscientific research in Indonesia are also discussed such as active collision processes, mechanism of ophiolite emplacement, geometry of subducted lithosphere etc. |
| Island arcs and the origin of folded ranges | 1979 | Brunn, J.H.; Burollet, P.F. | 58(2) | It is attempted to reconsider the problem of orogeny through a review of three arcuated systems: Tyrrhenian, Aegean, and Ceram. The Tyrrhenian Sea is inherited from a sheaf of Alpine ridges and furrows located between the Corso-Sardinian block to the west and the African-Adriatic platform to the south and east. The abyssal plain represents the tearing apart of these zones following the gradual curving of the Calabro-Lucanian arc. The Aegean Arc is part of the Hellenic-Tauric ranges. Its folding and thrusting is not due to the northward movement of a'Tethysian plate', but to an active, outward thrust over its foreland. The Aegean bulge results from the westward movement of Anatolia, being barred to the west by the eastward thrusting Calabro-Sicilian Arc. The frontal trenches rising towards the south to the so-called Mediterranean Ridge should be compared to the mollassic furrows that surround all arcuated folded ranges. The Banda Sea may correspond to a longitudinal extension similar to that of the Tyrrhenian Sea: it would be due to a compressional effect related to the north-westward movement of Australia. Transcurrent faults play an important role with two main directions, both being left-lateral: NNW or NW and E-W. |
| Active or passive subduction at the Calabrian arc | 1979 | Ritsema, A.R. | 58(2) | The comprehensive list of earthquakes with focal depth > 50 km in the subduction zone of the Calabrian Arc is presented. The seismic zone dips towards the NW and strikes from SW-NE in the upper part to S-N at the deeper levels down to 490 km. The main activity occurs between depths of 220 and 350 km; relative minima are found above and below. The focal mechanisms of the earthquakes show a common feature in the position of one of the possible fault planes, and are indicative of a common stress pattern for the whole zone below 200 km. Subduction in the mantle is of the passive kind and seems to be determined by gravity only. This is not yet clear for the horizontal movements which in the first place generated the zone of subduction. |
| The geological evolution of NE Corsica | 1979 | Zacher, W. | 58(2) | A geologically mapped and investigated transect through NE Corsica is subdivided into its main tectonic units. The zone of the 'schistes lustrés' s.s. is overlain by two ophiolite units: the upper one shows no or weak metamorphism and has an eastern origin; it has overthrusted the metamorphic lower ophiolite unit and the 'schistes lustrés' zone s.s. in a westerly direction. Blueschist metamorphism is confined to the overridden 'schistes lustrés' zone, the lower ophiolite unit and small parts of the Hercynian basement. |
| Sedimentological-stratigraphic considerations regarding the Triassic 'reefs' of the dolomites (Italy) | 1979 | Leonardi, P. | 58(2) | Some authors maintain that a good part of the carbonate assemblages of the Dolomites do not correspond to true 'reefs' in an ecological sense. In contrast, they suggest that these rocks belong to masses of lime mud that are part of the indented edge of a broad, shallow-water platform, the formation of which was only scarcely influenced by corals and other reef-building organisms. This hypothesis is probably correct for several carbonate bodies (i.e. Marmolada, Latemar) in which these organisms are either absent or rare. But this is not the case in other bodies where corals are abundant and are often found in growth position. It is clear that, in some cases at least, the carbonate bodies of the Dolomites correspond to true'reefs', even in an ecological sense. This is true, above all, for the dolomitic reefs of post-Ladinian age (San Cassian and perhaps lower Raiblian). It has not been demonstrated that volcanic activity in the Dolomites ceased before the San Cassian period, since a lava bank in the most elevated part of Mount Sciliar (Schlern) is included in the Rosetta dolomite, which can be referred precisely to the lower Carnian (San Cassian). According to the author the Pachycardia Formation is synchronous with the upper part of the St. Cassian Formation. |
| Nappes of the Alta Romagna | 1979 | Haaf, E. ten; Wamel, W.A. van | 58(2) | The structure of the Romagna Apennines is less simple than has been supposed. Between the Ligurid allochthon and the true autochthon of the Romagna there are several superposed thrust sheets. each with a distinctive stratigraphy. Their emplacement in the Romagnan flysch basin was a submarine and synsedimentary process, driven by gravity. |
| Reconstructions of the Western Mediterranean area for the Mesozoic and Tertiary timespan | 1979 | Vandenberg, J. | 58(2) | Based on seafloor data and palaeomagnetic results, reconstructions are given for the Western Mediterranean area, for the period of 165 Myr. to 10 Myr. ago. Reconstructions for 13 episodes provide a framework that can be used to unravel the history of Alpine orogeny. Of crucial importance in these reconstructions is the Adriatic continental block, the movements of which determined to a large extent the location of Alpine foldbelts in the Western Mediterranean. |
| Paleomagnetic data from the Western Mediterranean: a review | 1979 | Vandenberg, J. | 58(2) | A review is given of palaeomagnetic data that have become available during the last years. The accent of this review is on the palaeomagnetic results from the Italian peninsula, since most of the new data came from there. It is shown that the data from the Italian peninsula are consistent and define the movements of the Adriatic block. The Adriatic block moved together with Africa during post-Hercynian times until the Early Tertiary. In a post-Early Tertiary movement phase this block was detached from the African continent. The Tertiary rotation pole that describes this detachment is derived according to a new method for fitting apparent polar wander curves. |
| The implications of some paleomagnetic data from Iran for its structural history | 1979 | Wensink, H. | 58(2) | For palaeomagnetic studies oriented samples were collected from several formations of different ages from various parts of lran. Palaeomagnetic data are presented from four formations with volcanic rocks from the Central Alborz. An outline of the geology of Iran is given, and particularly that of the Alborz Mountains. The palaeomagnetic results from rocks of Late Palaeozoic age -Late Devonian to Early Carboniferous and Middle Permian- indicate that lran, probably with West Afghanistan attached, was located at the edge of Gondwanaland not very far from Arabia's east coast. Palaeomagnetic data of Early Jurassic and Cretaceous age point to a position of Iran that practically coincides with its present location. Iran could have performed its main translation and rotation during the important tectonic phase in Middle and Late Triassic times. The Iranian block is probably bounded in the SW by the Zagros Thrust, and in the N by the Kopet Dagh-Caspian Fault. |
| On the geodynamics of the Andes orogen | 1979 | Zeil, W. | 58(2) | The Precambrian-Palaeozoic basement of the Andes consists of material from the continental crust. This basement experienced multiple and intensive orogenies and metamorphoses. The Andine tectal orogen, however, has only been slightly deformed by compression since Triassic time. The high mountain range seen at present originates from massive block-faulting since Tertiary time. Deep canyon-like depressions, filled in up to a height of 10,000 to 15,000 m, were formed concomitantly within the orogen. This geodynamic development cannot reasonably be explained by a simple model of subduction. |
| The volcano-tectonic history of the Maninjau caldera, Western Sumatra, Indonesia | 1979 | Purbo-Hadiwidjoyo, M.M.; Sjachrudin, M.L.; Suparka, S. | 58(2) | Recent investigations help elucidate the volcano-tectonic history of Mt. Maninjau, Sumatra. Three stages may be distinguished: the pre-volcanic edifice stage, the pre-caldera stage and the caldera-formation stage. During the pre-caldera stage, fissures opened in this part of Sumatra as a result of stresses, the largest presumably being vertical. In the next stage basaltic to andesitic magma ascended to the surface, building up a number of strato-volcanoes, one of which formed the N-S oriented Maninjau compound volcanic complex. The caldera-formation stage was preceded by the ejection of some 220-250 km3 of pumiceous tuff. This was subsequently followed by the collapse of the 1op part of the volcano, and the radial failure of the western flank. Two eruptions of acid magma have taken place, the first yielding an unwelded and the second a welded tuff. the latter presumably ejected from the southernmost crater. Since then, obvious volcanic activity has ceased at Mt. Maninjau. |
| Statistics applied to facts and concepts in geoscience | 1979 | Agterberg, F.P. | 58(2) | This is a brief review of alternative methods of problem-solving in geoscience. Special attention is given to applications of the theory of probability, mathematical statistics, computers and artificial intelligence. It is desirable to maintain a clear-cut distinction between reliable facts which can be stored in data banks and concepts which should be incorporated in the specifications of statistical models designed for specific purposes. Two illustrative examples deal with the probability of occurrence of mineral deposits. This probability is conditional upon the occurrences of geological features systematically quantified and processed for large regions. |
| Flood basalt volcanism on the moon and mars | 1979 | Beneš, K. | 58(2) | Comparative studies of the surfaces of the terrestrial planets reveal that processes of flood basalt volcanism were common to all of them, irrespective of their stages of evolution either primitive, intermediate or progressive. On the Moon manifestations of flood basalt volcanism have been recognized in basins (maria); on the planet Mars both in basins (planitiae) and in higher topographic (continental) levels. The mare-epoch of the less developed planets led to significant changes in their relief and in the crustal structure. Examples of volcanic flows from the lunar and martian surface are introduced. Some crustal uplifts on Mars can be interpreted in terms of Van Bemmelen's undations. |
| The relationship between tectonic earthquakes and volcanic eruptions with particular reference to Santorini (Aegan Sea) and Indonesia | 1979 | Hédervári, P. | 58(2) | In certain cases tectonic earthquakes can trigger volcanic eruptions; or outbreaks are followed by tectonic shocks within some hundred kilometres of the volcano and within some weeks or months after the beginning of the eruption. For the gradation of the cases which were analysed a space-time parameter, denoted by q, was introduced. At first altogether 47 cases are summarized in Tables I, II and III, respectively. After them almost all known eruptions of the Santorini volcano are treated. Also many eruptions of a number of Indonesian volcanoes are discussed. Finally some reasonable models are presented with the help of which one can give a rather simple geophysical explanation for the relationship in the case of both phreatic-phreatomagmatic and true magmatic eruptions. The paper is dedicated in honour of Mrs. Luus van Bemmelen and Professor Dr. Dr. h. c. Reinout Willem van Bemmelen. |
| Volcanism as a tracer in geodynamic processes | 1979 | Rittmann, A.; Villari, L. | 58(2) | The use of volcanological studies in the reconstruction of geodynamic processes is discussed, pointing out that a valuable contribution only follows from a critical evaluation of all available data. Any simplistic generalization that is based on a too fragmentary knowledge of the topic under discussion, leads to completely erroneous conclusions and suggests models that hardly fit a more general geological picture. Volcanological data actually contribute to a better knowledge, if the research that aims to understand the mechanism of magma origin and ascent strictly avoids any kind of constraining dogmatic premises. |
| Precambrian crustal evolution in the light of plate tectonics and the undation theory. | 1979 | Kröner, A. | 58(2) | The difference between Phanerozoic orogens and Precambrian mobile belts and granite/greenstone terrains suggests non-uniformitarian crustal evolution, probably related to changes in the asthenospheric convection system and lithospheric thickness as the earth cooled. Sea-floor spreading and modern-type plate tectonics did not operate during the Archaean and may only have begun in the upper Proterozoic as a result of increased rigidity of the crust following lithospheric thickening. Archaean and Proterozoic belts developed over primitive spreading centres where the heated lower crust was rendered ductile and reacted by laminar flow, thus leading to upper crustal grabens and deep ensialic basins. Only in rare cases did crustal rupture lead to small ocean basins. Many high-grade mobile belts were not produced during distinct orogenic periods, but represent sections of the lower continental crust which were brought to the surface through internal rotation of rigid blocks in large continents and/or through large-scale over- and underthrusting along straightening zones. Some features of the Precambrian evolution are in agreement with the undation theory, but the overall pattern seems to favour a systematic development characterized by increased rigidity and mobility of the earth's crust with time. Modern plate tectonics is the logical consequence of this evolution. |
| Spiral geotectonics | 1979 | Caire, A. | 58(2) | Large fans and sheafs of transcurrent faults, cutting off series of trenches or rifts in echelon fashion, develop in a similar orderly way in both continental and oceanic settings. They graft themselves on to the large bundles and the long faults paths of transcurrent tectogenic zones. In between these'macro,-groves' or 'geocoulisses' lithospheric blocks or plates show a tendency to differential spiral movement and creep. Arcs and orogenic involutions develop along these macro slip zones, caused by the major transcurrent tectogenic zones. The curls and wrap-around phenomena, within the involuted, inwardly curling structures, resemble spirals, whirlpools and vortices. |
| Recumbent folds and boudinage structures formed by subglacial shear: an example of gravity tectonics | 1979 | Berthelsen, A. | 58(2) | A contorted drift sequence involving displaced pre-Quaternary and Quaternary sediments is described from the coastal cliffs of southern and eastern Møn, SE Denmark. The principles of proglacial and subglacial deformations in a permafrozen sedimentary environment are outlined, and an analysis of the structures is presented. Large-scale thrusting and stacking of permafrozen thrust slices are referred to proglacial deformations. Superimposed simple-shear deformation, recorded by large recumbent folds with boudinage structures in their stoss-side flanks and with shortened to ultimately stretched leeward flanks, is ascribed to a subglacial origin. It is stressed that the driving force for these natural small-scale models of orogenic tectonics was nothing but the force of gravity. |
| Perturbed mantle: a unifying characteristic of plate boundaries | 1979 | Shaffer, F.R. | 58(2) | Ocean-spreading ridge-, basin-and-range-, graben-, young-alpine-, island-arc-, and intra-continental- geosynclinal types of terrestrial crust are indicative of 'unstable' lithosphere. Whether undergoing tensional or compressional tectogenesis, these areas have certain geological and geophysical characteristics in common. Observations and measurements include anomalously high heat flow (>1.8 HFU), shallow intermediate P-wave velocities (7.2-7.8 km/s), low Q (i.e. a high attenuation factor), attenuated S-wave velocities (<4.5 km/s), and high electrical conductivity. Most 'unstable' areas are also marked by shallow seismicity and outpourings of basaltic volcanics which testify to shallow mantle sources. The data suggest welts of raised mantle as a common denominator under all types of 'unstable' crust. Therefore, seismicity, which presently defines the plate boundaries in plate tectonic theory is only a conspicuous effect of a deeper and more fundamental global phenomenon. I propose that the concept of plate boundaries be redefined on the basis of the wider range of geological and geophysical characteristics indicative of sublithospheric perturbations. |
| Vertical crustal movements and the rifting of continents | 1979 | Fairbridge, R.W. | 58(2) | Verticalism and mobilistic philosophies in geotectonics are seen as integrally joined in modern plate tectonic theory. This theme is illustrated under two topics: lineaments and rifting (with examples from Gondwanaland); and cratonic planation-surface chronology (with an example from Western Australia). |
| Overthrusts in the Central Bergamasc Alps, Italy | 1979 | Jong, K.A. de | 58(2) | Earlier tectonic interpretations indicated the presence of northward as well as southward overthrusts in the Central Bergamasc Alps. In the present study it was found that all overthrusts are southward. The extent of the overthrust sheets is much greater than previously believed. All Late Triassic and younger formations south of the Central Bergamasc Alps, previously thought to be autochthonous, have been moved a maximum of 9 km to the south. Overthrusting in the Bergamasc Alps was the result of gravity tectonics. |
| Overthrusts in the Central Bergamasc Alps, Italy | 1979 | Jong, K.A. de | 58(2) | Large Enclosure |
| Obituary H.M.E. Schürmann (1891-1979) | 1979 | Dozy, J.J. | 58(3) | |
| The groundwater thermal regime in the Flevo polders and Gelderse Vallei (Southern IJsselmeer area, the Netherlands) | 1979 | Jong, S.J. de; Geirnaert, W. | 58(3) | The relationship between regional groundwater-flow systems and groundwater temperatures has been studied. Temperature/depth profiles were recorded in 70 observation wells. Low temperature gradients were observed in the infiltration areas. In these areas the observed temperature/depth profiles and those calculated with the theory of one-dimensional steady-state heat flow, showed significant correlation. Temperature/depth profiles in discharge areas showed lower shallow vertical temperature gradients than expected. This could be explained with a simple heat-budget equation of the regional groundwater-flow systems. In the area studied recharge of groundwater occurs at a lower temperature than discharge. Part of the geothermal conductive heat flow is used for warming up the relatively cold recharge water. This results in relatively low shallow temperature gradients in discharge areas. |
| Structural and sedimentological characteristics of a Weichselian kame terrace at Sønderby Klint, Funen, Denmark | 1979 | Schwan, J.; Loon, A.J. van | 58(3) | At a coastal cliff near Sønderby, SW Funen, the internal structure of a Weichselian kame terrace is well exposed. It exhibits, though in a rather deformed state, a sequence of lodgement till overlain by stratified glaciofluvial beds plus a capping of flow till. An elongated ridge, interpreted as an intraglacial crevasse-infilling, is perched right on top of the kame terrace, whereas laterally the terrace body passes into a small sandur. The kame terrace and the overlying kame ridge are interpreted to be the result of two subsequent oscillations of the Belt glacierization stage. The effect of static load diapirism is demonstrated and the presence of slump structures in a seemingly anomalous spatial attitude is explained. By combining geomorphological, sedimentological and tectonic data, the depositional and deformational history of the kame terrace and associated landforms is reconstructed. |
| Bauxitic and other duricrusts in Suriname: a review | 1979 | Aleva, G.J.J. | 58(3) | The bauxite deposits and ferritic duricrusts of Suriname are arranged in four groups, based on their geology and a number of other parameters. In an appendix five examples are described in sufficient detail to illustrate the essential mutual differences and similarities. The four groups of deposits are related to the geomorphological history of Suriname, from which a genetic history for the bauxite and other duricrusts evolves. It also becomes clear that, although saprolitic weathering occurred four or five times during Tertiary and Quaternary history, in Suriname only the Late Eocene-Oligocene weathering period was of sufficient intensity to produce accumulation zones and duricrusts that could withstand later erosion, denudation and planation activities. Several of these old duricrusts are now being mined for bauxite. |
| A Pleistocene cyclothem in the Rokel estuary (Sierra Leone, West Africa) | 1979 | Strasser-King, V.E.H. | 58(3) | Pleistocene sediments overlie the area around the Rokel estuary of Sierra Leone. These are part of a series of Tertiary and Quaternary sediments forming the Bullom Group. Borehole samples of the Pleistocene sediments reveal a sequence of interbedded sands and clays with horizons of lignite. Repetition of the sequence is observed and has led to the establishment of a cyclothem. It is concluded that the cyclothem results from sea-level changes in the area during the Pleistocene. |
| Effects of environmental parameters on metal dispersion patterns in stream sediments from the lead-zinc belt, Benue Trough, Nigeria: using factor analysis | 1979 | Olade, M.A.; Kraats, A.H. van de; Ukpong, E.E. | 58(3) | Pb, Cu, Zn, Mn, Fe, pH and organic matter (OM) data on 350 reconnaissance stream sediments obtained from the lead-zinc belt of Nigeria's Benue Trough around Abakaliki are examined by R-mode factor analysis, with the objective of isolating the significant factors accounting for the sample composition as derived from mineralization and environment. The orthogonal varimax solution yields a three-factor model that accounts for 72% of total data variance. Factor 1, an OM-Pb-Cu factor shows the influence of organic matter on Pb and Cu dispersion in the stream sediments. Factor 2, a Zn-Fe factor shows the chelating effect of iron oxides on Zn in an oxidizing environment. Factor 3, a pH-Mn factor is explained as depicting the effect of pH on Mn precipitation in areas with calcareous shale horizons. The results have aided in isolating effects of surficial processes on metal dispersion within a complex tropical environment. Thus in the search for polymetallic deposits in tropical terrains, the presence of organic matter and iron oxides are factors detrimental to the exploration for Pb and Zn respectively. The pH is of no importance for these two elements although it affects Mn precipitation in localized environments. |
| Holocene deposits of the Northern North Sea: evidence for dynamic control of their mineral and chemical compostition | 1979 | Johnson, T.C.; Elkins, S.R. | 58(3) | Tidal currents and waves have caused some reworking and redistribution of Holocene sediments in the northern North Sea, with preferential deposition of fines in topographic depressions. This has led to a patchy distribution of sediments in terms of their textural, mineralogical and chemical composition. Nevertheless discernable relationships are found to exist between mean grain size and composition of the sediments. The relative abundance of biogenic components (primarily benthic Foraminifera) in the sand-size fraction of the sediments increases as mean grain size decreases, thus biogenic components are relatively more abundant in bathymetric lows. Coarse-grained sediments rich in detrital quartz show higher values of Si/Al than do fine-grained sediments. Smectite is concentrated in the finest-grained sediments, whereas illite is relatively more abundant in coarser deposits. Thus clay mineral segregation processes previously reported to occur near river mouths also occur in an open shelf environment. Fine-grained, smectite-rich sediments show correspondingly higher values of Fe/Al and lower values of K/Al compared to the coarser deposits enriched in illite. |
| K-Ar and Rb-Sr dating in the Cretaceous island-arc succession of Bonaire, Netherlands Antilles | 1979 | Priem, H.N.A.; Andriessen, P.A.M.; Beets, D.J.; Boelrijk, N.A.I.M.; Hebeda, E.H.; Verdurmen, E.A.T.; Verschure, R.H. | 58(3) | K-Ar and Rb-Sr analyses were made of suites of samples from different units in the island-arc succession of the Washikemba Formation (from late Albian through Turonian/Coniacian) on western Bonaire. Whole-rock K-Ar determinations yield ages of 78 ± 2 Ma (Campanian) and 61 ± 4 Ma (Palaeocene). Both ages are younger than the time span of the magmatism and they are interpreted as reflecting two separate events of low-grade metamorphism. No conclusive ages can be calculated from the Rb-Sr data, but they seem to agree with the corresponding K-Ar ages. The initials 87Sr/86Sr ratios of two volcanic units are about 0.7039 and 0.7050, respectively, within the common range of the andesitic-dacitic associations of oceanic island arcs. Hornblendes from a tuffaceous layer indicate an age of 88 ± 2 Ma, in accordance with the biostratigraphic position (Turonian/Coniacian). |
| Preliminary report on the distribution of the Lower Oligocene in the Netherlands | 1979 | Verbeek, J.W. | 58(3) | Evidence is given for a much wider distribution of Early Oligocene sediments in The Netherlands than hitherto known. |
| Herbs as july temperature indicators for parts of the Pleniglacial and Late-Glacial in the Netherlands | 1979 | Kolstrup, E. | 58(3) | From the present July temperature demands of plant species also found as fossils in Weichselian Pleniglacial and Late-Glacial deposits in and near The Netherlands a reconstruction of the former minimum mean July temperatures is attempted and compared to a previous record. Analysis of a section near Epe suggests that there may have been a warmer interval around 14.000 years B.P. and the name of 'Epe Interstadial' is provisionally proposed for this interval in The Netherlands. |
| Chronology of the perimarine fluviatile depositional phases at Molenaarsgraaf | 1979 | Woude, J.D. van der | 58(3) | |
| #REF! | 1979 | 58(3) | ||
| Preface PROCEEDINGS OF THE SYMPOSIUM ON ENGINEERING-GEOLOGICAL ASPECTS OF DELTAIC AREAS (RENESSE, 1979) | 1979 | Nieuwenhuis, J.D. | 58(4) | |
| Hydrology of various delta types | 1979 | Volker, A. | 58(4) | The hydrology of deltaic regions is characterized by the interaction of fluviatile and marine changes in water level, by the small gradients that may cause extensive inundations, and by the influx of saline sea water into fresh surface- and groundwater. Deltas possess a large development potential, both for agricultural and industrial purposes, provided water management and flood control is adequate. The measures taken may profoundly change the natural hydraulic environment. Several large deltas, in particular in Asia, still are in a primitive stage of hydrologic development, although they belong to the most productive and densely populated regions of the world. Hydrological water management depends on the characteristics of the river basin (variable discharge, speed of flooding) and of the ocean (astronomical tides and storm surges). Agrohydrologically, the climate in a delta region is of prime importance. Examples are provided from deltas in the temperate (Rhine), arid (Nile) and humid tropical (Ganges, Irrawaddy and Mekong) climatic zones. |
| Contstruction problems in deltaic areas: roads, airport runways and shallow foundations | 1979 | Tomlinson, M.J. | 58(4) | The wide variety of soil types present in deltaic deposits, the occurrence of weak compressible soils extending to considerable depths, and the unstable topography of the deltaic terrain can give rise to difficult problems in the design and construction of roadworks, airports, and the shallow foundations of buildings and engineering structures. This paper describes some of the topographic features and geotechnical characteristics of deltas, as they affect the siting, design, and construction of highways, airports and buildings. Examples are given of construction projects in each category. |
| Some considerations with regard to the bearing capacity of foundation piles | 1979 | Weele, A.F. van | 58(4) | A practical approach is made to analyse the stresses and deformations in the ground before, during and after installation of foundation piles of various types. This exercise leads to the following conclusions: (1) Displacement type of piles improve the stress state in the surrounding soil during installation, while non-displacement type of piles will have an adverse effect. (2) A foundation on many small diameter piles will show less deformation than an alternative foundation on a small number of large-diametre piles. When an equal deformation is aimed at, the factor of safety to be applied to the large-diametre piles, should be substantially larger. (3) Driven piles improve the stress-state in the soil around their lower ends most, but increasing pile penetration during installation deteriorate this good result progressively. (4) There seems to be room for increasing the stress [eve[ around the pile section in the bearing stratum after pile installation. Such an approach would enable pile-installation techniques, which are more friendly to the pile and its environment than the techniques applied nowadays. (5) Theories for the prediction of pile capacity do not take into consideration, in a sufficient manner, the way piles are installed. (6) Pile-installation techniques do not exploit the possibilities to improve pile capacities. (7) Researchers approach the problem of pile capacities as if this is a matter of arithmetics without studying in detail what really happens with the pile and the ground. (8) The predetermination of pile capacities will require a lot more attention in the future. Using our knowledge about the geology of the underground, about the installation techniques to be applied and about the pile-shape and the pile-material needs more attention than hitherto. |
| Tunnels and excavations | 1979 | Oud, H.J.C. | 58(4) | Most tunnels are formed by tubes at the place where there are large traffic intersections of waterways and/or roads. Tubes are constructed at the deepest location and basin structures consisting of a floor and walls are constructed on each side. In these the road is returned to the normal level, which is either at or above ground level. Reinforced concrete is used as the building material. After completion, the road is beneath the groundwater level over practically the entire length of the works. The construction of the tube and the basin ensure that no groundwater is withdrawn from the surroundings. This is in contrast to the end phase, during the implementation of which the groundwater conditions in the tunnel surroundings are indeed affected. The cheapest building method is practically always obtained by carrying out the work in an open excavation. It is generally advisable for the civil engineer to be aware that although he may know the geological composition of his building land, he is not always in a position to complete specific projects on the basis of his own knowledge and experience. The assistance of a geologist having specific civil engineering knowledge is frequently very important so that he can help to assess a project and the steps required for its implementation. |
| In situ soil-investigation methods for soil mechanics and foundation engineering in delta regions | 1979 | Lubking, P | 58(4) | There now exists a great variety of investigation methods and measurements which can be applied in the field to derive appropriate and reliable information from the soil strata with respect to their behaviour as a foundation for civil engineering constructions. The basic principles of in situ measurements in deltaic areas and especially in The Netherlands are given and some of the most interesting and recently developed devices are described. Although every apparatus causes a certain disturbance of the soil strata, in practice the measuring results often appear to be sufficient and serviceable. |
| Engineering geology and the Thames barrier project | 1979 | Wakeling, T.R.M.; Jennings, R.A.J. | 58(4) | The Thames Barrier, now under construction, is a structure containing movable gates which will prevent extra high tides flooding London. The majority of the piers are founded in chalk and a few at the northern end of the barrier will be set in the overlying Thanet Sand. The site investigation in these strata posed problems since the samples from boreholes are only of limited quality and the strata, being mostly under water, cannot be examined in situ. The investigation was carried out by boreholes using an extensive series of standard penetration tests and borehole permeability tests, together with tube samples for visual examination and classification testing. The detailed geological structure beneath the site was inferred from a geophysical survey and from a micropalaeontological investigation and was extended by visual examination of exposures of the strata in adjacent dry land sites. The results showed that there was a series of faults in the Chalk, but their presence did not appear to affect its engineering properties. |
| The storm-surge barrier in the Oosterschelde | 1979 | Rijkswaterstaat deltadienst | 58(4) | |
| Foundation aspects of the eastern Scheldt storm-surge barrier | 1979 | Boon, T.J. | 58(4) | |
| Engineering-geological investigations in the mouth of the Eastern Scheldt (SW Netherlands) | 1979 | Mulder, E.F.J. de | 58(4) | |
| Geophysical methods and monitoring | 1979 | Borm, G. | 58(4) | |
| Modern river deltas | 1979 | Elliott, T. | 58(4) | |
| Ter herdenking van Ir. G.J. de Vooys | 1980 | Hellemans, A. | 59(1) | |
| The Rotliegend in the Netherlands and its gas accumulations | 1980 | Wijhe, D.H. van; Lutz, M.; Kaasschieter, J.P.H. | 59(1) | The Rotliegend in the Dutch part of the Mid-European Basin contains recoverable gas reserves of at least 2.1 x 1012 m3. A combination of the following favourable conditions is the cause of these prolific accumulations: (1) up to 2500 m of Late Carboniferous coal-bearing strata form excellent source rocks for gas; (2) burial of these source rocks to depths of 4000-6000 m has led to generation of methane over a wide area; (3) excellent reservoirs in aeolian and alluvial Rotliegend sandstone are present, often not adversely affected by diagenesis; (4) favourable sealing qualities are offered by Zechstein evaporites; (5) abundant structural traps occur, often formed before the main gas-generation periods. |
| Deltaic sedimentation during the Jurassic in the Norwegian-Danish Basin (North Sea) | 1980 | Dypvik, H.; Vollset, J. | 59(1) | In the Norwegian-Danish Basin, several minor Middle to Late Jurassic deltas (Haldager Formation) were built out from the different highs, which acted as local sediment source areas. The cores studied fromwell 8/3-1 most probably represent the Middle Jurassic Haldager Formation, while wire-line logs and mineralogical composition indicate that the 17/4-1 core may represent the Late Triassic/Early Jurassic Gassum Formation. The analysed sediments of wells 8/3-1 and 17/4-l were deposited in delta-front environments, probably as distributary mouth bars. While the 17/4-1 delta had the Utsira High as a major sediment source area, the 8/3-1 delta material was mainly derived from the Sele High. The composition of the Oxfordian marginal-marine deposits of 16/9-1 indicates both the Utsira and Sele Highs as important source areas, reflecting derivation of sediments by reworking of underlying formations. The studied Oxfordian sandstones of well 16/9-1. may represent sandy equivalents to the Egersund Member of the Bream Formation. |
| Trace fossils and grazing traces produced by Littornia and Lepidochitona, Dutch Wadden Sea | 1980 | Jüch, P.J.W.; Boekschoten, G.J. | 59(1) | Fossil grazing traces of molluscs are regularly encountered but have not yet been studied in detail. This paper presents data on the grazing traces produced by a periwinkle (Littorina littorea) and by a chifon (Lepidochitona cinereus) both under laboratory conditions and in the Dutch Wadden Sea. It is found that the traces are different for both species, but that the traces made by one particular species are not necessarily uniform. |
| Optimum well sampling distance of groundwater levels in till and coversands. | 1980 | Ryckborst, H.; Leusink, A. | 59(1) | Spectral decomposition of groundwater-table profiles from the extremely wet year 1965 shows that the wavelength of 1710 m is the most significant for fluctuations in Pleistocene till and aeolian coversands in The Netherlands. Consequently, the optimum well sampling distance of groundwater levels in till and coversands is 855 m, whereas the average distance in the national groundwater network (12,000 wells) is 1600 m. The distance of 855 m corresponds to half the average distance between soil classes, mapped on the 1:25,000 soil maps. The design of an optimum groundwater well network will thus benefit from 1:25,000/1:50,000 soil maps and land use maps. |
| New palaeomagnetic data from the Iberian Peninsula | 1980 | Vandenberg, J. | 59(1) | The results of a palaeomagnetic investigation of Mesozoic sediments from the Betic Cordillera, the Iberic Chain and Cantabria in general confirm earlier conclusions about the rotation of the Iberian peninsula. The start of the rotational movement could be specified as post-Barremian/Aptian. Palaeomagnetic results from the Bilbao synclinorium show that the Iberia-Europe plate boundary has to be situated south of the synclinorium. Along the coast of Cantabria near Gijon Mesozoic European-like poles have been found probably indicating a complicated fault system along which the rotational movement of the Iberian peninsula was achieved. A model for the development of the Iberia-Europe plate boundary in its final stage is presented. A magneto-stratigraphic correlation of a Santonian-Campanian section from the Betic Cordillera with the Italian 'Gubbio'section is discussed. |
| The geochemistry of high-pressure gneisses from Cabo Ortegal (NW Spain): residues of deep anatexis | 1980 | Drury, S.A. | 59(1) | Garnet-hornblende gneisses from the eclogite to high-pressure granulite facies complex of Cabo Ortegal, NW Spain, show three main geochemical characteristics: (1) low K, Rb, Th and Rb/Sr ratios, and high K/Rb ratios compared with upper crustal rocks; (2) high Ca, low Sr and Ba, low Ba/Sr ratios and high CalSr ratios compared with low - to intermediate - pressure granulite facies gneisses; (3) low REE and absence of positive Eu anomalies compared with granulite-facies gneisses. These geochemical peculiarities reflect the gneisses being residues of partial melting at depths in excess of 35 km, which may have been induced by rise of hot ultramafic diapirs from the underlying mantle. |
| Facies changes in the Upper Devonian and Lower Carboniferous of South Cork, Ireland - a re-assessment | 1980 | Maccarthy, I.A.J.; Gardiner, P.R.R. | 59(1) | The North Ringabella section, critical to an understanding of the sub-carbonate facies changes in south Co. Cork, is redescribed. Three successive formations are detailed: the alluvial West Cork Sandstone Fm. (800+ m), the shallow-marine Coomhola Fm. (96+ m) and the fault-based Kinsale Fm. (340+ m), here a pro-delta and shallow-marine sequence. This is overlain by the calcareous Courtmacsherry Fm. The Devonian/Carboniferous boundary occurs about the base of the Kinsale Fm. Comparison with adjacent sections reveals a complex transgressive-regressive interplay. Four cycles are recognised. The first, in the Late Devonian, was affected by differential subsidence and was initially localised. The second, at the base of the Carboniferous, abruptly cut across earlier deltaic depositional patterns. Further delta growth in the Cork Harbour area was terminated by the third transgression, while the fourth marked the end of deltaic activity and the formation of a low-energy platform area around Cork Harbour upon which carbonate reefs ('Carboniferous Limestone') were subsequently developed |
| A geoelectrical study of the Sana'a groundwater basin, Yemen Arab Republic | 1980 | Shaaban, M.A. | 59(1) | The ground water conditions and possibilities in Sana'a Basin were analysed for the purpose of locating a suitable source of water supply, and to delineate the structural set-up of the area. Resistivity vertical electrical soundings, previously performed in the area, were interpreted to construct geoelectrical sections of the subsurface along some selected profiles. Also, some parametric resistivity and conductivity measurements were undertaken at some locations for the different rock types and waters of wells encountered in the area. Correlation between the geoelectrical results and the available geological and hydrological data was made. The study ascertained the groundwater potential in the investigated area and defined the electrical properties of its different rock types. Furthermore, a reliable source of adequate quality and quantity of groundwater was revealed, at an economic depth and distance, to the north-west of Sana'a city. |
| Sedimentary mechanism in Spanish Devonian Carbonates | 1980 | Reijers, T.J.A. | 59(1) | In the Middle-Late Devonian Santa Lucía and Portilla Formations in the Cantabrian Mountains (NW Spain), a series of facies belts parallels the palaeo-coastline. They represent from N to S a backbarrier, barrier and fore-barrier setting. Mild sea-level changes and epeirogenetic movements governed the rate and mode of carbonate production and controlled movements of these facies belts basinwards and marginwards. Carbonate masses in which such sedimentary movements are reflected can be correctly mapped regionally only if the interval is subdivided into units, each representing one movement. On a more local scale, carbonate masses reflect the same sedimentary mechanisms in the internal organization of carbonate build-ups. |
| The effect of a storm surge on near-shore sediments in Ameland-Schiermonnikoog area (N. Netherlands) | 1980 | Winkelmolen, A.M.; Veenstra, H.J. | 59(2) | After a severe storm part of the sample localities have been resampled in the shallow off-shore (to about 20 m) and the beach of an area, which was previously surveyed under quiet conditions. It appeared that in the shallow off-shore: (1) the depth had not changed much, (2) half of the samples were finer after the storm, some were coarser and some had not changed much, (3) the garnet percentages as well as the mica concentrations had both decreased after the storm, (4) the post-storm sands were considerably less rollable than before and the Shape Disribution Character had changed into an upsloping type, which is characteristic for receiving deposits. The observed features are explained by erosion of the shallow sea floor with transport by undertow towards deeper water. Subsequently, deposition took place of finer material that had been eroded in the tidal flat area and taken out in front of the coast by the first post-storm ebb tide. This material was reworked and spread out later on, loosing its mica and part of the fines by winnowing. Since most of the depositional processes were due to capacitive overloading rather than to competency, the grain 'size' largely failed as a diagnostic criterion and the conclusions reached in this paper are mainly based on grain-shape and density differences. |
| Geology and geomorphology of a fossil aeolian landscape in the Liemers (Eastern Netherlands) | 1980 | Meene, E.A. van de | 59(2) | A fossil aeolian landscape of 15 km2 has been investigated with help of drillings and study of exposures. The sands show a gently undulating surface and an average thickness between 0.8 and 1.8 m. In one place they have a low dune morphology. The sands are underlain by Late Weichselian floodplain deposits and overlain by Holocene floodplain deposits. Pollenanalytical dating limits the time of deposition to the interval Late Dryas Stadial/Atlantlcum. As it is presumed that in this environment strong aeolian action is possible under periglacial circumstances only, the time of deposition must be restricted to the Late Dryas Stadial. Stratigraphically the deposit represents an aeolian phase in the predominantly fluviatile Kreftenheye Formation. It is closely associated with the Late Glacial river-dune deposits that are present along the major rivers in The Netherlands. |
| Geomorphological changes after river-meander surgery | 1980 | Ryckborst, H. | 59(2) | A meandering river, upon preliminary inspection, looks like a very inefficient system, in need of serious correction. That the contrary is the case is shown by geomorphological changes which occur when sets of river meanders are cut off and replaced by straight or curved channel sections. Subsequent to the meander cutting, the potentially available energy per metre of channel increases dramatically and the water velocity increases. The excess energy causes erosion of bed and banks, while eroded material is deposited in the downstream channel. Before equilibrium can be reached again, a river bed must incise deeply for considerable distance upstream. Thereupon the river will start to make a new set of meanders not unlike the old meander pattern. The one-dimensional open-channel flow equation. when applied to river erosion (triggered by meander cutting), shows that the 'half life' of such man-made disturbances ranges from hundreds to a thousand years. Consequently, man-made interference with natural rivers represents a costly capital operation, which requires a long term (50-100 years) commitment for up-keep, improvement and replacement, if not in the short run, then in the long run (next 500 years). |
| The sedimentary sequence of a Weichselian intraglacial lake at Ormehøj (Funen, Denmark) | 1980 | Schwan, J.; Loon, A.J. van; Gaauw, P.G. van der; Steenbeek, R. | 59(2) | Weichselian deposits have been investigated in a high kamiform hill of the Vissenbjerg dead-ice landscape. The sediments were formed by the gradual infilling of an intraglacial lake underlain by a basal till. Normal deposition by a prograding delta was interrupted by the catastrophic bursting of a supraglacial lake. resulting in a boulder bed. Various facies can be distinguished. though vertical and lateral relationships often are obscured by diapiric activity of a subjacent clay. The meaning of the terms 'supraglacial' and 'intraglacial' (often used in a confusing way) is shortly discussed |
| Micro-ripples on silt-dominated beds: observations at the glacier Austerdalsisen, Norway | 1980 | Theakstone, W.H. | 59(2) | Micro-ripples (wavelength 0.5-2.0 cm, amplitude less than 0.2 cm) form on silt-dominated beds at the margins of ephemeral stream channels in reworked glacial lake sediments as a result of unidirectional currents, oscillatory flow or both. Pulsation of flow and the presence of bed irregularities much larger than the dominant particle size result in local stress concentration, and micro-ripples may form even though the mean stress is below the theoretical threshold for the grain sizes involved. Grain shape and composition may be partly responsible for differentiation of crest and trough material. X-ray diffraction studies have confirmed that samples of sediments from micro-ripple troughs and crests at one site differ in mineralogical composition, and differences of grain size and shape are confirmed by scanning electron microscope investigations. |
| Petrographic investigation of sarsens (Cenozoic silcretes) from southern England | 1980 | Summerfield, M.A.; Whalley, W.B. | 59(2) | The petrography of sarsens (Cenozoic silcretes), which occur extensively as scattered surface deposits over southern England, is investigated through thin-section observations and scanning electron microscopy. Attention is focused on the general characteristics of the various types of sarsen fabric (GS-(grain-supported), F-(floating) and C-(conglomeratic)), and on the nature of quartz-overgrowth development. Evidence for possible host materials is considered and some provisional conclusions are drawn about the diagenesis of these sediments and the environment in which they formed. |
| Mesozoic palaeogeographic evolution of the External Zones of the Betic Cordillera | 1980 | Garcia-Hernandez, M.; Lopez-Garrido, A.C.; Rivas, P.; Sanz de Galdeano, C.; Vera, J.A. | 59(2) | The main events characterizing the Mesozoic palaeogeographic evolution of the External Zones of the Betic Cordillera are outlined. The Triassic sediments show a 'germanic' type facies over the entire region. ending with Late Triassic evaporites and variegated clays of Keuper facies. At the beginning of the Jurassic a transgression takes place, and a broad shallow-marine carbonate-platform environment appears. During the Carixian (180) Ma) the carbonate platform breaks down leading to the differentiation of two large palaeogeographic units: the Prebetic Zone where shallow-water environments prevailed throughout the Mesozoic, and the Subbetic Zone where the sediments alc clearly pelagic. Within the Prebetic Zone, two palaeogeographic rearlms are differentiated: the External Prebetic showing important stratigraphic gaps in the Jurassic and Early Cretaceous sequence, and the lnternal Prebetic with a thicker and more continuous stratigraphic sequence. Between the Prebetic and Subbetic Zones. a palaeogeographic realm is distinguished (lntermediate units) where turtbeditic and pelagic materials were deposited. This zone corresponds approximately to a slope environment during most of Mesozoic times. In the Subbetic Zone a marked differential subsidence occurs during the Jurassic, leading to trough (Median Subbetic) and swells (External and Internal Subbetic). In the Median Subbetic, the deposits consist mainly of marls, pelagic limestones. radiolarites and calcareous turbidites, with mafic volcanic and subvolcanic rocks. During the Cretaceous pelagic marls and marly limestones were laid down. Mesozoic sedimentation took place along the southern margin of the European plate, in an Atlantic-type continental margin underlain by continental crust. Three-dimentional schemes, explaining the main palaeogeographic events are included. |
| Lithophile, calcophile, siderophile: can these terms be quantified | 1980 | Schuiling, R.D. | 59(2) | |
| A note on the age of the Paramaka metavolcanics in northeastern Suriname | 1980 | Priem, H.N.A.; Roever, E.W.F. de; Bosma, W. | 59(2) | |
| Ingredients for a first degree geological education | 1980 | Rondeel, H.E. | 59(2) | |
| Holocene deposits in the northern North Sea: evidence for dynamic control of their mineral and chemical composition? -a comment- | 1980 | Jansen, J.H.F. | 59(2) | When studying superficial sediment samples of the North Sea, one should discriminate between areas with different oceanographic and sedimentary history. The demonstrated relationships between the chemical compositions and the grain-size distributions of the samples are not the same for the distinguished deposits. The variations are therefore not the result of one single hydrodynamic regime acting throughout the North Sea, but point to differences in source material. In the north-central North Sea the grain-size distributions, and consequently also the associated chemical parameters, reflect the succession from Weichselian arctic to Holocene temperate marine conditions. The abundance of planktonic Foraminifera is also due to the postglacial evolution. The ratios of illite to smectite suggest a change in source area of the clays. |
| Holocene deposits in the northern North Sea: evidence for dynamic control of their mineral and chemical composition -Reply- | 1980 | Johnson, T.C.; Elkins, S.R. | 59(2) | |
| In Memoriam, W. Nieuwenkamp (1903-1979) | 1980 | Schuiling, R.D. | 59(2) | |
| #REF! | 1980 | 59(2) | ||
| Geohydrology and geotechnical aspects of dewatering of open tar sand mines along the Athabasca River (Canada) | 1980 | Ryckborst, H. | 59(3) | About 5% of the giant tar sand deposits along the Athabasca River in Western Canada can presently be mined by open-pit mining methods. Under certain conditions, groundwater depressions are created by continuous pumping to keep the tar sand mines dry. Groundwater depressions for plateautype mines are expected to expand beyond an area of 150 km2 after ten years. The volumes of groundwater flowing into a plateau-type open mine may range from 17,000-400,000 m3/day, depending on type of mining methods and the presence of water-tight clays. The Cretaceous tar sands are separated from underlying rock salt by a karstified Devonian limestone. Some of the groundwater flowing into an open mine consists therefore of saline waters and brines. Modern, but as yet unproven dredging methods may offer an economic alternative to 'dry' open-pit mining methods. |
| Estimation of heat flow in oil wells based on a relation between heat conductivity and sound velocity | 1980 | Houbolt, J.J.H.C.; Wells, P.R.A. | 59(3) | Based on published data, it is assumed that the ratio of sound velocity to thermal conductivity exhibits a linear relationship with formation temperature for most sedimentary rocks. Combination of this assumption with Fourier's heat-flow law yields q*=ln(TL+c/TU+c)•(1/A(tL-tU)) where TL and Tu, are the subsurface temperatures at the top and the bottom of an interval, respectively, tL and tU the sound travel times, and q* is the heat flow. This relation has been tested in the case of 10 wells, for which accurate data were available. The relation generated very satisfactory fits with the measured data for siliciclastic and carbonate rocks. The parameters a and c take respective values of 1.039 and 80.031; heat flow (q*) is expressed relative to the heat flow in the standard well Bolderij-1 in the Groningen gasfield (Bolderij Unit, BU). A method for estimating the relative heat flow from bottom-hole temperatures as observed during logging operations, and sound-travel times from well-shoot in combination with sonic-log data, has been developed and tested in the Viking and Central grabens of the UK sector of the North Sea. In this region the mean relative heat flow using data from 120 wells is 0.601 BU, with a standard deviation of 0.055 BU. Comparisons of calculated relative heat-flow values in BU, with heat-flow values in SI-Units conventionally obtained suggests that the Bolderij unit is equivalent to about 77 mWm-2. |
| Mining subsidence in Twente, East Netherlands | 1980 | Wassmann, T.H. | 59(3) | A method for forecasting the vertical and horizontal movements of points at the surface caused by saltmining subsidence has been developed for the special case of the Hengelo field. All possible data of a first case of caving-in of cavities created by the solution mining of salt were collected and studied. A theory was set up to explain two striking differences from other subsiding areas, i.e. the duration in time of the subsidence and the small area influenced at the surface in relation to the depth of the cavity mined out. Special attention is paid to the behaviour of the Triassic claystone formation ('Red Beds') above the salt layer. In 1973 this theory was used to predict the rate of subsidence of a second case over a 10 year period. This second area of subsidence was situated just under a new brine purification and vacuum plant. For each part of the installation within this area the movement with time was calculated. With these figures it was possible to arrange a long-term planning for preventive maintenance and by doing so to keep the complete plant operating. |
| The Tertiary and Quaternary subbottom of the Schelde estuary near Antwerpen (Belgium) | 1980 | Wartel, S. | 59(3) | The subbottom stratigraphy of the Schelde estuary near Antwerpen was studied using an O.R.E. subbottom profiler. The estuary valley is incised in Tertiary and Quaternary deposits, still eroded at several places. In the Boom Clay (Oligocene) uparching and diapirs occur. They result from an unloading of the clay after one or more erosion periods. The top of the Boom Clay consists of an undulating erosion surface, dipping roughly NNE and covered unconformably by Miocene (Edegem Sands) and Pliocene (Kattendijk Sands) deposits. The contact between Miocene and Pliocene has not been observed. The lowermost Quaternary deposit consists of a gravel and shell layer irregular in thickness and unconformable with the older deposits. The recent sediment cover, where present, is less than 1m thick. |
| Intraformational clay diapirism and extrusion in Weichselian sediments at Ormehøj (Funen, Denmark) | 1980 | Schwan, J.; Loon, A.J. van; Steenbeek, R.; Gaauw, P. van der | 59(3) | A kamiform hill in the Vissenbjerg dead-ice landscape consists of a basal till, overlain by various glaciolacustrine sediments. Within these sediments diapiric phenomena can be observed; the source is a clay layer, probably occurring just beneath the lodgement till. Pressure gradients between the intraglacial lake and the surrounding dead-ice blocks induced diapiric strain in the clay. Both intrusive behaviour and subaqueous (partly possibly subaerial) extrusive spreading were the result. Deformational structures, caused by this plastic flow, are described, depicted and interpreted. |
| Sedimentary deformations in Saalian Glaciolimnic deposits near Wlostów (Żary area, Western Poland) | 1980 | Brodzikowski, K.; Loon, A.J. van | 59(3) | Three quarries near the village of Wlostów show a sequence of 16 m of glaciolimnic deposits, dating from the Odra (= Drenthe) and Warta stadials of the Saalian glaciation. Eighteen units can be distinguished, many of them with deformational structures: diapiric folding, breccias, load casts, fault structures and cryogenic disturbances. An analysis of the deformations shows that some of them must be considered to be syn- or metasedimentary; others are formed by early diagenetic processes. The sediments are also deformed in a postsedimentary stage, viz. by cryogenic and diapiric (glacitectonic) activity. The nature of these deformations is explained and examples are depicted. A scheme with spatial and genetic relationships between the various sediments in a glacial environment is presented, in order to facilitate the environmental interpretation of the eighteen units exposed. |
| petrology and geochemistry of granitic intrusions in the Viana do Castelo area, northern Portugal | 1980 | Barr, S.M.; Areias, L. | 59(3) | Granitic intrusions in the Viana do Castelo map-area in northern Portugal are part of the Hercynian plutonic belt of the Iberian peninsula. They consist predominantly of muscovite-biotite granite of varied textures with minor granodiorite and quartz monzonite. Chemically they exhibit typical calcalkalic differentiation trends and appear to represent a co-magmatic suite. They are peraluminous and show typical characteristics of S-type granites. An age of 316 ± 4 Ma was obtained from a Rb-Sr whole-rock isochron. |
| #REF! | 1980 | 59(3) | ||
| Underground gasification of coal: The filling of dipping underground cavities | 1980 | Grupping, A.W.; Pieterson, R. | 59(4) | In deep underground coal gasification the all-important parameter is the volume of coal that can be gasified between two boreholes. This volume depends to a large extent on the maximum attainable linking distance. Spectacular advances in recent years in deviated drilling techniques suggest that the linking of deep boreholes can more easily be achieved by drilling than by conventional methods such as fracturing. Gasification methods could then be developed in dipping coal seams in which the combustion front is, from time to time, driven updip by backward filling of the cavity with a filler such as sand. The results of filling tests in a scaled model are described. It is shown that dipping underground cavities can be completely filled by a process of sedimentation, with the exception of an updip channel along the coal face. Through this channel combustion can be re-initiated after removing the excess water with high-pressure gas. In this way a number of roughly parallel strips of coal could be gasified between two boreholes; serious subsidence at the surface would then be avoided. The tests also show that localized caving-in of the roof of the cavity does not seriously disturb the filling process or the development of the updip channel. |
| Oil-pricing policy and government revenues per barrel of exports in the OPEC countries (1973-1979) | 1980 | Bos, C.F.M. | 59(4) | This paper covers the evolution of government revenues per barrel of exported crude oil in the OPEC countries as from 1973, when the first oil crisis triggered a radical change in the power balance between oil companies and oil-importing countries on the one hand, and oil-exporting countries on the other hand, through 1979. The background of price-increasing decisions is given in the light of common and clashing interests within OPEC and the mutual dependence of oil-importing and -exporting countries. In figures the government revenues per barrel of exported crude, volumes of exported crude, and total government revenues are given for four representative OPEC countries (Saudi Arabia, Libya, Venezuela and Indonesia) and for the total OPEC, both in current and in constant 1973 dollars. Furthermore, an overall picture of oil prices, pricing systems and government revenues is presented |
| The future of Dutch coal: possibilities and impossibilities, a personal view | 1980 | Velzeboer, P.T. | 59(4) | |
| Early Pliocene small mammals from the Aegean islands of Karpathos (Greece) and their Palaeogeographic significance | 1980 | Daams, R.; Weerd, A. van de | 59(4) | An association consisting of Muscardinus sp., Kowalskia sp.,Apodemus aff. dominans, Petauristinae gen. et sp. indet. (Rodentia) and Prolagus ct. michauxi (Lagomorpha) is described. The faunule is of Early Pliocene age and points to a forest biotope. The small but diverse faunule suggests that Karpathos was connected to Anatolia during the Early Pliocene. |
| Note on some Late Maastrichtian rhyncholites from Limburg, the Netherlands | 1980 | Tuuk, L.A. van der | 59(4) | Upper Maastrichtian rhyncholites (cephalopod mandibles) from the province of Limburg, The Netherlands, were described by Binckhorst as early as 1861. Recently discovered material makes a revision possible. A survey is given of the available material, which was identified as Rhyncolites minimus Binckhorst, from the Late Cretaceous deposits of various localities of the Maastrichtian type area. |
| Holocene water level changes in the Rhine-Meuse delta as a function of changes in relative sea level, local tidal range, and river gradient | 1980 | Plassche, O. van de | 59(4) | Published time-depth data from peat-covered slopes of early Holocene river dunes in the Rhine-Meuse delta are reviewed in the light of a new sea-level graph by Jelgersma. It is argued that the irregular convergence of the river-dune data on this curve with time can be explained in terms of a gradually decreasing gradient of the (tidal) rivers and a variable reduction - both in time and space - of the tidal range behind the coastline. A curve is constructed for the Brandwijk-Hazendonk area and shows the decrease of the raising effect of the river gradient on the local mean high-water level or groundwater level with time. For each time-depth point from the Brandwijk-Hazendonk area this gradient-effect reduction curve allows an estimate of the extent to which the decrease in tidal amplitude behind the coastline has compensated the gradient effect. |
| Outlines of the Late Quaternary history of the Drentsche AA valley (Drente, the Netherlands) | 1980 | Gans, W. de | 59(4) | An outline is given of the geomorphology and Late Quaternary history of the Drentsche Aa valley. The valley sediments are subdivided in fluvial, slope and aeolian sediments on lithological arguments. The vertical succession of the river valley sediments demonstrates a decreasing fluvial activity during the Weichselian. Tentatively four erosion phases are distinguished in the valley system |
| On the geology of the Alpujarride complex in the Western Sierra de las Estancias (Betic Cordilleras, SE Spain) | 1980 | Akkerman, J.H.; Maier, G.; Simon, O.J. | 59(4) | The Alpujarride complex in the western sierra de las Estancias comprises a pelite-psammite Sequence and an overlying carbonate sequence. A Ladinian to Late Triassic age seems most likely for the carbonate sequence, while a Middle Triassic and possibly older age is inferred for the remaining part of the section. The tectono-metamorphic evolution took place during the Alpine orogeny. No indications have been found for pre-Alpine metamorphism and deformation. The rock sequences have been affected by plurifacial metamorphism during three metamorphic events' The first event (M1) involved an increase in temperature under low to intermediate pressure, resulting in a prograde metamorphism up to amphibolite facies. M1 seems related to the intrusion of hot ultramafic masses. This event was followed by retrograde metamorphism (M2). Renewed increase of temperature, without a change of the existing low-pressure conditions, locally caused a third metamorphic event (M3). The plurifacial metamorphism was accompanied by polyphase deformation. The first phase (D1) resulted in mainly isoclinal, similar folds. During the second phase (D2) important translations gave rise to the superposition of at least three major overthrust masses. Associated folds have a vergence to the north, indicating a northerly direction of transport. Subsequently the rock sequences have been deformed into S to SE vergent folds, N to NW dipping reverse faults, E-W trending subvertical faults and into NNW trending wrench faults. |
| Studies on the foraminifer sorites orbiculus | 1980 | Kloos, D.P. | 59(4) | The exclusively epiphytic and sedentary living foraminifer Sorites orbiculus (FORSKÅL) has been found in several lagoons and bays on Curaçao (Netherlands Antilles). Only megalospheric specimens were found. Living S. orbiculus, attached to their favourite substratum, the marine phanerogam Thalassia, were kept in aquaria for three weeks. Positive phototaxis was observed. Symbiotic algae colour the protoplasm and show its irregular distribution within the test; they also provide a criterion for recognition of living specimens. Most S. orbiculus specimens are enveloped in a pellicle and are encircled by a rim of sediment which is probably a feeding-cyst; both are left behind when the specimen moves away. |
| Dérive Cénozoique de la corse et de la Sardaigne et ses merqueurs géologiques | 1980 | Orsini, J.B.; Coulon, C.; Cocozza, T. | 59(4) | Drifting in a southeastern direction of Corsica and Sardinia was the major feature during the recent evolution of the northwestern Mediterranean basin. The reality of this phenomenon is demonstrated by geological and geophysical data. Furthermore, values of palaeomagnetic declinations, ocean continent limits and linear geological markers, lead to a reconstruction of the pre-drifting Cenozoic position of the two islands with respect to the European margin. Finally, the age and kinetic system of drifting are defined with the help of the significance, age and palaéomagnétic characteristics of calc-alkaline Cenozoïc volcanism of Sardinia. |
| Sources of information for the preparation of engineering-geological maps in the Netherlands | 1980 | Burgers, W.F.J. | 59(4) | The growing interest for engineering-geological maps in The Netherlands has led in recent years to a search for possible sources of engineering-geological information. The object of this paper is to show where the necessary information for the construction of this type of maps is available. The data in this paper were obtained through interviews and by means of an inquiry. The results indicate that the large governmental and semi-official organisations and the geotechnical bureaus are the principal sources of engineering-geological information in The Netherlands. |
| Palynological evidence concerning the Middle/Late Devonian age of the Green Sandstone Formation, McGillycuddy's reeks, Southwest Ireland | 1980 | Veen, P.M. van; Zwan, C.J. van der | 59(4) | From the Green Sandstone Formation (Devonian), outcropping in the McGillycuddy's Reeks (Co. Kerry, Ireland), a palynological assemblage is recorded, indicating a late Givetian-early Frasnian age. The importance of this assemblage with regard to the establishment of a realistic chronostratigraphical framework for the Devonian of Southwest Ireland is briefly discussed |
| A short note on the presence of the eltville-tuff layer in the surroundings of Maastricht | 1980 | Meys, E.P.M. | 59(4) | |
| #REF! | 1980 | 59(4) | ||
| Preface Special Issue The Variscan Orogeny in Europe | 1981 | Zwart, H.J.; Dornsiepen, U.F. | 60(1) | |
| Geotectonic cross sections through the Cantabrian Mountains, Northern Spain | 1981 | Savage, J.F. | 60(1) | The Variscan Orogen in this central part of northern Spain is made up of a practically unmetamorphosed sedimentary succession detached from the underlying crust. The kinematics of the suprastructural elements had an essentially centripedal pattern which, moving separately, formed the Knee of Asturias. It is postulated that gravity powered the formation of these structures in their present general form. The crust is considered to have been most likely cratonised during the whole of the Phanerozoic over most or the whole of the region. This craton must have been fractured into blocks capable of limited relative movements, both vertical and horizontal. Crustal events leading to the deformation were probably much more intense outside the limits of the orogen considered; for example the Hesperian Massif along the western edge of the Iberian Peninsula. The reconstructions made rule out the possibility of a subsurface connection between the Variscan infrastructures of the Hesperian and Pyrenean orogenes. |
| Geotectonic cross sections through the Cantabrian Mountains, Northern Spain | 1981 | Savage, J.F. | 60(1) | Large Enclosure 1 |
| Geotectonic cross sections through the Cantabrian Mountains, Northern Spain | 1981 | Savage, J.F. | 60(1) | Large Enclosure 2 |
| Geotectonic cross sections through the Cantabrian Mountains, Northern Spain | 1981 | Savage, J.F. | 60(1) | Large Enclosure 3 |
| Geological characterization of the Variscan and Pre-Vasriscan in Hungary | 1981 | Jantsky, B. | 60(1) | Five pre-permian megatectonic units can be distinguished in Hungary: a high-grade Precambrian crystalline complex, two Variscan greenschist-facies complexes, the amphibolite-facies complex of the Sopron massif,-and the unmetamorphosed Palaeozoic. These five units are described. The Variscan orogeny has reactivated the older basement, which forms part of a number of median massifs. These can be traced towards Greece and Turkey. |
| Variscan volcanism of Central and Western Europe | 1981 | Perekalina, T.V. | 60(1) | The type of volcanism in Central and Western Europe clearly reflects the tectonic conditions of the time of its manifestation. Two main types of Variscan volcanism can be distinguished: (1) spilitokeratophyre (pre-orogenic); and (2) postorogenic calc-alkaline. The spilito-keratophyre associations are widespread in space and time and form belts related to regional faults, intraplate rifts and grabens. This reflects a tectonic regime of tension. Spilito-keratophyre sequences are connected with the initial stages of the individualisation of new basins (Devonian, Carboniferous). They can appear several times in one region. It seems possible that the spilitic belts mark the boundaries of small plates or blocks. The source of magma was the upper mantle. The tectonic conditions during the time of eruption of postorogenic volcanics is quite different. They are characterised by folding, vertical movements, compression arid anatectic melting in the sialic crust. Two associations can be distinguished: (1) a late-orogenic one of monotonous acid (rhyolites, dacite) composition, forming magmatic structures of the central type related to cauldron subsidence; and 2) a postorogenic or final one of bimodal composition on (trachybasalts- rhyolites) marking the beginning of a new period of tension related to the uplift of the region. |
| Variscan volcanism of Central and Western Europe | 1981 | Perekalina, T.V. | 60(1) | Large Enclosure 1 |
| Variscan volcanism of Central and Western Europe | 1981 | Perekalina, T.V. | 60(1) | Large Enclosure 2 |
| A geological section across the Hesperian Massif in Western and central Galicia. | 1981 | Tex, E. den | 60(1) | A section across the axial zone of the northern Hesperian massif in Galicia is presented. It is extrapolated to a depth of 5 km on the basis of gravity data obtained over key areas near Mellid and Santiago de Compostela. Several lithotectonic units are distinguished in this part of the massif. Lower Palaeozoic supracrustals, closely associated with late Palaeozoic migmatites, granitic and metamorphic rocks constitute the regional tectonic framework. Infracrustal rock complexes occur in subcircular to elongate outcrops. Those representing the higher basement levels are of mesozonal metamorphic grade and contain abundant amphibolites and calcalkaline as well as peralkaline granite gneisses. Others, representing the lower basement levels, are predominantly catazonal and have prominent constituents of the continental upper mantle. Some of the latter are associated with dismembered metaophiolites of Palaeozoic age. For the evolution of the northern Hesperian Massif a mantle-plume/rift-system model is preferred. An outline of this model is provided. |
| A geological section across the Hesperian Massif in Western and central Galicia. | 1981 | Tex, E. den | 60(1) | Large Enclosure |
| A geotraverse through the Variscan Fold Belt in Portugal | 1981 | Ribeiro, A. | 60(1) | A geotraverse through the Variscan Fold Belt in Portugal is described. The main geometric and chronologic features of the different deformation phases are drawn for each palaeogeographic and tectonic zone (Middle Galician - Trás-os-Montes Subzone; Centro-Iberian, Ossa-Morena and South Portuguese Zones). The problem of the tectonic position of the Bragança and Morais Massifs is referred to. The pattern of vergences and the mechanical origin of the Ibero-Armorican arc are briefly discussed. |
| A geotraverse through the Variscan Fold Belt in Portugal | 1981 | Ribeiro, A. | 60(1) | Large Enclosures |
| Cross-sections through the Belgian Variscan Massif | 1981 | Geukens, F. | 60(1) | Two profiles through the Belgian Ardennes are described and depicted. The Cambrian to Silurian rocks, folded during the Caledonian orogeny, show a weak metamorphism. The cover, consisting of Devonian and Carboniferous, thickens towards the south and is thrown into a number of major folds during the Variscan orogeny. This was accompanied by a second stage of low-grade metamorphism. |
| Cross-sections through the Belgian Variscan Massif | 1981 | Geukens, F. | 60(1) | Large enclosure 1 |
| Cross-sections through the Belgian Variscan Massif | 1981 | Geukens, F. | 60(1) | Large enclosure 2 |
| The Variscan fold belt in Ireland | 1981 | Naylor, D.; Sevastopulo, G.D.; Sleeman, A.G.; Reilly, T.A. | 60(1) | The major geological features of Ireland south of Latitude 52°30' are described. Palaeofacies and isopachyte maps, combined with stratigraphic cross-sections, are used to trace the Late Palaeozoic development of the region. A thick red-bed sequence of Middle-Late Devonian age accumulated within an east-west trough, the Munster Basin, which was fault-controlled at its northern margin. The northward marine incursion across the region in late Devonian - early Carboniferous times is described. South of the Cork-Kenmare line (in the South Munster Basin) the dominantly Cork Beds sequence was developed and reflected a gradually deepening marine facies through Early Carboniferous time. Isopachyte data show the influence of an important intra-basinal positive element, the Glandre High, which effectively separated east and west depositional sub-basins. North of the Cork-Kenmare line the shelf area was dominated by carbonate deposition until the end of Early Carboniferous time. Turbidite deposition was a feature of Namurian deposition across the region, whilst evidence of the Westphalian is limited to the coal-bearing measures of Westphalian A in the small Kanturk Coalfield. The considerable control of structural styles exercised by bulk lithologies is demonstrated with the aid of structural cross-sections. Basement controls on both structural style and sedimentation are discussed, with particular reference to the Glandore High and the northern margin of the Munster Basin. Finally, the concept of a clearly-defined northern thrust front to the Variscan fold belt is examined and the conclusion reached that the supposed 'front' is better considered as a complex zone within which the northward diminution of tectonic intensity is affected by basement configuration, the thickness of sedimentary cover and the presence of older structural features. |
| Variscan events in the Alpine re gion | 1981 | Raumer, J.F. von | 60(1) | Relics of the pre-Permian history are preserved in the five crystalline basement complexes of the External or Helvetic realm. Their evolution can be compared with the Variscan regional evolution in Central Europe. Precambrian to Palaeozoic sediments interlayered with acid and basic magmatic rocks suffered an early regional anatexis with contemporaneous formation of granitoid rocks. This event (5-6 kb/700 °C) supposed to be at least of Caledonian age is followed by the formation of blastomylonite zones probably contemporaneous to large scale B 3-folds. A second regionaI anatexis (of probably early Variscan age, 650-700 °C/4 kb) is characterized by the regional occurrence of cordierite-bearing granitoids, accompanied or followed by a regional growth of biotite and plagioclase. The later history is dominated by the intrusion of distinct granite bodies. Although Variscan events are of importance for the structural evolution, the main metamorphic history is of pre-Variscan age. No considerable break could be seen in the rather continuous history of evolution from Caledonian until Variscan time. |
| Variscan structures in Southwest Wales. | 1981 | Hancock, P.L.; Dunne, W.M.; Tringham, M.E. | 60(1) | Palaeozoic rocks in the Variscan domain of SW Dyfed, Wales, were deformed under anchimetamorphic conditions during the late Carboniferous. Within the Pembrokeshire Coalfield a 1 km wide zone of conjugate folds and thrusts, external to the northern limit of slaty cleavage, is used to define the Variscan orogenic front. South of the front there is a progressive increase in the average amplitude of macrofolds across three further structural zones. Folding about a WNW axial trend was single phase except within a few narrow belts of refolded folds. Wrench and normal faults which developed during and after folding resulted in the axial elongation and clockwise rotation of the region. Structures in the paratectonic Caledonides controlled the locations of four WSW trending Disturbance Belts of Variscan age to the north of the front. In the Druidston Haven Horst, the westernmost of these Disturbances, Caledonian folds and cleavage were refolded approximately coaxially during the Variscan. The Variscan fold belt is cut by several, laterally impersistent, major strike faults which cannot be regarded as separating allochthonous blocks. Although displacements were dominantly reverse or normal the evolution of the faults during folding probably involved some scissor motion. On the Johnston Thrust northward overthrusting was followed by dextral strikeslip. |
| Variscan structures in Southwest Wales. | 1981 | Hancock, P.L.; Dunne, W.M.; Tringham, M.E. | 60(1) | Large Enclosure 1 |
| Variscan structures in Southwest Wales. | 1981 | Hancock, P.L.; Dunne, W.M.; Tringham, M.E. | 60(1) | Large Enclosure 2 |
| The geosynclinal development of the Rheinische Schiefergebirge (Rhenohercynian Zone of the Variscides; Germany) | 1981 | Walliser, O.H. | 60(1) | The Palaeogeographical distribution and evolution of facies in the Rheinische Schiefergebirge reflect the geosynclinal development of the Mid-European part of the Rhenohercynian zone of the Variscan geosyncline. The geosynclinal development of the Rheinische Schiefergebirge was strongly influenced by the Mid-Cerman Crystalline Rise in the south and by the Old Red Continent in the north. From late Precambrian up to Early Ordovician, the Mid-German Crystalline Rise has been a zone of rapid accumulation of sediments and volcanics, thus indicating an early tensional phase and the beginning of fracturing and mobilization of the European crust. With that the Variscan geosyncline proves to belong to a Proterozoic-Palaeozoic, resp. Caledonian-Variscan megacycle. The tension of the crust did not lead to the creation of an ocean in the described area. The Mid-German Crystalline Rise delivered debris into the southern part of the Rheinische Schiefergebirge during the Early Devonian. But the main part of this episialic sea was characterized by a large deltaic spread off the Old Red Continent. The delivered material accumulated in rapidly subsiding shelf troughs which followed asymmetrical graben-like structures and which retreated episodically northward. Tension at this time is also proved by an important volcanic activity. Outside of the shelf areas relatively thin pelagic sediments were deposited in a relatively stable basin of no great depth. The Givetian transgression caused a maximum of reef development. After the suppression of reefs by another global event in the late Frasnian, the further development led to an equalization of relief and facies. The pre-flysch phase in the Dinantian is characterized by another tensional episode with basic volcanism and by regionally limited deposition of limestone turbidites. The first occurrence of flysch sediments, delivered from the Mid-German Crystalline Rise, is already low in the Upper Devonian. A prominent acceleration of flysch accumulation and of northward shifting of the trough began in the late Dinantian. Already during the Namurian the flysch trough gradually changed into a molasse trough with paralic conditions |
| Three profiles through the Central Pyrenees | 1981 | Zwart, H.J. | 60(1) | The Palaeozoic stratigraphic sequence of the Pyrenees, folded in Late Carboniferous time during the Variscan orogeny, consists of Cambro-Ordovician phyllites and quartzophyllites, Silurian carbonaceous shales, Devonian limestones, calcslates and slates with local sandstones, and Early Carboniferous shales. Igneous rocks consist of a pre-Variscan granite and late- to posttectonic granodiorites. Several generations of folds were formed during the Variscan orogenic period, of which the first two are responsible for most of the major structures. A large part of the folds shown on the profiles date from the second fold generation, usually called the main phase. These structures are accompanied by an axial-plane cleavage in low-grade rocks. In these rocks in the axial zone the cleavage forms half of a fan, which was formed by a late phase of tilting. In the high-grade infrastructure axial planes of folds and foliations are usually gently dipping. These structures were formed later and at the expense of earlier steep structures. Yet later fold generations have in general only resulted in small-scale structures. |
| Three profiles through the Central Pyrenees | 1981 | Zwart, H.J. | 60(1) | Large Enclosure 1 |
| Three profiles through the Central Pyrenees | 1981 | Zwart, H.J. | 60(1) | Large Enclosure 2 |
| Three profiles through the Central Pyrenees | 1981 | Zwart, H.J. | 60(1) | Large Enclosure 3 |
| A cross-section through the northern part of the Iberian Massif | 1981 | Julivert, M. | 60(1) | The Iberian Massif forms the western extremity of the Variscan Fold Belt in Europe, which from the Armorican Massif describes a sharp bend (the lbero-Armorican arc) to cross the Iberian Peninsula from northwest to southeast. A cross-section through the massif shows the existence in the belt of two branches with an opposite polarity, which gives a certain mirror-image symmetry to the structure of the belt. An east-west section parallel to the Cantabrian coast provides the best cross-section of the northern branch of the Iberian Massif. This section shows the typical zonation of linear fold belts. It consists of an 'external' part (Cantabrian zone) formed by carbonaceous and terrigenous rocks in a varied platform facies (at least the pre-Carboniferous rocks) and with thin-skinned tectonics, and an 'internal' part with a more monotonous, pelitic facies, and in general with cleavage, metamorphism and plutonism. The facing of the main structures is towards the 'external' part of the belt. During pre-Carboniferous Palaeozoic time, the geological evolution can be explained as the result of tension resulting in normal faulting, synsedimentary volcanism and intrusion of peralkaline and calcalkaline granitoids. The source of terrigenous supply was near the core of the arc, where an uplift tendency existed. Coinciding with the Devonian-Carboniferous boundary there was a break in the geological history and the subsequent geological evolution has been controlled by compressional orogenic events. This break is shown by a change in terrigenous supply now derived from the rising chain, by the development of foredeeps in the frontal part of the chain, and by the change from anorogenic to orogenic conditions with folding, metamorphism and plutonic intrusion. |
| A cross-section through the northern part of the Iberian Massif | 1981 | Julivert, M. | 60(1) | Large Enclosure |
| A geological cross section through the Variscides in the German Democratic Republic (Eastern Erzgebirge, Central Saxonian Lineament, Saxonian Granulite Complex, Harz Mountains). | 1981 | Schwab, M.; Mathé, G. | 60(1) | Two cross sections of the Variscides in the territory of the GDR are described. The section of the Saxothuringian Zone (Eastern Erzgebirge, Central Saxonian Lineament, Granulite Complex) includes deeper tectonic levels with metamorphic rocks of Barrow type (Erzgebirge) and granulite facies (Granulitgebirge). In shear zones in the Central Saxonian Lineament low-grade, high-pressure rocks with a tendency to glaucophanitic facies occur. Intercalated mafic and ultramafic rocks are considered to be tectonically displaced relics of the upper mantle. The cross-section of the Rheno-Hercynian Zone (Harz Mountains) demonstrates a higher tectonic level with tectonic structures and rocks typical of slate regions and a low to very low grade of metamorphism. Whilst in the Saxothuringian Zone the vertical component is stronger, horizontal movements directed towards the margin of the orogeny dominate in the internal Rheno-Hercynian zone. Therefore in the Harz a strong NW-vergence and gravitational sliding is exhibited (i.e. olistostromes and downsliding nappes). |
| A geological cross section through the Variscides in the German Democratic Republic (Eastern Erzgebirge, Central Saxonian Lineament, Saxonian Granulite Complex, Harz Mountains). | 1981 | Schwab, M.; Mathé, G. | 60(1) | Large Enclosure |
| The Variscan Black Forest | 1981 | Maass, D.R. | 60(1) | In the Black Forest three large gneiss regions, consisting of paragneiss with several intercalations of other rocks, are present. Low-grade metamorphics have probably an Early Palaeozoic sedimentary age. Dated Upper Devonian and Carboniferous up to Westphalian is strongly folded. Stephanian and Permian occur as an unconformable cover. Two different structural regions can be distinguished, a northern one with NE trending folds, and a southern one with basin structures and more variable fold trends. Four major faults occur: the northern two underthrust towards the south; the other two in the south have a reverse movement direction. In the two structural regions there are indications for a different metamorphic evolution. |
| The Variscan Black Forest | 1981 | Maass, D.R. | 60(1) | Large Enclosure 1 |
| The Variscan Black Forest | 1981 | Maass, D.R. | 60(1) | Large Enclosure 2 |
| A cross section through southwest England | 1981 | Matthews, S.C. | 60(1) | The stratigraphy of the Devonian-Carboniferous of SW England resembles that of the Rheinische Schiefergebirge. The structures are different in that flat-Iying folds and cleavages a¡e common in SW England. Folds have vergences to the north or to the south. The Lizard Complex is regarded as a basement high and not as a Variscan plate margin. The structural history including the emplacement of the granite batholith is discussed. |
| The structural development of the Rheinische Schiefergebirge | 1981 | Weber, K. | 60(1) | The structural framework of the Rheinische Schiefergebirge is characterized by NW-facing folds with a more or less strongly developed slaty cleavage and by listric overthrusts. The listric overthrusts of the Subvariscan Foredeep often are folded. Nappe displacements are assumed for the southeastern Rheinische Schiefergebirge. Based on their tectonic movement pictures two different types of listric overthrusts can be distinguished in the Rheinische Schiefergebirge: (1) Listric overthrusts forming simultaneously with folding. As the upward decreasing displacement may be compensated by folding, the overthrusts may die out at higher tectonic levels. During folding and thrusting fold-axial planes and thrust planes are rotated to NW. As a result of uplift and rotation to NW, both being related to folding and thrusting, secondary structures occur: low dipping NW-facing overthrusts and, locally, a SE-dipping post-crystalline crenulation cleavage. (2) Listric overthrusts which cut pre-existing NW-facing fold structures. This gives rise to an antithetic rotation of the overthrusted block and thus to a steepening of the originally NW-facing folds and cleavage planes. This rotation is intensified by further tectonic shortening and finally results in NW-dipping axial planes and cleavage planes. As a consequence of the SE-directed rotation of the overthrusted blocks a cleavage fan develops, which becomes overprinted by a predominantly flat-lying post-crystalline second cleavage. The youngest tectonic fabrics are kink bands. They occur in areas of late tectonic uplift and must be interpreted as extension structures. The character of metamorphism in the Rheinische Schiefergebirge is of a low pressure and high temperature with metamorphic temperatures not higher than 350°C except in the metamorphic zone of the Taunus, where temperatures of 400-450°C were reached. The metamorphism in the Rheinische Schiefergebirge is syntectonical with respect to the folding and its associated first cleavage. According to radiometric datings the age of folding in the southernmost part of the Rheinische Schiefergebirge is about 330 Ma and increases continuously towards the north to about 300 Ma. Folding and metamorphic development are continuous processes without distinguishable phase-like events. The Rheinische Schiefergebirge must be regarded as an ensialic orogen. Its geodynamic development is interpreted as being the result of A-subduction, i.e. subduction of lithospheric mantle below continental crust. |
| Geological sections through the Variscan Orogen in the Bohemian Massif | 1981 | Suk, M.; Weiss, J. | 60(1) | The construction of sections through the Variscan Orogen in the Bohemian Massif is discussed to solve the following problems: the age of the Moldanubicum and the relationship between the Moldanubicum and the Proterozoic of the Barrandian region, the Precambrian/Palaeozoic boundaries, the differentiation of the effects of the Variscan and Cadomian orogenies, the delimitation of the Variscan units in the Bohemian Massif, and the zonal structure of the Variscan orogen in central Europe. The development of the Variscan orogen in time and space is also discussed from the viewpoint of the influence of the supracrustal structure and the secular tendencies of the development of the earth's crust in the central European region. |
| Geological sections through the Variscan Orogen in the Bohemian Massif | 1981 | Suk, M.; Weiss, J. | 60(1) | Large Enclosure |
| The Variscan in Austria | 1981 | Ebner, F.; Fenninger, A.; Schönlaub, H.P. | 60(1) | In the last years several comprehensive reviews of the Variscan in Austria have been published. The fundamental data to this subject have previously been summarized by FLUGEL (1970,1978),TOLLMANN (1977) and SCHÖNLAUB (1979); they also mentioned the relevant literature. With regard to the attempt to present the pre-Alpine history of the Austrian Palaeozoic within the framework of the IGCP project no. 5 (pre-Variscan and Variscan events of the Alpine Mediterranean mountain belts), it seems not very useful to anticipate to that report in the present paper. Moreover, the above-mentioned publications document the state of knowledge up to about 1979; a correlation table compiled by SCHÖNLAUB (1979) gives additional information (Encl. I). It might be useful, however, to provide the most recent information to current investigators; for that reason a bibliography is presented with additional data. |
| The Variscan in Austria | 1981 | Ebner, F.; Fenninger, A.; Schönlaub, H.P. | 60(1) | Large Enclosure |
| Structural and palaeogeographic lineaments of the Variscan cycle in Sardinia | 1981 | Carmignani, L.; Cocozza, T.; Minzoni, N.; Pertusati, P.C. | 60(1) | In the Variscan orogen of Sardinia it is possible to distinguish: (1) A Southwestern zone (foreland), restricted to the SW of the Cenozoic graben of Campidano, with slight metamorphism and minor folding without important overthrusts. (2) A central zone that runs across the entire island from Nurra to Sarrabus, characterized by important overthrusts and a rather uniform metamorphism never exceeding the greenschist facies. The metamorphism grades towards the NE into the higher-metamorphic area. (3) The Northeastern zone (granitized root zone) that includes the northern tip of the island and is characterized by the superimposition of several metamorphic episodes and by tectonic events that have intensively remobilized the pre-Variscan basement. A conventional boundary between the two last belts may be drawn along the NW-SE line joining Stintino and Dorgali. Furthermore, there seems to be a parallellism between post-Cambrian palaeogeographic domains and Variscan tectono-metamorphic zones. The absence of ophiolite associations, the Ordovician magmatism, the Silurian one with continental alkaline affinity and the Variscan metamorphism of low or intermediate pressure suggest that the Variscan orogenic cycle in Sardinia had an ensialic evolution. The structural style of the different zones, the asymmetry of the belt, the division into metamorphic zones and the relationship between crystallization and deformation suggest also that the northeastern Sardinian Variscan belt represents the portion of the crust deeply subducted along intracontinental shear zones dipping towards the NE. |
| In memoriam L.U. de Sitter | 1981 | Zwart, H.J. | 60(1) | |
| #REF! | 1981 | 60(1) | ||
| Stratigraphy, palynology and radio carbon data of Eemian amd Early Weichselian fluvial deposits in the Drentsche Aa valley system (Drente, the Netherlands) | 1981 | Gans, W. de | 60(2) | A survey is given of the Eemian and early Weichselian erosional and depositional fluvial history of the Drentsche Aa valley. In between these fluvial deposits four mor-like organic levels are dated on stratigraphical and palynological criteria. The lowest three levels are dated as late Eemian and the Brørup and Odderade Interstadials of the early Weichselian respectively. The fourth mor-like level is dated as middle Weichselian and tentatively called the Papenvoort pollen zone. The fluvial deposits intercalated with mor-like levels are reckoned to be the lower Aa deposits. |
| Differences in tectonic evolution of superposed malaguide and Alpujarride tectonic units in the Espuña area (Betic Cordilleras, Spain) | 1981 | Mäkel, G.H. | 60(2) | A description is given of the tectonic evolution of rock sequences of the Malaguide and Alpujarride complexes in the Espuña area. Two phases of folding and thrusting, the first accompanied by metamorphism, affected the Alpujarride sequences. Subsequently Malaguide rocks were folded and thrust over the Alpujarride rocks and Malaguide tectonic units were formed. Afterwards folding and thrusting to the south affected the pile of units. Subsequent Tortonian and younger faulting took place alongh E-W and N-S trending, subvertical faults. In the Espuña area there exists, besides marked differences in stratigraphy and degree of metamorphism, a clear distinction between the tectonic evolution of the Malaguide and Alpujarride sequences. Therefore it is concluded that intermediate tectonic units do not exist in the Espuña area where they were originally defined. As a consequence of these data, arguments in support of a close palaeogeographic relation between the Malaguide and Alpujarride complexes cannot be founded on the existence of intermediate units. |
| Isotopic dating of the post-alpine Neogene volcanism in the Betic Cordilleras, Southern Spain | 1981 | Nobel, F.A.; Andriessen, P.A.M.; Hebeda, E.H.; Priem, H.N.A.; Rondeel, H.E. | 60(2) | The post-Alpine lamproitic volcanism in the Prebetic of the External Zone of the Betic Cordilleras of southern Spain is dated at 7.6-7.2 Ma by the K-Ar data from two richterites, two sanidines, a phlogopite and a whole-rock, and the fission-track analysis of an apatite. Biotite from a lava of the rhyolitic-dacitic suite in the post-orogenic Vera basin of the Internal Zone produces the same age. Phlogopite from a lamproitic (veritic) subvolcanic body in the Vera basin yields an age of about 8.6 Ma; as lavas belonging to the veritic suite reportedly overlie Late Messinian sediments, pointing to an age of less than about 5 Ma, this type of volcanism in the Vera basin must have been active over several million years |
| Water-supply constraints on oil sufficiency through heavy-oil development by western Canadian oil industry | 1981 | Ryckborst, H. | 60(2) | A serious effort to restore Canadian oil sufficiency would require the offset of oil imports at a rate of 600,000 barrels per day plus the balancing of a 15% annual decline in present light-oil production. Oil sufficiency may require significant developments of offshore frontier oil, but also the phased construction of one to six world-scale heavy-oil production and upgrading units. In onshore Western Canada heavy oil has been found in abundance in Western Canadian areas where water deficiency prevails. World-scale heavy-oil plants require the implementation of large-scale diversions of fresh river water ranging from 2-22 m3/s. Additional off-line storage reservoirs sized from 5-170 million m3 would also be necessary to provide security of water supply from the North Saskatchewan River during the low-flow winter months and to avoid high-flow sedimentation problems. Super-large on-line water-storage schemes, considered 15 years ago, would reduce the need for off-line water storage, but would encompass construction of some eight large dams and diversion canals at a cost of 14 billion dollars. Development of economic water-recycling technology appears essential and realistic in the overcoming of water supply constraints to Canadian oil sufficiency. |
| The shallow structure of the Roggenplaat (The Netherlands) as deduced from High-resolution multi-channel seismic profiling | 1981 | Herber, M.A.; Runia, D.J.; Helbig, K. | 60(2) | High-resolution seismic profiling requires special instrumentation and special acquisition techniques, with a high-frequency source being the key factor. In a feasability study on the Roggenplaat, a tidal flat in the mouth of the Oosterschelde (SW Netherlands), the CDP-method was applied using standard recording equipment together with a specially developed weight-drop unit. On areas with a high clay content results were obtained which were, in principle, good enough for a detailed investigation of the upper 120 m. However, due to the lack of well control in the area of investigation, only two major interfaces could be identified with some confidence. The registration techniques used can be easily improved by using digital enhancement seismographs with digital recording on magnetic tape. However, the resolution obtained (about 2-3 m) can be repeated only in areas where the surface conditions are comparable to those of the survey area on the Roggenplaat: no weathered layer, high clay content, and a nearly complete water saturation. |
| A theory of compound decisions on mill-dump cutoff grades | 1981 | Schaap, W. | 60(2) | For a large-scale mine and concentrator, working a low-grade orebody by open-pit methods, the mill-dump cutoff grade decision is of crucial economic importance. Lane has provided a sound theoretical basis for this decision-making. His approach to the problem is extended to allow for the effect of taxation, and to include deliberate decisions concerning the concentrator operations that must be taken in conjunction with the cutoff grade selection for optimal overall results. The cutoff grade decision is thus seen as a compound decision upon which the government is able to exert influence through its tax formula It is assumed that a grade distribution is available for selective mining units, as well as mathematical expressions that describe the processes of comminution, liberation of valuable mineral from gangue, and mineral recovery by separation from gangue. Typically, the operation may be thought of as the mining and processing of the massive chalcopyrite-bornite zone of a poryhyry orebody. Apart from its operational use, the theory enables the identilication of taxation schemes that enhance overall mineral recovery and government revenue, without affecting the economic feasibility point of the operator. Two simple tax formulae that achieve this are discussed. |
| Outlines of the stratigraphy and structural framework of Southern Dhofar (Sultanate of Oman) | 1981 | Hawkins, T.R.W.; Hindle, D.; Strugnell, R. | 60(2) | Recently drilled deep water wells have provided new information of the succession and structure of Southern Dhofar. A small segment of the Pan-African Shield, composed of acid gneisses, granites, pegmatites, aplites and a basic dyke swarm underlies the Mirbat Plain. Furthermore, two windows of bedded basement rocks occur in south-west Dhofar. A restricted development of post-basement Palaeozoic clastics occurs as the Mirbat Formation, which may equate with the Ordovician to Permian Haima Formation elsewhere in Oman. The Cretaceous sequence (Mahra Group) is similar to that found in eastern South Yemen, except that a newly defined mixed clastic and carbonate Qamar Formation is recognized. The Kenozoic succession broadly resembles that of South Yemen and much of Saudi Arabia and the Gulf area. Structures in the post-basement rocks are: east-northeast trending folds which commenced in middle Eocene times, north-south open folds and arcuate normal faults subparallel to the coastline, associated with the Gulf of Aden Rift. |
| The crustal structure and evolution of the continental margin off Senegal and the Gambia, from total-intensity magnetic anomalies | 1981 | Linden, W.J.M. van der | 60(2) | Magnetic anomalies over the Cape Verde Basin and the continental margin off Senegal and The Gambia help define the boundary between oceanic crust and attenuated continental crust. Development of the Atlantic continental margin in the region through continental fragmentation, rifting, attenuation and subsidence began presumably in Early Mesozoic, or possibly in Palaeozoic time. Sea-floor spreading and formation of oceanic crust started in the Middle Jurassic. Later, during the Middle Tertiary, after initial uplift, the oceanic and transitional lithosphere off West Africa cracked into a set of fissures through which deep seated magmas intruded abundantly into overlying Mesozoic and Tertiary sediments and in places threw up substantial volcanic mounts. It is suggested that the origìn of the Cape Verde Rise and Cape Verde Islands is also due to this process, which is probably related to African and Eurasian plate collision. |
| Osumilite, an approximately 970 Ma old high-temperature index mineral of the granulite-facies metamorphism in Rogaland, SW Norway | 1981 | Maijer, C.; Andriessen, P.A.M.; Hebeda, E.H.; Jansen, J.B.H.; Verschure, R.H. | 60(2) | In SW Norway mineral assemblages in metapelites indicate three stages of Precambrian high-grade metamorphism, M-1, M-2 and M-3. An osumilite-in isograd is recognized in the higher-grade part of the M-2 high-temperature granulite-facies aureole surrounding the Bjerkreim-Sokndal lopolith. Osumilite separated from a metapelite yields K-Ar and Rb-Sr cooling ages of 987 ± 30 Ma and 952 ± 25 Ma, respectively, indicating that it may be a suitable mineral for isotopic dating with a closure temperature to Rb-Sr and K-Ar similar to or slightly higher than that of hornblende to K-Ar. |
| Frost cracks of the Saalian age near Lunteren (The Netherlands) | 1981 | Meer, J.J.M. van der; Semeijn, J. | 60(2) | |
| First record of typhine gasteropods from the Eocene of southeastern Nigeria | 1981 | Arua, I. | 60(2) | Siphonochelus nigeriensis sp. nov., found in the Eocene Ameki Formation of southeastern Nigeria, is described and figured. With four smooth varices and tubes which are incorporated into it per whorl, and which are nearer to succeeding than to preceding varices, it is a typical siphonochelus. This is the first record of fossil typhine gasteropods from African strata and therefore seems to be of considerable interest, also from a palaeobiogeographical point of view. |
| Recent uplift in Northern Cyprus | 1981 | Dreghorn, W. | 60(2) | Geomorphological, geological and archaeological evidence suggest that the coast of Northern Cyprus has undergone about 1 m of uplift since the Byzantine period (330-1100 A.D.). This movement forms part of the intermittent uplift that has affected the area since the Pliocene and that has produced a series of intertidal platforms and terraces. |
| Quaternary geology: a farewell to A.J. Wiggers - preface | 1981 | Hageman, B.P. | 60(3) | |
| Introduction | 1981 | Loon, A.J. van | 60(3) | |
| Holocene shorelines in Britain: recent studies | 1981 | Jardine, W.G. | 60(3) | Recent studies of Holocene shorelines in Britain have included only a few investigations of the nature and positions of shorelines, but five individual categories of mappable shorelines may be recognised. Shorelines in relation to vegetation and to marine transgression and regression have been subjects of extensive study along several parts of coastal Britain. Vegetational change may denote marine transgression or regression but need not denote changes of sea level. Similarly, marine transgression and regression are changes in the position of the land/sea interface rather than events determined by changes of global sea level. About half of the recent shoreline studies in Scotland have been concerned with the gradients of tilted shorelines. A growing interest is the relationship between former shorelines and sites of early human occupation. Few investigations have been concerned primarily with the chronology of Holocene shorelines. |
| Quaternary glaciation and changes of sea level in the south Ireland | 1981 | Synge, F.M. | 60(3) | In the south of Ireland the glacial succession consists of two major glacial episodes (Munsterian and Midlandian), considered to be Elsterian (or Saalian) and Weichselian respectively. These are separated from each other by two phases of high sea level along the south coast, at 72-73 m and 3-5 m above present mean sea level. Foci of local glaciation were particularly prevalent in highland areas outside the limits of the Midlandian ice sheet. |
| Were there locally two ancylus stages in the Baltic? | 1981 | Königsson, L.K. | 60(3) | Radiocarbon dates from shells in Ancylus fluviatilis bearing deposits on the islands of Öland and Gotland in the Baltic are reported. The deposits are situated at a much lower altiltude than the Ancylus limit for the two islands and have been dated at the pre-Boreal pollen zone (IV, Jessen). Ancylus layers in Finland have been dated at approximately the same ages. In 1927 the Early Ancylus Substage (A I) was defined by Thomasson for the pre-Boreal. It is suggested that the numerous deposits on the Island of Gotland with 'too low' Ancylus faunas should be studied for further evidence of pre-Boreal age, and to elucidate the question of whether these finds belong to the classical Ancylus stage or to an earlier stage separated from the classical by the Yoldia stage. |
| The marine Pleistocene sediments in the Flandrian area | 1981 | Paepe, R.; Baeteman, C.; Mortier, R.; Vanhoorne, R.; Centre for quaternary stratigraphy | 60(3) | A review of the Pleistocene marine stratigraphy of the Belgian coastal plain is given, including a critical discussion of the formerly used nomenclature. A stratigraphical revision of formations introduced in the first edition of the legend of the Geological Map of Belgium is made. Hence the Oostende Formation (type locality Oostende) stands for marine deposits of Eemian age, the Herzeele Formation (type locality Herzeele in France) stands for marine deposits of both Holsteinian and 'Cromerian' age. In the Flemish Valley as well as in the eastern part of the coastal plain both formations are found to exist generally superposed. Here the Zeebrugge Member of the Herzeele Formation is introduced to indicate marine deposits with Corbicula fluminalis and Tapes senescens var. eemiensis. Neither fossils are therefore considered as solely belonging to the Eemian stage. |
| Natural C-14 variations and consequences for sea-level fluctuations and frequency analysis of periods of peat growth | 1981 | Jong, A.F.M. de; Mook, W.G. | 60(3) | The rise in sea level during the past 18,000 years has been studied largely by means of radiocarbon dating. The question of whether small fluctuations are superimposed on the steadily rising sea level is discussed. Support for this is the observed succession of clastic deposits and peat layers, resulting from alternating periods of transgressive and regressive activity. However, irregularities in the 14C time scale might not only give rise to apparent steps in the relative sealevel rise, but also to clustering of 14C dates of geological finds at certain 14C intervals. Therefore, until there is more evidence the succession of clastic deposits and peat layers is interpreted as caused by local disasters at certain times and random regressive peat growth during quiet periods. |
| Fluvial sedimentation from the Fennoscandian area into the North-West European Basin during the Late Cenozoic | 1981 | Bijlsma, S. | 60(3) | Late Cenozoic deposits in the North-West European Basin with a typical gravel composition, called the Baltic Gravel Assemblage, have been studied from the literature and in the field. The gravel indicates a provenance from the Fennoscandian area and is characterized by a high proportion of translucent quartz and the presence of silicified palaeozoic sediments. From the available data it is concluded that one river system, called the Baltic River System, was the transporting agent of the Miocene, Pliocene and Pleistocene deposits containing the Baltic Gravel Assemblage. In the Miocene the sedimentation was to the south and west. From-the Late Miocene into the Early Pleistocene the main transport was towards the west. The Baltic River system was destroyed by the inland-ice of the Menapian glacial. |
| Summer thaw depths in cold regions and fossil cryoturbation | 1981 | Maarleveld, G.C. | 60(3) | An analysis of data from the literature, on summer thaw depths and cryoturbation in present-day cold areas, shows that the thickness of fossil cryoturbated deposits cannot be correlated to the July temperature of that time. It is suggested that the thickness of fossil cryoturbated deposits has been positively influenced by thermokarst. |
| Problems of holocene lithostratigraphy | 1981 | Loon, A.J. van | 60(3) | Many lithostratigraphic units have been introduced in the geological literature without clear definitions. This has led to serious problems, especially in cases where various authors have used the same name with apparently different meanings. Holocene lithostratigraphy knows the same problem, but there are two more important disturbing factors: (1) many sedimentary units are still being formed, thus prohibiting a unit delineation on the basis of both the lower and the upper boundary; (2) much field work is carried out by scientists who are interested in the ecological and sedimentary development of the area or in the land-use potential rather than in its purely stratigraphic aspects. This implies that the existing definitions are often based upon a non-lithostratigraphic aspect. In order to solve these problems it is suggested that Holocene lithostratigraphic units should be defined by their lower boundary and their lithological characteristics. Some examples are mentioned to illustrate the practical and theoretical possibilities. |
| Fresh and salt groundwater in the Dutch coastal area in relation to geomophological evolution | 1981 | Vries, J.J. de | 60(3) | Historical sequences of encroaching seawater and recharge of fresh water under different geological and geomorphological conditions during the Quaternary are responsible for a rather complicated distribution of fresh and salt groundwater in the Dutch coastal area. A qualitative genetic model is propoped based on the Holocene landscape evolution. |
| Stratigraphy, palynology and radiocarbon dating of middle and late Weichselian deposits in the Drentsche AA valley system (Drente, the Netherlands) | 1981 | Gans, W. de; Cleveringa, P. | 60(3) | A survey is given of the Middle Weichselian (Pleniglacial) and Late Weichselian (Late Glacial) deposits found in the Drentsche Aa valley system. The middle Pleniglacial succession consists of humic loam layers wich are interpreted as thaw lake deposits. The upper Pleniglacial coarse fluvial sand is correlated with the lower part of the Beuningen Gravel Bed. Late Glacial aeolian and slope deposits cover these Pleniglacial deposits and relief. The tentative stratigraphic interpretation of these valley sediments is based on superposition and palynological data of pollen-bearing organic levels. However, the radiocarbon dates from the thaw lake deposits do not agree with this interpretation. Possible causes are discussed. |
| Structure and genesis of a buried ice-pushed zone near Rold (Funen, Denmark) | 1981 | Schwan, J.; Loon, A.J. van | 60(3) | In the Rold area indications have been found for two subsequent Weichselian ice transgressions: an older one from the SE and a younger one from the N or NE. The older ice advance could be inferred from the presence of partly buried and distorted glacial sediments which are exposed in four sand and gravel pits. The steeply tilted and strongly folded beds share an almost identical NW vergence at all four sites the farthest of which are 2 km apart. Where buried the distorted glaciofluvial beds are unconformably overlain by fine-textured glaciolacustrine deposits, ill-sorted solifluction material or both. The younger glacierization phase is evidenced by both oriented surface features with roughly NW-SE trend and by scattered glaciolacustrine surface deposits. Together these two phenomena appear to form a time-correlative complex of deglacial origin. Various glacitectonic classes are discussed in older to evaluate the ice-push event associated with the older ice transgression. |
| Interaction between wind and sand surface | 1981 | Vugts, H.F.; Cannemeijer, F. | 60(3) | Sand transport takes place when the wind speed is higher than some critical value. When the wind speed is not too high and the sand has a monodisperse size distribution it is possible that ripples are formed. Simple relationships are derived between the wavelength of the ripples, the sand-grain motion, and the increase in drag due to sand transport. The theoretical results are in agreement with field observations. |
| Sea level, groundwater, and basal peat growth - a reassessment of data from the Netherlands | 1981 | Plassche, O. van de | 60(3) | An analysis is made of the relative time-depth positions for published data from the base of the so-called Lower Peat in The Netherlands. Development of this peat is generally linked with the Holocene sealevel rise. Emphasis is placed on the location of samples with respect to pre-existing subsurface topography. This factor is thought to govern the moment at which peat formation commenced at a given site. However, in those cases where topographical influence has been small, it becomes apparent that other (dynamic) factors, such as seepage and local tides, in fact control the initial time-depth position of Lower Peat growth. |
| Palynological investigations of Eemian deposits in the Drentsche AA area (Drenthe, the Netherlands) | 1981 | Paris, F.P.; Cleveringa, P.; Gans, W. de | 60(3) | Two organic layers from the Upper Pleistocene of the northern Netherlands are investigated in detail for their pollen content. Comparison of the pollen diagrams with the standard Eemian biozones indicates that the continental peat growth and/or accumulation of organic material (mor) started during the E4/E5 phase. A hiatus in the deposits with an Eemian age is discussed. |
| Stratigraphy and genesis of Pleistocene deposits at Alphen (southern Netherlands) | 1981 | Vandenberghe, J.; Krook, L. | 60(3) | A detailed study was carried out on a large outcrop at Alphen in the southern Netherlands. At the base fluvial, gravel-bearing sands were found with a stable heavy-mineral association. These deposits, referred to as 'Alphen Sands', are of Early or Middle Pleistocene age. They are overlain by Eemian peat and Weichselian aeolian deposits. Besides loamy coversands, the latter comprise a compact aeolian loam layer, fine dune sands and superficially reworked coversands. During two separate periods the sediments have been subject to periglacial deformations under permafrost conditions. Furthermore they show two gravel pavements. Mineralogically they are characterized by an association of both stable and unstable heavy minerals, probably indicating a mixture of allochthonous Rhine-derived sediments and more or less local deposits. |
| An areal classification by means of cluster analysis using abiotic landscape data | 1981 | Hof, G.T.A.; Reiling, R.; Zilverberg, E.; Levelt, T.W.M. | 60(3) | For an area NW of Roermond, province of Limburg, a landscape classification has been developed on the basis of four variables: loam content of the soil, water-table class, soil type and altitude. The presented variables are more or less associated with each other. A hierarchy of the variables, which implicitly means the existence of an overall theory of landscape genesis, has not been used. The classification was performed by means of cluster analysis and reflects the association between the variables in the structure of the agglomerative legend system. For every desired number of groups the legend system gives the mapping units, which have a maximum homogeneity for the combinations of the variables. With the graphical facilities of the computer programme a map can be drawn at any desired grouping level. As an example, the grouping level 8 is discussed in the text. |
| Earth-science conservation: no science without conservation | 1981 | Gonggrijp. G.P.; Boekschoten, G.J. | 60(3) | The first call for the conservation of geologically important sites in The Netherlands was made by Van Baren in 1908. In the decade that followed, some reserves were established, mainly through the efforts of interested individuals as no lead was given by the professional societies and only a few scientists chose to play an active role. Further, those conservation societies which were in existence and in receipt of support from numbers of professional scientists, had interests which were largely confined to biological features. It was not until 1969, when the Gea working group was inaugurated, that systematic governmental involvement in earth-science conservation began. Descriptive inventories of sites of scientific and/or educational value are produced province by province; in addition special reports dealing with individual sites threatened with destruction are also prepared. Some case histories in geological conservation are outlined in this paper. |
| Weichselian pingo remnants and permafrost on the Drente plateau (the Netherlands) | 1981 | Gans, W. de; Sohl, H. | 60(3) | Geomorphological and geological investigations on closed topographic depressions and valley systems on the Drente plateau allow correlations to be made between the location of pingo remnants on the plateau and the Weichselian drainage pattern. In general, the depth of the remnants varies between 2 and 7 m, but locally the geological structure of outcropping sediments is responsible for the development of extremely deep pingo remnants, reaching a maximum of 17 m. This figure gives a tentative estimate of the minimum depth of the permafrost then prevailing, |
| Radiocarbon dating of vegetation horizon, illustrated by an example from the holocene coastal plain in the northern Netherlands | 1981 | Schoute, J.F.T.; Griede, J.W.; Mook, W.G.; Roeleveld, W. | 60(3) | Radiocarbon dating of vegetation horizons (fossil A0/A1-soil horizons occurring within the younger Holocene marine deposits) is subject to contamination by old carbon which forms part of the sedimentary matrix. Samples of recent mud from several locations in The Netherlands give apparent radiocarbon ages of up to 5900 years BP, demonstrating that a significant ageing effect may occur. Notably the age of the organic residue, left after alkali pretreatment of the sample of vegetation horizons, is affected by this contamination. A substantial part of the total amount of the organic matter in these vegetation horizons consists of humic substances. Since the larger part of these humic substances has actually been formed in situ by humification of fresh organic material. it is to be expected that radiocarbon dating of humic substances (dissolved in the alkaline extracts) gives a better indication of the true age of the vegetation horizons than the dates from the (apparently too old) residues. This hypothesis is compared to geological evidence in the coastal plains of the northern Netherlands and of Suriname. |
| #REF! | 1981 | 60(3) | ||
| From the editors | 1981 | 60(4) | ||
| Middle East: stratigraphic evolution and oil habitat | 1981 | Murris, R.J. | 60(4) | The post-Hercynian sequence of the Middle East is dominated by carbonate sedimentation on a stable platform flanked on the northeast by the Tethys ocean. Two principal types of depositional systems alternated in time: (1) ramp-type mixed carbonate-clastic units and (2) differentiated carbonate shelves. The first type was deposited during regressive conditions, when clastics were brought into the basin and resulted in 'layer-cake' formations. The second type was formed during transgressive periods and is dominated by carbonate cycles separated by lithoclines, time-transgressive submarine lithified surfaces. Differentiation is marked, with starved euxinic basins separated by high-energy margins from carbonate-evaporite platforms. The tectonic development of the Middle East can be divided into several stages. The first stage, which ended with the Turonian, was characterized by very stable platform conditions. Three types of positive elements were dominant: (1) broad regional paleohighs, (2) horsts and tilted faults blocks trending NNE-SSW, and (3) salt domes. All three influenced deposition through synsedimentary growth. The subsequent stage, from Turonian to Maestrichtian, was one of orogenic activity, with the formation of a foredeep along the Tethys margin and subsequent ophiolite-radiolarite nappe emplacement. From the late Cretaceous to the Miocene the platform regained its stability, only to lose it again at the close of the Tertiary, when the last Alpine orogenic phase affected the region, creating the Zagros anticlinal traps. Source rocks were formed in the starved basins during the transgressive periods. Marginal mounds, rudist banks, oolite bars and sheets, and regressive sandstones form the main reservoirs. Supratidal evaporites and regressive shales are the regional seals. The spatial arrangement of these elements and the development of source maturity through time explain the observed distribution of the oil and gas fields. |
| Ordovician rocks in the Oman mountains: the Amdeh formation | 1981 | Lovelock, P.E.R.; Potter, T.L.; Walsworth-Bell, E.B.; Wiemer, W.M. | 60(4) | Recent work in the Saih Hatat region of the Oman Mountains has established an early Ordovician age for the Amdeh Formation. This dating is based on assemblages of brachiopods, trilobites, and lamellibranchs together with microflora and trace fossils from several localities. The formation comprises a sequence of shallow marine clastic rocks at least 3400 m thick which has been measured in detail in Wadi Kahza, some 40 km southwest of Muscat. The sequence may be divided into five members and a preliminary account of the stratigraphy is given, accompanied by illustrations of some of the characteristic sedimentary structures, macrofauna, and trace fossils. The Amdeh Formation is a marine equivalent of the continental to shallow marine sediments of interior Oman and the Saq and Tabuk Formations of Saudi Arabia and southwest Jordan. It has apparently been subjected to Late Paleozoic orogenic movements tentatively related to the Hercynian Orogeny |
| Structural geology of the central Sesia Lanzo zone | 1981 | Passchier, C.W.; Urai, J.L.; Loon, J. van; Williams, P.F. | 60(4) | A synthesis of the metamorphic and structural history of the Central Sesia-Lanzo Zone. (Western Alps) is proposed, based upon detailed mapping. Four lithologic units are distinguished. The metamorphic history can be divided into a pre-Alpine amphibolite facies event, an early Alpine HP-LT event and a late Alpine greenschist facies event. Five generations of folds are distinguished. F0 is probably of pre-Alpine age. F1 produced isoclinal folds, part of the regional foliation and major shear zones along which the lithologic units are brought into their present relative positions. F2, F3 and F4 are subsequent phases of folding, each producing a locally developed foliation. Some F2 folds occur on a km scale and can be seen on the map. F4 might be related to a young, postulated major fold that trends NE-SW through the entire Sesia-Lanzo Zone. A detailed map and three-dimensional interpretation of the major structure in the central Sesia- Lanzo Zone are presented, including a new interpretation of the IIDK body at Mt. Nery.. |
| The Neogene of the island of Euboeda (Evia), a review | 1981 | Katsikatsos, G.; Bruijn, H. de; Meulen, A.J. van der | 60(4) | The Neogene sediments in the three major basins on the Island of Euboea (Evia) (the Aliveri-Kymi, the Palioura-Gides and the Limni-Istiea Basin) show roughly similar lithological successions, but differ in age. Fossil rodent associations show that sedimentation started in the Early Miocene (Early Aragonian) in the Aliveri-Kymi Basin, in the Late Miocene (Vallesian) in the Palioura-Gides Basin and in the Early Pliocene (Early Ruscinian) in the Limni-Istiea Basin. The lignite occurences in the Aliveri-Kymi Basin are shown to be of Early Aragonian (MN3) Age, while those in the Palioura-Gides and Limni-Istiea Basins are assigned a Vallesian (MN10) and Villanyian (MN16) Age, respectively. It is concluded that lignite formation in the area depended primarily on the local circumstances of sedimentation and not on climate. |
| Ore-textural and geochemical features of Bohnerz and Rasenerz concretions in Gutland (Luxembourg) | 1981 | Riezebos, P.A.; Bruin, M. de; Duin, R.P.W. | 60(4) | Rasenerz and Bohnerz concretions from Gutland have been studied geochemically and by reflected light microscopy. The greater part of either type can be characterized by a single microscopic feature: more than 50% of the Rasenerz samples has an oolitic texture which is considered indicative of the Minette Formation; about 65% of the Bohnerz samples displays festoon development that is regarded as a sign of supergene origin. Festoons that occur in ooid-lacking Rasenerz (27%) suggest that Rasenerz also derives in part from destructed iron-bearing crusts. Common population statistics of individual trace element abundances fails to discriminate between the two types, but a statistical interpretation of 13 normalized concentrations enables their distinction. When clustered on textural grounds into oolitic Rasenerz, festoon-bearing Rasenerz, and festoonbearing Bohnerz categories, only the Na values of the first and the second category are significantly different. Especially on the basis of the rare earth chemistry, the festoon-bearing Rasenerz and Bohnerz concretions are thought to derive from different surface crusts. |
| Schoonebeek oil field: the RW-2E steam injection project | 1981 | Troost, P.J.P.M. | 60(4) | The Dutch Schoonebeek oil field initially contained 170 x 106 m3 of 25° API crude. primary recovery is low mainly due to the high viscosity of the oil. It varies between 6% of stock tank oil initially in place (STOIIP) in the west (solution gasdrive) to 18% in the east (waterdrive). Research on enhanced recovery began in 1950 and concentrated on thermal processes. As a result hot water injection has been applied on a large scale increasing the recovery of oil by 8% of STOIIP. The performance of hot water injection projects is declining and a gradual switch is being made towards steam injection. Steam injection was applied already in 1960 in a depleted part of the field. In 1972 a pilot project was started to test the feasibility of steam injection in the much larger waterdrive part where pressures are kept at the hydrostatic level of 85 bar by aquifer water influx. This project indicated that steam injection under waterdrive conditions is a very effective recovery process and that a recovery increase of 14% of STOIIP can be obtained at an extra-oil/steam ratio exceeding 0.6 m3/ ton. On the basis of the pilot results a large scale project was designed, the RW-2E steam injection project. It consists of 14 steam injection wells,43 producers and 14 water disposal wells. Steam will be injected at a total rate of about 3000 tons/day for a period of 6 years. Additional oil recovery of the RW-2E,project is estimated at 4 x 106 m3. The maximum additional oil production rate is estimated at 1500 m3/day. During the design and construction of the RW-2E project extreme care was taken to minimise the impact of the project on the environment. The project started in January 1991. Total project life is estimated at 15 years. |
| Carbon-oxygen stable isotope stratigraphy of the Cretaceous-Tertiary boundary interval; data from the Biarritz section (SW France) | 1981 | Romein, A.J.T.; Smit, J. | 60(4) | The patterns displayed by the ratios of stable Carbon and Oxygen isotopes of calcareous nannofossil assemblages from the Cretaceous-Tertiary boundary interval in a section near Biarritz closely match those from the same interval in the Gredero section (SE Spain). The data give additional support to the occurrence of a catastrophic event at the end of the Cretaceous that was probably coupled with a drastic increase in temperature and a decrease in marine phytoplankton productivity. |
| The Northeastern Bering Shelf: New perspectives of epicontinental shelf processes and depositional products - An introduction | 1982 | Nelson, C.H.; Nio, S.D. | 61(1) | |
| Late Pleistocene - Holocene transgressive sedimentation in deltaic and non-deltaic areas of the Northeastern Bering epicontinental shelf | 1982 | Nelson, C.H. | 61(1) | The distribution of late Pleistocene and Holocene surface sediments on the northern Bering Seafloor is patchy and dependent upon locations of seafloor bedrock and pre-late Pleistocene glacial debris, late Holocene river sediment influx, and modern strong bottom currents. Seafloor vibracores and high-resolution profiles record two different sedimentary environments in the northern Bering shelf: late Pleistocene-Holocene shoreline transgression (<16.000 years BP) in Chirikov Basin, and Holocene deposition from the Yukon River in Norton Sound. Lag gravels remain exposed on the margins of Chirikov Basin where the transgression of the late Pleistocene-Holocene shoreline reworked pre-Quaternary bedrock and Pleistocene glacial moraines. In central Chirikov Basin. the transgressive deposits cover Pleistocene limnic peaty mud of emergent shelf deposition. In places, a few centimeter thick basal transgressive facies of pebbly Medium or fine sand is left above which is a widespread sheet of thin (< lm) inner-shelf fine-sand facies. Water circulation patterns have inhibited deposition of Holocene Yukon River silt over trangressive sand and lag gravels of Chirikov Basin. About 10.000 BP. a rapid marine transgression caused the deposition of a basal nearshore facies of thick storm-sand layers in marine silt over the Pleistocene freshwater peaty mud of Norton Sound. This has been covered by an offshore bioturbated silt. A younger progradation of thick storm-sand lavers and Holocene brackish-water silt (up to 14 m) in southern Norton Sound has been deposited since a shift of the active Yukon Delta into its present position about 2.500 BP. |
| Microfaunal analysis of the Late Quaternary deposits of the Nortern Bering Sea | 1982 | McDougall, K. | 61(1) | Holocene microfaunal associations and distribution patterns define three inner-shelf (<20m) biofacies in Norton Sound, northern Bering Sea. The first biofacies is composed of typical bay faunas dominated by the species Eggerella advena, Buccella frigida, Ammotium cassis, and Reophax dentaliformis. The second biofacies contains bay to inner-shelf faunas indicative of deeper, more marine waters; such inner-shelf species as Reophax arctica, R. fusiformis, Spiroplectammina biformis, and Textularia torquata dominate. The third biofacies, common in deltaic areas with high sedimentation rates and freshwater input, is characterized by abundant Elphidium orbiculare and E. clavatum. The distribution of other microfaunal groups (diatoms, ostracods, tintinnids, and fragments of larger invertebrates and plants) corresponds to current and sedimentary patterns. These Holocene facies relations are the basis for interpreting early Holocene and late Pleistocene environmental conditions in the northeastern Bering Sea area. Within older deposits the sequence of biofacies can be used to interpret the Holocene transgressive cycle in Norton Sound. Norton Sound cores provide evidence of two marine transgressions and a varying river input. |
| Sedimentary structures on a delta-influenced shallow shelf, Norton Sound, Alaska | 1982 | Howard, J.D.; Nelson, C.H. | 61(1) | Sedimentation in an epicontinental sea influenced by deltaic progradation is exemplified by the Norton Sound-Yukon Delta region. Norton Sound is a large embayment of more than 24,000 km2 with water depths of less than 25m. The Yukon Delta. on the south side, is a major North American source of sediment that enters the Sound. Progradational deposits on the seaward part of the delta are highly reworked by storm waves and currents, and serve as a model for a depositional sequence that encroaches on a shallow shelf. To describe the primary physical and biogenic sedimentary structures of the several facies in this embayment, we utilized X-ray radiographs, relief casts, and grain-size analyses of 83 box cores. Primary physical sedimentary structures are best developed in and adjacent to the Yukon Delta and include parallel- and ripple-laminated sand and silt and crossbedded sand. Biogenic sedimentary structures are found throughout Norton Sound and, in the northern part, completely obliterate physical sedimentary structures. Bioturbation close to the northern shoreline suggests that rates of sedimentation there are low. Dominance of physical structures near the delta results from (1) increased wave and current energy in this very shallow water, (2) reduced biological activity in brackish water, and (3) increased rates of deposition. As a result, the Holocene progradational sequence in Norton Sound consists of basal beds with well developed physical structures deposited during lower eustatic sea level, a thin middle interval of bioturbated mud and a thick upper section of structured beds deposited by the prograding delta. |
| Variation in sand body types of the eastern Bering sea epicontinental shelf | 1982 | Nelson, C.H.; Dupré, W.R.; Field, M.; Howard, J.D. | 61(1) | The eastern epicontinental shelf of the Bering Sea is characterized by variations in river and glacial sediment supply, wave energy, tidal range (microtidal to mesotidal). and tidal, geostrophic, and storm-induced currents. These factors, combined with the effect of the Holocene rise in sea level, have resulted in the formation of a complex assemblage of generally linear sand bodies of similar morphology and lithology. but different origins. The sand bodies are large features > 10 km long. found from the present shoreline to tens of kilometers offshore, in water depths up to 50 m. They include modern sand bodies formed by present-day processes. relict sand bodies formed during lower stands of sea level, and palimpsest sand bodies formed under past conditions but modified by modern day processes. Linear tidal sand ridges (5-35 by 1-3 km) which form at the present time in the macrotidal, funnel-shaped Kuskokwim Bay, are oriented perpendicular to the shoreline. enclosed by tidal flat and shelf mud, and sometimes sigmoidal in shape. The modern shore parallel shoals (including barrier islands, 5-10 by 0.5-1 km) form in mesotidal environments, are the smallest of the shelf sand bodies, and typically are bounded bij tidal flat mud inshore and shelf mud offshore. Delta front channels (20-30 by 2-4 km) extend seaward from the modern river distributaries and form sand bodies perpendicular to the shoreline; they are enclosed by graded overbank sandbeds and muds and are characterized by large to small-scale trough-cross lamination. Lee side shoals. (25-100 by 5-25 km) form behind obstructions to unidirectional shelf currents, are the longest, possess the finest grain size, and exhibit the most consistent rhythmic flat lamination of any sand bodies encountered on the Bering shelf. Ancient shoreline shoals are remnant shoreline features paralleling strand lines of lower sea levels; they contain cycles of ripple and trough-cross lamination, alternating with high angle foreset beds formed by modern sand waves that cover crests of these sand bodies. Relict sand and gravel bodies modified from moraines are distinguished by their coarse grain size and irregular size and shape. |
| Depositional and erosional features of the inner shelf, northeastern Bering Sea | 1982 | Hunter, R.E.; Thor, D.R.; Swisher, M.L. | 61(1) | Sonographs and bathymetric profiles from water depths less than 1-5 m in the Nome-Solomon, Port Clarence, and Yukon Delta areas of the Alaskan Bering Sea coast show features generated by waves, currents, and drifting ice. The surficial sediments in the Nome-Solomon and Port Clarence areas range in grain size from sand to boulder gravel and have many surface features visible on sonographs, whereas the sediments off the Yukon Delta are fine sands and silts that have few such features. Materials in the Nome-Solomon and Port Clarence areas have been segregated by grain size into ribbons and irregular, elongate, and lobate patches. The sand patches commonly have convex-up profiles and probably rest on gravel lag deposits that are exposed in adjacent gravel patches. Coarse sand and fine gravel patches and ribbons are characterized by symmetrical ripples, spaced 0.5 to 2 m apart, that could only have been generated by storm waves. Gravelly sand waves in the Nome-Solomon area were formed by westward shore-parallel currents. Boulder gravel ridges in this area are of unknown origin. Sand and gravel ribbons are common near the entrance to Port Clarence. Unlike ribbons elsewhere, which have been attributed to tidal or other currents. the ribbons in the port Clarence area show features suggesting generation by storm waves. These ribbons are oriented approximately normal to the associated large wave ripples, and both the ripples and ribbons vary in orientation in ways that can be explained as effects of wave refraction over a shoaling bottom. Ribbonlike features of unknown origin occur locally on the Yukon delta front. Ice-gouged furrows, though less common than in areas farther offshore. occur in all the nearshore areas studied. The gouges are 5 to 15 m wide, as much as hundreds of meters long. and usually less than 0.25 m deep. |
| Depositional environments of the Yukon Delta, northeastern Bering Sea | 1982 | Dupré, W.R. | 61(1) | The Yukon River provides approximately 90% of the sediment presently entering the northeastern Bering Sea. Most of that sediment is initially deposited in Norton Sound, a broad, microtidal embayment typically less than 20 m deep. The shallowness of the depositional basin has allowed extensive reworking of the deltaic sediments by a variety of processes. These include waves, Tidally and wind-induced currents, and oceanic currents, as well as processes associated with the movement and deformation of sea ice. The relative importance of these processes varies systematically throughout the year. The seasonal variability is best described by the definition of an ice-dominated, river-dominated. and storm-dominated regimen. each consisting of a characteristic suite of geologic processes. The morphology of the Yukon Delta also reflects the climatic extremes of this high-latitude, epicontinental sea. The subaqueous profile of the delta differs from most previously described deltas in that the shoreline is separated from the prograding margin of the delta by a 'sub-ice platform' which is typically 2-3 m deep and extends up to 25 km offshore. The platform is crossed by a series of 'sub-ice channels' which extend up to 25 km beyond the mouths of the major distributaries. The platform and associated subaqueous channels are related to the presence of shorefast ice which fringes the delta for half of the year. and appear to be characteristic of ice-dominated deltas formed in high-latitudes. |
| Velocity and bottom-stress measurements in the bottom boundary layer, outer Norton Sound, Alaska | 1982 | Cacchione, D.A.; Drake, D.E.; Wiberg, P. | 61(1) | We have used long-term measurements of near-bottom velocities at four heights above the sea floor in Norton Sound, Alaska, to compute hourly values of shear velocity u., roughness zo. and bottom-drag coefficient cD. Maximum sediment resuspension and transport, predicted for periods when the computed value of u- exceeds a critical level, occur during peak tidal currents associataed with spring tides. The fortnightly variation in u, is correlated with a distinct nepheloid layer that intensifies and thickens during spring tides and diminishes and thins during neap tides. The passage of a storm near the end of the experiment caused significantly higher u, values than those found during fair weather. We attribute these increases in u. to stronger bottom currents and larger surface waves |
| Distribution of gas-charged sediment in Norton sound and Chirikov basin, northeastern Bering Sea | 1982 | Holmes, M.L.; Thor, D.R. | 61(1) | Numerous zones of anomalous acoustic responses caused by gas in the subsurface sediment layers have been detected on seismic reflection records from Norton Sound and Chirikov Basin. Sound sources used range in size and power from 3.5 kHz transducers to 1326 in3 (21.71) air gun arrays. The frequency and distribution of these zones suggest that as much as 7000 km2 of the northeastern Bering Sea may be underlain by gas-charged sediment. Much of the gas is of shallow biogenic origin, having been generated in buried peat deposits. Compressional velocity is about 1.5 km/s in these Iayers. 7 percent below the velocity in gas free areas as determined from seismic refraction studies. Seismic velocity beneath a large gas seep south of Nome decreases to about 1.2 km/s in the interval from 250 to 440 m below the seafloor. where thermogenic gases of deeper origin are migrating upward along a system of basin margin faults. |
| Geotechnical characteristics of bottom sediment in the northeastern Bering Sea | 1982 | Olson, H.W.; Cluckey, E.C.; Nelson, C.H. | 61(1) | Sediment of Holocene age derived from the Yukon River, consisting dominantly of silty fine sand and sandy silt, covers the bottom of central and western Norton Sound, which is a high energy environment involving extensive ice loading, high waves, and strong bottom currents. The sediment contains significant amounts of sand in some areas and a generally minor amount of clay-size material ranging from 0 to 20 percent. Moreover, the sediment is generally dense, although loose and weak zones occur at the surface and also at depth between relatively dense layers. These characteristics, evidence of storm sand layers and scour depressions, and the results of preliminary analytical studies indicate that this sediment is susceptible to liquefaction during major storms. Substantially finer grained, weak, and highly compressible sediment of Holocene age, derived from the Yukon River and from local rivers and streams, covers eastern Norton Sound and the Port Clarence embayment, which are low energy environments with negligible ice loading, low waves, and weak bottom currents. Transgressive deposits of late Pleistocene age that cover the bottom of Chirikov Basin include an inner-shelf fine sand underlain by a basal transgressive medium sand that is exposed on the north and east flanks of the basin. Geotechnical data in the latter, obtained in the sand waves fields near Port Clarence, show that the material is loose near the surface but becomes firm rapidly with depth and could not be penetrated more than about 3 m with the Alpine vibratory corer. Pleistocene peaty deposits underlie the Holocene and late Pleistocene deposits in both Norton Sound and Chirikov Basin and are somewhat overconsolidated, probably because of subaerial desiccation during low sea level stands in the late Pleistocene. These materials have a higher clay content than the overlying deposits and they contain substantial amounts of organic carbon and gas. The presence of gas suggests that in situ pore pressure may be high. If so, the strength of the material could be low even though the material is generally overconsolidated. |
| The North Sea and northeastern Bering Sea: a comparative study of the occurrence and geometry of sand bodies of two shallow epicontinental shelves | 1982 | Nio, S.D.; Nelson, C.H. | 61(1) | The present-day shallow marine basins can be subdivided into marginal and epicontinental shelf areas. The occurrence, geometry and formation of large sand bodies in the southern bight of the North Sea and the Chirikov Basin in the northeastern Bering Sea are discussed here. The North Sea is mainly used as an example for reconstructing a sedimentation model. The large sand bodies which occur in the two basins consist of a lower sequence of sand banks and an upper sequence of stacked sand waves. The geometry and arrangement of the different lithotypes are not only controlled by the latest sea level rise, but also by the basin geometry. Peripheric basins. such as the southern bight of the North Sea show a concentric aggradational pattern; semi-peripheric basins. such as the Chirikov Basin, show an onlap pattern. Based on data from the North Sea and partly from the Chirikov Basin a hypothetical stratigraphic cross section is constructed which can be used for interpreting ancient analogues. |
| In memoriam - Dr. Ernst Kündig | 1982 | Murris, R.J. | 61(1) | |
| #REF! | 1982 | 61(1) | ||
| Terminology and lithostratigraphic division of (surficial) sandy eolian deposits in the Netherlands: an evaluation | 1982 | Koster, E.A. | 61(2) | The terminology of the eolian sand deposits and related form and relief types in The Nethertands is reviewed and evaluated. Because there is as yet no consensus on the criteria for a division of eolian sediments into lithostratigraphic units, the various lithological properties of the following 'sand types' are discussed: Younger and Older Coastal Dune Deposits of the Westland Formation, (Younger and) Older River Dune Deposits of the Kreftenheye Formation, Younger and Older Cover Sand Deposits of the Twente Formation, Older Inland Dune Deposits of the Twente Formation and Younger Inland Dune Deposits of the Kootwijk Formation. Geomorphological criteria, that can facilitate in distinguishing between these seemingly homogeneous 'sand types', have been summarized. A simplified lithostratigraphic division of surficial eolian sediments into three formations is tentatively proposed. |
| Late Tertiary and Quaternary coastal landscape development of the Kroya Beach ridge area (South Java, Indonesia) | 1982 | Goffau, A. de; Linden, P. van der | 61(2) | Topographical, lithological and paleo-pedological features enable the reconstruction of the Late Tertiary and Quaternary development of the Kroya coastal plain. Climatic changes and sea level fluctuations during the Pleistocene, and tectonic and volcanic activity which persisted up to the present, are the main factors that determine the current morphology of the area. The coastal plain represents a horst-graben structure, both in an east-west as well as in a north-south direction. The central part is characterized by a Pleistocene beach ridge complex which is covered by younger volcanic ashes, and which is bordered to the east, north, and west by the lagoonal-fluvial sedimentation areas of the grabens. Only to the south there is an almost uninterrupted southward extending Holocene beach ridge system. |
| Size shape and origin of the sands of the East Frisian Islands (North Sea, Germany) | 1982 | Veenstra, H.J. | 61(2) | Beach and dune quartz sands of the East Frisian Islands (Germany) demonstrate an irregular tendency of coarsening eastwards. The sands contain flint, feldspar and igneous fragments. The sediments of the offshore probably determine grain-size of the sands: the coarse fractions are derived from reworked Pleistocene sands at Borkum Rough and Wangerooge Ground. On each island the dune sands form one population in size and shape. By means of rollability analyses it appears that the dune sands are more angular than their source, the beach sands. |
| Location, age and origin of pingo remnants in the Drentsche AA valley area (The Netherlands) | 1982 | Gans, W. de | 61(2) | Cross sections of five pingo remnants in the Drentsche Aa valley area reveal that the remnants are situated on the floors of small Pleniglacial tributary valleys. Lithological and palynological data from organic levels below some ramparts of these pingo remnants suggest growth of most of the pingos in a thaw lake environment. A hydrostatic (closed-system) origin of the pingos is suggested. Radiocarbon data from the organic levels and the Iithostratigraphic position of the ramparts indicate that the pingos developed between 25,000 and 19,000 BP. Transformation of the pingos into pingo remnants was not isochronous, but occurred until the middle Late Glacial (Late Weichselian). |
| Problems in diatom analysis of deposits: allochtonous valves and fragmentation | 1982 | Beyens, L.; Denys, L. | 61(2) | A review of the various sources of allochtonous diatom valves in deposits is given. The importance of these problems in palaeoecological research is discussed and some simple methods for their approach in quantitative analysis are introduced. |
| Till variation in a Weichselian glacial section along the coast of southwest Funen, Denmark | 1982 | Schwan, J.; Ritzema, W. | 61(2) | In a 5 km long coastal cliff section in SW Funen till variation in Weichselian glacial sequences has been studied. In the central part of the exposure the presence of two till units separated by stratified sands and gravels is immediately apparent. Within each of these two units several lateral facies could be distinguished. The lower till unit is a basal till consisting of a massive and a brecciated facies. In the genetically complex upper till unit four different facies are present: two flow till facies, a supraglacial lacustrine facies and a transitional facies. The fourth type has been classified as transitional since it presumably represents a flow till which after its supraglacial deposition has been partly transformed into a subglacial till during a later glacierization phase. This interpretation is based on both the general glacial history of the cliff and specific characteristics of this facies type, primarily its gradual lateral change in sedimentary structure |
| Marine organic-walled microfossils at the Cretaceous Tertiary boundary in the Barranco del Gredero (S.E. Spain) | 1982 | Coninck, J. de; Smit, J. | 61(2) | Assemblages of marine organic-walled microfossils have been studied in four samples (SM 75 -502, -504, -505, and -506) that represent the Maastrichtian-Danian boundary layers in the Barranco del Gredero (S.E. Spain). No sharp changes can be seen in their composition and the marine organic walled microfossils give no indication here at which level the Cretaceous-Paleocene boundary has to be placed.. |
| A Maastrichtian Conchorhynch (Conchorhynchus limburgicus n. sp.; Cephalopoda) from Limburg, the Netherlands | 1982 | Tuuk, L.A. van der | 61(2) | Conchorhynchs (calcareous parts of cephalopod lower jaws) are reported for the first time from the Maastrichtian of Limburg, The Netherlands. These fossil remains are described as Conchorhynchus limburgicus n.sp. |
| The structure of the Northern Umbrian Apennines, Italy | 1982 | Feyter, A.J. de | 61(2) | The structure of the Northern Umbrian Apennines is broadly comparable to the structure of the Alta Romagna to the north. Three major tectono-stratigraphic units can be distinguished. The lower two are the Umbrian parautochthon and the Nero unit. The Nero unit, comprising the Alpe della Luna sequence, can be seen as an internal, southwestern part of the parautochthon, that was thrust upon the external parautochthon to the northeast. The Nero unit was overridden from the southwest by the third tectono-stratigraphic unit, the Tuscan nappe. The structure of the area is complicated by the presence of a structural high, which seems to be related to large, north-south running dextral strike slip faults. It overprints a paleo-high, which is the consequence of the southwest-northeast directed Apenninic orogenic compression. |
| The influence of the development of a Weichselian coversand ridge on the drainage of a river valley in Noord Brabant (The Netherlands); A geomorphological and palynological study | 1982 | Heijnens, M.H.L.G.; Tijssen, J.M. | 61(2) | Pollen analysis of cores from an area with a river valley that is blocked by a coversand ridge shows that the three beds of which the ridge consists were deposited respectively before the Lateglacial, during the Earlier Dryas stadial, and after the Allerød interstadial. During the first part of the Lateglacial the valley was only partly obstructed and occupied by a local Cyperaceae vegetation. Later, from the Earlier Dryas stadial onward, the valley became completely blocked and that resulted in a change in drainage pattern. The pollen diagrams show a local lacustrine environment, caused by the progressing obstruction of the valley. Wetter and drier phases are recorded in the sediments and mark the climatic development during the Lateglacial. |
| Destruction of tests of the foraminifer Sorites orbiculus by endolithic mircroorganisms in a lagoon on Curaçao (Netherlands Antilles) | 1982 | Kloos, D.P. | 61(2) | After reproduction or death, the empty shells of the epiphytic foraminifer Sorites orbiculus, living in a lagoon on Curaçao, sink to the bottom and are there intensively bored by endolithic algae. Fragmentation of S. orbiculus skeletons due to boring algae contributes to the generation of the silt fraction of the sediment; part of the calcareous tests is dissolved. The proportion and composition of Sorites-derived grains in a sediment sample taken in August differ from one taken in February. There is no trace of micritization in or around the bored soritid grains. This suggests that the demolition of a S. orbiculus test by endolithic algae is completed in a few weeks, or at the most in a few months |
| The fauna from Trinil, type locality of Homo erectus; a reinterpretation | 1982 | Vos, J. de; Sartono, S.; Hardja-Sasmita, S.; Sondaar, P.Y. | 61(2) | A reinvestigation of the Pleistocene mammals of Java from the Dubois collection at Leiden sheds new light on the relative age of the Homo erectus localities. The fauna of the type locality of Homo erectus Trinil is older in age than the 'Jetis fauna' of von Koeningsswald, 1934. The latter is similar to the fauna of Kedung Brubus. The Trinil fauna is poor in species with many endemics, which points to little or no faunal exchange with the Asian mainland; it cannot be excluded that during the Pleistocene Trinil was situated on an island. The Kedung Brubus and Jetis faunas are characterized by the presence of new Asiatic elements absent in Trinil. The fauna from the same level as the type locality of Homo modjokertensis is of the Kedung Brubus type and there are no arguments to suppose that this Homo modjokertensis antedates Homo erectus from Trinil. |
| #REF! | 1982 | 61(2) | ||
| The sedimentary facies and setting of eocene point bar deposits, Monllobat formation, southern Pyrenees, Spain. | 1982 | Meulen, S. van der | 61(3) | Point bar deposits from a small, Eocene, molasse-type basin have been studied in detail in order to establish a spatial point bar model, which can be used to locate a vertical section in a threedimensional sence. A model is designed which shows the sedimentation processes in the palaeochannel and the evolution of point bars. However, some of the deposit characteristics can only be explained in terms of the wider, environmental setting. The development of facies and of larger sedimentary features can be recognised in the surface of a meander lobe, associated palaeochannel and fine fill, and in the vertical section of a comparable meander lobe. Most deposits comprise a lower, medium- to coarse-grained sandstone facies with trough-shaped crossbedding (0.15 m thick) and an upper facies with an inclined interbedding of sandstone and mudstone. Epsilon Cross Stratification has been developed extensively. Strong mottling has destroyed most of the sedimentary structures in the upper lithofacies interval. The exposed palaeochannel varies considerably in width and depth. Palaeochannel sediments are well graded in a vertical sense; laterally, however, there is only a minor gradation. During high discharge the lower lithofacies developed on a low platform at the point bar base. The upper facies originated on a steep upper point bar slope. Mud drapes were deposited during falling discharge. During periods of low discharge the upper part of the deposits was exposed to the air and strongly mottled and oxidized. Point bar deposits are arranged in meander lobes. A uniform dip direction often appears in transverse sections. Lateral grain-size variation in these sections can be large. In this respect the relatively coarse, initial part is important. Mud fills are found in the last stage channel. A fine member is present, but not all fine material was deposited by meandering rivers. The meander lobes developed in the distal parts of a small, highly energetic, alluvial system with marked fluctuations in discharge. In the sedimentary basin there was strong tectonic control on the sedimentation. |
| Geochronology of the precambrian in the Amazonas region of southeastern Colombia (Western Guiana Shield) | 1982 | Priem, H.N.A.; Andriessen, P.A.M.; Boelrijk, N.A.I.M.; Boorder, H. de; Hebeda, E.H.; Huguett, A.; Verdurmen, E.A.T.; Verschure, R.H. | 61(3) | The Amazonas region of southeastern Colombia is underlain by the western part of the Guiana Shield. Isotopic age measurements are reported on granites and gneisses of the shield basement, mafic intrusives, and a sequence of rhyodacitic lavas overlying the shield. Rb-Sr whole-rock analysis of 46 granites and gneisses and U-Pb analysis of two suites of zircons and a monazite reveal that during its development the Guiana Shield passed through at least two major orogenic episodes. The present basement was essentially formed during the Parguazan tectonomagmatic episode by large-scale granitic plutonism and metamorphic reconstitution of older crustal material, about 1560-1450 Ma ago. Most of the older isotopic record was obliterated during the Parguazan reworking, but some Rb-Sr whole-rock and U-Pb zircon systems indicate relict ages of at least 1850-1800 Ma, suggesting that the pre-Parguazan crust may be related to the Trans-Amazonian Orogenic Cycle. Rb-Sr and K-Ar analyses of 37 micas from basement rocks which are widely distributed over the area display ages cluster between about 1350 Ma and 1250 Ma; they are attributed to a general resetting of the isotopic systems by the Nickerie Metamorphic Episode about 1300 Ma ago. Evaluation of the Rb-Sr whole-rock data from five mafic intrusives and a suite of six samples from the rhyodacitic lavas suggest ages of about 1200 Ma and 920 Ma, respectively. |
| Further evidence for Devono-Carboniferous rifting in Central Ireland | 1982 | Deeny, D.E. | 61(3) | Based on the body of available data it is argued that the Irish midland Devono-Carboniferous developed as a graben structure of the type currently exhibited at the Red Sea/African and Rhine upwarp systems. Evidence, both data-based and inferential, is drawn from studies of basement framework, regional Devono-Carboniferous stratigraphy and inferred palaeogeography, igneous geology, geophysical (gravity) patterns and known Irish Devono-Carboniferous fault systems. Examples of two of the latter are presented. This Irish central graben is argued to have developed in Late Devonian times along the axìs of a crustal upwarp inferred to have resulted from plate collision during Late Ordivician to Early Devonian times. It is hypothesized that rifting may have been preceeded by possible deepseated carbonatite intrusion along the upwarp axis, possibly coeval with and/or following intrusion of the Late Caledonian Irish granites. Carbonatite evidence may have been subsequently destroyed by intrusion of 'embryonic spreading centre' magmas, so providing a possible explanation for present day regional Irish gravity values. For reasons presently unknown this 'foetal' spreading centre failed, the rift tilled and subsequent (Hercynian) overthrusting and crustal shortening has resulted in Irish regional geology as it is today. |
| Migration of large-scale bedforms and preservation of crossbedded sets in highly accretional parts of tidal channels in the Oosterschelde, SW Netherlands | 1982 | Berg, J.H. van den | 61(3) | Recent large-scale crossbedded sands have been studied in two construction pits of the 'Delta Project' in the Oosterschelde, The Netherlands. The deposits form long crested megaripples of about two metres high at a depth of 4 to 17 metres below Mean Sea Level. Crossbedded sets have been analysed for stand-still phases of megaripple migration during the subordinate tide (pause planes). An average lee side accretion rate ofthe dunes was calculated from the cyclic neap to neap tide change in thickness of the sand layers between successive pause planes. Information on the morphodynamics of the environment of deposition and the rate of accumulation of the discussed units was acquired through some particular sedimentary structures and through the study of series of hydrographic charts of the area. The latter information also strongly suggests a wide occurence of alike sedimentary units in the subsurface of shoals of the Oosterschelde mouth and outer delta. Finally the thickness and the number of the sets in relation to sandwave migration and rate of accumulation is discussed. |
| Lithostratigraphy of the Misool Archipelago, Irian Jaya, Indonesia | 1982 | Pigram, C.J.; Challinor, A.B.; Hasibuan, F.; Rusmana, E.; Hartono, U. | 61(3) | The Misool Archipelago contains one of the most complete and richly fossiliferous Mesozoic sequences in southeast Asia and the southwest Pacific. The excellent exposures offer an opportunity to establish a reference biostratigraphy for the region as well as a detailed lithostratigraphy. Metamorphics form a basement overlain by ?Triassic flysch which was block-faulted and uplifted during the Carnian, after which platform carbonates were deposited followed by a period of non-deposition. Marine sedimentation resumed in the Early Jurassic with fine clastics and bathyal carbonates. Early Cretaceous volcanism was accompanied by a change to a fluvio-deltaic environment. By Tertiary times sediment supply waned and a marine carbonate regime was established. Marl was deposited after Late Oligocene folding and by middle Miocene times a carbonate regime was re-established until Quaternary uplift formed the Misool Archipelago. The Misool stratigraphy is a continuation of the northwestern Australian rift-drift sequence formed during the breakup of northern Gondwana. It provides precise timing for these events and hence vital information for the assessment of hydrocarbon potential. |
| Finite element models of passive continental margins with implications for the initiation of subduction zones | 1982 | Cloetingh, S.; Wortel, R. | 61(3) | Passive continental margins are in general characterized by the lateral contrast between oceanic and continental lithosphere and by the presence of thick sedimentary deposits which cause flexure and stressing of the lithosphere. Passive margins therefore, are potential sites for plate rupture and initiation of subduction. To investigate the evolution of passive margins, we have constructed finite element models, in which we have incorporated a complex system of forces, depth-dependent rheological properties and lateral variations across the margin. Sediment loading generates differential stresses of several kilobars and dominates the state of stress at passive margins. Stresses of this order of magnitude may cause failure of the lithosphere and initiation of subduction. We have found that the aging of passive margins alone does not make them more susceptible to initiation of subduction. However, extensive sediment loading on young lithosphere might be an effective mechanism for closure of small oceanic basins. This phenomenon plays an important role in the process of mountain building. |
| Temperature log analysis with a pocket calculator: interpretation program for discrete temperature logs in small-diameter wells | 1982 | Keet, B. | 61(3) | A program is presented to obtain a fine-scale correlation between discrete temperature logs and lithology. The algorithm is essentially the least square method. The limitations and an example of application of this program are given. |
| An outcrop of the late glacial Laacher See ash near Kirf (Rhineland-Palatinate) | 1982 | Jungblut, G.; Riezebos, P.A.; Slotboom, R.T. | 61(3) | Heavy mineral and palynological investigations of slope-covering materials near Kirf (Rhineland-Palatinate) reveal the presence of the Allerød Laacher See ash. This ash is characterized by the brown amphibole-pyroxene-sphene association, that was described earlier from peat bogs of the Semois valley (Belgium) and from several maars in the western Eifel (Germany). |
| Isotopic age determinations in Bergslagen, Sweden: I. introduction | 1982 | Oen, I.S.; Verschure, R.H. | 61(3) | |
| Isotopic age determinations in Bergslagen, Sweden: II. The Filipstad-type granite of Rockesholm, Grythyttan area | 1982 | Oen, I.S. | 61(3) | |
| Isotopic age determinations in Bergslagen, Sweden: III. The Hyttsjö suite of gabbro-diorites and Tonalite-Granites, Filipstad area | 1982 | Oen, I.S.; Wiklander, U. | 61(3) | |
| Crystal faces: structure and growth | 1982 | Hartman, P. | 61(4) | A review is given on current theories about the growth mechanisms of a crystal face. The growth depends on internal factors (crystal structure and defects) and on external factors (supersaturation, temperature and presence of impurities). Three categories of faces are distinguished, depending on the number of periodic bond chains (PBCs) present in a slice dhkl. Only F (flat) faces containing two or more PBCs can grow according to a layer mechanism. They grow slowly and are important. Other faces grow continuously and fast. Impurities adsorbed on the crystal usually retard, but sometimes accelerate the growth and may even provoke the apparition of other faces. Beyond the roughening temperature TR the flat surface structure of an F face transforms into a rough surface and the growth occurs continuously and is faster. TR becomes lower when the interaction between crystal and fluid increases. The growth rate of an F face increases when the attachment energy of a new layer is higher. This allows to define a theoretical habit as exemplified for fluorite, quartz, olivine, feldspar, dolomite and calcite. |
| A new hydrogeological map of Guelderland and Flevoland | 1982 | Meinardi, C.R. | 61(4) | A new mapping technique is proposed to represent on one sheet the hydrogeological data of a region. The main features represented are: - the structure of the alternation of aquifers and resisting layers. The map gives the transmissivity of aquifers and the ranges in hydraulic resistance of less pervious layers. The symbols used are coloured beams (thickness indicating transmissivity values and colour the geological origin). - Ground-water heads in the form of contour lines and the relevant surface water pattern. - The location and the extent of ground-water extraction, indicated by circles of squares of a variable size. - Ground-water quality by means of the distribution of fresh and brackish ground-water. The map has been composed for the situation of the Netehrlands, but can most likely be used for any area, where the aquifer systems consist of unconsolidated sediment. Another requirement is that the available data allow a quantitive representation. |
| A new hydrogeological map of Guelderland and Flevoland | 1982 | Meinardi, C.R. | 61(4) | Enclosure |
| A Grenvillian granulite belt in the Colombian Andes and its relation to the Guiana Shield | 1982 | Kroonenberg, S.B. | 61(4) | Precambrian high-grade metamorphic rocks emplaced tectonically in the Central and Eastern Cordillera of Colombia define a granulite belt which is lithologically, petrologically and geochronologically distinct from the adjacent part of the Guiana Shield. This Garzón-Santa Marta Granulite Belt was formed at the western border of the Early to Mid Proterozoic nucleus of the Shield by an orogenic event around 1.2-1.4 Ga. The Nickerie Metamorphic Episode, characterized in the whole western part of the Guiana Shield by mica age resetting around 1.2 Ga, extensive mylonitization along prominent ENE-WSW shear zones, and low-grade metamorphism, is brought into relation with this orogenic event. A continental collision model and a relationship with the Grenville Orogeny are suggested for this orogeny. |
| On the origin of feldspatic mudrocks associated with quartz arenites | 1982 | Nwajide, C.S.; Hoque, M. | 61(4) | Two lithostratigraphic units in southeastern Nigeria, the Maastrichtian Ajali and the Eocene Nanka Formations, described as quartz arenites, have been found to contain significant amounts of feldspars in their intercalated mudrocks. If intense chemical weathering prior to transport could eliminate feldspars from the source rocks of these formations, it ought to have been reflected equally in both the sandstones and the mudrocks. Diagenetic elimination (intrastratal solution) may be discounted in these cases on the grounds of lack of petrographic evidence as well as its demonstrable ineffectiveness in the older (Turonian) Makurdi Formation of the same area whose sandstones and mudstones both are dominantly feldspathic or arkosic. It is therefore suggested that feldspars, which are characteristically mechanically unstable, become progressively comminuted along cleavage and twin composition planes, and bypass the coarser bedload during transport. The result is the impoverishment of bedload in feldspar and simultaneous enrichment of suspension load. The impervious nature of mudrocks protects the feldspars from intrastratal solution. The result is a feldspathic mudrock in a feldspar-poor sandstone. Comminution and sorting together are therefore considered effective processes that are capable of producing quartz arenites in a sedimentary system. |
| An Eocene tidal inlet/washover type barrier island complex in the South Pyrenean marginal basin, Spain | 1982 | Donselaar, M.E.; Nio, S.D. | 61(4) | Several barrier island sand bodies are well exposed in the southern Pyrenees, Spain. They belong to the Pano Formation of Lutetian (Upper Eocene) age and were formed in an environment which was strongly influenced by rising sea level. A detailed sedimentological study of a calcarenitic sediment body in this Formation is presented. The larger part of the barrier system described here is made up of tidal inlet deposits and washover sequences. The sediment body has a lense-shaped geometry. The width of the exposed body is 260 m and its maximum thickness is 20 m. It is made up of thin to thick bedded calcarenites. The tidal inlet part consists of massive, and tabular to lense-shaped beds. Laterally, in a landward direction, massive beds alternate with thinner washover beds, which have a primary landward directed dip. The marl/sand ratio increases in this direction. In their proximal parts, washover beds are subdivided by horizontal erosional surfaces. The subdivision shows a regular pattern and is attributed to varying storm intensities during one single storm event. Vertical stacking of tidal inlet and washover deposits is ascribed to a balance between the amount of sediment deposited and the rate of relative rise of sea level. |
| I - Introduction | 1982 | Dozy, J.J. | 61(4) | Research on Coal in The Netherlands |
| II - Geological/Geophysical reconnaissance - 1. The Geology of coal in the Netherlands | 1982 | Harst, T.H. van der | 61(4) | Research on Coal in The Netherlands |
| The Geology of coal in the Netherlands II - Geological/Geophysical reconnaissance - 2. Seismic exploration for coal in the Netherlands | 1982 | Voogd, N. de; Staudt, C. | 61(4) | A brief description is given of the programme for coal exploration in The Netherlands. The problem of detailing coal scams in the Dutch geological environment is described. With respect to resolution and lateral continuity promising results have been obtained using a field technique with the following main features: single deep shots with 0.5 kg charges, 10 m receiver group interval, and six 50 Hz geophones per group. |
| The Geology of coal in the Netherlands III - Conventional deep mining research - Rock support by a destressed ring of rock around a gallery under severe stress | 1982 | Roest, J.P.A. | 61(4) | The aim of the project is to control the fracturing process of rock surrounding underground galleries under severe stress conditions. Model experiments indicate that a considerable decrease of convergence of galleries will occur if a circular zone of rock with a certain width around the gallery is artificially weakened and destressed. An underground field test confirmed that a destressed tubular rockmass around the excavation could support serious stress deviations of the surrounding bedrock, so that the gallery remained practically undamaged. It is expected that procedures following the lines of the described tests will improve the economy and the extent of deep coal mining |
| The Geology of coal in the Netherlands IV - New production methods - 1. Underground gasification of coal, past and present | 1982 | Dozy, J.J. | 61(4) | The history of underground coal gasification and the achievements in the USSR and the USA are briefly reviewed. The different conditions under which coal occurs in Western Europe and The Netherlands are indicated and field tests in Belgium and France are mentioned. In The Netherlands research is mainly undertaken by the Delft University of Technology. |
| The Geology of coal in the Netherlands IV - New production methods - 2. Stability of an underground coal gasification cavity | 1982 | Baaren, J.P. van; Ketting, J. | 61(4) | A concept for coal gasification of deep lying thin coal layers via borehole linking and repeated sand-fill of the reaction chamber is described. The influence of high temperatures (up to 1000° C) on the rock properties are summarised. The stability of a borehole leading to an underground coal gasification chamber can be simulated by means of a finite element computer programme. Forthcoming research on this subject for the next 3 years is indicated. |
| The Geology of coal in the Netherlands IV - New production methods - 3. Directional drilling | 1982 | Coppes, J. | 61(4) | The practice of directional drilling in the petroleum industry is explained. It is shown that the drilling of horizontal boreholes of a few hundred meters is technically feasible. Measuring-while-drilling techniques have been developed and experiments are carried out towards achieving 'steered' drilling. |
| The Geology of coal in the Netherlands IV - New production methods - 4. Underground coal gasification with heat recuperation | 1982 | Dietz, D.N.; Bruining, J. | 61(4) | Gasification of coal occurs at high temperatures. The energy present in the coal, as far as it is not converted into the chemical energy of the gas produced, is liberated in the form of sensible heat. This heat will be carried along by the gases and is partly lost to the cap and base rock of the thin coal layer; the rest of this heat is carried off through a production well. During the cooling process, part of the combustible gas will be reconverted into non-combustible components. This generates further heat. All this heat represents an important part of the energy originally present in the coal. This part can approach values of 100% under unfavourable process conditions or even more than 100% if steam is injected. Because coal in The Netherlands occurs in thin layers and at great depth only small amounts of this sensible heat can be recuperated at the surface. By adapting a heat recuperation method from the oil technology we aim to transfer the heat left upstream of the reaction zone back to this process zone, to accomplish a more efficient gasification process and to avoid excessive temperatures in the production well. |
| The Geology of coal in the Netherlands V - Summary and conclusions | 1982 | Dozy, J.J. | 61(4) | |
| Significance of a new basal peat date for the trend of Holocene mean sea level rise in the Netherlands | 1982 | Plassche, O. van de | 61(4) | |
| An example of extrusion of fluid mud through mudcracks and an origin of sediment dikes | 1982 | Wells, N.A.; Asif Jah, M. | 61(4) | Wrinkles of mud forming a mudcrack-like pattern across the top of a small mud-filled depression are explained as the result of extrusion of slightly overpressured underlying fluid mud. On a small scale, this confirms a mode of formation of soft-sediment dikes hypothesized by Oomkens (1966). |
| #REF! | 1982 | 61(4) | ||
| Petroleum geology of the southeastern north sea and the adjacent onshore areas (the Hague, 1982) - Preface | 1983 | Kaasschieter, J.P.H.; Reijers, T.J.A. | 62(1) | |
| Graben hydrocarbon plays and structural styles | 1983 | Harding, T.P. | 62(1) | Hydrocarbon occurrences, types of traps, and structural styles have been synthesized from the Sirte, Suez, and Viking grabens. Hydrocarbons occur in a stacked succession of one or more basins: pregraben, graben and interior sag. Preservation of pregraben reservoirs depends on late initiation of crustal arching and limitation of uplift to the graben shoulders. Trap closure in pregraben and graben-fill deposits is primarily dependent on the multidirectional orientation of normal faults, tilting of fault blocks, and flexing or erosion parallel to block edges. Fault patterns include dominant longitudinal faults parallel to the graben axis and oblique faults. Block rotation is influenced by fault profile, amount of extension, fault pattern, downwarping of the sag basin, and isostatic adjustments between large blocks. Fold closures result from the upward termination of faults into forced folds that are subsequently accentuated by fault drag. Folds extend to shallower depths and into the interior-sag base by passive drape and differential compaction. Traps above this level are dependent on factors other than graben tectonics. |
| Geological history of the southern Horn Graben | 1983 | Best, G.; Kockel, F.; Schöneich, H. | 62(1) | The structural history of the southern Horn Graben is analysed based on the data of the released German offshore wells Q-l, R-1 and S-1 and two E-W directed seismic lines. Rifting presumably already started during the Late Carboniferous. The main phase of taphrogenesis took placè during the deposition of the Lower and Middle Buntsandstein (Bacton interval) and an asymmetric graben with a more pronounced western flank was formed. During Röt and Muschelkalk sedimentation, Permian salts mobilized at the boundary faults and in the graben center, forming salt pillows. These salt structures entered the diapiric stage mainly during Keuper deposition while subsidence continued. At the beginning of the latest Jurassic and during the Early Cretaceous general subsidence and tilting towards the west took place, following a Middle-Late Jurassic period of uplift and erosion of the Graben and its surroundings. The negative movements have continued at incieasing rates till present times. Weak diapiric movements in the salt structures persisted until the Late Miocene. |
| Late palaeozoic to Early Cenozoic structural development of the South-Southeastern Norwegian Sea | 1983 | Skjerven, J.; Rijs, F.; Kalheim, J.E. | 62(1) | The Late Palaeozoic to Cenozoic structural development of the southern and southeastern Norwegian offshore sector is described, based on detailed maps of Top Chalk, Base Valanginian and Base Zechstein levels. The history of the main structural elements confirms that block faulting has occurred through the Permian, Triassic and Jurassic along NW-SE, N-S and E-W trending fault systems. Shear movements occurred in the Late Jurassic and in the Late Cretaceous/Early Tertiary, mainly along the N-S and E-W trends. |
| The structural outline of the Horn Graben | 1983 | Olsen, J.C. | 62(1) | The structural outline of the Horn Graben is discussed on the basis of four seismic lines and the Danish North Sea wells R-1, S-1 and C-1. The basic outline of the general N-S trending Horn Graben is defined by several deep-seated faults established during the Early Permian or possibly pre-permian. During the Late Permian, Triassic and Jurassic, these faults were reactivated, and created in the southern area an asymmetrical graben with a very pronounced western flank. The western flank becomes less pronounced towards the north, where the tectonic activity created an asymmetrical graben with a pronounced eastern flank |
| Recent exploration in pre-permian rocks around the Brabant Massif in Belgium, the Netherlands and the federal republic of Germany | 1983 | Bless, M.J.M.; Bouckaert, J.; Paproth, E. | 62(1) | The palaeogeographic evolution of NW Europe during the Pre-Permian has been controlled by three important orogenic periods since the Late Precambrian. Since the end of Cadomian times, a blockfaulted platform seems to exist to the southwest of the Fenno-Scandian Shield: the Belgo-Dutch Platform. One of the main structural elements in this platform is the London-Brabant Massif that was uplifted by the Late Caledonian movements. The Brabant Massif and its surrounding areas form the best-known part of the Belgo-Dutch Platform. Recent geological work in this area has focussed, e.g. on the extension of the allochthonous thrustsheets south of the Brabant Massif (Dinant Nappes), the rapid lateral facies and thickness changes in the Devono-Dinantian carbonate deposits (e.g., in the St.-Ghislain and Visé-Puth areas, respectively south and east of the Brabant Massif), and the Upper Carboniferous (Silesian) coal deposits to the north and northeast. The present review is meant as a preliminary synthesis of the state of these exploration projects. |
| Gas fields of Bergen concession, the Netherlands | 1983 | Lith, J.G.J. van | 62(1) | The Bergen Concession is located onshore in the Netherlands province of Noord-Holland, about 25 km NW of Amsterdam and 150 km SW of Groningen gas field. The Concession was granted on May 1, 1969, on the basis of gas discoveries drilled in 1964 and 1965. In 1972 the first field came on stream. Currently five fields are producing and one more is planned to be connected in 1983. The gas from all fields is treated at a central gas drying plant and is delivered to the Netherlands marketing organization N.V. Nederlandse Gasunie. The gas is sold to German power companies. Productive reservoirs have been found in Permian Upper Rotliegend Slochteren sandstone, Upper Permian Zechstein 3 Carbonate (Platten dolomite) and Lower Triassic Main Buntsandstein (Middle Bunter sandstone). Operations in the Concession have progressed slowly due to environmental considerations. The area contains nature-reserve and drinking-water areas in the dunes which protect polder areas from the sea. The ecological and economic quality of the polder land below sea level is maintained by strict management of surface and ground water. The geology of the Concession area and the impact of environmental requirements on the gas exploration and producing operations are discussed. |
| Rotliegend and main Buntsandstein gas fields in Block K/13 - A case history | 1983 | Roos, B.M.; Smits, B.J. | 62(1) | In the Dutch offshore Block K/13, two Lower Permian Rotliegend and two Triassic Main Buntsandstein gas fields were discovered between 1972 and 1976. The coincidence of these gas accumulations is the result of a combination of several factors: - excellent reservoir sands sourced by Carboniferous gas, - gas trapped in salt-sealed Rotliegend structures flanking the Broad Fourteens Basin prior to inversion. Some gas re-migrated into Main Buntsandstein traps during and after Late Cretaceous inversion movements. |
| The development of the Zechstein in the Netherlands | 1983 | Adrichem Boogaert, H.A. van; Burgers, W.F.J. | 62(1) | The Zechstein Group can be divided into four, locally five, evaporitic cycles. The margin of the Zechstein basin passes through the southern Netherlands and adjacent offshore area. It is characterized by fringing carbonates and clastics. In the southern offshore area a strong influx of sand is evident. The Zechstein is absent by erosion on the Late Kimmerian Texel-IJsselmeer High. A few indications suggest that part of this High was a positive area during Zechstein times. The first evaporitic cycle forms an E-W trending anhydrite platform in the central Netherlands and offshore continuation with a thickness of over 250 m. Halite is locally developed in this platform region. The major basinal halite sequences of the second and third cycle tie north of the platform. The carbonate members of these cycles have their main development along the basinward edge of the first cycle anhydrite platform. The fourth and fifth cycles are of modest dimensions and contain no carbonates. |
| Mesozoic structural and sedimentary development of the Danish Central Graben | 1983 | Michelsen, O. Andersen, C. | 62(1) | The structural framework of the Central Graben, probably created in Late Palaeozoic times, controlled the sedimentary conditions during major parts of the Mesozoic. The Danish Central Graben is subdivided into a number of sub-areas each characterized by specific structural styles, the most important being the Northern and Southern Salt-dome provinces. the Tail End Graben and the Dogger High. During the Triassic subsidence a sedimentary sequence not surpassing 2000 m was deposited. The Early Kimmerian tectonic phase caused erosion into the top of the Triassic sequence on anticlinal structures. The Jurassic and Early Cretaceous periods were dominated by strong subsidence and more than 4000 m of sediments were accumulated in the Tail End Grabèn. Both the Mid and Late Kimmerian tectonic phases affected the Central Graben. During the Late Cretaceous the change from a rifting phase into one of gradual subsidence was accompanied by inversion tectonics. |
| Jurassic stratigraphy and tectonics of the south-southeastern Norwegian offshore | 1983 | Hamar, G.P.; FjÆran, T.; Hesjedal, A. | 62(1) | Three major Early - Middle Jurassic unconformities in the Fiskebank Sub-Basin are represented by a hiatus in the Central Graben. The axial North Sea dome collapsed in Late Callovian, initiating the Central Graben, and causing coarse clastic sedimentation near topographic highs. The facies developments within the Norwegian-Danish Basin are controlled by the Lista Ridge. Anaerobic conditions are typical of the Late Jurassic, but highly radioactive shales are found only in the Central Graben and the Fiskebank Sub-Basin. A Mid-Volgian transgression established a seaway connection between these basins. Fifteen lithostratigraphic units are mapped. Evidence of strike-slip faulting in the Farsund Sub-Basin, and of halokinetic effects on the Jurassic sedimentation are presented. |
| Sedimentology of Middle and Upper Jurassic sandstone reservoirs of Denmark | 1983 | Koch, J.O. | 62(1) | A regional review is presented of the sedimentology and reservoir parameters of the Middle Jurassic Haldager Formation and J-2 unit, as well as the Upper Jurassic Frederikshavn Member, W-1 and V-1 units from the Danish Subbasin and the Danish Central Graben, respectively. New coredata are presented from the Haldager Formation of two D.O.N.G. wells in the Danish Subbasin and from the Upper Jurassic W-1 unit of the D.U.C. W-1 well in the Danish Central Graben |
| Stratigraphic correlation of the Vlieland and Delfland units in the Dutch offshore, based on palynology | 1983 | Dunay, R.E.; Dronkers, A.J. | 62(1) | A palynostratigraphic examination of the Early Cretaceous Vlieland and Delfland units was undertaken. The Vlieland Sandstone and the overlying Vlieland Shale in all locations contained among others, the dinoflagellates Broomea/Batioladinium, Spiniferites dentatus, Hystrichodinium furcatum and Lithodinia pertusa. Furthermore, recycled Triassic taxa were found in the Vlieland Sandstone in the southwestern portion of the study area. The underlying Delfland sediments usually exhibited a typical Early Cretaceous, probably Valanginian, terrestrial palynoflora. The P/6-2 well was, however, anomalous in that it contained an extremely thick shale sequence exhibiting such Early Cretaceous dinoflagellates as Subtilisphaera. |
| Lower Cretaceous stratigraphy and tectonics of the south-southeastern Norwegian offshore | 1983 | Hesjedal, A.; Hamar, G.P. | 62(1) | The Early Cretaceous sedimentary sequence is subdivided into seven formations in the southern Norwegian Offshore. It is dominated by marine fine-grained argillaceous sediments with varying calcareous content. The Sola Formation is found to be relatively rich in organic carbon and is, therefore, expected to have a good source rock potential. A small number of sandstone accumulations is located in the vicinity of penecontemporaneously reactivated highs. The northern part of Fiskebank Sub-Basin was inverted during the Cenomanian. This correlates with renewed strike-slip movements along the Fjerritslev Fault and at other places at the edge of the Fennoscandian Shield. The 'Late Kimmerian Unconformity' is discussed. |
| The Harlingen field, the only gas field in the Upper Cretaceous chalk of the Netherlands | 1983 | Bosch, W.J. van den | 62(1) | The Harlingen gas field, at the top of the Chalk, is situated in Petroland's Leeuwarden Concession in the province of Friesland, northern Netherlands. The structural closure developed partly during the Early Oligocene, after approximately 500 m of sediment had been deposited on top of the Chalk. Shortly hereafter, gas migrated into the structure. The presence of the gas strongly reduced the further loss of porosity and permeability by diagenesis, whereas the overpressuring reduced further compaction. A final deformation phase, probably at the end of the Early Miocene, slightly enhanced the curvature at the top Chalk and gently folded the then relatively porous gas cap, resulting in a folded gas-water contact. Unlike the situation in the Chalk fields in the Central North Sea, fracturing of the reservoir is very limited and has not resulted in increased effective permeability. This is probably due to the weak curvature of the structure. Notwithstanding the low average permeability (1-2 mD), a production rate of over 60 000 m3/day was maintained for a period of five months after stimulation, without any signs of pore collapse, common in many unfractured chalk reservoirs-elsewhere. A field development plan is being considered. |
| Petroleum geology of the Gorm Field, Danish North Sea | 1983 | Hurst, C. | 62(1) | The Gorm field is located within the Central Graben of the North Sea. It is a broad, domal, saltinduced structure of 750 ft closure, cut by a major, NNE-SSW striking, normal fault. The downthrown, 'western A block is dissected by high angle, tensional faults while the upthrown, eastern B block is relatively unfaulted. Downthrow of the A block appears to have been accompanied by a southward tilt relative to the B block. The reservoir rock comprises high porosity, low permeability, Danian and Maastrichtian chalks which are in pressure and fluid equilibrium. The upper Maastrichtian, with porosities of 30-40% , contains the bulk of the reservoir volume, porous Danian also contributing significant volume in the B Block. Gorm is an undersaturated oil reservoir with no initial gas cap and an oil column of up to 500 ft. Fluid levels are horizontal in the B block and apparently dipping to the south in the A block. To date, production performance in A block wells is better than that in B block wells. |
| Depositional conditions during chalk sedimentation in the Ekofisk area Norwegian North Sea | 1983 | Skovbro, B. | 62(1) | A study of Late Cretaceous-Early Paleocene deposits in the Ekofisk area is based on a large amount of data available in the Norwegian Petroleum Directorate. The quality of this material was furthered by additional detailed micropalaeontological. sedimentological, structural and diagenetic studies. Several prominent units ol allochthonous chalk deposits have been recognized. Based on micropalaeontological and sedimentological data. it is now possible to define these units properly. It has been attempted to map these allochthonous units as well as their source areas in order to gain a better understanding of the depositional environments during Chalk deposition in the Central Graben. |
| Sedimentological and reservoir parameters of the chalk group in the Danish Central Graben | 1983 | Nygaard, E.; Lieberkind, K.; Frykman, P. | 62(1) | The Chalk Group is subdivided into Chalk Units. The regional development of these is the basis for a depositional model implicating a high degree of redeposition and resulting in a geographic zonation of the Danish Central Graben into 'Deposit Zones'. Wireline log interpretations suggest good reservoir-intervals to coincide with specific lithologies. These are proximal allochthonous deposits, i.e. debris flows, which are found to be most common in the Chalk Units 6 Upper Part, Unit 5 and locally in Unit 2. The matrix permeability is best developed in the highly porous intervals. In the most favourable reservoirs fracturation has enhanced the permeability up to hundred times. |
| Reservoir geology, structural framework and petrophysical aspects of the Wijk gas field | 1983 | Gdula, J.E. | 62(1) | The De Wijk gas field is situated near the town of Meppel in the Dutch province of Drenthe. It produces gas from Carboniferous, Triassic and Tertiary. The largest gas accumulation is contained within a system of Triassic reservoirs and is trapped in a broad salt induced structure some 10 by 11 km. Within this structure Triassic sediments, ranging from the Lower Muschelkalk Member in the east to the Main Claystone Member in the west, subcrop with marked angularity on the Late Kimmerian erosion surface. Vertical sealing is provided by Lower Cretaceous shales and marls which unconformably overlay the Triassic sediments. So far economic gas production has been established from the shallow Basal Dongen Tuffite Member in the lower part of the Tertiary, from the Triassic Rogenstein oolite, Volpriehausen Sandstone and Lower Muschelkalk members, as well as from a small Carboniferous reservoir. The fact that gas is produced from the Basal Dongen Tuffite, Rogenstein oolite and Lower Muschelkalk makes the De Wijk field unique among Dutch gas fields; nowhere else in The Netherlands are any of these reservoirs gas productive. The reservoir properties of the Triassic reservoirs are due to diagenetic effects; in particular to leaching of anhydrite during the Kimmerian erosional phases. |
| The East Groningen Massif - detection of an intrusive body by means of coalification | 1983 | Kettel, D. | 62(1) | Coalification data measured in Late Carboniferous strata are available from wells in the Ems estuary and in the southern part of the German North Sea. The grade of maturity was calculated for the surveyed horizons using Lopatin's method, from the burial history, present temperature gradient and surface temperature, and these calculated data were compared with the measured ones. Positive differences (measured value higher than calculated) indicate the presence of a heat anomaly probably caused by a buried intrusive body. The 'East Groningen Massif'. The shape of this anomaly coincides with the present and past regional structural trend in this area. The same applies for a positive aeromagnetic anomaly in this area. It can be assumed that the age of the East Groningen Massif is around the Jurassic-Cretaceous boundary. i.e. Late Kimmerian. |
| Bit-metamorphism, illustrated by lithological data from German North Sea Wells | 1983 | Taylor, J.C.M. | 62(1) | Permo-Carboniferous redbeds encountered in some deep German North Sea wells are commonly altered when drilled with diamond bits. The process has been referred to as 'bit-metamorphism' by well-site geologists and others. Severely altered cuttings constitute over 80% of samples; they are hard, and when oil-based muds have been used are almost black and generally magnetic. Study of cuttings using petrographic, X-ray and chemical methods, supplemented by scanning electron microscopy, demonstrates that the process involves the reduction of particle size by shearing, followed by cementing or welding of the particles into a matrix superficially resembling a glass. The bulk chemical analysis of strongly altered cuttings is similar to that of accompanying unaltered material, though slightly richer in silica, but X-ray reflections of all minerals except quartz and feldspar are reduced or lost. All rock types are believed to be affected, but abundance of quartz and accompanying above-average hardness probably favour the process. Oil-based muds are not thought to be a necessary factor, but when used their breakdown may give rise to spurious gas readings. It is not certain whether the altered cuttings are bound together by precipitation of colloidal silica or by fusion to a glass. Further research is needed and might be expected to lead to better cuttings, reduced drilling torque, and less bit wear. |
| Investigation on the source rock potential of Denmark | 1983 | Thomsen, E.; Lindgreen, H.; Wrang, P. | 62(1) | Source rock analyses are carried out at the Geological Survey of Denmark using mineralogical, coal petrographical and organo-chemical methods. Investigations have been concentrated on Mesozoic deposits from the Danish part of the Central Graben and on Palaeozoic and Mesozoic deposits from the Danish onshore area. The results from the Central Graben indicate that the Kimmeridgian deposits are the principal source rocks for the known oil fields in the Danish sector, but with regional variations with respect to richness and maturity, the northern part of the study area being the most promising. From the Danish onshore area coal petrographical analyses indicate that Rhaetian-Jurassic-Early Cretaceous deposits are mainly immature-premature with respect to oil generation. Combined mineralogical and coal petrographical analyses on a limited number of samples from the Palaeozoic indicate post-mature Early Palaeozoic deposits. while Carboniferous and Permian sediments have been found to be in a premature-mature stage. |
| Igneous and metamorphic complexes of the Guiana shield in Suriname | 1983 | Bosma, W.; Kroonenberg, S.B.; Maas, K.; Roever, E.W.F. de | 62(2) | The crystalline basement of Suriname was formed essentially in the Lower Proterozoic during the Trans-Amazonian orogeny around 2000 to 1870 Ma ago. Two belts of high-grade metamorphic rocks probably developed as intracratonic basins within an older, possibly Archaean continent. A greenstone belt with basic and intermediate volcanics, volcaniclastic greywackes and coarse-clastic (molassic?) sediments is supposed to have formed in an island-arc-back-arc marginal basin environment at the northern margin of the older continent. Deformation and metamorphism took place around 2000 Ma ago. Extensive acid magmatism around 1870 Ma represents a subsequent stage in the Trans-Amazonian Orogenic Cycle, marked by acid ignimbritic volcanism, and next by granitoid and gabbroic intrusions. Most of the older basement was remobilized and reworked during this stage. Cratonization of the region was completed before the deposition of the Roraima Formation sandstones and pyroclastics around 1650 Ma and the intrusion of the Avanavero and Käyser Dolerites. Metamorphism, mylonitization and mica age resetting occurred around 1250 Ma in western Suriname during the Nickerie Metamorphic Episode. The intrusion of the Permo-Triassic Apatoe Dolerite around 230 Ma marks the beginning of the separation of South America and Africa. |
| Igneous and metamorphic complexes of the Guiana shield in Suriname | 1983 | Bosma, W.; Kroonenberg, S.B.; Maas, K.; Roever, E.W.F. de | 62(2) | Enclosure |
| Stratigraphy of the Neogene-Quaternary Pulpi Basin, provinces Murcia and Almeria (SE Spain) | 1983 | Veeken, P.C.H. | 62(2) | Within the mainly clastic sediments of the Neogene-Quaternary Pulpi Basin several transgressions are recognized: a Late Burdigalian, a Langhian, a Late Langhian-Serravalian, a Tortonian, an Early Messinian, and an Early Pliocene transgression. Each of these transgressions is preceded by either a phase of structural deformation, erosion, a hiatus and/or by deposition of red-bed sediments. No evaporitic Messinian sediments are exposed; at the southwestern border of the Pulpi Basin, however, an erosional and slightly angular unconformity is present between marine Late Messinian marls and fine-grained marine Early Pliocene deposits. Evidence is provided for considerable horizontal displacements along the sinistral 'Aguilon' wrench-fault which disrupts the Sierra Cabrera and the Sierras de Almagrera-Almenara, during Serravalian, Tortonian, and Messinian times. In and since the Pliocene only minor faulting occurred. During the Pliocene-Pleistocene regression a conglomeratic massflow dominated shallow-marine fan-delta prograded from the north to the south in the Pulpi Basin. In the adjacent Vera Basin this delta system it was subsequently divided in a westerly direction. |
| Modelling of Pleistocene European ice sheets: the effect of upslope precipitation | 1983 | Sanberg, J.A.M.; Oerlemans, J. | 62(2) | Results are presented from a numerical model of the Scandinavian Ice Sheet, in which the effect of upslope precipitation is included explicitly. The model is forced by changing the environmental conditions, formulated in terms of the annual mean temperature and the annual temperature range. These factors determine snowfall and melting rates, in dependence of the local conditions. It appears that orographically induced precipitation, which causes zones of high precipitation to shift with the ice-sheet edge, and ocean temperature are very important with regard to the growth rate of the Scandinavian Ice Sheet. In particular, upslope snowfall causes the ice sheet to advance westwards into the North Sea region much more easily. Stable equilibrium states of the ice sheet were calculated for various climatic conditions. A large ice sheet is only possible in cold conditions, whereas under very warm conditions no ice cover can be maintained. However, in between is a range of temperatures (2.5 to 6 K lower than present temperature) for which three stable equilibrium states exist: (i) no ice sheet, (ii) small ice sheets in them Scandinavian mountains, and (iii) a large ice sheet. This indicates that the response of the Scandinavian Ice Sheet to time-dependent forcing will be very complex. |
| Structure and general chemistry of table mountain Santa Barbara phosphates, Curaçao, Netherlands Antilles | 1983 | Stienstra, P. | 62(2) | Rock-phosphates front Table Mountain Santa Barbara (Curaçao, Leeward Netherlands Antilles), were investigated in the field and by evaluating data from cores of 203 drill holes. The distribution of phosphate- and fluorine-contents and recovery were studied in detail. Arrangement of several zones of maximum mineralization suggests that phosphatization, caused by the influx of a guano-derived phosphate-brine, was mainly governed by (a) the primary stratification and other primary petrological trends, and (b) the hydrogeochemical environme nt as defined by a phreatic fresh water-salt water mixing zone. A direct relationship is suggested between the two main zones of mineralization and two specific periods of relative stable sea level during the Pleistocene. |
| Lithology, stratigraphy, and palynology of Holocene deposits in the Drentsche Aa valley system | 1983 | Gans, W. de | 62(2) | The brook deposits of the Singraven Formation in the Aa valley are described and dated by respectively six cross sections and seven pollen diagrams. Three lithozones are discriminated: a sand bed, a detritic gyttja bed and a peat bed. The influence of the Holocene sea level rise on the deposition of the detritic gyttja bed in the downstream part of the valley is discussed. From the palynological data it is concluded that the Singraven Formation in the valley is confined to the Holocene. Two fluvial erosion phases causing headward erosion are distinguished: a Late Dryas phase, anticipating the deposition of the Singraven Formation, and a Late Boreal/Early Atlantic phase. Possible causes of these erosion phases are mentioned. |
| A new species of Rhinobatos (Elasmobranchii, Batomorphii) from the Upper Maastrichtian of the Netherlands and Belgium | 1983 | Bor, T.J. | 62(2) | Teeth of a new species of Guitarfish (Elasmobranchii, Batomorphii), Rhinobatos mariannae nov. sp., are described from three exposures of the Maastricht Formation (Upper Maastrichtian, Cretaceous) in the Netherlands and Belgium |
| Isotopic age determinations in Bergslagen, Sweden: IV granites of the Grängen area, east of Hjulsjö | 1983 | Oen, I.S. | 62(2) | Rb-Sr whole-rock isotope analyses of ten samples of Grängen granite yield a best-fit line corresponding to an age of 1663 ± 51 Ma with an initial 87Sr/86Sr ratio of 0.70844 ± 0.00578. Four samples of Tallåsberget granite give a best-fit line corresponding to an age of 1639 ± 185 Ma with an initial 87Sr/86Sr ratio of 0.70191 ± 0.04241. Isochron relationships appear disturbed by the low-grade retrograde metamorphism which has affected the granites. Taking account of the limits of error it is suggested that the Grängen and Tallåsberget granites in the Hjulsjö region, Bergslagen, Central Sweden, are coeval with the 1.7-1.6 Ga granites of the Småland and Värmland Groups in S and SW Sweden. |
| Tertiary stratigraphy of the Netherlands | 1983 | Letsch, W.J.; Sissingh, W. | 62(2) | Analysis of stratigraphic relationships and depositional characteristics shows that the deposition of the Paleogene of The Netherlands was governed particularly try global cycles of (marine) transgressions and regressions. Shorelines generally lay in the south and southeast. Intercalated sands were derived from the Central European hinterland. The depositional history of the Neogene is closely related to the development of the Lower Rhine Embayment and the Rhine River system. It also manifests the onset of the formation of the deltaic fan system which has characterized the onshore Netherlands since the early Pleistocene. |
| Acoustical reflection profiles, sediments and late Quaternary history of the Norwegian channel north of Bergen | 1983 | Weering, T.C.E. van | 62(2) | Acoustical reflection profiles of the area show four sedimentary units which reflect depositional events in and since the last glaciation. Two units (4 and 3) have a morainic character. The morainic units are covered by late Weichselian glacio-marine (unit 2) and Holocene (unit 1) sediments. The distribution of the postglacial basin infill has been mapped and shows that at present sedimentation rates are low. Storm induced wave abrasion of Vikingbank has resulted in selective removal of fines from west to east. The recent hydrographic regime is expressed in the distribution of the sand fractions, in the carbonate- and organic carbon content, and in the C/N ratios of the bottom sediments. Pockmarks are present along the western slope of the Channel which becomes highly dissected and irregular towards the south. |
| Comments and reply on: The fauna from Trinil, type locality of Homo Erectus: A reinterpretation | 1983 | Bartstra, G.J.; Hooijer, D.A.; Sondaar, P.Y.; Vos, J. de; Leinders, J.J.M. | 62(2) | |
| #REF! | 1983 | 62(2) | ||
| Preface special issue Prof dr J.D. de Jong | 1983 | Berg, M.W. van den; Felix, R. | 62(3) | This special issue of Geologie en Mijnbouw is dedicated to prof. dr. J. D . de Jong on the occasion of his retirement on August 31, 1982, from the chair of Geology at the Agricultural University Wageningen, The Netherlands. |
| Surveying the Netherlands: sampling techniques, maps and their application | 1983 | Oele, E.; Apon, W.; Fischer, M.M.; Hoogendoorn, R.; Mesdag, C.S.; Mulder, E.F.J. de; Overzee, B.; Sesören, A.; Westerhoff, W.E. | 62(3) | In 1953, under J. D. de Jong's supervision, a new mapping programme was started to meet the expected demand for more detailed information. At that time, the only available method of collecting data was based on rather simple hand-operated sampling equipment. Technical developments as well as the demand for more detail information led to the application of improved sampling techniques and geophysical methods. More information is now presented on the maps whereas other types of maps, such as the offshore geological maps, have been added to the programme. As expected, the demand for geological information today is great. The present article reviews the surveying methods applied by the Survey and the maps which are in preparation. Some case histories are given to illustrate the application of the results of the mapping programme. |
| Aspects of the distribution and disintegration of siliceous duricrusts in arid Australia | 1983 | Twidale, C.R.; Milnes, A.R. | 62(3) | Topographic, chronologic and climatic implications of siliceous duricrusts that are widely developed and preserved in inland arid Australia are discussed. Plateaux capped by siliceous duricrusts are characteristic, but are probably manifestations of large-scale relief inversion. Such duricrusts have been widely used as morphostratigraphic markers, and despite many possible difficulties, these interpretations may well be valid; but caution and consideration of the local evidence are necessary. The climatic context of silcrete both from the viewpoint of its formation and its degradation is uncertain. It may be that the various solutional features developed on these siliceous materials offer evidence on this point complementary to that derived from stratigraphic studies. |
| On weathering and denundation of humid tropical interfluves and their triple planation surfaces | 1983 | Aleva, G.J.J. | 62(3) | Divide areas and associated interfluves of upstream tributaries, mark the outer boundaries of the wide, flatly concave final landscape forms resulting from BÜDEL’S (1957) concept of double planation surfaces. The details of the weathering and denudation processes in these divide and interfluve areas have been studied during exploration work for placer tin and bauxite deposits. resulting in two distinct profiles: (i) the saprolite-mass flow profile and (ii) the saprolite-laterite profile. In addition to the denudation Ievel and the weathering front level, making up BUDEL’S double planation surfaces, each of these profiles have one additional level. Both profiles are described in some detail; the effects of unequal downward progress of the various levels and the separation in space of both types of weathering profiles are discussed in the light of parent rock composition and climatic variation. |
| Summit levels, bedrock control and the etchplain concept in the basement of Suriname | 1983 | Kroonenberg, S.B.; Melitz, P.J. | 62(3) | A comparison between summit levels distinguished by various authors in the basement of Suriname, photogeological landscape units, lithological information from the new geological map and LANDSAT imagery shows that many summit levels coincide with photogeological and lithological units in the lowlands that form the main part of the basement. Steps that separate summit levels of different altitude commonly are also lithological discontinuities. Such steps might originate under humid climatic conditions as jumps in the weathering front due to differential chemical weathering of contrasting rock types. The steps are exposed at the surface during periods of semi-arid conditions under savanna vegetation by stripping of the saprolite. In this etchplain model, summit levels at different heights do not differ essentially in age but only in resistance of underlying rocks to deep weathering. Only those levels that are protected by means of duricrusts against further surface lowering, or that were exhumed as domed inselbergs survived several cycles of etching and stripping. |
| The inversion of part of the southern border of Central Graben in South Limburg during the Late Cretaceous | 1983 | Kuyl, O.S. | 62(3) | During the Late Cretaceous Sub-Hercynian tectonic phase, transitory inversion of movements took place in the Central Graben. This NW-SE running graben is limited in the NE by the Peelrand Fault and in the SW by the Feldbiss (Fig. 1). During this period the graben floor became uplifted. Inversion first occurred in the SW part of the graben north of the Feldbiss and the Heerlerheide Fault during the deposition of the Vaals Formation (Campanian) and spreaded further south, during the deposition of the Vaals and the Gulpen Formation (Campanian to Maastrichtian) to the faults blocks north of, respectively, the Benzenrade - the Kunrade - and the Schin op Geul Fault and its southeastern extension into Germany, the Laurensberg Fault. These conclusions are based on the study of the formation thicknesses and age on opposite sides of the respective faults. On the base of similar facts it has been deduced thât the inversion has been discontinued during the deposition of the Maastricht Formation (Kunrade facies) after which the Central Graben became a sedimentation area again. |
| Zeolites and palygorskite as weathering products of pillow lava Curaçao | 1983 | Boekschoten, G.J.; Buurman, P.; Reeuwijk, L.P. van | 62(3) | Infillings between pillows in the lavas of Curaçao consist of zeolites, notably offretite, as well as the clay minerals palygorskite and smectite. The material is dissected by veins of analcite. The zeolites have been formed from the glassy crust ofthe pillow lava upon subaerial weathering in a dry and hot climate creating a pseudo-closed system. Under these conditions, hydrolysis of the glassy basaltic material generates a saline alkaline environment favourable for zeolite formation. Behind the weathering front the altered material will be exposed to gradually less saline and less alkaline interstitial fluid and the zeolites are transformed to palygorskite. Next, at a still greater distance, palygorskite is transformed to smectite. Analcite is precipitated from a brine formed by evaporation of the interstitial fluid in fissures. |
| Introduction to incident-light microscopy of oil and gas source rocks | 1983 | Gutjahr, C.C.M. | 62(3) | Microscope investigation of oil and gas source rocks has experienced a rapid development during the last two decades. This is mainly due to the advent of improved fluorescence microscopes, the development of new sample preparation techniques and the availability of computers. The new observations have led to the recognition of three main source rock types and six sub-types. This classification is similar to that proposed by Van Krevelen and by Tissot and Welte. However, it is not based on time-consuming elemental analyses, but can be achieved by simple and efficient incident-light microscopy. Differences in optical behaviour of source rocks with increasing maturation can now be observed in much greater detail than in the past. With increasing levels of organic metamorphism the hydrogen-rich, insoluble organic matter (precursor of oil) in source rocks shows: 1) changes in fluorescence colour;2) a decrease in fluorescence intensity; 3) plastic behaviour;4) generation of mobile products and immobile residues. These changes occur in bacterial organic matter at lower levels of maturation than in well preserved algal source rocks. |
| A petrography of 'Jade-axes' from the eastern and southern Netherlands | 1983 | Overweel, C.J. | 62(3) | Nine stone axes, examined macroscopically, and by a comparative specific gravity investigation, proved to be made of rocks composed essentially of jadeite. Two X-ray powder diffraction exposures affirmed the results. Since the first petrographical studies of European jadeite implements at the end of last century, the attempts to determine the sources have been without much success. A collection of references of the European jadeites might facilitate the search for the unknown source areas. |
| The stratigraphic position of the enigmatic Tertiary deposits called Holset sands, and of related sands in Belgium | 1983 | Buurman, P.; Janssen, A.W. | 62(3) | The Holset Sands are Tertiary sands of uncertain age that occur on old surfaces in Dutch South Limburg. By comparing the extent and facies of well-known Tertiary deposits in the neighbourhood with those of the Holset Sands, the authors arrive at a likely correlation with the Latdorfian Grimmertingen and Neerrepen Sands. The lower part of the Boncelles Sands from the region of Liege. which were considered to belong to the Upper Oligocene. is also correlated with the Latdorfian sands, while the upper Boncelles Sands are correlated with the Rupelian Berg Sands. This model requires a minimum number of large transgressions and assumes that the Grimmertingen transgression was the only one to reach high Belgium. |
| Sea-level changes in the Netherlands during the Eemian | 1983 | Zagwijn, W.H. | 62(3) | This paper deals with the determination of relative heights of the seal-level during the Eemian in The Netherlands and adjacent parts of the North Sea region. Dating was based on pollen analysis. Eight levels have been established, four of them determining the phase of rising levels. one indicating the peak height of the sealevel, which is estimated at 8 m below the present sea-level at high tide during the period of the Carpinus zone, and three indicating the phase of falling sea-level, which took place in the last part of the Interglacial. After the beginning of the Weichselian, the sea-level dropped below minus 40 m and remained below that level until the early part of the Holocene. Comparison with the Channel area yielded a value of 1.42cm/century for long-term subsidence of The Netherlands since the Eemian. |
| A note on ventifacts and the shape, angularity and surface polish of lydites in fluviatile deposits and in stone pavements | 1983 | Maarleveld, G.C. | 62(3) | Possible differences in shape, angularity of edges, and surface polish in lydites sampled from fluviatile deposits (Urk Formation) and the stone pavements have been investigated. Lydites from the Hattem Layer have been included in this research in connection with the question whether they orginate from stone pavements. |
| A new subdivision of crystalline Fennoscandian erratic pebble assemblages (Saalian) in the Central Netherlands | 1983 | Zandstra, J.G. | 62(3) | The inland-ice cap in the Saalian in the central part of The Netherlands caused the formation of glacial basins and ice-pushed ridges and the deposition of till as well as glaciofluvial and glaciolacustrine material (Drente Formation). Crystalline assemblages of pebbles in these deposits, especially in till, are discussed and a new subdivision based on the Fennoscandian area of origin is introduced. The composition of the indicator pebbles made it possible to distinguish various deposition areas as the effect of one inland-ice cap. |
| The Bergen inlet, transgressive and regressive Holocene shoreline deposits in the Northwestern netherlands | 1983 | Jelgersma, S. | 62(3) | This paper deals with the sediments that have filled up the Bergen inlet. The scouring effect of the inlet caused significant erosion of the Pleistocene sandy sediments. In the deepest part of the inlet a 15 m sandy clay deposit is encountered interpreted als Regression L This deposit was caused either by enlargment of the ebbtidal delta or by clogging of the smaller inlets situated further inland. During the deposition of the sandy clay the coastline south of the inlet is supposed to be near the present one. After that time this shoreline moved landwards to the region of Uitgeest. In the inlet itself the clay deposits were covered by sandy deposits. North of the inlet curved spits moved landwards. Finally a significant progradation of the coastline south of the inlet and a retreat in southeastern direction of the hooked spits north of the inlet resulted in the closing of the Bergen inlet. Dating by mean of pollen analysis indicate a short 'life' of the Bergen inlet (5300-3300 B.P.). Investigation of the underlying Pleistocene layers give evidence of a deep valley at the end of the Saalian glaciation overlain by a late Eemian estuarium. The formation of the Bergen inlet is thought to be related to these Pleistocene erosion phenomena. The sources of the sediments in and near the Bergen inlet are discussed |
| Sedimentation in the Mid-Netherlands river area during the Late Weichselian | 1983 | Verbraeck, A. | 62(3) | This paper is focussed on the distribution of river-dune deposits and characteristic overbank deposits, the so called 'Hochfluthlehm', in the central Netherlands river Rhine area. They are reckoned to the Lateglacial member of the Kreftenheye Formation. By means of pollen analyses and 14C-datings, the age of these deposits can be fixed. As a consequence of this lithological study a more precise picture can be presented of the changes from a Pleniglacial braided river system into a more channel-bound river system. |
| The stress systems in mudflows during deposition, as revealed by the fabric of some Carboniferous pebbly mudstones in Spain | 1983 | Loon, A.J. van | 62(3) | In the Cantabrian Mountains (northern Spain) the Upper Carboniferous contains various formations with a typically syntectonic character; one of them is the Westphalian Prioro Formation which crops our in the Tejerina Syncline (province of León). This formation mainly consists of fine-grained turbidites (laminites), but intercalations of pebbly mudstones are present. In 11 exposures the pebble fabric has been determined. In most cases the orientation of 50 pebbles was measured, in two cases this was possible only for 25 pebbles: it appears that these restricted numbers do not influence the overall picture. Another observation is that the orientation of the pebbles is not influenced by the degree of flatness, if the flatness value is 1.25 at least. The fabrics of the pebbly mudstones are pictured in contour diagrams: it appears that various patterns can be found. but in relative frequencies which are unexpected. The explanation for this phenomenon is that the tail of the mudflow should be considered as built up by a large number of individual small tongues (which behave like separate frontal lobes), moving more or less independently. |
| Megaripple cross-bedding as a tool for the reconstruction of the Palaeo-hydraulics in a Holocene subtidal environment, S.W. Netherlands | 1983 | Nio, S.D.; Siegenthaler, C.; Yang, C.S. | 62(3) | Large-scale cross-bedded sets from a Holocene subtidal sequence exposed in a construction pit at the mouth of the Oosterschelde were used for comparative studies with present-day tidal processes. The periodic variation which can be observed within a large-scale cross-bedded set of a subtidal megaripple is used to reconstruct the tidal hydraulic parameters such as the shear velocity, the tidal current velocity and the tidal range. In addition to this, the aperiodical variation of the set is used to evaluate the storm-induced components of these parameters. The main steps of the procedure are: (1) the identification of the tidal features of the set such as the lateral bundle sequence; (2) an appropriate selection of the sediment transport rate function; and (3) the development of a function relating the tidal range with the shear velocity based on an estimate of the water depth. Additionally a simple expression is derived, which relates the ratio of the astronomical tides and the atmospheric disturbance to the mean standard deviation of the bundle thicknesses. The calculated tidal current velocities, tidal ranges and its standard deviations from a subrecent example show a good agreement with the actual hydraulic parameters. |
| Surface water and groundwater in the basin of the Gulp Creek - some major characteristics | 1983 | Nota, D.J.G.; Bakker, A.M.G. | 62(3) | Within the framework of a training project for students from the Agricultural University in Wageningen. hydrogeological studies have been undertaken in the valley of the Gulp creek in the SE part of The Netherlands. This report deals with the chemical characteristics of natural surface and groundwater; the analytical data cover a 4-years period of sampling. The water composition is studied not only to determine the overall chemical character of the water the data of the water-analyses are primarily used as a tool to investigate the relation among basin geology and the groundwater and surface water regimes as a sequential dynamic unity. The water bearing sequence in the Gulp Basin is not homogeneous, but a multiple layer aquifer composed of a Mesozoic series of fine grained sands, silty clays and limestones overlying the Palaeozoic bedrock. Generally, the surface water and groundwater are of the calcium-bicarbonate type. Differences found for samples from wells are related to the geological formations. Surface water samples show seasonal variations of the dissolved solid species that are related to the varying contributions of base flow and subsurface flow to the total discharge; the period of drought in 1975 and 1976 is also reflected. |
| The gehydrological situation of the Western part of the Netherlands | 1983 | Pomper, A.B. | 62(3) | This paper gives a conspectus of the geohydrological situation of the area. Based on surveys carried out during the last decade. Not only a description of the geological situation to establish which layers in the subsoil have importance for groundwater flow has been given, but also the hydrological properties of the observed layers were calculated. It appeared that there is a basic difference between the geohydrological situations in the northern and the southern part of the area studied. The observed variations in transmissivity mostly are due to differences in thickness and less to different hydraulic conductivities. Beside this the hydrological units appeared to belong to layers of different geological origin. Also, intercalating clay layers may divide stratigraphic units in parts belonging to different aquifers. |
| Preface - Developments in physical geography, a tribute to J.I.S. Zonneveld | 1983 | Terwindt, J.H.J.; Steijn, H. van | 62(4) | |
| Die landschaft als integrationsebene Gesellschaftlicher Raumgestaltung | 1983 | Neef, E. | 62(4) | The interpretation of the landscape as the integrative field of human activities leads to some new theoretical questions. Whereas single disciplines study landscapes as defined systems, natural or cultural, the integrative aspects must regard the full reality of a landscape. The interdisciplinary combination of studies depends on the kind of problem structure. The main view point is the changing landscape under the influence of modern technology. |
| On the nature of physical geography | 1983 | Galon, R. | 62(4) | |
| Geomorphological significance of paleosol analysis; a case study of a drift sand section with podzols on the ice-pushed ridge West of Uelsen, W. Germany | 1983 | Jungerius, P.D.; Wiggers, A.J. | 62(4) | Geomorphologists have shown an increasing interest in soils. This also applies to paleosols, which provide information on past environments in terms of their age, landscape development and geomorphic processes. The nature of these aspects of paleopedology is demonstrated with the analysis of a sequence of buried podzols in drift sand overlying a truncated periglacial soil on the ice-pushed ridge of Uelsen, W. Germany. Evidence for the reconstruction of the geomorphic history of this area is derived from grain size, heavy mineral and pollen analyses. The sequence of buried soils reflects the same climatic periodicity as was observed in peat of Atlantic/Subboreal age found in the Wilsumer Moor, 4 km to the NE; dry phases with eolian activity were followed by humid phases with soil formation and splash erosion. The present surface is formed by an exhumed podzol of Atlantic/Subboreal age. |
| Two different volcanic ash-falls of Alleröd age in High Belgium | 1983 | Juvigné, E. | 62(4) | In the last 15 years several authors have mentioned the occurrence of volcanic ash in high Belgium. Because different preparation techniques have been used, the quantitative results cannot be compared. Applying the same method to different ash layers, two volcanic ash-falls of Alleröd age are distinguished: the 'Brackvenn ash-fall' (14C age: 10 830 ± 45 a B.P.) and the 'Konnerzvenn ash-fall' (14C age: 11 030 ± 160 a B.P.). |
| Remnants of periglacial mounds in the Hautes fagnes (Belgium): structure and age of the ramparts | 1983 | Pissart, A. | 62(4) | Five new sections were cut through ramparts surrounding depressions of the Hautes Fagnes plateau. When earlier work of 1974 and 1980 is included, a total of seven sections have been studied. For six of the seven, the internal structure of the ramparts is similar to Fig. 3. The other section shows only solifluction lobes (Fig. 6). A polyhedric structure which appears related to the growth of segregation lenses was seen in several sections. A new 14C age determination show that a second mound grew during the last Dryas. The facts suggest a periglacial genesis for the Hautes Fagnes depressions. They are not pingo scars but probably remnants of palsas without peat which are not yet well known today. |
| Glacial forms and ice distribution in the Northern Vosges during the last ice age | 1983 | Tricart, J.L.F. | 62(4) | During the last ice age, the Northern Vosges have been intensely glaciated. The climatic snow line was at an altitude of approximately 700 m. Nevertheless, the floors of some typical cirques do lay at even lower altitudes, as a result of important snow drift by SW winds. Comparison of snow drift mechanisms and of the loess distribution pattern in the Alsatian graben suggests frequent anticyclonic conditions during winter in Central Europe. This was probably in the form of a high pressure bridge linking the early autumn. High temperatures resulted in more abundant precipitation, mostly snow which played a major role in the glaciation, principally replenishing glaciers on leeslopes, facing NE, in the Buntsandstein plateau area. Nevertheless, 'typical' glacial landforms are uncommon. They are restricted to cirques. This suggests that the so-called 'typical' glacial landforms are an extreme case, their occurrence depending on specific lithological characteristics. |
| Geology, palynology and age of pingo remnant near Daarle, Province of Overijssel, the Netherlands | 1983 | Bijlsma, S.; Lange, G.W. de | 62(4) | Detailed investigations were carried out on a pingo remnant near Daarle in the province of Overijssel, The Netherlands. The pingo developed in an abandoned alluvial plain after the end of the fluvial activity. The time of both the pingo growth and the first part of the decay must be placed before the end of the deposition of the Older Coversand I, which means between about 28 000 BP and 23 000 BP. After partial melting the remaining ice-core formed a level surface that was covered with Older Coversand I and deposits of the Beuningen Complex. Final melting of the ice-core was retarded until shortly before the Bølling Interstadial, when a lake was formed in which organic material accumulated. |
| The development of the landscape of the nature reserve De Hamert and its environs in the Northern part of the Province of Limburg, the Netherlands | 1983 | Teunissen, D. | 62(4) | As appears from geomorphological and palynological data, the Heerenven lake in the nature reserve De Hamert forms a remnant of a branch of the river Meuse, dating from the Weischselian Glacial Period. In the early Holocene this river branch was almost completely covered by eolian sands; only the Heerenven remained free of an eolian cover. In the area between the Heerenveir and the present valley of the river Meuse there is a clay layer with peaty intercalations between the eolian cover and the underlying terrace sediments; the peat/clay layer could palynologically be dated in the Weichselian Late-Glacial. The combined data permit the conclusion that the terrace west of the Heerenven-Meuse belongs to the Weichsel-glacial Lower Terrace. The terrace at the east side of the Heerenven is older and can be correlated with the 'Krefelder Mittelterrasse', the sediments of which were formed during the height of the Saalian glaciation. |
| Relationship between Quaternary history and groundwater in the IJsselmeer area | 1983 | Berg, J.A. van den | 62(4) | Concentrations of salt ions in groundwater bearing Quaternary sediments in the IJsselmeer area have been changed by different processes such as transport, diffusion and dispersion. and the exchange of dissolved and adsorbed ions. Two case studies at Oostelijk Flevoland, the IJsselmeerpolder which was drained in 1957, illustrate how the predominating process alternated, in relation with the geological and hydrological configuration and with human interference. At Lelystad, in the central part of the IJsselmeer, the variation of chloride content with depth could originally be explained by diffusion. However, recently ion exchange and mixing of different types of groundwater are the main processes which determine groundwater quality, as the drainage of the polder Oostelijk Flevoland has initiated significant groundwater flow. Using the Piper diagram an interpretation is given for the origin of the various groundwater types, found near Lelystad. A second case study (Bremerberg) revealed the importance of a semi-impermeable layer of Eem clay in the underground. The groundwater under this layer initially had low concentrations of ions as it originated from the Veluwe area. As a consequence of the polder construction and the subsequent Iowering of the piezometric head, the seepage direction was inversed. Surface water from the border lake with higher ion contents started to affect the original groundwater. Contrary to this negative development, the initiated downward seepage resulted in a decrease of the relatively high ion content of the groundwater outside the area with Eem clay. The importance of the water quality in the border lake is stressed, in relation to use of the groundwater for the public water supply. |
| Observations on the hydrochemical groundwater situation of the Western Netherlands | 1983 | Pomper, A.B. | 62(4) | The western Netherlands encompasses a polder area with the land surface predominantly some tens of cm to several m below mean sea level. The history of salinization of this area has been and is governed by the geologic history, the reclamation history of the former lakes, and the hydrological groundwater situation. This has resulted in a complicated hydrochemical groundwater situation. The practical significance of studies like the one described is that processes in progress can be explained, that earlier situations can be reconstructed, and that a prediction of future situations can be made. At the start of the study only the chloride contents of the groundwater were taken into account; at a later stage other ions were included, and this gives a good conspectus of the hydrochemical groundwater situation of the area. Since in many parts of the area upward seepage occurs, the groundwater composition is of great importance for the composition of the open water. |
| A study of Late-Pleistocene river deposits of the Rhine system based on static penetrometer soundings | 1983 | Meene, E.A. van de | 62(4) | Penetration testing is basically aimed at the assessment of soil mechanical properties, especially the bearing capacity of the soil. It can, however, be applied to determine the dimensions and composition of lithological units as well. A short description of the method is given and a case study presented. This case concerns the survey of a horizon with fluviatile clay and silt and peat deposits overlain and underlain by sands. It was found that 85% of the sounding graphs could be adequately interpreted and that the geometry of the deposit could be established with reasonable accuracy. The paper concludes with a brief discussion of the expenditure involved, showing the relatively low cost of soundings compared with bailer drillings. |
| Holocene shorelines of Tioman island in the South China Sea | 1983 | Tjia, H.D.; Fujii, S.; Kigoshi, K. | 62(4) | Ten new radiocarbon ages of biogenic shoreline indicators from tectonically stable Tioman island, Malaysia, demonstrate that regional sea level was between 1.4 m and 3.7 m above present mean sea level during the period 6000 BP to 1900 BP, and that the sea level fluctuated several times in the order of 1 to 2 metres. The dates also suggest that sea level rose twice at rates of 1 m in 300 years but dropped at least twice at slower rates of about 1 to 2 m in 1400 years. In general, a very good correspondence is shown between the eustatic sea level curve constructed on the basis of about 40 dated shorelines from Peninsular Malaysia and that of Tioman island. |
| Mapping in physical geography, three maps of a formerly glaciated lowland | 1983 | Dorsser, H.J. van; Salomé, A.I. | 62(4) | Three mapping systems are applied to an area of the North German Lowland. on a scale 1:25000. The Dutch and German systems have been developed for geomorphological mapping of those particular countries. The Polish map is a more general environmental map. The mapped area comprises an icepushed ridge and a river valley. Large parts of the area are overlain by coversand. Human activity changed the physiognomic appearance of the landscape. The mapping systems are introduced and the maps are compared. The two geomorphological maps contain much information for the professional geomorphologist. The maps are not intended for the general public. The accessibility for application purposes, e.g. in environmental planning, is restricted. With the data contained in the geomorphological maps it was easy to construct a physicogeographical map according to the Polish system. This map gives less information on the morphogenesis of the area but is more suitable for environmental planning. |
| Detailed systematic geomorphological mapping in The Netherlands and its applications | 1983 | Cate, J.A.M. ten | 62(4) | Detailed systematic geomorphological mapping in The Netherlands started in 1966. Since 1975 these maps have been printed in colour. This paper describes the structure of the legend of the 1:50000 geomorphological map of The Netherlands and discusses the practical applications. These include geological and soil surveys, the conservation of important localities of earth science interest. The execution of multidisciptinary projects and mappings for contractors. |
| Developments in applied geomorphological survey and mapping | 1983 | Meijerink, A.M.J.; Verstappen, H.T.; Zuidam, R.A. van | 62(4) | Considerable progress has been made in the standardization of concepts and legends of geomorphological maps. Diversity inevitably persists where applied maps are concerned. Three types can be distinguished: analytical geomorphological maps emphasizing morphogenetic and chronological aspects, synthetic (holistic) geomorphological maps encompassing also terrain parameters related to soils, hydrology, etc., and pragmatic maps, tailor-made for specific purposes, such as natural hazard zoning. The contents of applied geomorphological maps can either be derived from analytical and/or synthetic data or be decided upon prior to the survey. Storage of all data gathered in a geobased information system and the subsequent retrieval of the data relevant for specific purposes only, holds a promise for the future. |
| Numerical assessment of geology and geomorphology in landscape ecological surveys, some examples | 1983 | Vink, A.P.A. | 62(4) | Landscape ecological surveys are used for mapping landscapes as carriers of natural and cultural ecosystems. Some examples from two regions are briefly discussed. These are: 1) the Upper Arno basin (Tuscany, Italy),2) a Prealpine Flysch area of Switzerland. In the Upper Arno basin different landscapes were recognized on the basis of geological formations. Calculations on the land characteristics of these landscapes resulted in the characterization of correlative complexes and differentiative complexes to characterize and differentiate the mapping units. In the Prealpine landscape of Fribourg (Switzerland), calculations of the 'mutual information values, Im' made it possible to give a quantitative characterization of the land mapping units as correlative complexes. Good correlations were found between the biotic variables and the abiotic and land management variables. Geological formations proved to be major indepent variables in all cases where such differences occurred within a mapping area. One or more geomorphic variables also proved to be independent variables (differentiating characteristics). |
| Geomorphology of subtidal and intertidal areas in the Southwest of the Netherlands | 1983 | Kooistra, M.J. | 62(4) | For centuries tides have played a major role in the estuaries and sea-arms in the southwest of the Netherlands. Tidal currents are responsible for deposition of subtidal and intertidal sediments in which several characteristic geomorphological units can be distinguished. The tidal wave comes from the south of the North Sea. The tidal amplitude decreases from south to north and consequently the induced tidal currents reduce in velocity in the same direction. These changes are reflected in the deposits and their geomorphology. First an overview is given of the occurrence of different geomorphological units and their stability in estuaries from entrance landinward and the changes in the successive estuaries from south to north. Secondly an example is given of the differentiation and stability in a high silted-up intertidal area. The stability of the geomorphological pattern in these areas is not only governed by the tides. Aeration and physical ripening also become important. |
| Application of the theory of island biogeography in the design of a structural concept of nature and landscape conservation | 1983 | Colaris, W.J.J. | 62(4) | For a long term strategy on nature and landscape conservation in behalf of a revision of the regional plan for Twente, a structural concept together with a map has been composed. The theory of island biogeography has been used for the design of the nature part of the concept. The most important factor in the landscape part is the spatial structure of hedgerows, copses, clumps of trees, etc. Thoughts about improving this structure, emphasizing the contrast between hill-side open field and lowland enclosure and emphasizing landforms have been worked out for Twente. The article catches on the conception of vulnerability as a central element in the structural concept. The realization of the map of the structural concept including the mapping units is described. A major application of the map is the creation of zones within the rural area for the regional plan. Some conclusions are: - Segregation of nature and agriculture is proposed in areas with large extended nature areas; - Concentration areas are most important for nature conservation; it is desired to concentrate attention and application of means on these areas; - In case of protection conservation of characteristic ecotopes has to be pointed out; - The importance of a structural concept is the creation of an instrument that can be used to carry out a consistent policy on nature and landscape with an eye on the future; - Application of ideas described here seems to be possible in other landscape types; - Regular evaluation and, if necessary, adjustment of the structural concept is proposed, running parallel with the design of a regional plan. |
| Physical geography and rural settlement planning in western Jamaica | 1983 | Scholten, J.J. | 62(4) | In western Jamaica detailed land use planning was carried out between 1977 and 1981 for the development of ten agricultural settlement schemes. The planning process included three steps, i.e. inventory survey, quantitative land capability assessment, and development plan preparation. In this paper the role of physical geography as a basic attribute to the physical planning activities in western Jamaica, is discussed for all three steps. |
| Volcanic cover deposits and streamflow behaviour in the Central North Island of New Zealand | 1983 | Schouten, C.J. | 62(4) | Distribution in time and space of the catchment-outputs of water, dissolved matter and suspended matter of streams in the Lake Taupo basin of New Zealand has been investigated. The hydrological data base is formed by a small number of instrumented sites and relatively few gaugings on streams, that were not instrumented permanently. It appears that the Lake Taupo catchment can be divided into regions with similar flow- and concentration duration characteristics. The forcing factor behind these flow duration characteristics is the presence of unconsolidated volcanic cover deposits in the catchment of a stream. |
| Geomophology, soils and vegetation differentiation in a tropical rain forest environment in Suriname | 1983 | Riezebos, H.T. | 62(4) | A landscape model of a tropical rain forest environment is described. The main events of the geomorphological evolution of the study area since the late Tertiary comprise the development of a planation surface during the Miocene followed by deposition of Pliocene continental Upper Coesewijne sediments and subsequent dissection during Quaternary times. Parent material and geomorphology led to the development of Entisols and Ultisols. The occurrence of various subgroups of these orders is closely related to the distribution of the main vegetation formation types, mesophytic semideciduous forest. Xeromorphic forrnations like walaba forest and savanna forest, and mixed mesophytic and walaba forest. Differences in chemical properties of four respresentative soils which are all very poor, appear to be small and it is suggested that they cannot be regarded as main causes of the vegetation differentiation in the study area. Differences in soil physical properties are more pronounced resulting in distinct variations of soil water retention characteristics. Under the given climatic conditions a comparison is made of the water balance of the representative soils. Results suggest that the mean monthly plant-available soil moisture is a major variable in vegetation differentiation. whereas the length of the edaphically dry period is of lesser importance. In relation to the implementation of the Kabalebo storage lakes project these findings imply the necessity for research into the risks of savannisation and increased sediment production. |
| Stability of slopes near Barcelonnette (Alpes de Haute Provence, France): A case study in slope stability mapping | 1983 | Steijn, H. van; Hof, G.J.J. van den | 62(4) | A systematic inventory of geomorphological phenomena combined with general information about lithology, climate, and the hydrological situation of a region can be used to draw a slope stability map at intermediate scales (1:10000 to 1:25000). As a case study the realization of such a map for a small area in the French Alps is described. The map not only shows stability classes, but also summarizes important features with regard to slope stability, such as slope angle. lithology. and signs of present-day geomorphological processes. Applications are the identification of unstable areas early in a planning procedure and of areas where site investigation will be necessary prior to construction. It appeared that in the area around Barcelonnette town enlargement plans include many unfavourable places. |
| The stability of slopes in the Ardennes region | 1983 | Asch, T.W.J. van | 62(4) | A number of slope studies in the Ardennes region have revealed that the mode of slope angle frequency distribution for the steep slopes is about 30°. It has been suggested by several authors that this angle corresponds to 'the angle of rest' of the regolith materials on these slopes. Recently, however, new concepts of slope development under mass failure have been elaborated, which show that there may exist more than one critical slope angle value. Steep straight slope segments were measured and the stability properties of regoliths were determined in a part of the Ardennes region. Stability analysis performed with the obtained strength parameters, revealed that the slopes can develop by mass failure towards two so called ultimate threshold values, one of about 42° in case no pore water pressure develops in the regolith, and one of about 21° in case the regoliths are completely saturated with ground water that runs parallel to the slope. It turns out that the population of the measured steep slope segments is enclosed between these two threshold values. The mode of the measured slope angle values does not differ between the different lithological units. It is suggested that in periglacial times the slopes became unstable, due to a blockage of the groundwater by the permafrost in the subsurface. At that time the slope population changed from the upper threshold value for dry regoliths to the lower one for completely saturated regoliths via a flattening of the slopes. |
| In memoriam - Prof. Dr. C.G. Egeler | 1984 | Rondeel, H.E.; Simon, O.J. | 63(1) | |
| In memoriam - Prof. Dr. Ir. R.W. van Bemmelen | 1984 | Linden, W.J.M. van der | 63(1) | |
| In memoriam - Ir. C.P.E.M. Raedts | 1984 | Debets, G.B. | 63(1) | |
| Note on the presence of Pre-Weichselian Loess deposits along the Albert Canal near Kesselt and Vroenhoven (Belgian Limbourg) | 1984 | Mees, R.P.R.; Meijs, E.P.M. | 63(1) | Loess sections along the Albert Canal and in Kesselt (Belgium) are described. The presence of pre-Weichselian loess is demonstrated. This is done on the basis of the occurence of the Rocourt tuff near Vroenhoven and on differences in the heavy mineral composition of the various loess deposits (fraction 30-63 pm). Besides the Rocourt Paleosol (Eemian interglacial), two other interglacial paleosols have been observed. |
| Nature and source of aeolian deposits near the summit of Ben Arkle, Northwest Scotland | 1984 | Pye, K.; Paine, A.D.M. | 63(1) | An extensive blanket of white sandy silt near the summit of Ben Arkle, northwest Scotland, consists of recent wind-transported material derived from frost-weathered quartzite regolith. Cryogenic processes are operative to a limited extent at present, but much of the weathered debris may have formed during the Last Glacial period. The aeolian silt grains are predominantly sub-angular and have irregular blocky surface textures with numerous adhering particles of clay-size quartz and kaolinite. Current aeolian reworking of the formerly-vegetated frost-weathered debris may be due to a slight climatic deterioration or to grazing by animals introduced since the late 19th century |
| Devonian carbonate facies patterns in the Dinant synclinorium, Belgium | 1984 | Reijers, T.J.A. | 63(1) | The Middle-Upper Devonian carbonate facies of the Dinant Synclinorium, Belgium are discussed. During the Middle Devonian the influence of the Old Red Continent is still appreciable and coarse to fine siliciclastics fringe the continent and the positive elements on the shelf. From Couvinian times onwards the shelfs of the Cornwall-Rhenish basin are partially covered by carbonate masses. During the Givetian and the Frasnian the influence of siliciclastic sediments on. Carbonate production is only noticeable in the northern lagoonal settings. In the Frasnian a distinct separation into a northerly carbonate platform and a southerly basin is apparent. Carbonate bodies within the basin are 'stacked' in the south, whereas they 'float' in the north. The 'stacked' bioherms are perhaps related to rejuvenation of block faults, whereas the 'floating' mud mounds are characterised by their red colour, their age and the fact that they overstep the middle Frasnian carbonate platform from a southerly direction. Textural and structural differences are discussed, illustrated and interpreted. The carbonate platform is characterised by a porous dolomitised edge and a lagoonal interior with cyclic carbonate deposition. |
| Molayan (Afghanistan) and the Khaur Siwaliks of Pakistan: an example of biogeographic isolation of Late Miocene mammalian faunas | 1984 | Brunet, M.; Heintz, E.; Battail, B. | 63(1) | The mammalian fauna from Molayan (Afghanistan) is compared with that of the Khaur Siwaliks of Pakistan. The detailed comparison reveals that, in spite of the geographical proximity of the two faunas, there is no recorded species in common between them. The differences cannot be attributed to a chronological gap; they can be partly explained by a difference in the palaeoenvironments. Another cause of the faunal differences must have been the existence of a mountain barrier separating the Indian subcontinent from Afghanistan. As a consequence, the Late Miocene hominoid primates from the Indian subcontinent were isolated from the Greek and Turkish ones. |
| Sediment-petrography of Malaguide rocks from the Sierra de Espuña (Betic Cordilleras, Spain): comparison of results from a descriptive and a quantitative analysis | 1984 | Mäkel, G.H.; Roep, T.B.; Kate, W.G.H.Z. ten | 63(1) | The sediment petrography of Malaguide sequences from the Sierra de Espuña has been studied with an 'intuitive and descriptive' method for the analysis of sediments in thin sections. This method comprises an initial intuitive grouping based on a few characteristics of the sediment and a subsequent detailed description of the thin section. Differences between specific members of the Malaguide sequences, that were found with this method, are confirmed by a quantitative analysis based on point count data. It is concluded that the intuitive and descriptive method is an adequate tool for the study of the sediment petrographical aspects of a sedimentary sequence and that it produces results in a relatively short time. |
| Size and shape-sorting of coastal sands in the eastern part of the German Bight (North Sea) | 1984 | Veenstra, H.J. | 63(1) | Size analyses of sand samples taken from the islands and sand flats in the eastern part of the German Bight indicate that each island shows a separate grain size population. This rules out important longshore sand transport from island to island. Comparison with sediment maps of the adjacent seafloor suggests that the islands were formed by wave action. On the other hand rollability analysis reveals that the percentages of angular grains in the samples increase towards the north. It is held that this increasing angularity reflects the shape sorting of the sediments of the seafloor. The spit of Skallingen shows a drecreasing angularity of the sand grains towards its end, probably caused by prevailing influence of shape selection by coastal erosion over longshore transport. In most cases the dune sands contain more angular grains than the beach sands. |
| Sedimentological framework of late Pliocene and Pleistocene alluvial deposits in the Bhittani range, Pakistan | 1984 | Nio, S.D.; Hussain, T. | 63(1) | We measured a section along the southern limb of the Marwat Kundi anticline near the village of Malagan in northwestern Pakistan. Three major depositional systems were differentiated that were based on the sampled data from this section and on some comparisons with their lateral equivalents. The lower system, the Kargocha Formation, consists of a thick succession of mainly mudstones with intercalations of conglomeratic and sandy sheet- or ribbon-like alluvial bodies. This lower depositional system was characterized by relatively small fluvial systems. The following Marwat Formation consists mainly of very thickbedded sandstones, followed by thinner bedded sandstones in its upper parts. The thick sandstone beds represent large fluvial channel complexes that were formed by a large sandy braided river, comparable to the present-day Indus river. The thin-bedded succession represents an abandonment of this large river system and a migration of the paleo-Indus towards the east to its present-day position. Finally, the Malagan Formation is formed by terminal fluvial fans, of which its modern analogue can be found within the present-day intramontane basins. |
| A Late Precambrian Ediacara-type fossil from Calicia (NW Spain) | 1984 | Dozy, J.J. | 63(1) | For the first time a Precambrian trace fossil, possibly a sea pen, has been found in Spain. A description of the find and its stratigraphic position is given. |
| On the paralellism of bedding and cleavage in deformed rocks from the internal zone of the Betric Cordilleras-S.E. Spain | 1984 | Biermann, C. | 63(1) | Bedding-parallel foliations may cause serious problems for structural geologists who try to unravel the sequence of deformational events in polyphase deformed rocks. In many cases it may be difficult to prove whether an early bedding-parallel foliation represents an inherited sedimentary fabric or has formed during an early phase of deformation. In the past there have been such problems in several tectonic units in the Internal Zone of the Betic Cordilleras of S.E. Spain. This paper describes the microstructure of early foliations in low grade slates and metasandstones from the Almagro and Almanzora Units in the Sierra de Almagro and upper greenschist facies micaschists from the Variegato Unit in the N.E. Sierra de los Filabres (province of Almeria). It is shown that the dominant planar structure in the Almagro and Almanzora Units represents the first tectonic cleavage (St) that has been formed in these rocks. The foliation is axial planar to first phase folds and shows different stages of cleavage development from initial sedimentary microstructures to the fully developed slaty cleavage fabric. In upper greenschist facies micaschists of the Variegato Unit there is a preferred orientation of phyllosilicates parallel to bedding. In contrast to previous interpretations it is argued that this fabric does not represent an inherited sedimentary fabric. Pressure solution processes were involved in cleavage formation indicating non-hydrostatic stress conditions during tectonic deformation. Metamorphic conditions-culminating in upper greenschist facies grade after formation of the early foliations-can not be explained by contact metamorphism during burial underneath a thick pile of undisturbed sediments. They indicate that the rocks have been transported deep into the crust during a tectonic event prior to the peak of metamorphism. |
| Isotopic age determinations in Bergslagen, Sweden: v. de Horssjö Granite, Filipstad area | 1984 | Oen, I.S.; Verschure, R.H.; Wiklander, U. | 63(1) | Rb-Sr whole rock data of 17 Horrsjö granite samples from 5 localities show a best-fit line Corresponding to an age of 1.76 ± 0.04 Ga. This result is unsatisfactory in view of the presumed age of the Horrsjö granite, which is coeval with the 1.84 ± 0.06 Ga Hyttsjö; Suite of rocks. Six samples from one locality give a best-fit line corresponding to 1 .86 ± 0.12 Ga; three samples from another locality show a best-fit line corresponding to 1.84 ± 0.44 Ga. These two localities presumably represent relic domains of Hörrsjo granite that have escaped post-emplacement, metamorphic- Rb-Sr isotopic resettings of whole-rock samples. The data show a large geological variance in excess of the analytical variance. This may be due to variation in initial 87Sr/86Sr in the samples, possibly caused by contamination of the granite magma by basic magma and/or seawater. |
| The structure of the Gran Paradiso basement (Pennine zone, Italian W. Alps) | 1984 | Vissers, R.L.M.; Compagnoni, R. | 63(1) | Detailed structural analysis and mapping in the northern part of the Gran Paradiso massif suggest that the massif is a gneiss-cored fold nappe. The timing of the associated deformation relative to the Alpine metamorphism points to development of the nappe structure in a stage between the Eoalpine HP metamorphism and the peak of the Lepontine greenschist facies event. |
| Caledonian and Hercynian crustal consolidation of Western and Central Europe - A working hypothesis | 1984 | Ziegler, P.A. | 63(1) | The crystalline basement of Western and Central Europe consists of a mosaic of crustal elements which were consolidated during pre-Grenvillian, the Grenvillian-Dalslandian, Morarian, Cadomian, Caledonian and Hercynian orogenic cycles. Contemporaneous with the Caledonian suturing of the Precambrian Laurentian-Greenland and Fennosarmatian shields a number of Gondwana-derived Cadomian micro-cratons were accreted to the southern margin of Laurasia. Following the Late Caledonian paroxysm, the Devonian and Early Carboniferous evolution of Europe was dominated by continued subduction of the Proto-Tethys plate at an arc-trench system parallelling the southern margin of Laurasia, the accretion of additional Gondwana-derived continental fragments, back-arc rifting, and a sinistral translation of major proportions between the Laurentian-Greenland and the Fennosarmatian sub-plates. The Acadian and Bretonian orogenies were of the Pacific type. The Visean collison of Gondwana with Laurasia marked the onset of the Himalayan-type Variscan orogeny during which collision related compressive stresses overpowered the Devonian-Early Carboniferous back-arc rift systems and caused the development of A-subduction zones. The Central Armorican-Saxothuringian successor basin became folded and destroyed during the latest Visean, whilst the Variscan foredeep became scooped out, in part by basement nappes, during the latest Westphalian. Major crustal shortening during the Variscan diastrophism was accompanied by the anatectic remobilisation of subducted lithosphere and a widespread syn- and late orogenic magmatism. The latest Carboniferous-Early Permian reorientation of the convergence direction between Gondwana and Laurasia induced the development of a complex wrench-fault system transsecting the Variscan fold belt, and extensive post-orogenic volcanism. The hypotheses summarised here require confirmation by further palaeomagnetic and radiometric data. |
| Caledonian and Hercynian crustal consolidation of Western and Central Europe - A working hypothesis | 1984 | Ziegler, P.A. | 63(1) | Enclsoure 1 |
| Caledonian and Hercynian crustal consolidation of Western and Central Europe - A working hypothesis | 1984 | Ziegler, P.A. | 63(1) | Enclsoure 2 |
| On the uso of the VLF signature in geological mapping | 1984 | Ketelaar, A.C.R.; Giberti, I.; Menne, B. | 63(1) | One of the electromagnetic methods of geophysical prospecting is known as 'VLF'. The method is outlined in the introduction. The traditional use of VLF lies in the exploration for sulphide orebodies. 'We suggest that a VLF survey contains information about the geology in a wider sense and indicate ways of extracting that information by applying techniques borrowed from seismic data-processing. Unlike the large and expensive computers which are used in the seismic industry, for our application we only need 'pocket computers'. |
| Comment and reply on - Structure and general chemistry of Table mountains Santa Barbara phosphates, Curaçao, Netherlands Antiles | 1984 | Heijnen, W.; Have, T. ten; Stienstra, P. | 63(1) | |
| #REF! | 1984 | 63(1) | ||
| To Professor Dr. Emile den Tex - on the occasion of his retirement from the chair of Petrology, Mineralogy and Crystallography, which he held at the State Universities of Leiden (since 1959) and Utrecht (1978-1983) | 1984 | Zwart, H.J.; Hartman, P.; Tobi, A.C. | 63(2) | |
| Cabo Ortegal, mantle plumbe or double Klippe? | 1984 | Vogel, D.E. | 63(2) | Petrological, structural and geochemical data are consistent with emplacement of the Cabo Ortegal Complex by two separate Paleozoic thrusting events which elevate successively deeper levels of crust. The existence of only one, premetamorphic, 'ophiolite' suite is argued for Cabo Ortegal, as well as for the other catazonal metamorphic complexes in Galicia. |
| The diversity of ophiolites | 1984 | Coleman, R.G. | 63(2) | Present studies reveal that ophiolites from the Alpine and Cordilleran orogenic belts may not represent deep abyssal oceanic crust but seem to have formed mainly in interarc or small ocean basin spreading centres. Abundant petrologic data on basalts from mid-ocean spreading centres (MORB) reveal a uniform and characteristic chemical nature. Current petrologic studies have shown an apparent scarcity of MORB within lavas of ophiolites from Phanerozoic orogenic belts. Peridotites from ophiolites reveal a complicated history of sub-solidus deformation and partial melting resulting from their diapiric rise into spreading centres and final incorporation into the oceanic crust. Structural studies reveal that ophiolites are emplaced either across passive continental margins or as basement fragments in accreted terraines. Attenuation of continental crust along passive margins in the formation of small ocean basin characterizes the tectonic setting for Tethyan ophiolites, whereas the ophiolites of Western North America are usually the oldest units in allochthonous tectonostratigraphic terraines and have formed in interarc spreading centres along the continental margins. Terraine accretion of these arc complexes preceded the continuous subduction of the Pacific and Farallon plates consisting of abyssal oceanic crust (MORB). Thus, ophiolite associations are mainly products of continental break-up or interarc spreading. Abyssal oceanic crust has been mainly consumed by subduction and only in extremely rare instances has it become accreted into continental crust. |
| Speculations on the origin of the ophiolites of northeastern Oregon (U.S.A.) | 1984 | Avé Lallemant, H.G. | 63(2) | Ophiolite complexes in northeastern Oregon are distinctive because of the large volume of silicic plutonic and volcanic rocks, the similar radiometric ages of mafic and silicic rocks, a mild iron enrichment trend in the ultramafic and mafic cumulates, similar REE abundances and patterns in silicic and basaltic rocks, the lack of dike complèxes, and the presence of sill complexes. It is speculated that the ophiolites formed in mantle diapirs ascending beneath pull-apart basins within a volcanic island arc. The basic magmas formed by partial melting in the upper mantle and the silicic magmas by partial melting of hydrous mafic rocks at the base of the volcanic island arc. |
| Orogeny and ophiolites: plate tectonics revisited with reference to the Alps | 1984 | Vlaar, N.J.; Cloetingh, S.A.P.L. | 63(2) | We develop a geodynamic scenario that explains many features of Alpine orogeny and ophiolite thrust sheet emplacement. Important elements of this scheme are: 1. age-dependent subduction and a related compressive regime upon the closing of small and young oceanic basins. 2. the induction of thermal upper mantle anomalies by spreading and lithospheric doubling and subsequent apparent migration by lithospheric shifting. It is shown that these processes. which have hitherto not been taken into account in intra-continental tectonics, play a crucial role in mountain building. This applies in particular to their function in gravity tectonics, metamorphosis and post-orogenic epeirogenesis and foreland uplift. |
| Transitional top normal MORB affinities in ophiolitic metabasites from the Zermatt-Saas, Combin and Antrona units, Western Alps: implications for the paleogeographic evolution of the Western Tethyan Basin | 1984 | Beccaluva, L.; Dal Piaz, G.V.; Macciotta, G. | 63(2) | The Zermatt-Saas, Combin and Antrona ophiolite units represent tectonic fragments of the oceanic to transitional lithosphere of the upper Jurassic-lower Cretaceous Piedmont basin, a section of the Western Alpine Tethyan basin. The investigated area is located around the Monte Rosa massif between the middle Aosta valley and the Ossola valley, Italian Northwestern Alps. The Piedmont ophiolite nappe, i.e. the couple of the Zermatt-Saas and Combin juxtaposed tectonic elements, is interposed between the overlying paleo-African continental crust (the Austroalpine tectonic system of the Dent Blanche and Sesia-Lanzo nappes) and the underlying paleo-European continental crust (the Pennine Monte Rosa and St. Bernhard nappes). On the contrary, the Antrona ophiolite unit occurs at a lower structural level. and is sandwiched between the overlying Monte Rosa nappe and the underlying Comughera-Moncucco units, the 'root zone' of the St. Bernhard nappe. Bulk rock analyses of 29 selected samples from these units demonstrate: 1- that the petrogenetic characteristics of the metabasalts and metagabbros from both the Zermatt-Saas and Combin units are strictly comparable to those of normal-MORB magmatism, and 2- that the features of the Antrona metabasalts indicate an oceanic nature for these metamorphic ophiolites with a distinct transitional-MORB affinity. This seems to reflect incipient oceanic rift conditions for the related segments of the Piedmont basin. The available petrochemical data from the Alps, Northern Apennines, Corsica and Calabria, indicate that ophiolites with transitional-MORB affinity represent an early ocean-type magmatism. This was later confined to the external sectors of the accreting Alpine-Apennine oceanic basin, while ophiolites with normal-MORB affinity appear to be related to a subsequent well-established mantle convection in a more developed ocean-ridge system. |
| Structural study of the Balmuccia Massif (Western Alps): A transition from mantle to lower crust | 1984 | Boudier, F.; Jackson, M.; Nicolas, A. | 63(2) | Among the ultramafic bodies included in the Ivrea zone, the Balmuccia lherzolite massif offers a particularly well-preserved contact with the granulitic lower crust. The eastern margin of the massif presents a transition to the granulitic gabbros through a layered sequence including pyroxenites and dunites. A chronological evolution of textures in the peridotite is established, showing a continuous evolution from mantle-derived textures (porphyroclastic) located in the southwestern domain to recovered textures (equigranular) developed to the northeast along the preserved transition with the granulites. This recovery process is considered to be enhanced by fluid circulation, it would occur in granulite facies temperature conditions. The map of penetrative structures confirms this chronology: the foliation and lineation attitude follows a progressive evolution with a steep lineation associated with mantle textures and a flat one associated with crustal textures, this last orientation being concordant with that of the surrounding granulites. The structural analysis is consistent with a diapiric emplacement model of the Balmuccia lherzolite developed in asthenospheric mantle conditions and ending in the granulite facies conditions of the lower crust. |
| Kaersutite-bearing mylonitic gabbro from the Lanzo-peridotite (Western Italian Alps) | 1984 | Compagnoni, R.; Radicati di Brozolo, F.; Sandrone, R. | 63(2) | A mylonitic gabbro, intruding and partly re-equilibrating the Lanzo peridotite in Val di Viù, is described. It consists of Ol + Opx + Cpx + Ti-rich Ho porphyroclasts included in a fine-grained matrix, where primary plagioclase is replaced by the Jd + Zo + Qz assemblage. Geothermobarometric calculations have given T: 1000 'C and P : 0.5 GPa (5 kbar) for the gabbro crystallization. Both gabbro and host spinel/plagioclase lherzolite are crosscut by mm-sized mylonitic veins of brown Ho + Ilm + Ap + Plag. Geologic and petrologic considerations suggest that these veins crystallized from a highly differentiated tholeiitic magma, introduced - most likely immediately after gabbro crystallization - into both gabbro and peridotite. Mineralogic and petrologic evidences indicate that both gabbro and host lherzolite experienced a subsolidus polyphase HT deformation and recrystallization from hornblende granulite- to amphibolite-facies conditions. The metamorphic re-equilibrations, characterized by initial Hp mineral assemblages and late greenschist-facies parageneses, indicate an Alpine orogenic history consistent with that inferred elsewhere for the internal Western Alps. |
| Tectonic shift of ophiolites | 1984 | Bogdanov, N.A. | 63(2) | The mechanism of emplacement of ophiolites in recent and pre-Mesozoic mountain chains is different and depends on their occurrence in Pacific-type fold belts or intercontinental orogenies. A correlation can be made between spreading events in the Cretaceous and periods of increased tectonic activity on continents. |
| The accretion of ophiolitic terrains in the Scandinavian Caledonides | 1984 | Sturt, B.A. | 63(2) | The timing of ophiolite emplacement is discussed and it is demonstrated how the accretion of ophiolitic terrains is related to the Finnmarkian Orogeny. The continental miogeocline. of the Scandinavian Caledonides is shown to relate to the pre-Finnmarkian continental margin, and that it was effectively destroyed during the Finnmarkian Orogeny. The final assembly of the tectonostratigraphy of the Scandinavian Caledonides, is however the result of superimposed orogenic cycles. The pattern of development bears many resemblances to that of the Appalachian orogen in North America. |
| The effect of carbon dioxide on phase relationships for synthetic lherzolite and harzburgite | 1984 | Wyllie, P.J. | 63(2) | The system CaO-MgO-SiO2-CO2 includes mineral assemblages corresponding to model lherzolite: forsterite(Fo) + orthopyroxene(Opx) + clinopyroxene(Cpx), and model harzburgite: Fo + Opx, as well as model websterite and wehrlite. When fully carbonated, the peridotites are converted to limestones: dolomite(Do) + magnesite(Mc) + quartz(Qz), or Mc + Qz. When partly carbonated, the peridotites are converted to carbonate-lherzolite and magnesite-harzbuigite, which cannot coexist with CO2. Available experimental and calculated reaction data are presented for carbonate lherzolite: (6) Opx + Do = Cpx + Fo + CO and (6A) Opx + Cc = Cpx + Fo + CO2,where Do is dolomite and its solid solution, and Cc is magnesium calcite; for magnesite-harzburgite: (3) MC + En = Fo + CO2; for websterite + carbonate: (O) Mc + Cpx = Do + Opx and (01) Do + Cpx = Cc + Opx; and for carbonate-wehrlite: (9) Do + Cpx = Fo + Cc + CO2. Conditions for the occurrence of dolomite(stoichiometric)-lherzolite are evaluated. Comparison of fossil geotherms deduced from kimberlite nodules with the phase diagrams for model harzburgite and lherzolite, and solidus curves with H2O present, indicates that partially melted lherzolite may coexist with solid magnesite-harzbuigite between about 175 and 195 km depth. Dissociation of magnesite could disrupt the harzburgite nodules during eruption, distributing low-calcium garnet through kimberlite. |
| #REF! | 1984 | 63(2) | ||
| Some conclusions reached at the symposium on geological changes in the Western Netherlands during the period 1000-1300 AD | 1984 | Berendsen, H.J.A.; Zagwijn, W.H. | 63(3) | Factors that possibly influenced the events during the period 1000-1300 AD are: climatic changes, sealevel changes, changes in river pattern and human influence. The impact of these factors is briefly discussed and the most important conclusions of the symposium are summarized. |
| The evolution of the fluvial area in the western part of the Netherlands from 1000-1300 AD | 1984 | Berendsen, H.J.A. | 63(3) | The Dutch fluvial area changed drastically during the period 1000-1300 AD, mainly due to human influence. Four topics are discussed: 1. On the basis of new radiocarbon datings and calculations of the rate of sedimentation it is concluded that the River Lek came into existence about 2000 years ago; 2. The silting up of the Kromme Rijn near Wijk bij Duurstede did not occur before the second half of the eleventh century. A dam was constructed in the river in 1122 AD; 3. The present rivers have a steeper gradient than recently abandoned meander belts. Changes in gradient are shown to be complex and not necessarily related to changes that occurred between 1000 and 1300 AD. 4. During the period 1000-1300 AD the main rivers were embanked; smaller branches were dammed. The embankments made it possible to reclaim the low-lying peat areas. |
| Indications of severe drought during the 10th century AD from an inland dune area in the central Netherlands | 1984 | Heidinga, H.A. | 63(3) | In the Kootwijkerzand on the Veluwe (The Netherlands) a settlement has been excavated that was buried beneath wind-blown sands and that was dated 750-1000 AD. For its water supply, this settlement depended on a nearby pool, which owed its existence to an impervious horizon in the subsoil. Since fluctuations in the water level of this pool could be reconstructed it could be established that the pool dried out relatively quickly in the 10th century. In addition a rainfall chart for the 8th- 10th centuries was constructed. It appears that the first half of the 10th century heralded a period of drought, of a severity hitherto unknown, which must have affected large areas of Europe. A relationship, either direct or indirect, is sought between the lack of rainfall and features which appeared on the Veluwe and elsewhere around 1000 AD, such as: 1. turf-manuring and the shift in emphasis from summer cereals 1o winter cereals (rye) on the high, sandy soils; sand-drifting, both inland and along the coast; the reclamation of part of the high moor in the western Netherlands. |
| Progradation, erosion and changing coastal gradient in the coastal barrier deposits of the Western Netherlands | 1984 | Roep, T.B. | 63(3) | In this paper the literature on the dating of barrier progradation and erosion of the coastal barriers of the western Netherlands is critically reviewed. It is concluded that progradation started around 5000 BP when the rise of sea level diminished, and ended around Roman times' or even later. This conclusion is based on 14C dated peat from depressions behind a protecting coastal barrier, 14C dated shell pairs in the barrier deposits, a progradation distance-age diagram, and reworked dated shells on the recent beach. The coastline was drastically reshaped around 2300 BP and around 1200 AD. During active progradation the coastal gradient down to a depth of 5 m was about 1:200, compared with a present gradient of 1: 100. Supply of sand from the English channel region started after 7000 BP and ended before 2000 BP. Supply of sand by the rivers Rhine and Meuse probably stopped around 2000 BP. Some evidence points to a climatic change which might be an important factor affecting barrier behaviour and sand supply. |
| The formation of the younger dunes on the west coast on the Netherlands (AD 1000-1600) | 1984 | Zagwijn, W.H. | 63(3) | The formation of the Younger Dunes on the west coast of The Netherlands is discussed in some detail. The onset of overblowing along the beach can be placed around AD 1000. Around AD 1600, the general outline of today's dune morphology was already present except in areas close to the coast. The behaviour of the water table and the sedimentary processes of the Younger Dune formation are dealt with. |
| Age and vegetational history of the coastal dunes in the Frisian islands, the Netherlands | 1984 | Jong, J. de | 63(3) | This paper presents the results of radiocarbon datings and pollen analyses of the coastal dunes of the Frisian islands off the northern coast of The Netherlands. The oldest dates obtained at each individual island decrease in an easterly direction and range from about 2800 BP for Vlieland to about 400 BP for Schiermonnikoog. Two types of deposits are distinguished: a. Older Dunes and b. Younger Dunes. The Older Dunes are characterized by intercalated organic beds. They formed between well before the beginning of the Christian era (e.g., on the island of Vlieland) and 755 + 45 BP, locally even as late as 625 ± 50 BP (Ameland) or 430 ± 45 BP (Schiermonnikoog). The Younger Dune deposits, in which humic intercalations are very rare are related to a relief of parabolic dunes of considerable elevation. The formation of the Younger Dunes started before approximately AD 1400 (probably even more than a century earlier), and continues up to the present. A comparison with the coastal dune area of the Western Netherlands is discussed as well as some characteristics of the vegetational development. |
| Development of Dunkirk III near Alkmaar, the Netherlands | 1984 | Westerhoff, W.E.; Cleveringa, P.; Mücher, H.J. | 63(3) | Dunkirk III sediments (pik clay, rekere clay, and del soils) in the province of Noord-Holland lie on top of tidal-flat deposits (Calais IV and Dunkirk O) and/or Holland peat with a time stratigraphic hiatus in between. Deposition during the Dunkirk III transgression probably took place in various phases under changing environmental conditions with varying sedimentation rates between AD 1050 and 1250. This conclusion is based on geological and historical data. The initial sedimentation phase is represented by a thin layer of clay rich in organic matter, deposited under slightly brackish conditions. In the following phase of virtual non-deposition, sediment accumulated under almost freshwater conditions. Soil micromorphological, pollenanalytical, and malacological data confirm soil formation during the initial sedimentation phase while agriculture continued. Between AD 1150 and 1250 the bulk of the Dunkirk III sediments were deposited under brackish conditions. The interrelationships between pik clay, rekere clay, and del soils are discussed. |
| Geological investigations in the centre of Haarlem (the Netherlands) and the development of the river Spaarne | 1984 | Jong, J. de | 63(3) | The Spaarne river, exists since the Early Subboreal and drains into the former IJ estuary. Its main sand deposits date from the Early Subatlantic, other deposits from after the beginning of the Christian era. Sands of medium grain size are obviously derived from reworked dune and beach sands. They were deposited partially as point-bar deposits, but dune sands blown into the water of the Spaarne may also be present. Substantial amounts of organic material were deposited after the beginning of the Christian era. A clay bed Bakenes clay, covers the much older Holland Peat along both sides of the Spaarne. The clay probably dates from the XIIth century and reflects a period of flooding, including some storm surges which are mentioned in historical sources. In late medieval times a strip of land along the Spaarne was reclaimed; the resulting shift of the Spaarne bank is discussed. |
| The interaction between man and his physical environment in the county of Holland between circa 1000 and 1300 AD: a dynamic relationship | 1984 | Hallewas, D.P. | 63(3) | This paper gives a summary of the archaeological and historical datings concerning the reclamation of the peatbogs, the formation of the Younger Dunes, sedimentation, erosion and lake formation. The size of the areas, in which these changes in the physical environment took place was estimated for parts of the provinces of North and South Holland. These estimates enabled us to demonstrate the differences in the effects of these events on the society in both areas. |
| Detailed geologic information from seismic data | 1984 | Berkhout, A.J. | 63(3) | Seismic data provide an invaluable amount of information on the subsurface geology, particularly because of its dense lateral sampling. However, on the spatial resolution properties there is still a lot to be desired. In this paper the principles of seismic resolution are discussed and limitations in practical situations are indicated. |
| On the mechanics of lithospheric stretching and doming: a finite element analysis | 1984 | Cloetingh, S.; Nieuwland, F. | 63(3) | To investigate the thermo-mechanical aspects of lithospheric thinning and rift formation we have constructed finite element models for doming and stretching. We have found that the magnitude of stretching forces required to induce failure in oceanic lithosphere is proportional to lithospheric age. Updoming of the lithosphere caused by a temperature perturbation in the upper mantle can be an effective mechanism for rifting only when updoming is associated with a reduction in the thickness and the strength of the mechanically strong part of the lithosphere. These findings explain why relatively lew uplifts generate new rifts. |
| Flood tidal delta sedimentation in the Late Cretaceous Menefee formation (Mesaverde group), San Juan Basin, Northwest New Mexico | 1984 | Donselaar, M.E. | 63(3) | The Menefee Formation (Mesaverde Group, Late Cretaceous) in the San Juan Basin, northwestern New Mexico, consists largely of deltaic plain and paralic deposits. The deposits were formed along the west coast of the Cretaceous Seaway. The upper part of the Menefee sequence displays isolated sandstone bodies with a lobate geometry. The sandstone bodies are embedded in carbonaceous shales of coastal swamp/lagoonal origin. Sedimentary structures include inclined lamination, tabular and wedge-shaped cross-bedding in the lower parts of the sandstone bodies, and trough cross-bedding in the upper parts. The bipolar distribution of transport directions, as well as the presence of mud drapes on foresets and bottomsets, point to a tidal environment of deposition. The lobate sandstone bodies are thought to have been generated as flood tidal deltas. Based on theoretical models for the stacking of tidal delta deposits, an indication is given of the relation between relative rise of sea level and behaviour of the flood tidal deltas and connected tidal inlets on the barrier coast of the Cretaceous Seaway. |
| Iberiaella, a new fossil alga from the Middle Carboniferous of NW Spain | 1984 | Rácz, L.G. | 63(3) | A colony-forming organism, constructed of single, pairs or bundles of wavy, locally constricted tubular filaments, is described here as new Middle Carboniferous algal genus Iberiaella of uncertain affinity. Iberiaella superficially resembles Donezella, a widespread organism observed in shallow water carbonates of the Cantabrian Mountains. However, the multi-layered tubular tissue, the nonperforated wall structure of the tubes and the encrusting habitus make Iberiaella easily distinguishable from Donezella with its dichotomously branching single layers of detached septated tubes. It is believed that lberiaella with its anastomosing branching-network and encrusting character forms the rigid skeleton of the organic mounds which occur commonly in the carbonate beds on the southern slope of the Cantabrian Mountains. Donezella had the function of a stabilizer in the process. The fine (micritic) internal sediment - the bulk of the material filling up the open spaces in the algal network - suggests low to moderate energy during deposition and absence of drastic diagenetic alterations. |
| Plate tectonics at the treshold of middle age | 1984 | Andel, T.H. van | 63(4) | plate tectonics has been in the foreground of geological thinking for almost twenty years. It has proved to be an immensely useful concept and its consequences, especially for the history of the earth and life, have by no means been fully explored. As is inevitable with any comprehensive theory, however, flaws are also beginning to show, mainly in the form of a growing of ad hoc modifications which cast doubt on the claim that this is the ultimate unifying new global tectonics. What the future shall bring is a matter of conjecture, but any new dynamic theory of the earch is certain to include continental drift. |
| Quantitative analysis of radiocarbon dates of the perimarine area in the Netherlands | 1984 | Berendsen, H.J.A. | 63(4) | Until recently it was thought that sedimentation in the perimarine area of the Netherlands occurred synchronously with sedimentation in the marine area. The observed alternation of clastic sediments and peat in both areas was attributed to an alternation of transgressions and regressions. Quantitative analysis of available radiocarbon dates of the perimarine area leads to the following conclusions: 1-It is impossible to establish a chronology of periods of sedimentation and periods of sedentation (peat formation) which corresponds with any of the existing chronologies in the marine area. The observed alternation of clastic sediments and peat in the perimarine area is determined by avulsion rather than by an alternation of transgressions and regressions; 2-Peat formation in residual channels west of a line from Utrecht to Den Bosch is determined to a high degree by the general rise of mean high water in the Netherlands; 3-Peat formation in residual channels in the perimarine area starts mainly during periods of regression; 4-Avulsion occurred almost exclusively during periods of transgression. |
| Problems of lithostratigraphic classification of Holocene deposits in the perimarine area of the Netherlands | 1984 | Berendsen, H.J.A. | 63(4) | The definition and subdivision of the Westland Formation, especially with regard to the so-called 'perimarine deposits', has met with serious objections. These objections result from the mingling of the concepts of lithostratigraphy, chronostratigraphy, and genesis. It is concluded that the lithostratigraphic classification of the Holocene sediments in the Netherlands' coastal area has to be disconnected from the genetic concept of a 'perimarine' area. A new system for lithostratigraphic classification of the deposits in the perimarine area is proposed' |
| The Sangatte raised beach and the age of the opening of the strait of Dover | 1984 | Balescu, S.; Haesaerts, P. | 63(4) | This study is a pedological and mineralogical diagnosis of the loamy cover deposits of the Sangatte raised beach (Strait of Dover), presently at almost 10 m N.G.F.4, to determine their chronostratigraphy. The analytical data are compared with those obtained for the Cagny-la-Garenne (Somme, Picardie) section, which is considered a stratotype for Middle Pleistocene loesses of Northern France. Our results support the notion that formation of the Sangatte raised beach can be attributed to a high sea level of the Middle Pleistocene. This provides further evidence on the paleogeographical evolution of the Southern North Sea Basin during the latter half of the Middle Pleistocene. It confirms the previous assumption of an early opening of the Strait of Dover in the Middle Pleistocene. Furthermore, it demonstrates that the loesses with high green hornblende and garnet content, that were previously supposed to be restricted to the Weichselian, were already deposited during the Saalian. |
| Morphological changes of the ebb-tidal delta of the eastern Scheldt during recent decades | 1984 | Berg, J.H. van den | 63(4) | The ebb-tidal delta of the Eastern Scheldt consists of a complicated system of shifting channels and shoals. From 1959 onwards detailed soundings of the area have been carried out almost yearly and thus the most important morphological changes in the last 25 years have been established. An attempt has been made to trace the impact of 'Delta-project' constructions which have already been completed upon the trend of the morphological evolution. Attention is paid to implications of this investigation for the study of fossil examples of ebb-tidal deltas. A main conclusion is that a rather small increase in tidal discharge at the entrance of the Eastern Scheldt basin resulted in a remarkable and rapid expansion of the ebb-tidal delta. |
| Gradual pollen zone transition from Alleröd to younger Dryas in an eastern Netherlands' lake fill | 1984 | Woude, J.D. van der | 63(4) | A Late Glacial lake fill in the eastern Netherlands' acolian sand district shows a very gradual transition from the Alleröd to the Younger Dryas pollen zone. This contrasts with most pollen sections from the wide surroundings, where this transition is sharper. As, however, in most of these sections the pollen zone boundary coincides with a rather sharp lithologic change, local influences and/or time lags might have caused the sharper pollen zone transition there. Hence, the hypothesis is formulated that, as to regional vegetation history, the transition from Alleröd to Younger Dryas may indeed have been gradual. |
| The Nars array | 1984 | Dost, B.; Wettum, A. van; Nolet, G. | 63(4) | We present a detailed description of the instrumentation and design of the Network of Autonomously Registrating Stations (NARS). The instrumentation of each station consists of three Teledyne Geotech SL 210/220 long period seismometers and a Kinemetrics PDR-2 digital event recorder. This off-the-shelf technology was supplemented by specially designed pre-amplifiers, response shaping tilters and time receivers which calibrate the PDR-2 clock in an automatic fashion. Expressions for the full system response are derived. and station locations are given. |
| Reactivation of early reverse faults associated with oblique strike-slip faulting: a mechanism for crustal shortening (Macizo de Nevera, Sierra de Albarracín, Spain) | 1984 | Rondeel, H.E.; Weijermars, R.; Dorssen, H.G. van | 63(4) | Detailed structural and lithological analysis in the Macizo de Nevera, Spain, has revealed that the structure of the Palaeozoic basement rocks is much more complex than hitherto recognized. Alternations of pelite and psammite, separated by distinct thin intervals of orthoquartzite, are folded around shallow north-plunging fold axes. Detailed mapping of these folds disclosed that the synforms are consistently excised by reverse faulting along strike. In the western part of the Macizo de Nevera, this essentially simple structure is seriously complicated by a NE-SW trending system of en-echelon arranged dextral strike-slip faults, that partly reactivated the earlier reverse faults. Due to reworking of the latter faults, the crustal section was further shortened in an E-W direction, the motion being mainly concentrated on faults on either side of the Vallejo Hondo Anticline. Neither of the fault generations discussed continue into the Mesozoic cover of Triassic and Jurassic sediments which surrounds the Macizo. In an appendix to the paper, the Palaeozoic rock units are described. |
| A new interpretation of the structural and metamorphic history of the western Aston Massif (Central Pyrenees, France) | 1984 | Verhoef, P.N.W.; Vissers, R.L.M.; Zwart, H.J. | 63(4) | Detailed structural analysis has yielded new data on the structural and metamorphic evolution of the western Aston Massif and on the nature of the transition zone between the supra- and infrastructure in the central Pyrenees. The low-grade suprastructure is characterized by a steep axial-plane cleavage, whereas a flat-lying schistosity predominates in the high-grade infrastructure. Structural cross sections through the transition zone indicate that the steep cleavage is a first (F1) structure which becomes progressively deformed towards the higher grade rocks by second and third generations of structures (F2 and F3). The third deformation in particular is characterized by a flat-lying axial-plane schistosity. Two dome-shaped metamorphic isograd patterns occur in the area. These isograd patterns match with a structural dome which largely results from F2 deformation. Third generation flat-lying structures, while being moderately developed in the transition zone, predominate in the central part of the dome, suggesting thermally induced vertical shortening. Two younger generations of broadly post-metamorphic steep folds (F4 and F5) only slightly affected the major structure. The relationship of deformation and metamorphism is different for the two metamorphic thermal highs. In areas where these two thermal highs intersect, two phases of metamorphic mineral growth can be demonstrated, indicating the complex nature of the Pyrenean metamorphism in such localities. |
| Comment and reply on The North Sea and Northeastern Bering Sea: A comparative study of the occurrence and geometry of sand bodies of two shallow epicontinental shelves | 1984 | Stride, A.H.; Nio, S.D. | 63(4) | |
| In memoriam, Dr G.L. Krol | 1984 | Fick, L.J. | 63(4) | |
| #REF! | 1984 | 63(4) | ||
| Biopolymer-mediated Ca and Mn accumulation and biomineralization | 1985 | Westbroek, P.; Vrind-de Jong, E.W. de; Wal, P. van der; Borgman, A.H.; Vrind, J.P.M. de | 64(1) | Various metals are known to be accumulated by both intra- and extracellular biopolymers. Such accumulations may lead to the formation of biominerals, whereby the biopolymers may assume a regulatory role in crystallization processes. Two examples are discussed that are studied in our laboratory, calcium and manganese. Emiliania huxleyi is a unicellular marine alga that produces calcite discs - coccoliths - within an intracellular vacuole. Much attention has been given to the probable involvement of a complex acidic polysaccharide that is associated with the crystalline phase. E. huxleyi is the most productive lime-secreting species on earth and is likely to play an important role in the oceanic carbon cycle. Manganese-oxidizing bacteria occur associated with recent sedimentary Mn-deposits. Manganese oxidation in two species is briefly discussed. There are strong indications suggesting that extracellular biopolymers regulate the binding of reduced manganese and its subsequent oxidation. Biopolymer-mediated metal accumulation and biomineralization occur at a huge scale in the biosphere, and hence may have important geological implications. The processes may be utilized for the reclamation of heavy metals from natural and polluted environments, for the prevention of 'scaling' in industrial practice, and for the treatment of pathological (de)mineralizations in humans. |
| An outline of the Quaternary stratigraphy of the Netherlands | 1985 | Zagwijn, W.H. | 64(1) | A review is presented of the chronostratigraphy and lithostratigraphy of the Quaternary of the Netherlands. The influence of glaciations is discussed and correlations indicated with the terrace systems of the river Rhine. |
| Provenance of Cambro-Ordovician to Oligocene sandstones in the Southern Pyrenees, Spain | 1985 | Nagtegaal, P.J.C.; Weerd, J.T. de | 64(1) | The Cambro-Ordovician, Silurian and Devonian sedimentary sequences in the Southern pyrenees were deposited on the northern, then passive, margin of the early Iberian plate. Supply of an increasingly mature clastic assemblage was sourced from the south. In pre-Variscan Carboniferous time this margin was activated as is evident from the appearance of abundant metamorphic and volcanic lithics in the sandstones. The Variscan chain, which had emerged in the Late Westphalian, dictated a new clastic dispersal pattern with southwards-directed paleotransport. The sandstones of these early post-Variscan times typically represent a 'recycled orogen' facies with variations in composition that can be attributed to contemporaneous volcanism, relief and paleoclimate (Westphalian D - Early Triassic). Towards the end of the Mesozoic (Santonian) southern clastic sources, collectively referred to as the ,Ebro High', had again become active. They supplied stable terrigeneous assemblages until the end of the Maastrichtian' As a result of the Late-Cretaceous collision of Iberia with stable Europe, the main clastic dispersal systems changed drastically and in Paleocene time supply was from the northeast where uplifted Mesozoic carbonates were subjected to erosion. This dispersal system, which gradually also involved supply directly from the north and from deeper stratigraphic levels, became very important in Eocene and in Oligocene time, and, in essence, even persists today. |
| Devonian basin-fill histories of the Spanish Cantabrian Mountains and the Belgian Ardennes; a comparison | 1985 | Reijers, T.J.A. | 64(1) | The evolution of the Pre-Devonian and the Devonian sedimentary basin in the Cantabrian Mountains (N.W. Spain) and in part of the Belgian Ardennes is traced and compared. Emphasis is on the palaeogeography reflected by lithofacies in the carbonate platforms in both basins. Lithofacies from the Devonian system have been chosen because the Devonian is the Period of relative tectonic quiescence between the Caledonian and the Variscan orogenies. It could be attempted for such a Period to characterise sediment patterns and the nature of carbonate in terms of the megatectonic and geodynamic frame within which they are formed. For Iberia a geodynamic mobile model has been proposed in the literature, whereas the tectonically imbricated Belgian Ardennes are geodynamically a stable area. The Belgian carbonate platforms appear to have a Pacific faunal/particle affinity, and they evolved from rimmed margin to knoll-reef rimmed ramp platforms. The Spanish carbonate platforms appear to have an Atlantic faunal/particle affinity and evolved from ramp type to reef-rimmed carbonate platforms. |
| Problems of ore density determinations at Nanisivik mines | 1985 | Ruiter, H. de | 64(1) | One of the difficulties of ore reserve calculations is the determination of the factor to convert a volume to be mined into a tonnage to feed the mill. This factor is normally referred to as 'tonnage factor', 'density' or 'specific gravity'. At Nanisivik , a zinc-lead mine located in Canada's High Arctic problems occurred with the tonnage factor when,2½ years after start-up, a stockpile of 91 000 tonnes of ore had accumulated on paper, while actually only 11 000 tonnes could be identified. These stockpile differences indicated that the ore density of 4.4 t/m3 was probably no longer appropriate. The influence of survey errors in measuring were evaluated. Density calculations were carried out on 345 samples taken underground. The moisture content of the ore in the millfeed was used to calculate the density for two periods of about one year. Ultimately it was concluded that the actual density was around 4.0. This figure was then adopted and ore reserves were adjusted accordingly. |
| Problems of classification and maturity evaluation of a diagenetically altered fluvial sandstone | 1985 | Nwajide, C.S.; Hoque, M. | 64(1) | The fluvial sandstones of the late Cretaceous Makurdi Formation of the middle Benue Trough of Nigeria are composed of feldspathic wackes (average matrix content 25.4%) and subarkosic arenites (average matrix content 9.3%). Except for the differences in the matrix content, the framework mineralogy of the two groups of sandstones is very similar. The interstitial clay matrix is both primary and diagenetic in origin. Regression analysis shows an inverse correlation between the proportion of matrix and the incidence of detrital feldspars in the sandstones. It implies that postdepositional alterations of feldspars have given rise to a mineral assemblage which is more mineralogically and less texturally mature than the original deposit, thus invalidating genetic significance in sandstone nomenclature. Neither the clay content nor the zircon-tourmaline-rutile (ZTR) index is a reliable measure for textural or mineralogical maturity of the Makurdi sandstones. It is proposed that several other attributes, such as roundness, ratio of undulose-to-nonundulose quartz, and MQ/PQ ratio which are less susceptible to diagenetic alteration, can be used as reliable indices of textural maturity. A mineralogical maturity scale, based on inert versus labile components (Q/F+L) of framework composition of a sandstone, is proposed to facilitate quantitative analysis of maturity data. |
| The Feldbiss fault in the Maas valley bottom (Limburg, Belgium) | 1985 | Paulissen, E.; Vandenberghe, J.; Gullentops, F. | 64(1) | An intensive geoelectric campaign in the Maas valley (Rotem area, Limburg, Belgium) allowed the location of the Bichterweert scarp, a (buried) scarp at the base of the Maas valley bottom gravels. This scarp, tectonic in origin, is attributed to the Feldbiss fault system at the southern border of the Central Graben. The Bichterweert scarp is the result of Saalian and Weichselian movements. Due to this activity the thickness of the Maas gravel beds suddenly increases north of the scarp. The electric specific resistivities are a measure for the gravel quality. |
| Genesis of the flint eluvium and related beds in South Limburg, The Netherlands | 1985 | Buurman, P.; Jongmans, A.G.; Broekhuizen, J.; Miedema, R. | 64(1) | The flint eluvium in South Limburg and Belgium is a dissolution residue of Upper Cretaceous chalk which may occur either at the present surface or below a cover of Early Oligocene sand. Eluvia with sand cover contain weathered glauconite and iron accumulations but no birefringent, oriented clay. Similar eluvia without sand cover show strong orientation of clay throughout the residue. Such orientation of residual clay immediately follows dissolution of the chalk and is not derived from overlying deposits. As eluviation and orientation of clay are strictly bound to subaerial weathering, eluvia with this property must have formed after erosion of the Early Oligocene sands. Eluvia that are covered by sand do not represent a pre-Oligocene soil formation, but have formed below the sand cover. The kleefaarde, a weathering residue without flints, but with properties similar to those of the eluvia without sand cover, is probably a lateral equivalent of the latter and much older than presumed. Accumulation at the base of the beds continues to this day, but weathering at the soil surface is different from that during the Tertiary. The paper presents a dynamic model of the formation of such eluvia. |
| K-Ar date and biostratigraphic position of a volcanic ash-layer in the marine Pliocene of Crete, Greece | 1985 | Bianchi, F.R.; Driever, B.W.M.; Jonkers, H.A.; Kreuzer, H. | 64(1) | Four of five size fractions of two biotite samples from a volcanic ash bed in the marine Pliocene Prassas section on Crete yielded almost concordant K-Ar dates of 3.20 to 3.25 Ma. The youngest date of 3.20 ± 0.03 Ma is interpreted to be a close estimate of the age of the ash. The tephra layer is situated in the lower part of the planktonic foraminiferal Globorotalia crassaformis Zone. In terms of calcareous nannofossil biostratigraphy, the ash bed can be assigned to the Discoaster surculus Zone (NN16) . The ash bed was also recognized in the nearby sections of Aghios Vlassios and Finikia and on the island of Koufonisi, SE of Crete. A tentative correlation with an ash level in the Mediterranean D.S.D.P. site 378 is proposed. The biochronologic scheme of the Mediterranean Pliocene, based on four K-Ar dates from volcanic intercalations in marine sequences, differs by its greater age estimates from the one commonly constructed on the basis of age-extrapolation of geomagnetic or biostratigraphic horizons from other areas. |
| #REF! | 1985 | 64(1) | ||
| In memoriam - Prof. Dr. Ir. F.J. Faber | 1985 | Hageman, B.P. | 64(1) | |
| The origin of groundwater in Carboniferous and Devonian aquifers at Maastricht | 1985 | Glasbergen, P. | 64(2) | Two approximately 500 m deep boreholes were drilled in Maastricht (The Netherlands) and in one piezometers were placed at respectively 240 and 480 m depth. From the piezometric heads, which are several metres above ground level, and the existing groundwater contour maps of the area no firm conclusions concerning the groundwater origin can be drawn. However, oxygen-18 and carbon-14 isotope analyses of the groundwater indicate a meteoric source. The calculated subsurface migration times suggest infiltration in the Middle-Weichselian for water from the upper piezometer and an Early-Weichselian age for water from the lower piezometer. Ionic ratios for bromide and chloride indicate that both groundwater types are influenced by salts dissolved from the rock matrix. Dissolved salts are supposed to be taken up by diffusive transport from pores with stagnant water into the cracks where the main groundwater flow takes place. Well tests performed on both piezometers yielded hydraulic conductivity. It is concluded that the flow velocities in the upper and lower lavers are different. However, the area of origin of the groundwater found in both screens could be the same, taking into account the differences in conductivity and piezometric head. |
| Geochronology of the basement rocks, Amazonas Territory, Venezuela and the tectonic evolution of the western Guiana Shield | 1985 | Gaudette, H.E.; Olszewski, W.J. | 64(2) | The Amazonas Territory of Venezuela is a large area of Precambrian basement rocks overlain in some locales by the supracrustal sedimentary and volcanic rocks of the Roraima Formation. The basements rocks are medium to high grade gneisses with both igneous and sedimentary protoliths, plutonic rocks ranging in composition from granite to tonalite, and meta-volcanic rocks. Rb-Sr whole rock, and U-Pb isotopic analyses of zircons indicate a period of medium to high grade metamorphism and intrusion from 1860 to 1760 Ma. Post-tectonic plutonic activity continued to 1550 Ma. The volcanic rocks of the Roraima Formation in Venezuela give an age of 1746 Ma comparable to volcanic rocks of the Roraima Formation in other parts of the Guiana Shield. The ages and distribution of the basement rocks suggest the presence of a tectonic zone, approximately coincident with the Venezuelan-Colombian border, representing an active orogenic boundary between distinct tectonic provinces. The rocks to the northeast of this zone are part of the Trans-Amazonian of the Guiana Shield, while to the southwest and in adjacent Brazil and Colombia, new younger continental crust has been developed and cratonized. We suggest a model of collision and subduction followed by a change in tectonic style to extensional-vertical to produce the basement rocks of the western Guiana Shield in the Amazonas Territory. |
| Sedimentary lobes in a tidally influenced alluvial area, Capella Formation, Tremp-Graus Basin, Southern Pyrenees, Spain | 1985 | Cuevas Gozalo, M. | 64(2) | Among the coarse clastic deposits of the mainly alluvial Capella Formation several sediment bodies with characteristics of depositional lobes are recognized. These lobes are characterized and distinguished from other macroforms by their geometry, basal contact and lithofacies. A classification of the lobes is proposed on the basis of the geometry and the lithofacies. The most common geometrical type is tabular to wedge-shaped; a second geometrical type is sigmoidal. Two main lithofacies types are distinguished on the basis of the bedding pattern: a horizontally and an inclined bedded type. The lobes were deposited in the lower part of an alluvial fan system. The sedimentation of some of the lobes was influenced by tidal currents. Several models of sedimentary lobes are recognized: overbank splay lobes, terminal lobes, debris flow lobes and spillover lobes. |
| A phenomenon of unusual flattening in folds associated with a Himalayan thrust | 1985 | Bhattacharya, A.R.; Siawal, A. | 64(2) | The paper reports a phenomenon of flattening in mesoscopic folds around a major geotectonic element of the Himalaya, called the Main Central Thrust (MCT). The study demonstrates that the amount of flattening of folds gradually increases towards the MCT. The MCT zone itself shows the strongest flattening of associated folds. A direct control of the MCT is established over the fold shape in a zone of 5 to 6 km across. This phenomenon appears significant for the Himalayan terrain. It is held to represent a well-defined zone of ductile deformation around a 'ductile thrust'. |
| The age of the hominid-bearing deposits of Java: state of the art | 1985 | Leinders, J.J.M.; Aziz, F.; Sondaar, P.Y.; Vos, J. de | 64(2) | The new standard biozonation for the Plio-Pleistocene continental deposits of Java, and its paleogeographical implications, are discussed. The four oldest faunal zones, Satir, Ci Saat, Trinil and Kedung Brubus, of this biozonation are identified in the famous vertebrate-bearing strata around Sangiran. Thanks to this biostratigraphy and to the availability of lithostratigraphically controlled absolute dates from the Sangiran area (provided by the joint Indonesian-Japanese Research Programme CTA-41) it is now possible to date the biostratigraphy: Kedung Brubus fauna: around 0.8 Ma Trinil H.K. fauna: around 1.0 Ma Ci Saat fauna: Satir fauna: around 1,.2 Ma around L.5 Ma Semah's (1982) interpretation of the magnetostratigraphic data from the Sangiran area is not the most plausible one and an alternative is presented. |
| Isotopic age determinations in Bergslagen, Sweden: VI. acid metavolcanics of the Bergslagen Supracrustal Series, Grythyttan-Hjulsjö area | 1985 | Oen, I.S.; Verschure, R.H. | 64(2) | Metavolcanic rocks of the Bergslagen Supracrustal Series in the Grythyttan-Hjulsjö area, central Sweden, are 1.9-1.8 Ga old according to published zircon U-Pb data. Rhyolitic rocks from Gillershöjden-Kullberget and Norr-Algen and metatuffites from Salbosjön and Kranktorp give Rb-Sr whole-rock ages of 1.6 ± 0. 1 Ga and 1.8 ± 0.1 Ga, respectively. The rhyolitic rocks show reset Rb-Sr whole-rock ages due to a thermal event related to the intrusion of 1.7-1.6 Ga old granites,whereas the Rb-Sr whole-rock ages of the metatuffites still approximate the age of emplacement and earliest metamorphism of the supracrustals. |
| A structural geologic traverse through the Northern Apennines from Rapallo to Bettola (N. Italy) | 1985 | Wamel, W.A. van; Bons, A.J.; Franssen, R.C.M.W.; Lingen, W. van; Postuma, W.; Zutphen, A.C.A. van | 64(2) | Four nappes have been distinguished in the Ligurian units of the N. Apennines between Rapallo and Bettola. The uppermost Antola Nappe is non-metamorphic. It contains a rock sequence of distant origin, that has been folded during one single phase of deformation. The immediately underlying Lavagna Nappe shows signs of very low-grade metamorphism. The constituent rock sequences originate from the Internal Ligurian Basin and have been subjected to polyphase folding and thrusting. Contrary to all later folding, the first folding phase (Fr) produced large-scale isoclinal folds that originally had a SW facing. These seem to have formed in an accretionary wedge, associated with a NE inclined subduction zone. The Mélange Nappe underlies the Lavagna Nappe. It is non-metamorphic in the area studied and contains rocks from the Bracco Zone (Ridge) and the External Ligurian Basin. Synsedimentary deformation is common in the Mélange Nappe. This nappe is also characterized by the occurrence of large-scale isoclinal recumbent folds with a NE facing. Together with gravitational sliding and spreading phenomena, this isoclinal recumbent folding seems to have been coherent with the gliding of the rock sequences, now incorporated in the Mélange Nappe, off a NE slope. The Canetolo Nappe is the lowermost thrust unit treated in this paper. It is non-metamorphic and the constituent rocks originate from the Subligurian Basin. After one phase of internal folding, the Canetolo Nappe was coupled together with the earlier stacked nappes. This pile of nappes overthrust the Tuscan units in a NE direction. |
| Grain size distribution of different minerals in a sediment as a function of their specific density | 1985 | Schuiling, R.D.; Meijer, R.J. de; Riezebos, H.J.; Scholten, M.J. | 64(2) | A beach sediment from Ameland, the Netherlands was divided into 9 grain size fractions. For each fraction the heavy minerals were separated subsequently and split in a number of magnetic fractions, roughly coinciding with particular minerals. All these fractions were weighed, and their mineral composition determined. The resulting grain size distribution for each different mineral turns out to be determined mainly by its specific density, and only to a minor degree by differences in the shape of grains. |
| Note on a new rhyncholite from the Maastrichtian of Limburg, The Netherlands | 1985 | Tuuk, L.A. van der | 64(2) | Recently discovered rhyncholites (Cephalopod mandibles) from the Upper Maastrichtian of the province of Limburg make it possible to describe a new species: Rhyncolites marcellae. |
| Problems of lithostratigraphic classification of Holocene deposits in the perimarine area of The Netherlands | 1985 | Loon, A.J. van | 64(2) | Lithostratigraphic mapping always faces the problem of to what detail separate units should be distinguished. It is quite clear, for instance, that a rough first mapping requires other standards than a highly specialized investigation. Consequently, the choice of lithostratigraphic units should be based on flexible criteria (cf. Hedberg 1976).In practice the rules applied seem to be strongly influenced by national and historical developments. In the USA, for instance, hard-rock formations tend to be several hundreds of metres thick; in The Netherlands, in contrast, the Quaternary succession has been subdivided in formations and members which often have a local or even regional thickness of less than one metre. Berendsen (1984b), in an elegant analytical paper, recently argued that the detailed 'lithostratigraphic' subdivision of (sub)recent deposits in The Netherlands, as applied by the Dutch Geological Survey, gives rise to serious problems since various concepts are mixed and used simultaneously in an unacceptable way. In fact, he underlined rather similar views published earlier in a special issue of this journal on Quaternary geology (Van Loon 1981). A main problem is the term 'Westland Formation', formally introduced by Doppert et al. (1975) in an explanation to the new geological maps (Zagwijn & Van Staalduinen 1975). Berendsen (1984b) once more demonstrate that both the theoretical definition and the practical mapping of the Westland Formation are based on illogical concepts. |
| Central Irish sulphur isotope data in the light of the rift geological-metallogenic model | 1985 | Deeny, D.E. | 64(2) | The current state of central Irish sedimentary-exhalative metallogenetic theory is summarily reviewed. There is disagreement concerning the significance of primary sulphur in the genesis of the Tynagh/Silvermines ore deposits, the most popular view being that seawater sulphate, via biogenic reduction processes provided the bulk of the sulphur. It is shown that the extreme physico-chemical environmental conditions envisaged in a model which associates sulphide genesis with rifting may provide a framework wherein inorganic fractionation processses in primary sulphurous fluids may have contributed to a greater extent than currently recognised in producing the measured isotope distribution patterns at Tynagh and Silvermines. It is also noted that if catastrophic sulphide genesis on the scale of the Irish model were an historically recurring global event it might assist towards an explanation of the known isotopic history of the whole world ocean. |
| Geometry and lithofacies of sediment bodies in a tidally influenced alluvial area. Middle Eocene, Southern Pyrenees, Spain* | 1985 | Cuevas Gozalo, M. | 64(2) | Four types of sedimentary macroforms are described from well exposed Eocene deposits in the Tremp-Graus Basin, Spain: channel deposits, depositional lobes, sheet deposits and composite forms of lobe and channel origin. The channel deposits comprise sediment bodies either formed by lateral accretion or by vertical aggradation. Mixed forms also occur. The form of the channel base is used for further subdivision of the channel bodies. The association of the sedimentary macroforms indicates deposition on distal parts of alluvial fans. Influence of tides is suggested by the bipolar cross-stratification, reactivation surfaces and mud drapes occurring in some of the channel deposits and depositional lobes. At some locations intensive burrowing suggests marine conditions. |
| Eervolle vermelding - Hendrik Jan Zwart | 1985 | Tex, E. den | 64(2) | |
| A geochemical reconnaissance survey of Sri Lanka using panned mineral concentrates of stream sediments | 1985 | Ramakrishna, R.S.; Rajaseelan, R.E.; Karunaratne, J.M.T.B.; Balasubramaniam, M.; Brooks, R.R.; Ryan, D.E.; Holzbecher, J. | 64(3) | Thirteen elements (Au, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sn, Th, U and Zn) were determined in 120 heavy mineral concentrates from Sri Lankan stream sediments of the Highland Group of rocks in central Sri Lanka. The data indicate sporadic occurrences of gold, notably in the north of the region where this metal had not previously been found. The possibility of the existence of a previously unknown area of ultramafic rocks near Balangoda close to the plate boundary with the Vijayan Complex was indicated by high levels of chromium and nickel in the sediments. Background levels of uranium (8 μg/g) were relatively high and three anomalies (>35 μg/g) were detected in stream sediment concentrates. The project has pinpointed several areas where localized intensive exploration for specific minerals should be undertaken. Background levels have also been established for thirteen elements in stream sediment concentrates derived from the Highland Group of rocks. |
| Formation of gas hydrates in a permeable medium | 1985 | Boer, R.B. de; Houbolt, J.J.H.C.; Lagrand, J. | 64(3) | Gas migrating upwards in deep sea sediments can form a thin zone of solid gas hydrates, which can act as a seal below which free gas is trapped. The acoustical contrast between the water-bearing sediments above this seal and the gas-containing sediments below it could cause seismic reflectors with a negative polarity running subparallel to the sea floor. The gas hydrate seal itself would be too thin to be resolved by seismic methods. To clarify whether gas hydrates could form such thin seals that are still effective, the formation of gas hydrates in a sediment has been simulated in laboratory experiments. An effective seal was formed from propane and water within 15 minutes in a coarse sand pack. This seal when 5 cm thick, could withstand a pressure difference of 2.4 bar. This finding supports the above model. |
| Heat flow through thermally anisotropic media: A numerical method and its application to an area of the southwest Scottish Highlands | 1985 | Jones, F.W.; Ertman, M.E. | 64(3) | A numerical method is outlined for the solution of the conduction equation with source term for regions with thermal anisotropy. A number of general models are considered and temperatures, thermal gradients and heat flows are calculated to show the anisotropy effects. The model is applied to an area of the southwest Scottish Highlands to investigate the possible effect of thermal anisotropy on metamorphism. It is found that thermal anisotropy may have contributed to the metamorphism, but the most important effect is that of non-uniformity of thermal conductivity in the vertical direction. Deep local sources may also contribute to the conditions causing metamorphism. |
| Late Pleistocene periglacial conditions in Blaksmark near Varde (Denmark) | 1985 | Kolstrup, E. | 64(3) | During pipe line construction in Blaksmark north of Varde in Denmark a shallow depression with a tilted block of sand and gravel, and an infill of layered sand and silt was found. It is suggested that fluvio-thermal erosion has taken place here. Ice wedge casts present in the adjacent sand indicate that permafrost existed during a former cold period. It is suggested that the thermal erosion and the filling, as well as the formation of the frost wedges date from the last permafrost period of the Weichselian. |
| Directional variations of fold axes in progressive deformation, an example from a Betic fold nappe in S Spain | 1985 | Weijermars, R. | 64(3) | Singly folded and coaxially refolded rocks generally have axial directions that plot as unimodal clusters and either small or great circle girdles. Cluster distributions of axes are characteristic of either cylindrical folds or sheath folds developed at high shear strains. Girdle distributions may occur due to conical folding or sheath folds developed at intermediate shear strains. A variety of axial distributions can occur in non-coaxially refolded regions, since the variation of the axes of folds due to refolding depends on the initial interlimb angle and the angle between the older and younger axial planes. Characteristic fold axial distributions are summarised in a practical chart for general application (Table 1). This study is illustrated by the analysis of axial directions of isoclinal minor folds cogenetic with the final emplacement of the Aguilón fold nappe in S Spain. The axial directions of these (Ds) folds show a bimodal girdle distribution which is ascribed to their superposition on opposing limbs of the preceding (Dr) folds. Directional statistics suggests that D, folds were of chevron or similar type with interlimb angles of about 65 degrees before they all but disappeared after non-coaxial isoclinal D2 refolding. |
| Looping the loop; geotectonics of the Alpine-Mediterranean region | 1985 | Linden, W.J.M. van der | 64(3) | The Alpine-Mediterranean system consists of an African and a European orogenic belt which - with a few discontinuities - extend in great loops and bends between the Atlantic Ocean and the Middle East. The evolution and deformation of these belts or so-called oroclines is closely coupled to the relative movements of the African and European plates during the Mesozoic and Cenozoic. Oroclinal bending presupposes the evolution of relatively thick and rigid ribbon continents marginal to the African and European cratons. These ribbons are considered to have formed within the passive continental margins on either side of the Mediterranean while this seaway opened in a transtensional setting, starting in the Triassic. While the ribbons contorted the sedimentary basins in between were squeezed up and out in diapiric fashion to later be thrust (obducted) over their peripheries and to be emplaced as sedimentary and ophiolitic nappes. Orogenesis finished with the isostatic uplift of the oroclines and the subsidence of the deflated and denudated diapirs. |
| Cathodoluminescence activation and zonation in carbonate rocks: an experimental approach | 1985 | Have, T. ten; Heijnen, W. | 64(3) | Calcite crystals have been grown with the objective of studying the cathodoluminescence (C.L.) characteristics. No trace elements other than Mn2+ were needed to activate luminescence similar to that observed in natural carbonates. C.L. observations, combined with Mn and Fe analyses of synthetic crystals, natural calcites and dolomites, show that: 1. 15-30 ppm and 30-35 ppm Mn is sufficient to activate luminescence in calcites and dolomites, respectively. 2. The intensity of luminescence is controlled by the absolute amount of Mn2+ and not by the Fe2+/Mn2+ ratio. Both conclusions are valid provided Fe concentrations are low (< 200 ppm). 3. Luminescent zonation, common in synthetic and natural carbonates, reflects differential Mn2+ uptake during growth, caused by: a. changes in the Mn2+ concentration of the precipitating fluid, or b. changes in the rate of crystal growth independent of the Mn2+ concentration in the fluid. The latter process has not been considered sufficiently in former C.L. studies, but will have important consequences for interpretation of luminescence features: e.g. definition of the geochemical history of pore fluids by characterisation of the rock's C.L., may not always be justified. Specifically, the concept of cement stratigraphy (i.e. correlation of similar luminescent colours or intensities) should be handled with care and only applied when it can be demonstrated that the zones are the result of bulk geochemical changes in the pore fluids and not merely of differences in crystal growth rate. Tentative criteria for such a differentiation are discussed. |
| The Muschelkalk and its lead-zinc mineralization in the eastern Netherlands | 1985 | Boorder, H. de; Lutgert, J.E.; Nijman, W. | 64(3) | The Muschelkalk of the eastern Netherlands, as exposed in quarries east of Winterswijk, is made up of sequences of dolomitic lime-mudstones. These are interpreted as stromatolites, particularly because of their characteristic algal growth patterns around mudcracks which show evidence of intermittent cracking and sealing. Rare, intercalated skeletal packstone layers with cyclic grain-size grading are thought to represent storm layers deposited within the high intertidal to supratidal algal mat environment. Pyrite, marcasite, sphalerite and galena occur widely dispersed in the limestone but have been concentrated more conspicuously in the storm layers and mudcrack fillings. A widespread occurrence of algal mats could account for initial concentration of considerable amounts of base metals. These probably did not derive from the deeper portions of the main Triassic basin to the north but are more likely of southern provenance, transported in meteoric water draining the emerged Variscan massifs. Secondary concentration of metals during dolomitization and compaction has demonstrably occurred, preferably in coarser-grained fabrics. Supergene enrichment is inferred from high strontium, lead and zinc values below a red bed interpreted to be a paleosol. A further analysis of the metal distribution is required. The area investigated is considered immature as regards economic mineral concentration. However, a place for base metal exploration is advocated in the course of the systematic investigation of the Netherlands subsurface. |
| Clast-fabric strength in tills and debris flows compared for different environments | 1985 | Rappol, M. | 64(3) | Elongated-clast fabrics of Alpine till from western Allgäu (southern West Germany) and of lowland ice-sheet till from The Netherlands are compared with published results from other areas. A quantitative comparison is made through the use of an eigenvalue method which produces measures of fabric shape and strength for three-dimensional orientation data. Clast fabrics of subglacial till in Western Allgäu tend to have lower strength than those from The Netherlands. Similar differences have been noted by comparing melt-out till fabrics of the Matanuska Glacier (Alaska) with Cordilleran ice-sheet and Alpine tills in North America. The possible reasons for these differences are discussed. Clast fabrics of ice-marginal debris-flow deposits in western Allgäu are similar to fabrics from sediment-flow deposits reported from other areas. Eigenvalue plots of clast fabrics do not distinguish clearly between subglacial till and debris flows from western Allgäu. |
| The use of heavy mineral suites for loess stratigraphy | 1985 | Juvigné, E. | 64(3) | It is shown that Saalian loess deposits which accumulated in a cut-off meander of the Lesse River at Wanlin, is partly characterized by a mineralogical index similar to that of Weichselian loesses. This is in agreement with a similar observation for loesses of northern France published recently by Balescu & Haesaerts (1984). |
| Problems of lithostratigraphic classification of Holocene deposits in the perimarine area of the Netherlands | 1985 | Graaff, W.J.E. van de; Berendsen, H.J.A. | 64(3) | |
| Book reviews | 1985 | 64(3) | ||
| Uplift and subsidence history of the Alboran Basin and a profile of the Alboran Diapir (W-Mediterranean) | 1985 | Weijermars, R. | 64(4) | The cooling and subsidence history of the Alboran Basin suggests that it is underlain by a diapiric mantle bulge. Numerical models of crustal doming by Cloetingh & Nieuwland (1984) are applied to investigate the deep lithospheric structure beneath the Alboran Basin. At least two 300 km long high angle faults of east-west strike would be expected directly north and south of the Alboran Sea if the Alboran Diapir had penetrated far into the lithosphere. As there is no record of such faults, it is probable that the Alboran Diapir is a shallow bulge in the lithosphere-asthenosphere interface, which deformed the overlying MOHO. The suggested profile for the deep lithosphere in the Alboran area allows discussion of the details of Weijermars' (1985) model for the tectonic evolution of the Alboran Basin and peripheral Betic-Rif orogens during the past 30-25 Ma. |
| Implications of Campanian to early Maastrichtian deep-sea benthic foraminiferal distribution in the western North Atlantic | 1985 | Nyong, E.E. | 64(4) | Deep-sea benthic foraminiferal assemblages of Campanian to early Maastrichtian age in the western North Atlantic are taxonomically similar to coeval assemblages in deep-sea sections from various parts of the world, Species composition in the sections studied is largely the product of selective dissolution of less resistant species at depth in relation to a late Cretaceous CCD and partly due to local submarine volcanism or to local incursions of corrosive bottom water. The uniformity in distribution of these assemblages at different latitudes was also partly aided by the absence of vigorous bottom water circulation during the late Cretaceous in the world oceans. |
| Ichnology of the Cenomanian-Turonian of the Calabar Flank, SE Nigeria | 1985 | Akpan, E.B. | 64(4) | Trace fossils are described for the first time from Cenomanian-Turonian rocks of the Calabar Flank, SE Nigeria. The rocks essentially consist of SW dipping shales intercalated with thin beds of calcareous mudstone. In places, marly limestone occurs as low ridges parallel to the strike of the sequence. Thalassinoides are common in the calcareous rocks. Another, less numerous trace fossil, is probably the borings of phoronid. Marine benthonic pelecypods and gastropods, although of low diversity, are common in the mudstone and are rare or absent in most of the shale intervals which contain planktonic and impoverished benthonic foraminifera. Ichnological analysis supported by palaeontological and sedimentologicic evidence suggest a depositional environment with fluctuating shallow, aerated and oxygen-deficient bottom conditions. |
| The structure of the Lavagna Nappe in the region of Monte Ramaceto and Val Graveglia (Ligurian Apennines, Italy) | 1985 | Zutphen, A.C.A. van; Wamel, W.A. van; Bons, A.J. | 64(4) | Detailed structural analysis and mapping in the Lavagna Nappe reveals the effect of various phases of deformation on a regional scale. The earliest phase produced large isoclinal, originally SW-facing folds (F1). A second phase led to the development of open folds (F2). The vergence of the younger folds (F3, F4) is NE. Thrusting occurred in two stages: postF2-preF3 and synF4. Hereafter the previously stacked thrustsheets, together forming the Lavagna Nappe, were emplaced on top of the Mélange Nappe by NE-directed thrusting. A final phase of gentle folding (F5) caused an undulation of all older structures. |
| Isotopic age determinations in Bergslagen, Sweden: VII. The Fellingsbro-type Granite east of Kopparberg | 1985 | Oen, I.S.; Verschure, R.H. | 64(4) | Rb-Sr whole-rock analysis of seven samples of the Fellingsbro-type Younger Granite east of Kopparberg gives an age of 1715 ± 50 Ma and an initial 87Sr/86Sr ratio of 0.7046 ± 0.0026 (errors 95% confidence level). This age falls in the age range determined for the Younger Granites of the Värmland-Småland, Dala and Fellingsbro Groups, 1.74-1.64 Ga. Reliable age data from from the Malingsbo-type granites in the Kopparberg area are still lacking, however, so it is uncertain whether they can be included in the Fellingsbro Group of Younger Granites |
| The character of glaciotectonism | 1985 | Aber, J.S. | 64(4) | Glaciotectonic features are those structures and landforms produced by deformation and dislocation of pre-existing soft bedrock and drift masses as a direct consequence of glacier-ice movement. Some glaciotectonic structures form essentially in-situ; however, most glaciotectonic features involve detachment of a large rock or sediment mass, called a raft, floe, or megablock, and its transportation and deposition by the ice. The main factors in determining whether glaciotectonic structures could develop are: (1) competence of the bedrock relative to glacier ice, (2) distance of megablock transportation, and (3) mode of deposition. Development of glaciotectonic features depends to a large degree on lithology of the affected rocks or sediments. Glaciotectonism does not represent a special or unique process operating within the ice; the same dynamic conditions which cause normal glacial erosion and deposition also create glaciotectonic features in appropriate kinds of bedrock. |
| Uplift history of a Betic fold nappe inferred from Neogene-Quaternary sedimentation and tectonics (in the Sierra Alhamilla and Almería, Sorbas and Tabernas Basins of the Betic Cordilleras, SE Spain) | 1985 | Weijermars, R.; Roep, T.B.; Eeckhout, B. van den; Postma, G.; Kleverlaan, K. | 64(4) | Structural, stratigraphical and sedimentological studies of the Alhamilla region show that the Sierra Alhamilla was elevated relative to the surrounding basins by open folding towards the end of the Tortonian period (about 7 Ma ago) and before the onset of Messinian sedimentation. The main arguments are: (1) the dominant current direction in the Neogene cover changes from southward to southeast- and southwestward during the Late Tortonian, (2) Late Tortonian seismites suggest contemporaneous major tectonic activity which is contrasted by low tectonic activity during the Messinian, (3) Messinian reefs colonise Nevado-Filabride basement exposed (near Polopos) in the eroded hinge of the Alhamilla Anticlinorium, (4) the Northern Boundary Fault which is interpreted to be cogenetic with the formation of the Alhamilla Anticlinorium transects Tortonian sediments but is covered (near Cantona) by unfaulted Messinian reefs, and (5) the base of an almost non-tectonised Messinian succession (in the Sorbas Basin) unconformably overlies an erosion surface of folded Tortonian sediments, Neogene uplift of the Alhamilla region is interpreted here to be due to isostatic recovery after the emplacement of the Alboran Diapir between 20 and25 Ma ago. Estimates of the average uplift rates vary between 0.7 to 0.5 mm a-1 for the Miocene and 0.15 to 0.1 mm a-1 for the Pliocene and Quaternary. Pliocene and Quaternary uplift rates are almost identical to the sedimentation rates of 0.23 to 0.2 mm a-1 estimated previously for the Alboran Basin. |
| Contact metamorphism in synkinematic two-mica granites produced by younger granitic intrusions, Galicia, N.W. Spain | 1985 | Barrera, J.L.; Bellido, F.; Klein, E. | 64(4) | The thermal effects produced by relatively late granitoids on older synkinematic two-mica granites were studied. Both groups of granitoids are of late-Hercygian age and form part of the large Galician granite area in the N.W. of the Hesperian Massif. The thermometamorphic effects observed in the synkinematic two-mica granites consist of a complete recrystallization with progressive breakdown of biotite and muscovite and formation of andalusite, sillimanite, corundum, spinel, cordierite, quartz, plagioclase, K-feldspar and opaque minerals. Breakdown reactions of biotite and muscovite in the presence of quartz and under oxidizing conditions are proposed to explain the appearance of some of the newly formed minerals. |
| Book reviews | 1985 | 64(4) | ||
| Ter nagedachtenis aan Prif. Ir. Th.R. Seldenrath | 1985 | 64(4) | ||
| On the provenance of the Early-Pleistocene fluvial system in the southern Netherlands | 1986 | Vandenberghe, J.; Krook, L.; Valk, L. van der | 65(1) | Two series of Early Pleistocene fluvial deposits near Galder (southern Netherlands) are overlain by a series consisting of Weichselian aeolian and locally reworked aeolian deposits. Each of the three series is characterized by its own specific mineral association. Special attention is drawn to the origin of the upper fluvial unit which belongs to the 'Alphen Sands'. Mineralogical and petrographical analyses indicate a mainly southern ('pre-Scheldt') provenance of the sand fraction and a mixed southern and southeastern (Meuse) origin of the gravels. The Meuse transported gravel from the Ardennes and from the Cretaceous plateau between Liège and Maastricht. |
| The Kangean and Kediri, lndonesia meteorites | 1986 | Calsteren, P.W.C. van | 65(1) | Two meteorite falls in Indonesia were described and classified. Kangean has Fe/Si= .73, olivine Fo= 17.5 with 1.7 Percent Mean Deviation, paucity of clinopyroxene, plagioclase, and glass and with weakly undulose olivine, and is classified as H5b. Mineralogically Kediri is unshocked and shows virtually no signs of metamorphic reequilibration although the mineral chemical evidence is ambiguous. Classification of Kediri as L3a is proposed. Kediri contains grains that may have survived chondrule formation without melting, and shows evidence for hot accretion. |
| Ecophenotypic variation of the larger foraminifer Orbitoides apiculata from the Maastrichtian stratotype | 1986 | Baumfalk, Y.A.; Willemsen, F. | 65(1) | Morphometric analysis of the larger foraminifer Orbitoides apiculata Schlumberger from the type Maastrichtian shows that the general evolutionary trend within the genus continued in Maastrichtian times, but that the local evolutionary pattern is not gradual and unidirectional. Specimens from the lower part of the type section on the average have smaller embryons and fewer epi-auxiliary chambers than those from the upper part of the section. Besides, a new phenomenon can be observed: in the latest Maastrichtian the species had developed an asymmetric test, with one thin, superficial lateral layer of the ordinary Orbitoides type but with the other layer much thicker and lacking the usual subdivision into lateral chamberlets. The pattern, however, is not a strictly evolutionary one, but seems to be related to the prevailing environmental conditions. The more advanced populations are only found in debris layers overlying hardgrounds. In the intervals between the hardgrounds, O. apiculata is much less abundant and, moreover, has the same morphology as the older, more primitive populations. A comparison with O. apiculata from deposits in southern France, sometimes considered to be slightly younger than the type Maastrichtian, suggests that the development within the Maastrichtian stratotype may be the result of geographic separation. |
| Precambrian rocks in an Early Tertiary conglomerate on Bonaire, Netherlands Antilles (southern Caribbean borderland): evidence for a 300 km eastward displacement relative to the South American mainland? | 1986 | Priem, H.N.A.; Beets, D.J.; Verdurmen, E.A.T. | 65(1) | A U-Pb analysis of seven zircon fractions from a granulitic pebble in the Late Paleocene and/or Eocene fluviatile Soebi Blanco conglomerate on Bonaire, Netherlands Antilles (southern Caribbean borderland) indicates that the rock has been derived from a Precambrian basement with an age of approximately 1150 Ma. Such basement rocks do not occur on Bonaire. The nature of the conglomerate testifies to derivation from a nearby topographic high. It is suggested that the source area was located in the Guajira area, implying an eastward migration of Bonaire of some 300 km relative to the South American mainland since the beginning of the Tertiary. |
| The tidal character of the Formation of Tegelen in northern Belgium | 1986 | Kasse, C. | 65(1) | In northern Belgium a fining upward sequence in the Campine clays and sands (Formation of Tegelen) has been studied. Thinly interlayered sediments of fine sand and clay are overlaid by two claylayers with an intercalated peat-layer. In the sand-clay alternations small scale current ripples with opposed high-angle cross lamination indicate tidal movements. Ebb and flood ripples, covered with mud, point to subtidal deposition. The absence of bioturbation and the presence of fresh water peat indicate a fresh or brackish subtidal (lagoonal) depositional environment. |
| Proterozoic deformation in the Duchess belt, Australia: A contribution to the BMR Mount Isa Regional Tectonic History Program | 1986 | Passchier, C.W. | 65(1) | In medium to high grade metasediments of the Proterozoic Mt. Isa Inlier, Australia, at least three regional phases of deformation can be recognized. Early events of low angle brittle faulting at low grade conditions (D1a), probably followed by localized transcurrent flow along a N-S ductile shearzone (D1b) were overprinted by a phase of intense E-W shortening and vertical extension (D2). During this phase, strain was accommodated without significant flow localization, i.e. without development of major shearzones. Important granite and gabbro intrusion occurred before and early during D2. Crustal shortening values of up to 80% have been realized during D2 leading to large-scale folding and the development of spectacular strain shadows around the major plutons. D3 is characterised by strike-slip faults and minor accomodation structures. |
| Geology of the Tarfaya oil shale deposit, Morocco | 1986 | Leine, L. | 65(1) | A description is given of the Tarfaya oil shale deposit which is located in the Moroccan Sahara along the Atlantic coast, at the latitude of the Canary Islands. The deposit consists of kerogenous chalks of Upper Cretaceous age, which are colloquially called 'oil shales' following general usage. The paper discusses the tectonic setting, stratigraphy and depositional environment of the kerogenous chalks and provides details on their petrography, chemical composition and mineralogy. Some mining criteria are also given such as oil yield, thickness and geological reserves of the oil shales, as well as characteristics of the overburden. Preliminary remarks are made regarding the hydrology of the mining area. |
| Central Irish sulphur isotope data in the light of the rift geological-metallogenic model | 1986 | Boyce, A.J. | 65(1) | |
| Book reviews | 1986 | Linden, W.J.M. van der; Andréasson, P.G.; Boekschoten, G.J.; Harten, D. van; Rondeel, H.E.; Reijers, T.J.A. | 65(1) | |
| Preface - Dutch contribution to the International Lithosphere Program | 1986 | Zwart, H.J.; Wortel, M.J.R. | 65(2) | |
| Archaean global dynamics | 1986 | Vlaar, N.J. | 65(2) | Archaean global tectonics and continental growth is founded on the existence of a differentiated upper mantle of average lherzolite composition. A thick segregated basalt layer constitutes the upper part of the upper mantle. The geodynamic state is determined by a high deeper mantle temperature and a mobile cool shallow basalt layer and this can explain the growth of the Archaean craton and its geothermal state. Of particular importance for continental tectonics are isostatic conditions which differ from the present in allowing for large relative and absolute vertical displacements. |
| Tectonics of passive margins: implications for the stratigraphic record | 1986 | Cloetingh, S. | 65(2) | Thermo-mechanical modelling demonstrates that tectonically induced vertical motions of the lithosphere can explain the major part of the short-term fluctuations in apparent sea level deduced from the seismostratigraphic record at passive margins. The interaction of intraplate stresses and the deflection of the lithosphere caused by sedimentary loading can produce apparent sea level changes of up to 100 metres at the flanks of passive margins. This mechanism is most effective for young passive margins subject to rapid sediment loading. Stress variations in the lithosphere of a few hundred bar are sufficient to explain most of the lowerings in sea level shown in the Vail et al. (1977) curves. To induce apparent sea level fluctuations with magnitudes greater than 50 metres, changes in stress level of more than 1 kbar are required, which must be related to major reorganizations at convergent plate boundaries, fragmentation of plates, or collision processes. By its nature, the tectonic model can explain contemporaneous fluctuations in apparent sea level in neighbouring depositional environments. In principle, it implies the possibility of regional correlations in different basin settings. Specific short-term fluctuations in the Vail et al. curves can be associated quantitatively with particular plate-tectonic reorganizations of lithospheric stress fields. The seismostratigraphic record may provide a new source of information on paleo-stress fields to be correlated with results of independent numerical modelling of intraplate stresses. |
| Dynamical aspects of active continental margins | 1986 | Wortel, M.J.R. | 65(2) | Many tectonic processes along active continental margins (and convergent plate boundaries, in general) are closely related to the dynamics of the subduction process. A major force associated with the subduction of oceanic lithosphere is the slab pull, the result of the density contrast between the cold and dense descending slab and the surrounding warmer mantle. This force is generally assumed to be compensated by resistive forces acting on the slab. In this paper I emphasize that such a compensation may be valid for a plate's convergent boundary as a whole but certainly not always for each segment of the trench system. Stress may be transmitted from the subducted slab to the attached lithospheric plate at the surface, and taking this into account provides insight into the relationship between upper mantle processes and tectonic processes near the surface (e.g. fragmentation of plates, accretion of sediments at trenches, and vertical tectonics of active continental margins). |
| Thermal modelling of arc-trench regions | 1986 | Beukel, J. van den; Wortel, R. | 65(2) | The temperature structure of the shallow part of a subduction zone. i.e . the region between the trench and the volcanic arc, has been calculated with finite difference methods. Published heat flow measurements are used as a constraint for the thermal models. Heat flow in the arc-trench region is low (<40mW m-2) for subduction zones which have been active for more than about 60 Ma. In the central part of the arc-trench region of these subduction zones average heat flow values range from 30 to 36 mW m-2. From the thermal modelling it follows that such a heat flow level requires shear stresses of 20-60 MPa near the upper surface of the descending slab at depths between 25 and 75 km. In addition, it is shown that the pressure-temperature relations, inferred from mineral assemblages in high-pressure metamorphic belts, can only be reached if significant heat production by friction takes place, with shear stresses similar to those inferred from heat flow data. Subduction related volcanism is caused by high temperatures in the asthenospheric wedge above the slab. It is likely that the volcanic line marks the boundary of the asthenospheric wedge. |
| Subduction beneath Eurasia in connection with the Mesozoic Tethys | 1986 | Spakman, W. | 65(2) | In this paper we present new results concerning the existence and subduction of Meso-Tethyan oceanic lithosphere in the upper mantle beneath Europe, the Mediterranean and the Middle-East. The results arise from a large scale body wave tomographic analysis of the upper mantle in this region. It is shown that much more subduction has taken place beneath the Aegean and Tyrrhenean region than was previously estimated. The Eastern Mediterranean basins are linked to the old Meso-Tethyan passive margin and may in some parts be underlain by oceanic lithosphere. We demonstrate the existence of an old northward dipping subducted slab beneath Spain and the Western Mediterranean. A large zone of subducted oceanic lithosphere is found beneath the entire Alpine orogenic belt from Spain to Iran at depths between 250-600 km. This zone represents major parts of the Meso-Tethys. |
| The upper mantle under Europe: an interpretation of some preliminary results from the NARS project | 1986 | Nolet, G.; Dost, B.; Paulssen, H. | 65(2) | Using teleseismic recordings of 5 strong Japanese earfhquakes in 1983/84, Dost (in press) has recently determined average higher mode phase velocities with the broad-band digital NARS array. These are the first such results ever to be obtained for a single geophysical province, in this case the west European platform. Moreover, the frequency range has been doubled with respect to earlier higher mode phase velocity determinations. It is to be expected that we will refine and extend our measurements in the coming years. No strong earthquake at intermediate depth has so far occurred since the installation of the NARS network, which leaves important gaps in velocity measurements at several frequencies. Nevertheless we have made a preliminary interpretation of the data now available, giving us guidelines for future observational efforts. lnversion of the phase velocities for an average velocity/density structure for the west European platform results in an upper mantle with a low velocity channel between 120 and 250 km that is not very pronounced (average Vs is 4.35 km/s) and with remarkable layer of high velocity and density at roughly 100km depth. Comparison with older higher mode data enables us to determine the difference in shear velocity between the Scandinavian shield and the west European platform: shield Vs is 4.49 km/s averaged over 120-250km. The velocity difference between shield and platform can be explained by a temperature difference of at least 250 degrees, or effects of partial melting under the platform. We have extrapolated laboratory values of shear velocity and density of single crystal specimens of 4 different rock types (olivine, orthopyroxene, clinopyroxene and garnet) to ambient upper mantle pressure and temperature. Despite the uncertainty inherent to such a procedure, comparison of these curves with the inversion results suggests strongly that a layer of eclogitic composition is present between 80 and 120 km depth. |
| Mylonites in the continental crust and their role as seismic reflectors | 1986 | Passchier, C.W. | 65(2) | Shear zones in the continental crust can accommodate much of the regionally imposed shortening or extension. An analysis of the flow patterns and flow history in active shear zones and of their geometry and orientation contributes to the understanding of large-scale crustal deformation. Information on the flow behaviour in 'fossil' ductile shear zones can be obtained from deformation fabrics in exposed mylonitic fault rocks. Unfortunately, the geometry and orientation of such exposed zones have often been modified by uplift and overprinting, masking the original aspect. However, in situ information on the shape and orientation of active ductile shear zones can be obtained from deep reflection seismograms. Provided the zones have a gentle dip, the unique homogeneous nature of mylonitic fabrics in them can generate high amplitude seismic reflections of large lateral continuity. |
| New insights in the structural and metamorphic history of the western Lys-Caillauas massif (Central Pyrenees, France) | 1986 | Bresser, J.H.P de; Majoor, F.J.M.; Ploegsma, M. | 65(2) | We distinguish four deformation phases of major importance in the Cambro-Ordovician metasediments of the western Lys-Caillauas massif. During D1 a steep, regionally dominant, foliation developed. This foliation was folded during D2 into a large overturned isoclinal antiform. The third deformation phase D3 resulted in complex rotations of porphyroblasts, crenulation of the S1 foliation and development of a gently dipping crenulation cleavage S3. At a deep structural level, S1 was completely transposed into the plane of S3, which forms a dome-type D3 structure. D1,D2 and D3 are of Variscan age. D4 included Alpine thrusting along the Gavarnie thrust and accompanying folding and faulting. The Alpine folding led to a considerable amount of ductile shortening in the footwall rocks of the thrust. The Cambro-Ordovician rocks show a Variscan plurifacial metamorphism during D3. Peak values were 600-660°C and 2.5-3.5kbar. Two metamorphic domes of slightly different age with respect to D3 are distinguished. One of these metamorphic domes coincides with the D3 structural dome. The Alpine D4 occurred under low grade metamorphic conditions. In comparison with current notions on the Lys-Caillauas massif the data presented a) reveal a more complex deformation history; b) fit the development of some controversial large scale structures within the deformation history; c) give a more complete picture of the metamorphic evolution of the rocks and d) show that Alpine folding was more widespread than previously thought. |
| Petrology and gold mineralization of the amphibolite belt, Ilesha area, Southwestern Nigeria* | 1986 | Elueze, A.A. | 65(3) | The Ilesha amphibolite belt is composed of metasedimentary rocks and a mafic complex comprising mostly amphibolites and amphibole schists, with intercalations of talc bodies. These assemblages occur within a polycyclic basement of largely ancient gneisses and migmatites, and underlie alluvial gold deposits. In addition, the district is characterized by minor and major structural features including folds, fractures and lineaments which commonly have a northerly strike. Auriferous quartz veins are known to be emplaced along structural elements in the amphibolite complex. It is believed that the alluvial gold deposits were derived from weathered auriferous veins and veinlets. Sulfur contents of the amphibolites and amphibole schists are relatively high, supporting the occurence of sulfides, possibly in relation to primary gold. The mafic units are magmatic and are therefore considered the ultimate source of the vein-type gold deposits. On the basis of overall geological and geochemical characteristics, it is suggested that the mineralization was linked to metamorphic-hydrothermal processes. |
| Satellite radar interpretation of the Bintuni Basin area, Eastern Vogelkop Peninsula, West lrian, Indonesia | 1986 | Koopmans, B.N. | 65(3) | A synoptic view of radar images enables deduction of the regional structural setting which is often not possible from aerial photographs and/or fieldwork only. An interpretation is made of part of a Shuttle Imaging Radar strip of the eastern Vogelkop Peninsula (Jazirah Doberai). The principal structural units that can be distinguished are 1. the Paleozoic igneous metamorphic complex, including the Kemoem Formation, 2. the principal Mesozoic/Tertiary central Vogelkop monocline,3. the northern extension of the Cretaceous/Tertiary Lengguru fold belt, and 4. the Tertiary Bintuni Basin area. The abutment of the E-W running central Vogelkop monocline against the NNW-SSE running Lengguru fold belt appears to be fault-controlled. Also the Bintuni Basin seems to be controlled by faults that parallel the monoclinal structure on the northern and southern sides of the radar image, and by faults parallel to the Lengguru fold belt on the eastern side. The anomalous fold direction of the Imskin anticline is a surface expression of block movements along these faults. |
| Integral Rock Analysis: a new approach in lithogeochemical exploration with use of X-Ray Fluorescence spectrometry | 1986 | Gaans, P.F.M. van; Vriend, S.P.; Schuiling, R.D. | 65(3) | Integral Rock Analysis is a new approach to the acquisition and interpretation of (exploration) geochemical data. An integrated procedure for the rapid and cost-efficient sampling, sample preparation, analysis and statistical treatment of geochemical data is presented. Applicability of the method is discussed on the basis of some examples. The task of sample preparation is significantly shortened by omitting grinding and homogenization. Flat sections of solid rock-samples, sawn of (small) drill cores, are directly analysed by X-Ray Fluorescence spectrometry (XRF). Analytical results are generally in acceptable agreement with those of conventional methods. Conclusions based on the analysis are not adversely influenced by lower analytical accuracy and precision. Moreover, important additional information with respect to small scale features (mineralogy, texture, alteration processes) is obtained as well. Because the method is non-destructive, the same sections can be investigated by microscope, electron microprobe or X-Ray diffraction. This facilitates the correlation of chemical and mineralogical data and the study of small scale features. |
| Cyathidium vlieksi, a new holopodid crinoid from the Upper Maastrichtian (Late Cretaceous) of southern Limburg, The Netherlands | 1986 | Jagt, J.W.M. | 65(3) | On the basis of fairly well preserved specimens of a holopodid crinoid of the genus Cyathidium, a new species of this genus is described: Cyathidium vlieksi sp. nov. As yet, fossils of this crinoid were found only in the Upper Maastrichtian of the province of Limburg. They occur in the Kunrade facies of the Maastricht Formation as well as in the type-area of the Maastrichtian stage (Maastricht, The Netherlands). |
| Outline of the stratigraphy and the geological history of the Suriname coastal plain | 1986 | Wong, T.E. | 65(3) | The stratigraphy and the geological history of the Suriname coastal plain are reviewed, using recently updated and new information. The geological history covers an interval ranging from Late Cretaceous to Holocene. The various transgressive and regressive cycles during this time have been correlated with the global eustatic sea level movements. |
| A potential process for the neutralisation of industrial waste acids by reaction with olivine | 1986 | Schuiling, R.D.; Herk, J. van; Pietersen, H.S. | 65(3) | Industrial waste acids such as sulphuric and hydrochloric acid are produced in large quantities. This note deals mainly with waste sulphuric acid, although similar results have been obtained with hydrochloric acid. A method is described by which these acids can be neutralised using crushed olivine rock. This process produces silica. The heavy metals present can be precipitated from the resulting solution. The remaining clean magnesium-sulphate solution can be dumped at sea without adverse environmental consequences. The process has been patented (Dutch patent PCT NL 85/00026), and is being further developed in cooperation with Dutch industries. Silica, one of the major products of the process has been tested as an additive to concrete. An addition of between 5 and 10% silica greatly decreases the permeability of concrete, thereby increasing the resistance of concrete constructions under chemically aggressive conditions. |
| On the age of the Late Cretaceous tonalitic/gabbroic batholith on Aruba, Netherlands Antilles (southern Caribbean borderland) | 1986 | Priem, H.N.A.; Beets, D.J.; Boelrijk, N.A.I.M.; Hebeda, E.H. | 65(3) | Rb-Sr data of tonalitic whole-rocks and biotites and K-Ar data of hornblendes, biotites and mafic wholerocks are reported from the crystalline core of Aruba, a remnant of a Late Cretaceous oceanic island arc that collided in the Santonian (between approximately 88 Ma and 83-84 Ma ago) with the passive margin of northern South America. The age data are interpreted to indicate that the intrusion of the composite (tonalite/gabbro) batholith took place 88.5 ± 0.8Ma ago, in the Coniacian or around the Turonian/Coniacian boundary. This confirms that the intrusion has occurred prior to the collision. The tonalites of the batholith have an initial 87Sr/86Sr ratio of 0.70351 ± 0.00014. Thermal events about 72 Ma and possibly about 62 Ma ago have led to some isotopic resetting. |
| On fossil and recent borings produced by acrothoracic cirripeds | 1986 | Lambers, P.; Boekschoten, G.J. | 65(3) | This study on recent and fossil acrothoracic cirripeds describes burrows of the recent species Trypetesa lampas in the same way as fossil burrows. Subsequently, fossil and recent burrows are compared. Recent burrows of T. lampas were found in whelk shells (Buccinum undatum) inhabited by pagurids; fossil burrows resembling Brachyzapfes elliptica in belemnites (Oxyteuthis sp.) from the Barremian of Alstätte, West- Germany. The burrows of T. lampas are smaller but relatively deeper and wider than the Alstätte material. This is probably due to the reduction of the abdomen and appendages in T. lampas. The brood pouch and ovaria of T. lampas are probably larger than those of the fossil borer. In the present material, burrows of T. lampas were mainly produced by young barnacles. This may be explained by a frequent change of shells by hermit crabs which causes an early death of the acrothoracics. |
| Book reviews | 1986 | Boogaard, M. van den; Helmers, H.; Loon, A.J. van; Boekschoten, G.J. | 65(3) | |
| Grain surface characteristics of periglacial aeolian and fluvial sands | 1986 | Elzenga, W.; Schwan, J.; Baumfalk, Y.A.; Vandenberghe, J.; Krook, L. | 65(4) | Surface features of quartz grains from periglacial aeolian and fluvial deposits from two areas in The Netherlands and adjacent Germany have been studied with a Scanning Electron Microscope. The relative abundance of the 29 distinguished characteristics is statistically analysed in an attempt to correlate the surface features with the regionally and genetically determined sediment types. Frequencies of individual grain surface characteristics vary widely and are usually insufficient to separate the sediment types. This is partly due to the variable degree of surface pattern overprint caused by the polygenetic nature of the sediments concerned. However, linear combination of the sample variables (using principal component analysis) allows the discrimination of several distinct clusters, that show a fair correspondence with the macroscopically defined depositional groups. The regional and stratigraphical patterns observed, seem to be dominated by two factors: one which is related to the transport energy and the mode of deposition involved and perhaps connected with the prevailing wind regime; the other with chemical alterations, probably reflecting the source area of the sediment. New perspectives are opened for the genetical interpretation of sediments by grain morphoscopic analysis when combined with multivariate statistics. |
| Authigenic palygorskite and smectite in early paleogene paleosols of the SE Ebro basin (Catalonia, NE Spain)* | 1986 | Dolors Pi Pujol, M.; Buurman, P. | 65(4) | Paleogene distal fan and playa deposits in the SE Ebro Basin contain authigenic palygorskite and smectite. The formation of these minerals is related to sedimentary environment rather than to soil formation, although the sediments contain abundant traces of paleosols. Palygorskite was precipitated from solution, or formed from inherited mica minerals. Sedimentary conditions and soils suggest that palygorskite was formed in rather well-drained conditions while smectite is mainly found in lacustrine environments. There is no clear relation of palygorskite occurrence with caliche formation. |
| Ramblian; A new stage for continental deposits of early miocene age | 1986 | Daams, R.; Freudenthal, M.; Alvarez Sierra, M. | 65(4) | The name Ramblian is proposed for a new stage of continental deposits, covering a part of the Early Miocene, The Ramblian is stratigraphically higher than those beds that contain ancient Eomyidae (Rodentia, Mammalia) such as Rhodanomys and Ritteneria, and it is lower than the Aragonian. The Ramblian is subdivided into two zones on the basis of the fossil mammal content. The Aragonian is redefined. |
| Experimental redeformation of naturally deformed scaly clays | 1986 | Berg, L. van den | 65(4) | The Argille Scagliose (scaly clays) in the Apennines of Italy are intensely deformed clays that contain a characteristic shear fabric, defined by anastomosing slip planes. Experimental redeformation showed mechanical ductile behaviour along such slip planes. Direct shear tests at stresses up to 0.5 MPa resulted in common values of shear strength with a cohesion of 18 kPa and an internal friction coefficient of 0.31. However, triaxial tests at higher stresses up to 11.6 MPa resulted in a much lower internal friction coefficient of 0.026. This indicates a transition from cataclastic deformation at low stresses to a deformation at high stresses that is hardly dependent on confining pressure. This transition is correlated with yielding of weak bondings of interlayer water molecules in expanding clay minerals. It follows that nappes with Argille Scagliose at the base could spread if the surface slope was only a few degrees and without abnormally high fluid pressure as is frequently supposed. |
| The Urucum-Mutun iron and manganese deposits, Mato Grosso do Sul, Brazil and Sta. Craz, Bolivia - Part I. The regíon's potential as an economic source of iron and manganese | 1986 | Leeuwen, P. van | 65(4) | The Urucum-Mutun jaspilitic banded oxide facies iron-formation (BIF) which straddles the Brazilian-Bolivian border was discovered in 1894 and has a checkered history of exploration and development. The BIF contains segregations within the iron-formation of important beds and lenses of high grade manganese oxides. The BIF is predominantly of chemical sedimentary origin and suffered relatively little alteration after deposition. This condition profoundly affects the metallurgical behaviour of the iron ores compared to normal metamorphic BIFs. The manganese oxide beds and lenses do have a high alkali content throughout the entire region, particularly potassium which is troublesome and can be detrimental to furnace operation producing ferromanganese. Besides, a major economic problem has been the tranportation of the ores to industrial centres. However, the very size of the iron and manganese deposits in this region is a strong argument for stimulating studies and research into the development of these important resources. This requires an integrated study of economic-geology, metallurgical processing and transport involving all the Paraguay-Paraná River Basin nations. |
| The Urucum-Mutun iron and manganese deposits, Mato Grosso do Sul, Brazil and Sta. Craz, Bolivia - Part II. Stratigraphy, lithology and origin | 1986 | Leeuwen, P. van; Graf, J.L. | 65(4) | A description is given of the Urucum-Mutun iron and manganese deposits which lie astride the Brazilian-Bolivian border, directly south of Corumbá in Mato Grosso do Sul. The iron ore deposits are remnants of an unmetamorphosed banded oxide facies iron-formation (BIF), containing extensive segregated manganese oxide beds and lenses, of Late Precambrian or even Eocambrian age and, therefore, much younger than the more common BIFs. The paper discusses the stratigraphy, the age of the sedimentary rocks, the lithology of the ore deposits and the origin of the BIF. The BIF with segregations of manganese oxides is predominantly of chemical sedimentary origin. The required low Eh conditions for the accumulation of large quantities of iron, manganese and silica were provided by a glacial sheet cover on whose periphery the Urucum-Mutun region was located. The manganese oxide beds were formed by the introduction of high concentrations of K+ into a colloidal suspension rich in iron and manganese under the prevailing Eh-pH environment. Deposition of the BIF took place in continental or possibly epicontinental basins under relatively arid conditions. |
| Compositional characteristics in relation to the evolution of granitic rock units in the Ilesha area, SW Nigeria | 1986 | Elueze, A.A. | 65(4) | The granitic rocks of the Ilesha area include granites and pegmatites which are intrusive into metasediments. In terms of field and petrographic features, the units are quite distinct. The Itamerin medium-grained granite and the adjacent pegmatite in the western part of the area contain muscovite and biotite, whereas the southeastern Ipetu porphyritic granite bears biotite plus hornblende. Chemical data show that the Ipetu body unlike the Itamerin rock, commonly displays regular interelement variations. It has lower values of SiO2, K2O, Rb and Rb/Sr ratio, but is significantly higher in TiO2, total Fe, MgO, CaO, Ba, Sr and its Ba/Rb ratio. The pegmatite, though slightly more acid, is generally comparable in major and trace element data, with the Itamerin granite. It is surmised that the compositional differences between the Ipetu and the Itamerin granites, are partly or wholly due to disparities in the nature of parent magmas, crystallization and extent of post-magmatic alterations. The porphyritic type possibly consolidated from a relatively less fractionated magma, while the muscovite-bearing one probably evolved from a water-rich melt. The pegmatite is considered to be genetically related to the latter, a conclusion based on intimacy in field occurrence and petrochemical character. |
| The structural configuration of Cormorant Block IV in context of the northern Viking Graben structural framework | 1986 | Speksnijder, A. | 65(4) | The Cormorant Field is situated on the crest of one of the elongated N-S striking, westward-tilted fault blocks that characterise the western part of the northern Viking Graben, northern North Sea. Besides normal faults which separate these fault blocks, the Caledonian basement in the western part of the Graben has been affected by NE-SW and NW-SE oblique-slip faults; movement along these faults is synthetic to (and a result of) the opening of the Viking Graben during the Mesozoic. In the Cormorant area, N-S normal faulting and synthetic NE-SW and NW-SE oblique-slip faulting caused an overall eastward movement of the triangular Block IV with respect to the main Cormorant structure. These basement kinematics resulted in considerable 'growth' across normal listric faults in the sedimentary cover of Block IV, both at (Brent) reservoir level and in younger Jurassic deposits. Extension during the Early Cretaceous (post-'X'-unconformity) led to further movement along older - and the generation of new - listric faults. All listric faults flatten downwards and join in a common décollement level about a hundred metres above the Caledonian basement, inducing a complete or partial detachment of the sedimentary cover. Consequently, the sedimentary cover was affected by normal faulting only. Despite important differences in style, both the basement and cover structures formed as a result, of east-west horizontal extension. The production performance in Block IV suggests the presence of small reservoir blocks separated from each other by faults that act as barriers to cross-flow. Because faulting in the reservoir is of an extensional nature, the development of clay smears along the planes of normal faults is considered to be the only plausible explanation for fault sealing in Block IV. |
| Book reviews | 1986 | Loon, A.J. van; Rondeel, H.E.; Verschure, R.H.; Aleva, G.J.J. | 65(4) | |
| Isotopic age study of pre-Alpine rocks in the basal units on Naxos, Sikinos and Ios, Greek Cyclades | 1987 | Andriessen, P.A.M.; Banga, G.; Hebeda, E.H. | 66(1) | Isotopic dating proves the existence of pre-Alpine basement rocks on the islands of Naxos, Sikinos and Ios in the Greek Cyclades. The U-Pb systematics of a suite of zircons from the migmatite dome on Naxos shows that the main generation of zircons of late Paleozoic age contains a minor amount of old radiogenic lead. Rb-Sr analysis of whole rock samples of a metadiorite on Sikinos substantiates the existence of a late Paleozoic or early Mesozoic basement. K-Ar analysis of white micas from the augengneiss on Ios revealed ages of about 125 Ma to about 23Ma, intermediate between the Hercynian and the Alpine orogenesis. On the basis of textural- and chemical characteristics it is suggested that some of these micas represent partially reset Hercynian micas, other Alpidic micas with excess radiogenic Ar, and a few reflect a complete rejuvenation during the Alpine orogenesis. |
| The palaeoenvironment of deposition of Late Maastrichtian to Paleocene black shales in the eastern Dahomey Basin, Nigeria | 1987 | Enu, E.I. | 66(1) | Extensive black shale facies of Late Maastrichtian to Paleocene age are associated with the equally widely distributed tar sand sequence in the Nigerian sector of the Dahomey Basin. The shales are commonly finely laminated and are rich in organic carbon. They contain an abundance of pyrite and have yielded a rich faunal assemblage indicating shallow water conditions. The co-occurrence of abundant benthos, pyrite and enhanced organic carbon contents in the shales suggests an overall euxinic depositional palaeoenvironment that was episodically oxygenated. |
| Gravel- to sand-sized vivianite components in a Saalian till layer near Borne (The Netherlands) | 1987 | Riezebos, P.A.; Rappol, M. | 66(1) | Vivianite particles have been found within the gravel and sand fractions of a specific level of a Saalian till layer. Besides with gravel constituents, which are common in Dutch till deposits, the vivianite granules are associated with sedimentary rock fragments containing a.o. glauconite and a kind of phosphoritic grains that are cemented by carbonates. The vivianite aggregates can be observed inside this carbonate matrix. Individual vivianite granules were studied in thin section and by SEM, X-ray diffraction, microprobe and differential thermal analyses. Only the monoclinic phase of Fe3(PO4)2.8H2O could be established with certainty. The vivianite of the granules contains lower Ca, Mn, Mg, Si and Al abundances than the vivianite of the aggregates included in the carbonate matrix. It is concluded that the vivianite granules are of nondetrital origin. |
| Thermoluminescence dating of loess at Rocourt, Belgium | 1987 | Wintle, A.G. | 66(1) | Nine TL dates were obtained from a section at Rocourt. The dates were self-consistent. A date of 24.8 ± 2.1ka for a sample from the base of the Upper Weichselian loess indicated that it was part of the massive loess sheet deposited in Europe about 25 thousand years ago. The overlying decalcified loess gave dates indicating deposition after the glacial maximum. However, the proposed chronology is in disagreement with that based on radiocarbon dates on humic material from the 'horizon à langues' at two nearby sites. |
| 210Pb Dating in shallow moorland pools | 1987 | Wijk, A. van der; Mook, W.G. | 66(1) | Ten cores from seven shallow (average depth less than 2m) moorland pools in the Netherlands have been analysed for 210Pb in an attempt to obtain reliable chronologies to be used in acidification studies. Although the sediment stratigraphy may be disturbed by many external influences, the shape of 210Pb activity versus depth profiles appears to result in reliable chronologies in agreement with biological data. However, the time resolution is primarily determined by uncertainties about the validity of the basic assumptions in the dating model rather than by the accuracy of the measurements. |
| Cyclaster platornatus Kutscher, 1978: an addition to the echinoid fauna from the late Maastrichtian of NE Belgium | 1987 | Jagt, J.W.M.; Michels, G.P.H. | 66(1) | Two fairly well preserved specimens of the brissid echinoid Cyclaster platornatus Kutscher, 1978 are described from the late Maastrichtian Vijlen Member (Gulpen Formation) as exposed in the SA Ciments Portland Liégeois (CPL) quarry at Haccourt, municipality of Oupeye, province of Liège, Belgium Kutscher (1978) introduced this taxon for a small population of brissid echinoids from the early Maastrichtian white chalk of Rügen (GDR). Despite slight morphological differences the Belgian specimens are considered to be conspecific with the Rügen type population. The occurrence in the late Maastrichtian of NE Belgium constitutes the first record of this species beyond the North European white chalk facies of Rügen. The Belgian specimens are herein compared and contrasted with morphologically similar (Hemiaster aquisgranensis Schlüter, 1899 and Diplodetus species) from the Vijlen Member. Some remarks on other late Cretaceous spatangoids are added. |
| The possible significance of uncommon barium-rich mineral assemblages in sediment-hosted lead-zinc deposits | 1987 | Finlow-Bates, T. | 66(1) | |
| Cathodoluminescence activation and zonation in carbonate rocks: an experimental approach | 1987 | Machel, H.G. | 66(1) | |
| Book reviews | 1987 | 66(1) | ||
| Paleomagnetism of the Nakfunu Formation of Early Cretaceous age, Western Timor, Indonesia | 1987 | Wensink, H.; Hartosukohardjo, S.; Kool, K. | 66(2) | A paleomagnetic study has been carried out on deep sea sediments of the Nakfunu Formation of Early Cretaceous age. The sediments have an allochtonous position in the south-central part of Western Timor, Eastern Indonesia. To determine the characteristic remanence samples were partially progressive demagnetized by applying alternating magnetic fields and by heating. The following results were obtained: I = 34.7°, α = 5.7°, which implies a paleolatitude of 19.1°, derived from the mean of 11 sites; and I = 37.8°, α = 8.3° implying a paleolatitude of 21.2°, derived from a selection of the mean of 6 sites. Therefore, the original site of deposition of the Nakfunu sediments must have been 10° south of its present position on the island of Timor. The sediments have moved about 1200 km in a northerly direction since deposition in an oceanic environment, north of the former rim of the Australian continental margin. The remanence carriers in the sediments are both magnetite and hematite. |
| Subhorizontal shear zones and their relation to nappe movements in the Cantal and Miñarros units. Eastern Betic Zone (Spain) | 1987 | Alvarez, F. | 66(2) | The Cantal and Miñarros units, two of the tectonic units that belong to the Internal Zone of the Betic Cordillera, bear evidence of a ductile shear deformation which led to the development of mylonites. In the Cantal unit, the mylonitic deformation began during the last part of a second penetrative deformation phase; it is restricted to the unit and is unrelated to its present-day position over the Palomas unit on which it has been emplaced later, under much more brittle conditions. In contrast, the mylonitic deformation observed in the Miñarros unit extends for a few metres into its relative autochthon (Lomo de Bas unit) where it affects third phase folds; these observations allow us to establish a direct relationship between the shear deformation and emplacement of the Miñarros unit over the Lomo de Bas unit. The distribution of the stretching lineations in the shear zones considered and the study of the preferred crystallographic c-axis orientation of quartz in the associated mylonites show that the direction of movement within the Cantal unit was from WSW to ENE, and that the Miñarros unit was emplaced from S to N. |
| Isotopic age-determinations in Bergslagen, Sweden: VIII. Sveconorwegian Rb-Sr resetting and anomalous radiogenic argon in the Gothian Trans-Scandinavian Småland-Värmland Granitic Belt and bordering parts of the Svecokarelian Bergslagen Region | 1987 | Verschure, R.H.; Oen, I.S.; Andriessen, P.A.M. | 66(2) | Biotite Rb-Sr data from 1.70-1.65 Ga old rocks of the Gothian Trans-Scandinavian Småland-Värmland Granitic Belt and from 1.90-1.84 Ga old rocks of the adjoining Svecokarelian Bergslagen Region indicate complete Sveconorwegian resetting 0.90 Ga ago, but a K-Ar analysis of the same biotites and of coexisting hornblendes yields significantly older ages. Some biotites and hornblendes have exceptionally high apparent ages, much older than those of the host rocks, pointing to the presence of excess radiogenic argon. The other K-Ar mineral ages are intermediate between the age of the host rocks and the 0.90 Ga old Sveconorwegian resetting. The hornblendes and biotites with intermediate ages show a weak positive correlation between radiogenic argon content and whole-rock potassium content. It is concluded that there was only limited mobility of radiogenic argon during the Sveconorwegian event. Apparently, the physicochemical conditions during Sveconorwegian recrystallisation were suitable for complete resetting of the Rb-Sr biotite systems, whereas the behaviour of radiogenic argon in the biotites and hornblendes was complex, leading to anomalous K-Ar dates. |
| Evaporite facies and depositional environment of the Abu Dabbab Formation, Red Sea coast, Egypt | 1987 | Abdel Wahab, S.; Mahfouz Ahmed, S. | 66(2) | The Abu Dabbab Formation is part of a Middle Miocene sedimentary sequence along the Red Sea Coast that is composed of evaporites with some clastic and carbonate intercalations. These rocks extend for hundreds of kilometres in variable thicknesses and are capped by a fractured and brecciated limestone with surficial calcareous crusts of caliche type. Detailed field and petrographical studies helped in establishing ten lithofacies types within the Abu Dabbab Formation, mainly evaporites with some dolostones along the upper part of the sequence. These lithofacies types represent different subenvironments probably indicative of a coastal tidal flat that was intermittently flooded by the sea, thus creating shallow brine-filled depressions or ponds. There is evidence of alterations in the evaporites brought about by diagenetic processes that were associated with changing environmental conditions. The diagenetic sequence could be subdivided into three stages: (1) a pre-burial early stage, (2) a burial stage and (3) an uplift late stage. |
| Heavy minerals as a stratigraphical tool for the Eemian and Post-Eemian deposits in the lower Lys valley (Belgium) | 1987 | Lootens, M. | 66(2) | The lithostratigraphic units in the Upper-Pleistocene Lys valley may be subdivided into two distinct populations, each with its own characteristic heavy mineral assemblage. The Eemian and Early Weichselian sediments, which belong to the Formations of Oostwinkel/Templeuve, Dendermonde and Oostakker, are characterized by a very high opaque grains and ubiquists content and by rather low proportions of epidote, garnet and hornblende. These sediments originate mainly from the erosion of the Eocene deposits in the studied area. The overlying deposits, which make up the Formations of Oeselgem/Wevelgem, Eke, Gottem, St.-Baafs-Vijve and the youngest alluvial sediments, show a duplication in the number of garnets, epidotes and amphiboles and hence a considerable reduction in the amount of ubiquists. This heavy mineral association was influenced by an eolian supply from the north, in this case from the bottom of the then aerially exposed North Sea. |
| The distribution of Cretaceous deposits on the Hautes Fagnes plateau (Belgium) | 1987 | Demoulin, A. | 66(2) | A new Cretaceous sand deposit of supposedly Campanian age and coastal origin is described from the southern flank of the Baraque Michel massif on the Hautes Fagnes plateau. Also presented is an updated distribution map of Cretaceous sand and flint accumulations on the plateau. The data show that during the Campanian the shoreline in High Belgium lay south of the Hautes Fagnes ridge and that it still moved further south during the Maastrichtian. |
| Copper and phosphate mineralization in the lower Proterozoic mobile belt of Bakhuis mountains, Upper Nickerie, Western Suriname, Guiana shield | 1987 | Dahlberg, E.H. | 66(2) | Bornite and apatite mineralizations are found in a granulite facies secton of the Trans-Amazonian Central Guiana mobile belt. The copper and phosphate mineralizations are associated with monzonitic to syenitic metavolcanic rocks, which in part occur interbanded with gabbronorite gneiss. The country rocks include banded charnockitic granulites of the basement, granulites and gneisses of a Proterozoic supracrustal cover, and metamorphosed mafic to ultramafic intrusive rocks in basement and cover. Mineralization was located by a geochemical follow-up of coinciding aeromagnetic and electromagnetic anomalies, the latter with considerable in-phase components. The peculiar association of copper and phosphate mineralizations on the West flank of the Bakhuis granulite dome in the Central Guiana mobile belt shows aspects of volcanosedimentary phosphorus and copper accumulations in an intracratonic rift basin. The supracrustal sequence of volcanics, clastic and chemical sediments in the basin was intruded by mafic magmas, which assimilated phosphorus- and copper-rich supracrustal rocks and on crystallization gave rise to copper- and phosphate mineralized mafic-ultramafic rocks. The subsequent mobile belt-style deformation and granulite to amphibolite facies metamorphism of the Central Guiana mobile belt have given rise to copper-mineralized monzonitic-syenitic and clinopyroxene-apatite rocks, representlng a layered sequence of granulite facies metamorphosed cupriferous felsic volcanics and intercalated phoçhatic siliceous carbonate sediments of the supracrustal sequence. The copper- and phosphate mineralizations of this volcano-sedimentary association occur associated with the similarly metamorphosed and deformed copper- and phosphate-mineralized rocks of the mafic plutonic association. |
| Deformation mechanisms operating in naturally deformed halite rocks as deduced from microstructural investigations | 1987 | Urai, J.L.; Spiers, C.J.; Peach, C.J.; Franssen, R.C.M.W.; Liezenberg, J.L. | 66(2) | In this paper we describe the microstructures of naturally deformed rocksalt samples from the Asse salt anticline, FRG, as revealed by a chemical polishing-etching procedure, and by gamma-irradiation. Evidence is presented for the operation of dislocation creep processes, accompanied by extensive strain-induced grain boundary migration. Grain boundaries can be shown to have contained thin brine films during recrystallization, suggesting that solution-precipitation processes could also have been important deformation mechanisms. Recrystallization and solution transfer processes have not been reported in most experimental work to date, thus casting doubt on the validity of extrapolating these data to predict the long-term creep behaviour of salt during natural flow. |
| The petrogenesis of charnockitic and granitic migmatites of the high-grade metamorphic Precambrian of Rogaland/Vest-Agder, S.W. Norway – A statistical interpretation of major element rock chemistry | 1987 | Gaans, P.F.M. van; Schreurs, J.M.C.M.; Vriend, S.P.; Maijer, C. | 66(2) | A charnockitic and granitic rock suite from the high-grade metamorphic Precambrian of southwest Norway was investigated for its geochemical characteristics. Whole rock major element analyses of 37 samples, taken from 8 localities which cover a range of metamorphic grade, were made. Multivariate statistical methods, R-mode and extended Q-mode component analysis, were used to aid the interpretation of the complex data set. Application of these methods resulted in a main division into melanocratic and leucocratic sample groups. A further analysis of the two groups showed that while the melanocratic samples form a homogeneous group, the leucocratic samples display a geochemical variability which is explained here by partial anatexis. Combined geological and geochemical data suggest a primary formation of the rock suite as a series of basic and acid volcanic rocks, that are intercalated with sediments. The charnockitic rock suite (granulite facies) shows no evidence of depletion of magmatophile elements compared to the granitic rock suite (amphibolite-facies). |
| Devonian Old Red Sandstone sedimentation and tectonic history of Billefjorden fault zone, Spitsbergen | 1987 | Reed, W.E.; Douglass, D.N.; Lamar, D.L. | 66(3) | Devonian Old Red Sandstone exposed within and west of the Billefjorden fault zone in Dicksonland, central Spitsbergen, consists of up to 3000 m of conglomerate, sandstone, and mudstone that rapidly thin eastward. The Devonian sediments form a single, large-scale fining upward sequence of fluvial, paludal, and marginal marine origin. Low-sinuosity channel processes dominated the lower portion of the sequence; the middle portion was transitional, probably deposited in meandering channels, and by proximal overbank processes on levees and floodplains. The upper portion of the sequence consists of floodbasin and marginal marine sediments. Nodular calcrete zones suggest prolonged weathering and root mottles indicate plant growth. Trace fossils suggest periods of marine and brackish water conditions within the fluvial-appearing sequence. Current directions and facies distributions indicate gradual wearing down of a source area to the south. The sedimentation pattern within the Old Red Sandstone adjacent to the Billefjorden fault zone contrasts with that of known strike-slip fault-bounded basins: there is no repetitive stacking of facies, and there are no thick sequences of conglomerates or breccias; none of the units show coarsening near the fault. Units thin to the east and lack evidence of faulting contemporaneous with deposition. The eastern distal edge of the Devonian basin may coincide with the gently sloping edge of a half-graben. The early to middle Devonian passive basin margin, late Devonian reverse slip on the Billefjorden fault zone, and normal faults controlling the western margin of the Carboniferous depositional basin may coincide because all were controlled by a Caledonide zone of weakness along a pre-Old Red Sandstone fault in Hecla Hoek rocks. |
| Interference of compressional and wrenching tectonics in the Alicante region, SE-Spain | 1987 | Ruig, M.J. de; Mier, R.M.; Stel, H. | 66(3) | The Alicante region forms part of the External Zone of the Betic Cordilleras. The regional fold trend is ENE, but in the central part of the area studied, an anomalous N-S trend dominates. In previous publications the N-S folds have been interpreted as structures formed by diapiric movements of Triassic evaporites. However, analysis of tectonic stylolites and structural style of the folds show that both trends were formed by crustal shortening. Interference patterns suggest overprinting of the two fold trends. A model is proposed in which the N-S trending folds are interpreted as the result of right-lateral movement along a basement fault. The wrench fault involved would be an offshoot of the important Crevillente fault. The occurrence of both wrenching and compressional tectonics in the Alicante region is discussed in respect with existing plate tectonic models. |
| A review of some features potentially indicative of the presence of platinoid mineralization as deduced from the Stillwater Complex, Montana (USA) | 1987 | Veen, A.H. van der | 66(3) | The Stillwater Complex of South Montana is a layered differentiated ultramafic intrusive body of late Archaean age. It crops out along strike over 48km and contains one of the richest zones of platinum group elements (PGE) in the world - the JOHNS-MANVILLE Reef. This reef is almost two metres thick and consists of 0.5 to 2.0% sulfide enclosed in noritic rocks. The sulfides are principally pentlandite, pyrrhotite and chalcopyrite with locally minor pyrite. Minerals of the braggite-vysotskite series contain the bulk of the platinum group elements. A relatively high Ni/Cu ratio of 1.3, and extremely high - 32 g/ton – concentration of platinum and palladium, a (Pt + Pd)/(Os + Ir + Ru) ratio of 230 and a high magma/sulfide or R ratio are quite different from what may be expected from sequential differentiation and crystal settling in an ultrabasic magma chamber. The most acceptable genetic model for the chemistry and geometry is one suggesting turbulent injection of a second buoyant magma into the original magma chamber to so alter the magma/sulfur ratios that the observed metal abundances and ratios are reached. A number of the petrological and geochemical features of the Stillwater Complex, and particularly their geometrical distributions are of significance for the understanding of such complexes and can be used in exploration. Some of these can be summarized as follows: If in a sulfide zone, 400-1000m above the first appearance of cumulus plagioclase, one finds - the presence of chromitite layers, - that olivine is the cumulus mineral in addition to plagioclase, - the presence of 'pegmatoid' zones (i.e. distinct orthocumulate texture), - that there is evidence of magma injection (slump textures etc.), - that the Ni/Cu ratio is greater than 1, - that there is no apparent nickel depletion of the associated reef olivine, - and that rare earth element abundances and ratios of plagioclase change in a way suggesting magmareplenishment, then it is highly probable that such a sulfide zone has an economically interesting platinoid content. |
| Macrofossils and their palaeoecology in deltaic sequences of the Lower Carboniferous Yoredale Series, Yorkshire, England | 1987 | Masurel, H. | 66(3) | Deltaic sequences of the 5-Yard Limestone cyclothem forming part of the Yoredale Series, have been studied at different localities in Wensleydale and Bishopdale, N. Yorkshire. The northernmost, Wensleydale sections contain upward coarsening clastic sequences that are characterized by gradational passages from one lithology into another, suggesting slow deltaic progradation. Highly fossiliferous, calcareous shales, deposited in a shallow, open sea, pass up into less fossiliferous, sometimes evaporitic shales indicating a restricted connection with the sea. The latter show an increase of silt content, ultimately merging into finegrained sandstones of the delta plain facies. A different general picture is found in the Bishopdale sections located in the south. These locations apparently were frequently subject to fluctuations in sediment input and water turbulence, which resulted in periods of abundant algal growth, explosive colonization by the probably opportunistic brachiopod Gigantoproductus and minor transgressions of the sea. It is suggested that current patterns and sediment influx from the north initiated growth of a coastal barrier, causing development of different environmental conditions in the northern and southern part of the area. Due to partial separation from the sea, the northern part changed into a lagoon with variable salinity conditions, while progradation of the delta was slow enough to permit small-scale transgressions over the southern part of the area, eventually followed by deposition of fine-grained, evenly laminated sandstones and medium grained, cross-bedded sandstones characteristic of a seaward prograding barrier beach. |
| Frost-mound scars and the evolution of a Late Dryas environment (northern Netherlands) | 1987 | Groot, T. de; Cleveringa, P.; Klijnstra, B. | 66(3) | Small, oval to round depressions in Weichselian deposits near Scheemda in the northern Netherlands were formed in Late Dryas time. Lithology, sedimentology, and stratigraphic position indicate that these depressions were produced by seasonal frost action followed by thermokarst solution. Comparison with the results of earlier studies on similar features in the northern part of the Netherlands shows that climatic change during the Late Glacial was strongly influenced by local environmental factors. |
| Hydrothermal synthesis of ammonium-phlogopite | 1987 | Bos, A.; Haas, G.J.L.M. de; Voncken, J.H.L.; Eerden, A.M.J. van der; Jansen, J.B.H. | 66(3) | The hydrothermal synthesis of well-crystallized ammonium-phlogopite has been performed in our department's high pressure and temperature (HPT) laboratory. The experimental techniques are described. The experimental conditions for the synthesis of the mica were 550°C and 2000 bars. Scanning electron microscopy (SEM), infrared spectroscopy (IR), and X-ray diffraction (XRD) characteristics of the ammonium- phlogopite are discussed. Implications for the natural occurrence of the mineral are considered and potential environments for its discovery are suggested. |
| Hydrothermal synthesis of tobelite, NH4AI2Si3AIO10(OH)2, from various starting materials and implications for its occurrence in nature | 1987 | Voncken, J.H.L.; Wevers, J.M.A.R.; Eerden, A.M.J. van der; Bos, A.; Jansen, J.B.H. | 66(3) | Ammonium-bearing micas are prominent nitrogen containing minerals in the Earth's crust. Various starting materials and a range of conditions were applied for the hydrothermal synthesis of tobelite, the ammonium analogue of muscovite. The natural occurrence of the mineral is elucidated. The best crystallised tobelite is carefully investigated with XRD, SEM, DTA, TGA, and lR-spectroscopy. Cell parameters of the tobelite are a0: 5.230 ± 0.007; b0: 9.02 ± 0.01Å; c0: 10.55 ± 0.01 Å; β: 101.560 ± 0.01; V: 487.5 ± 0.7, Å3. Tobelite is indexed on the basis of a 1M cell. Tobelite decomposes at temperature above 500°C in TGA/DTA studies, using heating rates of 10° C/min. Ammonia loss and dehydroxylation are separate processes. Ammonia loss proceeds relatively faster and it is a lower temperature process. In an IR spectrum of tobelite the NH4+ vibrations are readily perceivable, and they are determinative for tobelite with respect to other dioctahedral micas. Tobelite is easily identified by X-ray diffraction. The present synthesis results and literature data indicate that tobelite is readily formed in NH3-rich environments. Such environments are likely to exist in fossil fuel deposits, where decomposition of amino-acids under reducing conditions normally yields NH3-rich gas or fluid phases. Ammonium micas may be formed directly from ammonium bearing clay minerals, or by ammonia incorporation in pre-existing micas. |
| Book reviews | 1987 | Veen, A.H. van der; Boogaard, M. van den; Rondeel, H.E. | 66(3) | |
| Isotopic tales of ancient continents | 1987 | Priem, H.N.A. | 66(4) | One of the features which makes the planet Earth a strange anomaly in the Solar System is the presence of continental crust, unknown on the other terrestrial-type planets. In contrast to the basaltic crust underlying the ocean basins, which is nowhere older than 200 Ma (million years) because of its continuous recycling through the mantle by plate-tectonic processes, the continental crust (with the average composition of diorite) is composed of rocks with ages ranging from zero to ~3,900 Ma. It is thus on the continents that 95% of the Earth's geologic record is to be found, including the origin of the unique geosphere-biosphere system. The mainstream of present-day opinion is that these ancient entities were derived from the mantle through magmatic processes, but conflicting views prevail with regard to their growth rates. In this lecture the view is taken that the continents have grown through geologic time by irreversible differentiation from the mantle. The task of gaining insight into the evolution of the continental crust has fallen mainly to the isotope geochemists. Application of radiogenic isotopes (Pb, Hf, Nd, Sr) provides reliable constraints on the age and temporal evolution of rock units, on the time of primary separation of continental material from the mantle, and on the assessment of the relative contributions of mantle and ancient continental crust to magma genesis. Recorded geologic history begins at ~3,900Ma with the oldest preserved continental crust. There is evidence that (some) continental crust was already in existence by ~4,300Ma ago. Most of the insight into the pre-recorded history of the Earth stems from studies of meteorites and other planets. One of the results of planetary exploration is the recognition of large-scale impact cratering by giant meteorites as a major, possibly even dominant geologic process in the early evolution of the Earth. The termination of the 'great bombardment' coincided approximately with the formation of the oldest preserved continental crust by-3,900Ma ago. Another major factor to be taken into account in the reconstruction of the early history of the Earth, is the much higher radiogenic heat production than today. Between 3,000 and 2,500Ma ago, the Earth acquired its modern appearance with the formation of huge volumes of juvenile continental crust from the mantle, and 50-80% of the present-day continental mass was in existence by ~2,500Ma ago. This fundamental change in the Earth's character marks the Archaean-Proterozoic transition. The growth of continental crust was not continuous through geologic time, but episodic, with five distinct periods of accelerated growth. After two successful decades of concentrated ocean-floor exploration, the target of international earth science in the 1980s has become the continents. |
| Predation intensity in an Eocene molluscan assemblage from southeastern Nigeria | 1987 | Arua, I.; Hoque, M. | 66(4) | A quantitative assessment of naticid and muricid borings in mainly small (<10mm) gastropod and bivalve shells from the Ameki Formation (Eocene) shows that the degree of shell ornamentation appears to have played a significant role in predation intensity. It was observed in gastropods that a smooth shell is preferred by predators to an ornamented one. In bivalves a growth-lined shell is preferred to either a ribbed or a mixed one (growth lines and ribs present) and a ribbed shell is preferred to a mixed shell. It is suggested that the predation intensity was controlled by the predator-defensive adaptation. The favoured predator food source during the Eocene in Nigeria was bivalves, as far as shown by fossil shells. |
| Late Glacial and Holocene development of semi-closed depressions (thaw lakes?) in the Limagne Rift Valley, French Central Massif | 1987 | Kroonenberg, S.B.; Berg van Saparoea, R.M. van den; Jonker, A.T.J. | 66(4) | Palynological, micromorphological, tephrochronological and sedimentological studies of the deposits in semi-closed depressions in the Limagne Rift Valley in France testify to development in five stages: (1) an erosional, probably interglacial stage, with differential fluvial erosion of soft Oligocene marls not protected by overlying terrace gravels; (2) a fluvial-periglacial stage, with deposition of fluvio-periglacial sediments, partly involuted subsequently; (3) a lacustrine stage, possibly related to thermokarst, with deposition of calcareous mud and volcanic ash layers in the Late Glacial; (4) peat growth and deposition of black clays in the Preboreal, Boreal and Atlantic, and (5), depending upon local conditions, fluvial deposition, soil formation, or lacustrine deposition until recent times. |
| Sedimentology, coalification pattern and paleogeography of the Campine-Brabant Basin during the Visean | 1987 | Muchez, P.; Viaene, W.; Wolf, M.; Bouckaert, J. | 66(4) | During the Visean, four major lithological and biostratigraphical sequences formed in the Campine-Brabant Basin, north of the London-Brabant Massif. The Visean strata are mainly composed of carbonates. The first sequence was formed during the Early Moliniacian. At this time, the Heibaart area was a structural high. During the late Moliniacian, when the second sequence was formed, the whole Campine-Brabant Basin was characterized by carbonate sedimentation on a broad shallow shelf. The third sequence formed during the Livean. Sedimentation was restricted in the Turnhout and Halen area. In the Heibaart area, sediments were deposited in an environment with open water circulation. During the Early Warnantian the fourth sequence was formed. Reef mounds developed in the Poederlee-Heibaart area and probably also in the Turnhout area. The sediments penetrated by the Halen borehole were deposited alternately in an open and in a restricted environment. The thickness variations of the different sequences and the facies distribution indicate that synsedimentary faults were active in the Campine-Brabant Basin during the Visean. A comparison with the Upper Westphalian of the Campine-Brabant Basin, and with the Lower Carboniferous of northern England suggests a block-faulted structural framework for the Campine-Brabant Basin during the Visean. The paleogeothermal gradient of the Visean and the Namurian-Westphalian A strata of the western zone of the Campine-Brabant Basin has been calculated. The coalification data at the top of the Visean confirm the existence of a fault zone near the London-Brabant Massif and of a shelf bordered to the north by a listric fault. |
| Geochemical constraints on the composition of sandstone matrix and interpretation of Detrital modes | 1987 | Reed, J.R.; Condie, K.C. | 66(4) | Using petrographic detrital modes and major-element concentrations in matrix-rich sandstones, it is possible to calculate upper limits of the amounts of various detrital components that may have recrystallized in sandstone matrices. With exception of samples in which the matrix includes large contributions of recrystallized detrital feldspar, detrital modes of graywackes can provide accurate provenance and tectonic setting information. |
| Basement topography and thrust fault ramping, a model to explain cleavage fans in the Mosel area (Rheinisches Schiefergebirge) | 1987 | Biermann, C. | 66(4) | The structure of the Mosel area is characterized by major NW-directed overthrust faults, that formed in a late stage of the deformation history, after two phases of ductile deformation. The traces of the major overthrust faults are indicated by discontinuities in stratigraphy, metamorphic grade and intensity of the pre-thrusting deformation structures. The thrust planes separate rock sequences that have rotated by foreland-directed movement on SE-dipping listric surfaces. Large scale normal and reverse cleavage fans have formed in the hanging wall of the main overthrust planes. It is suggested that the overthrust planes, cleavage fans and the large scale rotations have formed in relation to bending of the detached sedimentary cover over pre-existing ramps in the crystalline basement. These ramps represent inherited normal faults, that formed during syn-sedimentary differentiation of the Lower Devonian sedimentary basin. |
| Early diagenetic silica precipitation, in relation to redox boundaries and bacterial metabolism, in late cretaceous chalk of the Maastrichtian type locality | 1987 | Zijlstra, H.J.P. | 66(4) | Silica concretions, known as chert, flint or silex, are common in Late Cretaceous chalks of the Maastrichtian type locality (Maastricht, the Netherlands). They show differences in shape, size and distribution that can be related to depositional structure and texture of the carbonates. It is suggested that the source of the silica was biogenic opal (diatoms), dissolving in the sediment after deposition. Precipitation of dissolved opal started during early diagenesis, at the boundary between oxidizing and reducing sediment. Anaerobic decomposition of organic matter by archaebacteria lowered the hydrogen ion concentration in pore fluids. The alkaline conditions at the boundary between oxidizing and reducing sediment, caused dissolved biogenic silica to polymerize and precipit ate. Later , during further burial, a high concentration of primary silica precipitates enhanced further precipitation. The concentration gradient that was generated in this way, forced dissolved silica to diffuse from the surrounding sediment towards the sites of primary high silica precipitation. After all biogenic opal had been dissolved to nourish the growing 'protonodules', further precipitation resulted in the lowering of dissolved silica in pore fluids below the saturation level of the new polymorph. Then this polymorph started to dissolve and precipitated as a lesser soluble and more ordered polymorph at the most dense parts of the 'protonodule'. This process, resulting in the generation of dense, sharp rimmed nodules, ended when all silica was precipitated as stable quartz. Silica concretions in chalks can be used to determine palaeoredox zones and the depositional and early diagenetic conditions of the chalks. |
| Book reviews | 1987 | 66(4) | ||
| New discoveries of ichnofossils from the Middle Triassic of Winterswijk (the Netherlands) | 1988 | Demathieu, G.R.; Oosterink, H.W. | 67(1) | The Middle Triassic of Winterswijk has yielded an interesting ichnofauna (reptilian and amphibian footprints) during the past few years. Recently discovered new species add greatly to our knowledge of the Winterswijk fauna. Three vertebrate tracks are described and illustrated: Brachychirotherium paraparvum, Coelurosaurichnus ratumensis and Sustenodactylus hollandicus. Some remarks on species described earlier are added. |
| Evidence for gravity subsidence and granite diapirism in the 1.8-1.9 Ga Proterozoic succession of W. Bergslagen, Sweden | 1988 | Groot, P.A. de; Baker, J.H.; Oen, I.S. | 67(1) | Western Bergslagen, Central Sweden contains a number of large scale features including long, narrow, synformal, sediment-filled basins, separated by wide intervening areas of felsic metavolcanics in which anticlinal structures are absent. Synvolcanic granites intrude the felsic metavolcanics. Bedding, foliation and mineral lineations are sub-parallel both where bedding is sub-vertical or more rarely sub-horizontal. These features, taken in their geological context, are consistent with a dynamic system in which granite diapirism and gravity tectonic processes operated. Previous models (Oen et al., 1982; Oen, 1987) emphasize the continental rift setting of Bergslagen. We propose the following four stage tectono-magmatic model to account for the structure of the area: Phase 1: A primary crust forming event at about 2.1.Ga. Phase 2: Subsequent attenuation produced rifting accompanied by melting of the lower crust to give large scale felsic volcanism, contained predominantly in sinking grabens of a wider rift structure. Granite diapirism was initiated. Phase 3: Tectonic inversion followed, with an uplift of the graben floors, and a higher emplacement of the granite diapirs. At the same time a second generation of rift basins evolved on the flanks of the updomed areas, to be filled with debris derived from the felsic volcanics. A gravity instability developed as the heavier sediments filled the grabens, contributing to the overall tectonic process. Phase 4: A younger event of granitic magmatism. The development of the sediment filled rift basins is the surficial expression of the deeper gravity tectonic system. |
| Methodological aspects of paleo-ecological diatom research in coastal areas of the Netherlands | 1988 | Vos, P.C.; Wolf, H. de | 67(1) | A major problem in paleo-ecological research of diatoms in tidal environments is the distinction of autochthonous and allochthonous diatom valves. A new approach applying several diatom- and non-diatom-related criteria is introduced in order to solve the autochthonous/allochthonous problem. A classification of coastal diatoms in ecological groups, and the relation between these ecological groups and the sedimentary environments are discussed. |
| Geology and genesis of gold-bearing quartz veins at Bini Yauri and Okolom in the Pan-African domain of western Nigeria | 1988 | Akande, S.O.; Fakorede, O.; Mucke, A. | 67(1) | The Bini Yauri and Okolom primary gold occurrences are localized within the Precambrian to Lower Paleozoic schist belts of western Nigeria. These belts consist of gneisses, migmatite, quartzite, mica schist, phyllites, amphibolite, and granite which represent suites of metasedimentary, metavolcanic and intrusive rocks that are infolded into the Nigerian basement complex. Gold-bearing veins in the Bini Yauri lode occur as lenticular bodies within altered mica schists at the contactzone with a granite porphyry. At Okolom, the veins are hosted in sheared zones within a sequence of silicified biotite gneiss, amphibolite and schist. Vein contacts in the two deposits are generally sharp, steeply dipping at ca. 80°E and commonly contain stockworks and discordant stringers adjacent to the wall rocks. Vein constituents are essentially quartz, sericite, chlorite, albite, tourmaline calcite, magnetite and hematite. These are commonly intergrown with pyrite, pyrrhotite, chalcopyrite, arsenopyrite, galena, sphalerite and argentite which altogether may constitute up to 3% of the vein systems. Alteration minerals like sericite, chlorite, epidote, calcite and quartz are common in wall rocks adjacent to veins. The alteration minerals are commonly associated with quartz, magnetite, ilmenite, hematite, zircon, rutile and limonite. Fluid inclusion studies in vein quartz reveal a bimodal distribution of filling temperatures which suggests at least 2 temperature regimes centred on 170°C and 240°C up to a maximum of 320°C during mineral deposition. Salinity estimates for the ore fluid average 1.5 equivalent weight percent NaCl and ore precipitation appears to have taken place at a minimum depth of about 1.4km. Our study of the contacts, shape, petrography and fluid inclusion aspects of the Bini Yauri and Okolom vein systems suggests that gold mineralization in the two localities and in the Nigerian schist belts in general may have evolved as a result of the metamorphic dewatering of thick sequences of clastics, shales and their associated volcanic rocks within the Precambrian to Lower Paleozoic basement complex. Several stages of remobilization and reconcentration of vein constituents appear to have taken place during succeeding thermotectonic events. |
| Sea level rise and paleotidal levels from sedimentary structures in the coastal barriers in the western Netherlands since 5600 BP | 1988 | Roep, T.B.; Beets, D.J. | 67(1) | A trendcurve for the rise of mean sea level (MSL) since 5600 BP is given based on 14C-dated coastal sequences. Mean High Water level (MHW) is inferred from the deepest occurrence of dry eolian scour and the highest marine burrow-level and small-scale cross-lamination. Estimates of Mean Low Water levels (MLW) are based on the level of thickest shell beds, the range of structureless sand or bubblesand, the range of low-angle bars and the occurrence of cm-thick clay intercalations. Estimates of MHW have an error of a few decimetres. Those of MLW somewhat more. All data are presented in a 14C time-depth graph and also in a historical time-depth graph (calibrated years BC). MSL is drawn halfway MHW and MLW estimates. The MSL trendcurve indicates a rise of ca. 2 m between 4500 cal BC and 3000 cal BC and ca. 3.5 m during the last 5000 historical years. Our data suggest a tidal amplitude of ca.2m between 4500 cal BC and 3000 cal BC and of ca. 1.50m during the last 2000 historical years. |
| The spatial facies of a group of pingo remnants on the southeast Frisian till plateau (the Netherlands) | 1988 | Meulen, S. van der | 67(1) | A group of Weichselian pingo remnants on the southeast Frisian till plateau has been investigated in 2 m deep ditch exposures and in borings. Pingo geometry comprises a more or less continuous outer till rim, an inner till terrace, and a central depression, which runs down through the 3.5-5 m thick till. The rim developed in a peripheral stressfield, the inner terrace consists of sagged pingo skin, and the central depression approximately represents the former pingo crater. Sand, gyttja, and peat cover the inner terrace and fill the central depression, which possibly contains some till interlayers in the basal parts. The pingos originated at the flanks of a winding erosion valley (80 m wide), a tributary to one of the main valleys of the till plateau. This setting and the minor relief of the area indicate a closed-system pingo origin. However, the interpreted positions of the former pingo ice lenses at the base of the till layer, for pingos which are strongly different in size, may indicate some artesian influence (open-system processes). The pingos and sand wedges (2 m long, several decimetres wide) originated under an arid, arctic climate which succeeded a wet, Pleniglacial phase. Pingo degradation with some climatic amelioration was accompanied by minor lateral transport of the pingo skin, which explains the low relief of the rampart. Aeolian sand accumulated in the remnants, where furthermore loess became mixed with organic material (gyttja). Under Holocene climates aeolian transport ceased and peat growth started, together with the formation of podzolic soil profiles. |
| Geochemistry of the sands of the Allier river terraces, France | 1988 | Kroonenberg, S.B.; Moura, M.L.; Jonker, A.T.J. | 67(1) | The distribution of 24 major and minor elements has been studied in 66 sand samples of different grain sizes from six terrace levels along a stretch of 40 km along the Allier river, which drains an area mainly underlain by granitic and gneissic Hercynian basement and alkalibasaltic Cenozoic volcanic rocks in the French Central Massif. The river sands show a large spread in SiO2 63-97%). Principal component analysis shows two factors, F1 composed of Ti, Mg, Fe, Mn, Ca, P, Ni, Cr, V, Sr, Nb and Zr, together with -Si, mainly elements from basaltic components, and F2 composed of K, Na, Al, Rb and Ga, mainly elements of alkalifeldspar and micas. Within single terrace levels F1 varies mainly due to lateral and downstream density sorting of basaltic rock fragments, and F2 due to increasing concentration of micas in finer-grained samples. Variations in F1 between terrace levels reflect partly uplift and erosion history, partly increasing contribution of fluvioglacial basalt-rich sediment in glacial times and of basement-rich sediment in interglacial times. Weathering of basaltic components with increasing sediment age is reflected in decreasing Ca/Ti and Mg/Fe ratios with terrace height. The results show that the geochemical study of unconsolidated fluvial sands is a rapid and useful tool next to classical sedimentary petrography. |
| Late Cenozoic geohistory of NW Buru, Indonesia and plate tectonic implications | 1988 | Fortuin, A.R.; Smet, M.E.M. de; Sumosusatro, P.A.; Marle, L.J. van; Troelstra, S.R. | 67(1) | Mio-Pliocene deposits of Buru have been investigated in order to provide additional data concerning the timing, rate and magnitude of vertical movements in the northwestern end of the outer Banda Arc structure. Geohistory analysis of field and laboratory data of two sections recorded in NW Buru provide broad age-depth constraints only. Four episodes in the history of uplift and subsidence are distinguished and discussed in the light of present plate tectonic concepts. Deposition of the Early Miocene Hotong Formation, bathyal sandy clays and marls with intercalated turbidites, followed after a mid Tertiary period of open folding, uplift, erosion and, finally, partial resubmergence. These changes may be related to plate tectonic interaction with southeast Asia and not necessarily with the Australian continent - from which Buru initialy derived - which is now colliding with the Banda Arc. The Middle - Late Miocene (and possibly the Early Pliocene) left no sediments in Buru; it was a time of differential uplift (up to 20cm/ka), related to reorganisation of the regional deformation pattern, i.e. evolution of the Banda Arc system. During a poorly dated Pliocene depositional episode shallow marine fan-delta clastics were laid down in giant prograding sets, up to 50 m high and dipping up to 20 degrees, thus witnessing continuing differential movements in NW Buru. The same pattern of deformation exists to the present day. |
| Book reviews | 1988 | Verschure, R.H.; Vandenberghe, J.; Loon, A.J. van; Finlow-Bates, T.; Rondeel, H.E. | 67(1) | |
| Dedication to Professor I.S. Oen, on special volume on the geology and ore forming processes of Bergslagen, Central Sweden | 1988 | Baker, J.H.; Hellingwerf, R.H. | 67(2-4) | |
| Preface special volume on the geology and ore forming processes of Bergslagen, Central Sweden | 1988 | Baker, J.H.; Hellingwerf, R.H. | 67(2-4) | |
| Structure, stratigraphy and ore-forming processes in Bergslagen: implications for the development of the Svecofennian of the Baltic Shield | 1988 | Baker, J.H.; Hellingwerf, R.H.; Oen, I.S. | 67(2-4) | Bergslagen is the ore-bearing part of the 1.9-1.86 Ga Svecofennian of central Sweden, characterized by large thicknesses of felsic metavolcanics and sediments, with an intricate association of local and regional hydrothermal alterations and mineralizations related to the development of mostly submarine rift basins. Mineralization types show a change with time in response to the evolving geotectonic setting. The change in lithology from predominantly volcanic Bergslagen to more sedimentary in the easterly Stockholm region is accompanied by an increase in metamorphic grade and change in deformational style. The main geological features of the three granitoid magmatic regions, and intervening sedimentary areas of the Svecofennian are summarized and related to the processes affecting the northern Archean block during Proterozoic times. A two stage model for the evolution of the 1.9-1.86 Ga Svecofennian of the Baltic Shield is proposed. New crust of felsic to intermediate composition was generated in the period 2.6-2.1 Ga by multiple subduction from the SSE. In this period the Archean block underwent deformation as an active margin. Accretion of the newly formed crust occurred during a collision type orogeny with the Archean block in the period 2.1-2.0 Ga. Reworking of the accreted crust in Central Finland, Skellefteå-Kiruna and Bergslagen occurred in the period 1.9-1.86 Ga, with elongate volcanic basins developing in transtensional strike slip zones, where deep faulting penetrated to the lower crust. |
| Regional metamorphism in the Bergslagen Province, South Central Sweden | 1988 | Rickard, D. | 67(2-4) | Regional metamorphism in the Bergslagen Province of South Central Sweden reached but did not significantly extend beyond the granulite facies boundary. It occurred during a less than 20 Ma, and probably less than 5 Ma, period between 1.89 and 1.84 Ga. It resulted from burial metamorphism in an extensional basin under a moderately high geothermal gradient of at least 50°C km-1. Within this relatively warm terrane, submarine areas of recharge are delineated by zones with lower metamorphic facies. The high heat flow produced deep hydrothermal convection through the volcano-sedimentary pile resulting in extensive alteration, particularly alkali metasomatism, and concomitant ore formation. Migmatite development, related to incipient melting occurred in the pelite-infilled, deeper part of the basin. At this high heat flow, melting occurred at less than 13 km depth. The granitoids resulting from this process represent the urgranit of central Sweden and display mixed S- and l-type characteristics. Intrusive activity in a region with intense hydrothermal activity resulted in substantial explosive volcanic activity and the formation of large volumes of volcanoclastics. Sediment and subsequent volcanoclastic loading provided a virtually autocatalytic subsidence driving mechanism for the basin, resulting in extensive melting. The basin developed through lithospheric stretching and attenuation of an earlier continental crust. Nd isotopic systematics may be reinterpreted to suggest a substantial 2.2-2.0 Ga component in the older granitoids. This is consistent with other isotopic and geochemical data which strongly suggest an ensialic development for the district. The earlier crust is now represented by the older granitoids, which were produced by basement melting at the crust-mantle interface during burial. The pegmatite-rich younger granitoids are representatives of the L.8-1.7 Ga intrusives which mantle the Province to the west. These granitoids penetrate the Bergslagen crust sporadically; they may underlie the western edge and have given rise to an extensive veining and pegmatite formation, unrelated to the major metamorphic event. The development of Bergslagen is similar to Phanerozoic extensional basins, except that a deeper part of the crust is uncovered. In these deeper zones with high heat flow, major deformation was probably ductile rather than by brittle failure. The development of the Bergslagen basin immediately preceded plate collision at the end of the 1.9-1.8 Arizona-Finland Wilson cycle, which is expressed in Bergslagen as intensive folding rather than extensive thrusting. |
| Regional inter-relationships in the Proterozoic geology of Bergslagen and Southeastern Central Sweden | 1988 | Lundström, I. | 67(2-4) | The regional tectonic and metamorphic features common to western Bergslagen and to the region lying to the east are described. Metamorphic grade varies from low grade greenschist facies in the west to higher grade amphibolite facies in the east, where migmatized gneisses are also developed. Deformation is also stronger in the eastern region, where E-W trending isoclinal folds predominate, while N-S trending, more open structures are found to the west. Stratigraphic and lateral inter-relationships of the two regions indicate a volcanic proximal area in western Bergslagen, which fed tephra into a depositional basin to the east. |
| Evolution and tectonic history of the Bergslagen volcano-plutonic complex, central Sweden | 1988 | Lagerblad, B. | 67(2-4) | The Proterozoic Svecofennian volcano-plutonic rocks in Bergslagen, central Sweden, exhibit changes in both geochemistry, grade of deformation and metamorphism going from the west toward the eastern and more interior parts of the south Svecofennian volcanic belt. In the west geochemically homogeneous rhyolitic volcanic rocks cover vast areas while towards the east the magmatic variation is larger, and dacitic volcanic rocks become increasingly common. Andesites are locally present. Similarly coeval granitoids in western Bergslagen are granitic, while granodiorite and tonalite plutonic complexes are more common to the east. A change in the magmatic character of the rocks is substantiated by their trace element signatures. The rocks in the westernmost parts of Bergslagen have characteristics similar to modern continental within-plate settings, while those in the easternmost parts of Bergslagen have characteristics similar to volcanic arcs. The change in magmatic character is successive, and resembles the compositional polarity across a Phanerozoic magmatic arc at a destructive plate margin. The more continental character of the Svecofennian rocks in western Bergslagen implies thicker crust. This is substantiated by the more homogeneous magmatic character of the volcanic rocks which can be taken to imply larger magma chambers. Thus, when the Svecofennian crust, shortly after its consolidation, was subjected to an E-W compression, the crust in western Bergslagen acted as a more competent block relative to the thinner more 'primitive' crust in east. This resulted in stronger compression of the crust to the east, which in turn explains more intense folding and higher grades of regional metamorphism in these areas. |
| Carbonate rocks from W. Bergslagen, Central Sweden: isotopic (C, O, H) evidence for marine deposition and alteration by hydrothermal processes | 1988 | Groot, P.A. de; Sheppard, S.M.F. | 67(2-4) | Carbon and oxygen isotope ratios for calcite and dolomite from stratabound carbonates, carbonate veins and clots in W-(Mo-) and Zn-Pb sulphide skarns, and for a calcite from a Mn-skarn from the Bergslagen region, central Sweden, are presented. Stratabound carbonate carbon isotopes (δ13C - 0‰) imply a marine milieu of deposition. The δ18O values of stratabound carbonates can be divided into two groups: one associated with stratiform iron-oxide deposits (RSC) and the other unrelated (NRSC). Stratabound dolomites of the NRSC are depleted in 18O compared to the 'most Proterozoic dolomite' field. NRSC calcites have a range of δ18O values (+12 to +19‰) similar to the lower half of the 'most Proterozoic calcites' field. Whether the RSC δ18O values (+6 to +11‰) are primary values or values formed by exchange of the RSC with a hydrothermal fluid during the skarn alteration of associated stratiform iron-oxide deposits, is not clear. Calcites and dolomites, from skarn altered iron-oxide deposits, W-(Mo-)skarns, and a sulphide skarn, as late phase veins and clots, have distinguishable δ13C and δ18O values, placing the respective skarns into separate fields. They have, in general, low δ13C (-2 to -8‰) and low δ18O (+6 to +12‰) values, except for the calcite veins in the sulphide skarn. The 18O -depletion of the carbonates most probably occurred during exchange with sea water at temperatures of 300 ± 50°C, or meteoric waters if the temperatures were lower. The types of δ18O values and their range are comparable to well documented sea water hydrothermal systems of younger age from ocean floor ophiolites and many relatively low altitude meteoric-hydrothermal systems. The low carbon and oxygen isotope values of the carbonate veins and clots in W-(Mo-)- and Fe-skarns are typical for such skarns. They indicate the influx of CO2-bearing hydrothermal fluids where the CO2 is either of magmatic origin or derived from sedimentary carbonate formations after major loss of CO2 through decarbonation reactions. Slate hosted calcite from a Ca-Mn-skarn, is isotopically similar to both the skarn associated carbonates and a concretionary carbonate. Diagenetic modifications of organic matter-bearing sediments, exchange of a sedimentary carbonate with hydrothermal fluids, or, more probable, a combination of these two events, were responsible for the isotopic composition of the calcite in this skarn. |
| The metasediments associated with stratabound base metal mineralization, Ljusnarsberg District, Central Sweden | 1988 | Parr, J.M. | 67(2-4) | An extensive suite of exhalites of sub-economic potential occurs in a succession of Lower Proterozoic quartzofeldspathic gneisses in the Ljusnarsberg district, central Sweden. Previously economic varieties include Fe-Mn oxides, silicates, and carbonates, Cu-Pb-Znbearing and W bearing rocks all of which have been mined in the past. The stratigraphic succession of the Ljusnarsberg-Ställdalen area is conformable and changes from a lower metavolcaniclastic pile of >5 km thickness (the Kumlan Group) to a mixed metavolcanic and metasedimentary sequence (the Ställdalen Group). To the east the mixed metavolcanic and metasedimentary succession (the Wigström Group) is thought to be stratigraphically equivalent to the Upper Kumlan Group and Lower Ställdalen Group. The Kumlan Group is dominated by primary rhyodacitic volcaniclastic material partly subaerial. The rapid decline in volcanism is coeval with an increase in the sedimentary component and marks the conformable contact of the upper and lower groups. The dominantly stratabound mineralization is concentrated in two main ore horizons in the upper group: (1) a lower Cu-Pb-Zn sulphide-rich horizon with some magnetite and (2) an upper Fe-Mn enrichted horizon. The ore deposits are spatially associated with the metamorphic equivalents of a variety of clastic and chemical sediments including quartz-feldspar-biotite rocks, with minor calcite, hornblende, garnet, pyroxene, epidote and magnetite; quartz-K feldspar-plagioclase-garnet-amphibole-pyroxene-calcite-epidote- biotite rocks with minor chlorite, apatite and sphene; and pyroxene-epidote- K feldspar rocks. The varied chemistry of both ores and barren chemical sediments suggests the palaeoenvironment was continental with minor basinal development. Composition and pathways of the circulating fluids were restricted causing sharp changes in chemical precipitation. Clastic sediments are not common and reflect a low energy environment starved of sediment. Subsidence seems to have been the overriding tectonic trend. |
| Lithostratigraphic correlations in an asymmetrical rift-basin: the Grythyttan area, W. Bergslagen, Sweden | 1988 | Meerten, T.G. van | 67(2-4) | The predominantly felsic volcanics and intrusives of the Grythyttan basin in W. Bergslagen, are subdivided into four successive stages illustrating the development of a subaqueous continental rift zone. A change in the type of volcanism from Plinian type eruptions with thick fall deposits (stage 1) into Pelean type with extensive flows (stages 2, 3 and 4) is seen. A rift stage (stage 4) is unconformably superimposed on the former three stages and is characterized by bimodal felsic and mafic magmatism and the presence of turbiditic sediments. Fe-ore rich layers associated with fine ashes and limestones, are found throughout the sequence, with a major concentration in stage 3 preceeding the rift stage proper. This ore deposition is associated with large hydrothermal activity and the ascent of basic material. Mn-rich, Fe-ores are found in the stages 2,3 and 4, indicating the former presence of oxidation/reduction boundaries during ore formation. Ore formation and intrusive and volcanic activity should be considered as inter-related processes, linked to the development of an asymmetrical continental rift, presumably triggered by magmatic underplating. |
| Geochemistry of the Fellingsbro type granites, South Central Sweden | 1988 | Öhlander, B.; Zuber, J. | 67(2-4) | The Fellingsbro granite sensu stricto is a massive coarse-grained rock characterized by red, angular microcline megacrysts up to 7 cm long. The Lisjö granite is of the same type as the Fellingsbro granite but is situated 20km to the NE. Both intrusions belong to a belt of c. 1.78 Ga old granites coinciding with the major so-called Central Swedish Gravity Low. Gravity studies suggest that the Fellingsbro and Lisjö granites rose from a huge granite ridge through structurally controlled root zones, forming mushroom-shaped intrusions. These porphyritic granites have the geochemical characteristics (e.g. high Y, Nb, Zr and HREE) of granites generated in 'within-plate' or tensional rifting environments. Even-grained granites of approximately the same age occurring in heterogeneous mixtures of granites, pegmatites, xenoliths and partly assimilated country rocks e.g. in the Fellingsbro and Låsen areas, probably represent minimum melt type rocks that have not moved far from their source. The even-grained interior of the Lisjö granite and the contemporaneous Dingtuna and Pingstaberg granites, were generated by differentiation of granites with similar characteristics as the porphyritic Fellingsbro granite. Recently published U-Pb zircon datings have demonstrated that the Småland-Värmland granite-porphyry Belt has approximately the same age as the granites in this study. We speculate that both groups were emplaced in a tensional environment on the continental side of a subduction related calc-alkaline belt, remnents of which may be preserved in the SW Swedish Gneiss Region. The Fellingsbro and Lisjö granites were generated more towards the interior of the pre-existing c. 1.89 Ga old continent than the Småland-Värmland granites. |
| The major element geochemistry of the 1.9-1.86 Ga Bergslagen Older Granite Suite, W. Bergslagen, Central Sweden | 1988 | Baker, J.H.; Drucker, W.H. | 67(2-4) | The 1.9-1.86 Ga Bergslagen Older Granite Suite forms part of a co-magmatic series together with a > 10 Km thick sequence of felsic metavolcanics developed in the 3000 km2 of western Bergslagen, Central Sweden. The granites, divided into three geographical groups, are fine to medium grained biotite granites, with field and petrological evidence of high level emplacement, the intrusions cutting their own extrusiva. Postmagmatic hydrothermal alteration has resulted in albitization and variable iron oxidation ratios. Unaltered granite samples are characterized by a high silica content and weak inter-element variations, showing restricted minimum melt compositions. In terms of multicationic classifications the granites belong to an aluminous association, compatible with an origin by anatexis of a felsic to intermediate precursor, with no significant contribution from mafic sources. An origin by anatexis supports current models for a rifted intra-continental or continental margin setting. |
| The Falun supracrustal belt. Part 1: primary geochemical characteristics of proterozoic metavolcanics and granites | 1988 | Bromley-Challenor, M.D. | 67(2-4) | The main lithostratigraphic units of the felsic supracrustal sequence of the Falun area are described. The > 100 km2, E-W trending synformal enclave is bordered to the N and S by co-magmatic Svecokarelian granites. The 4.5 km thick sequence comprises lower units of rhyolitic tuffs with minor mafic intercalations, passing up through felsic volcanics to the sulphide-bearing ore horizon. The primary geochemical characteristics of the felsic volcanics and the Svecokarelian granites are illustrated using multicationic classification diagrams. The results for 360 samples collected at ± 50 m intervals along 3 lithogeochemical traverses reveal primary lithogeochemical features which in the B-A classification of magmatic associations diagram (Debon & Le Fort, 1983) are considered to reflect a horizontal to positive aluminous trend for the Falun supracrustals. The Svecokarelian (early - to synorogenic) granites (urgranit) close to the supracrustal border also reveal a similar trend. |
| Isotopic and geochemical data of the Pingstaberg Mo-bearing granite in Bergslagen, South Central Sweden | 1988 | Billström, K.; Åberg, G.; Öhlander, B. | 67(2-4) | An isotopic and geochemical investigation of the Pingstaberg Mo-occurrence in the Bergslagen region, south-central Sweden, has been undertaken. The mineralization is of an intra-granitic type, and is situated within an undeformed granite of a minimum melt composition. In comparison with a 'normal granite', the mineralized part of the Pingstaberg granite is enriched in Y, Nb, Rb, U, Th and HREE, and depleted in Zn, Cu, Zr, Sr and Ba. Several of its characteristic isotopic and geochemical features are probably due to the Mo-mineralizing solutions, and these are likely also to have caused the strongly corroded structure of the analyzed zircons. As a result the U-Pb zircon and Rb-Sr whole-rock isotopic systems have been affected in various ways. The achieved U-Pb zircon age of 1781 ± 46 Ma is, however, considered to be essentially undisturbed, and this age is considered to represent both the time of granite emplacement and the mineralization episode. The Rb-Sr whole rock age of 1.53 Ga, on the other hand, has been reset and is interpreted as reflecting a post-crystallization hydrothermal event. The results presented in this study suggest that the Pingstaberg granite was formed at a late-orogenic stage (1.80-1.75Ga) of the Svecokarelian orogeny. |
| Broken Hill, Australia and Bergslagen, Sweden - Why God and Mammon bless the Antipodes! | 1988 | Plimer, I.R. | 67(2-4) | The sulphide deposits of the Broken Hill and Bergslagen areas occur in Lower-Middle Proterozoic sequences of variably deformed low to high metamorphic grade rocks. The number of events of coeval deformation and metamorphism, intensity of deformation and grade of metamorphism at Broken Hill are higher than in the Bergslagen area. A long history of retrograde metamorphism has been recognised at Broken Hill. Furthermore, granitic rocks in Bergslagen are coeval with volcanicity associated with ore deposition or are post-tectonic whereas at Broken Hill all plutonic rocks can be related to events of metamorphism, specially retrogression. Bergslagen is characterised by abundant metavolcanics (especially explosive acid volcanics) and moderately shallow water sequences probably deposited in a rift whereas metasediments deposited in a deep rift predominate at Broken Hill. Mineralization at Broken Hill is at least two orders of magnitude larger than at Bergslagen, is intimately associated with three events of paired volcanism and is associated with a great volume of extremely diverse exhalite deposited in a moderately reducing environment. The Bergslagen mineralization was probably deposited from numerous small seawater-dominated convective geothermal systems leaching metals from porous, permeable hot acid volcanic rocks. These geothermal systems produced regional alteration and localised intense footwall Mg-metasomatism associated with egress and ore deposition. In contrast, mineralization at Broken Hill formed in a deep rift every time there was a massive invasion of basaltic magma into faulted wet sediments. This increase in the geothermal gradient resulted in lower crustal melting, paired volcanism, initiation of geothermal systems, fault-bounded fluid ascent at the graben margin and with the resultant hydrothermal precipitation above the fault and the lack of widespread hydrothermal alteration. It is suggested that the principal reason for the striking differences between Broken Hill and Bergslagen is that the proposed deep rift in thin crust at Broken Hill allowed tapping of anomalous metalliferous mantle fluid and the leaching of crustal rocks whereas at Bergslagen, there were possibly numerous small graben in an extenion zone hence heated seawater did not have access to a large volume of hot porous permeable crust for leaching, egress of the ore fluid was not focussed and there is no evidence for a mantle contribution to the ore fluid. |
| The geology and structural setting of the Håkansboda Cu-Co-As-Sb-Bi-Au deposit and associated Pb-Zn-Cu-Ag-Sb mineralisation, Bergslagen, Central Sweden | 1988 | Carlon, C.J.; Bleeker, W. | 67(2-4) | A complex sulphide mineralisation occurs within calc-silicate rich dolomite-calcite marble at Håkansboda, Bergslagen, Central Sweden. Exploration during 1980-86 has defined the distribution and nature of the mineralisation and its structural setting. Three zones of mineralisation are identified. The central or B zone, with up to 900 m strike length and 80 m wide, is proven to a depth of 600 m. It forms an envelope around previously mined massive and streaky chalcopyrite-pyrrhotite and chalcopyrite-arsenopyrite-tennantite ore shoots, containing minor antimony, bismuth, gold and molybdenum. A similar, but lower grade mineralisation forms the A and C zones. The deposit is spatially associated with strongly altered felsic volcanic rocks and volcaniclastics, especially in the stratigraphic footwall, and areally extensive exhalite horizons with Pb-Zn-Cu-Ag-Sb sulphides and Mn-rich magnetite ores in the stratigraphic hangingwall. The 'ore'-hosting sequence occurs on the overturned limb of a regional F, syncline and is refolded by steeply plunging F, folds. Brecciated host rock-sulphide lenses and the geometry of individual ore shoots indicate remobilisation and extension of the sulphides into pipe-like bodies parallel to local F, fold axes. |
| Stratiform Tungsten deposits: a review | 1988 | Cheilletz, A. | 67(2-4) | Based mostly on a review of the existing literature and on the experience of the author, a new classification and diagrammatic representation of stratiform tungsten deposits is proposed. It includes three classes of deposits: 1) continental weathering deposits essentialy of exogenic origin; 2) Exhalative-volcanogenic deposits divided into proximal, distal and metamorphic-amphibolite types; 3) Concordant replacement deposits divided into calc-silicate band and hornfels band types. An epigenetic two stage model is proposed for the formation of stratiform tungsten mineralizations associated with calc-silicate bands; this model can be applied to the genesis of Central Sweden tungsten deposits. |
| Stratiform Zn-Pb-Fe-Mn mineralization in the Ätvlången' Vikern area, Bergslagen, Sweden | 1988 | Hellingwerf, R.H.; Lilljequist, R.; Ljung, S. | 67(2-4) | The stratiform Zn-Pb sulphide mineralization of the Älvlången-Vikern area, central Sweden, is contained in an iron-rich meta-sedimentary unit at the base of a sequence of dolomitic marble and metachert of Mid-Proterozoic age, deposited in a fault-bounded sedimentary basin. This basin probably developed during a phase of extensional tectonics. The mineralized unit is a steeply south-easterly dipping zone of 6 km long, extending from Lake Vikern in the NE to Lake Älvlången in the SW. Sphalerite, galena, magnetite and minor arsenopyrite, pyrite, pyrrhotite, chalcopyrite and marcasite occur in fine-grained, well banded and laminated garnet-biotite-cummingtonite-tourmaline-rich rocks of presumably sedimentary-exhalative origin. Characteristic are the small quantities of scapolite and orthite, and the high Ba and C1 contents of various micas and amphiboles. Apart from Zn, Pb, Fe, Mn, Ba and Cl the ore zone is enriched in As, Sb, Ag, Ba, Th, U, Ti, Cr, Co, Ni and V. A distinct metal (Zn + Pb à Fe + Mn + Ba) and mineral (sulphides + tourmaline-+ oxides + cummingtonite) zonation has been observed along the ore zone from the centre, where Zn and Pb contents are highest, to the margin of the basin. The marbles just below the ore zone are locally brecciated, showing network veins with phlogopite, tourmaline and traces of chalcopyrite and pyrrhotite, and corroded rhyolitic fragments. This brecciation of marbles is associated with extreme calc-silicate alteration of intercalated metatuffites and metacherts along veins and fractures. The breccias and calc-silicate alteration, occurring in narrow zones following the fault-bounded basin, are considered to represent hydrothermal feeder channels. The metapyroclastic rocks below the ore-hosting marbles are albitized, microclinized, sericitized, biotitized, calc-silicate altered, silicified, and tourmalinized. Of these, the first three are regional alteration types, presumably not significantly related to the ore-forming processes, whereas the latter four are localized, ore-related alteration types, occurring mostly along network veins and fractures. Tourmaline is a characteristic, but minor, constituent of all rock types below and within the ore zone. The highest concentrations occur in and below the central part of the basin, where the highest sulphide contents occur. It is absent in rocks overlying the ore zone, suggesting tourmaline to be a mineralogical exploration guide. Circulation of the hydrothermal fluids is thought to have initiated during rifting and driven by a high geothermal gradient beneath the depression. This high geothermal gradient may partially be attributed to a hidden felsic magma plug below the ore zone, as indicated by the rhyolitic fragments in the hydrothermal marble breccias. |
| Textural evidence for seafloor, soft rock hydrothermal metamorphism in a garnet-scapolite-bearing metatuffite-exhalite -skarn-sphalerite ore sequence, Nora, Bergslagen, Sweden | 1988 | Oen, I.S.; Hellingwerf, R.H. | 67(2-4) | Metatuffites in a skarn- and sphalerite ore-bearing metatuffite-exhalite sequence near Nora, Bergslagen, Sweden, have preserved the petrographic structure of a felsic tuff with quartz pyroclasts in a very finegrained, strongly fractured and veined quartzo-feldspathic or sericite-rich matrix. Coeval differential compaction, recrystallization, and veining of tuffitic sediments is reflected by: parquet, rosette and parallel structures of micas; compaction-related 'ghost' veinlets, blind veinlets, and straight, folded, and refracted cross-veinlets; bending of schistosity around blind veinlets and quartz pyroclasts; rotation of pyroclasts in soft matrix; and compaction-controlled fracturing, veining, recrystallization and replacement of quartz pyroclasts, locally resulting in albite-quartz or carbonate-quartz pseudomorphs after the pyroclasts. Albite, garnet, scapolite, and other late mineral growths sequential to, but overlapping with the formation of the compaction-related structures, are indicated by: poikiloblasts in the pseudomorphs after quartz pyroclasts; late mineral growths in and along compaction-related veinlets; disseminated poikiloblasts traversed by compaction-related, often blind veinlets; and coarser grained bands and streaks of late minerals parallel to compaction banding. Garnet, scapolite, albite, carbonate, and other minerals show a layer-bound distribution. The paragenetic sequence of textures and minerals can be interpreted as the result of seafloor, soft rock hydrothermal metamorphism, involving interaction of different lithologies with hydrothermal fluids of rapidly changing PTX-characteristics, evolving from fluids in equilibrium with the host rocks to metasomatising fluids; these changes may be related to PTX-gradients around exhalative centres and interlayer rock-fluid-seawater-exhaled brine water interactions in unconsolidated tuffite-exhalite sediments. |
| Cryptic silver mineralization in the magnetite-sulfïde ore of Sågmurgruvan, Central Sweden | 1988 | Kieft, C.; Eriksson, G. | 67(2-4) | The ores of Sågmurgruvan consist of nearly massive magnetite with locally important concentrations of sulfides: pyrite, pyrrhotite, iron-rich sphalerite, galena, very minor chalcopyrite and accessorial cobaltite, linnaeite and Ag minerals. The Ag minerals are native Ag, acanthite, stephanite and pyrargyrite. However, the majority of the Ag is present as minute, nearly submicroscopic, inclusions of native Ag in porous pyrite. Younger granite, in contact with the massive magnetite-sulfide ores, locally contains small amounts of sulfides (pyrite, galena and nearly iron-free sphalerite) and rather large grains of native Ag. The magnetitesulfide ores are interpreted as the metamorphic equivalent of siliceous exhalative-sedimentary ores. Occasional spherical pyrite grains are thought to form relicts of the primary sedimentary texture. The mineralization in the granite is thought to originate from local selective remobilization of the magnetite-sulfide ore, caused by the hydrothermal activity accompanying the granite intrusion. The deposition of native Ag in the porous pyrite is probably a low temperature event, during retrogressive metamorphism. |
| Mineral parageneses of the sutphide ore deposits of Bergslagen metallogenic province: I. Ni-Cu deposits of southern Sweden | 1988 | Zakrzewski, M.A. | 67(2-4) | The abandoned Ni-Cu ore deposits of southern Sweden are associated with Proterozoic mafic intrusions. Their mineralogy is similar to that of Sudbury-type deposits. The dominant primary sulphides are: pyrrhotite or pyrite, pentlandite, chalcopyrite and sphalerite. Pentlandite in ores with primary pyrite has a high Ni/Fe ratio and is associated with millerite and siegenite. Secondary minerals include pyrite after pyrrhotite, bravoite replacing secondary pyrite, violarite after pentlandite. There is strong evidence that the formation of the observed violarite took place on the mine dumps during the last 40 years. |
| Geochemical variations in a Proterozoic hydrothermal mafic breccia dyke related to Ni-Cu-Fe skarn mineralization at Annehill, Bergslagen, Sweden | 1988 | Baker, J.H.; Andersson, L.G.; Marinou, A. | 67(2-4) | Nickel sulphide breccias form an uncommon type of Ni mineralization. The development of a Proterozoic mafic breccia dyke and Ni-Cu-Fe skarn in felsic metavolcanic wall rocks at Annehill, Bergslagen, Sweden, is genetically related to the emplacement of a continental tholeiite dyke. Hydrothermal alteration prior to and during brecciation distinguishes this mineralization from intramagmatic Ni mineralizations. Breccia development can be divided into two stages: An initial pre-brecciation stage of pervasive alteration of the felsic metavolcanics produced minerals in the paragenetic order hydromuscovite-tourmaline-phlogopite-amphibole. Microprobe data shows this corresponds to B, F and Cl metasomatism respectively, and can be correlated with major element variations. High Ti mobility is demonstrated by the development of sphene poikiloblasts in the metavolcanics. A second stage of mechanical fracturing developed a 1 km long, up to 20m wide, breccia zone, with fragments of more or less altered metavolcanics in an amphibole matrix. Amphibole compositions become more Fe-rich closer to the tholeiitic dyke, which itself has undergone autometamorphism, with no magmatic minerals present. Fe and V provide the best indicators of chemical variation in the altered rocks, breccia dyke and tholeiite. Highest B contents coincide with highest K, Rb, Li and Co in the altered rocks. There is a steady decrease in Fe, V, Ti, Mn, Co, and P from the tholeiite through the breccia and pervasively altered metavolcanic to least altered metavolcanic. With decreasing Fe there is an increase in Ca, Mg, and K, and Fe also shows a positive correlation with Be, Pb, Sc and Eu. REE contents of pervasively altered and brecciated samples generally lie between those of the least altered metavolcanic and the tholeiitic dyke. This supports a model for contamination of the felsic metavolcanics with material derived from the tholeiite dyke. The skarn ore comprises pyrrhotite with minor chalcopyrite and pyrite, and is located along the eastern margin of the breccia. Ni and V contents increase to 0.7%. Emplacement of the tholeiitic dyke, along a pre-existing fracture, initiated a hydrothermal cell in the upper crust. Volatiles derived mainly from the wall rocks were responsible for the alteration of the felsic metavolcanics. At the same time a Nibearing hydrothermal phase developed in the crystallizing magma. Brecciation could have been triggered by fault movements or pressure build up in the hydrothermal cell. Pressure release through brecciation allowed injection of the Ni-bearing hydrothermal phase into the felsic wall rocks to form the skarn mineralization along one side of the breccia dyke. |
| Activity diagrams for the MgO-Na2O-K2O-SiO2-AI2O3-H2O-HCI system in the temperature range 298 to 623 K and L bar pressure: application to the 1900 Ma phlogopite-Mg-chlorite-sericite schists of W. Bergslagen, Sweden | 1988 | Jasiński, A.W. | 67(2-4) | Both 2- and 3-dimensional activity diagrams for the MgO-Na2O-K2O-SiO2-AI2O3-H2O-HCI system at temperatures of 298 to 623 K and 1 bar pressure are presented, showing the stability fields and volumes of phlogopite, Mg-chlorite, muscovite, paragonite, microcline, albite, kaolinite, and Mg-, Na-, and K-montmorillonite. Additionally, the expressions of reaction constants also contain the pressure term. The geological application of these diagrams to geochemical interpretation is briefly discussed in relation to the formation of 1900 Ma phlogopite-Mg-chlorite-sericite-quartz rocks in W. Bergslagen, Central Sweden. |
| Cordierite-mica-quartz schists in a Proterozoic volcanic iron ore-bearing terrain, Riddarhyttan area, Bergslagen, Sweden | 1988 | Trägårdh, J. | 67(2-4) | The Riddarhyttan Proterozoic predominantly felsic, alkali-enriched metavolcanic rocks have been affected by extensive synvolcanic hydrothermal Mg-alteration. After amphibolite facies metamorphism and deformation this is reflected in the occurrence of large elongated zones of tourmaline-bearing cordierite-micaquartz schists, spatially related to numerous volcanogenic-exhalative iron formations. Geochemical evidence suggests that seawater-based fluids caused substantial mobilization of both major and trace elements, resulting in the formation of Fe-depleted and Fe-enriched Mg-schists. The latter is commonly gradational to cordierite-anthophyllite wall-rocks. The geochemical pattern is compatible with subseafloor hydrothermal circulation leaching iron and minor amounts of base metals from the felsic volcanic rocks, the emerging fluids precipitating these elements close to exhalative vents. |
| Petrographic and geochemical evidence for major and trace element metasomatism in recrystallized felsic metatuffites from the Persberg area, Bergslagen, Central Sweden | 1988 | Outhuis, J.H.M; Berkel, J.T. van | 67(2-4) | Felsic rocks with randomly orientated biotite crystals up to 1.5 cm long, occurring NE of Persberg, Sweden, are strongly recrystallized felsic metatuffites. There is a gradual transition from the surrounding weakly recrystallized to the strongly recrystallized metatuffites. Recrystallization resulted from hydrothermal alteration of the metavolcanic rocks, which also caused the development of mafic aggregates, mainly consisting of biotite and/or cordierite. Considerable mobility of major, trace and rare earth elements accompanied the hydrothermal alteration: the strongly recrystallized metatuffites are depleted in K, Rb, Ba and Sr, and enriched in Na, Fe, Mg, Zn, Zr, REE, Hf and W. Compared to their host rocks the mafic aggregates are depleted in Na, Si, Y, W, Th and REE, and enriched in K, Fe, Mg, Sc, Cr, Co, Ni, Ti, Zn, Rb, Sr, Ba and Cs. Mobility of Zr is illustrated by the morphological characteristics of the zircons present in the strongly recrystallized metatuffites and mafic aggregates. Many of the larger grains show a conspicuous zoning and it is argued that unusual clusters of small zircon grains, often occurring on the boundaries of quartz and albite grains, are probably non-magmatic. The hydrothermal alteration is thought to be driven by the ascending nearby Horsjö granite and enhanced by the Hyttsjö gabbro-tonalite-granite which intruded shortly after the Horssjö granite and probably before the collapse of the hydrothermal system. |
| Metasomatic alteration of a felsic metavolcanite to an actinolite skarn near Ställbergstorp: evidence for high LREE mobility | 1988 | Valbracht, P.J.; Helmers, H. | 67(2-4) | Felsic metavolcanites of the Lower Leptite Group of the 1.9-1.8 Ga Svecokarelian Bergslagen Supracrustal Series, Sweden, are locally pervasively altered into actinolite-magnetite skarns, showing euhedral magnetite blasts in an amphibole matrix. The alteration comprises two stages: after complete albitization the felsic metavolcanites are characterized by extremely low K and high Na contents and LREE depleted patterns relative to least altered metavolcanites. Incipient replacement of albite by amphibole leads to enrichment in MgO, CaO and FeO*, whereas the light rare earth element (LREE) abundances remain unchanged. Subsequent massive actinolite growth in the matrix and in veins is characterized by a strong enrichment in MgO, CaO, FeO* and LREE. |
| Exhalative-sedimentary manganiferous iron ores from the Gåsborn area, W. Bergslagen, Central Sweden | 1988 | Damman, A.H. | 67(2-4) | The Gåsborn metamorphosed manganiferous iron ore horizon consists of Mn-poor (<I wt% Mn) iron ore-bearing marbles and metavolcanics and manganiferous (5-25 wt% Mn) iron ore-bearing metavolcanics and metacherts, displaying lateral facies transitions. The ore horizon is concordantly intercalated in a pile of felsic metavolcanics. It shows a concentric zoning around two pipe-like structures which consist of extremely Mn-poor (<0.1 wt% Mn) iron ore-bearing Mg-enriched metavolcanics, located directly below the ore horizon. Major- and trace-element analyses suggest that (1) the ore horizon is of exhalative-sedimentary origin and (2) the Mg-enriched metavolcanics mark the top of a (now metamorphosed) conduit zone for hydrothermal fluids from which the ores were deposited |
| Geochemistry of wall-rock alteration and of mixed volcanic-exhalative facies at the Proterozoic Stollberg FePb-Zn-Mn(-Ag)-deposit, Bergslagen, Sweden | 1988 | Ripa, M. | 67(2-4) | The Proterozoic Fe-Pb-Zn-Mn(-Ag) ores at Stollberg in Bergslagen ore province, south central Sweden were formed as stratiform, stratabound exhalites in a volcano-sedimentary environment. The surrounding rhyolitic rocks were altered hydrothermally. This alteration predominantly affected the foot-wall rocks. The metamorphic mineral assemblages in the altered rocks were formed during a subsequent episode of regional metamorphism. They comprise gedrite, biotite and muscovite, indicating chlorite and sericite as original hydrothermal alteration products. Structures resembling hydrothermal breccias support an alteration model. More than 2500 samples have been taken from drill-cores and outcrops, and analyzed for major and trace elements. The geochemistries and the densities of the least and the most altered samples have been used to estimate gains and losses during hydrothermal alteration. Fe, Mg, Mn, Ti and K have been added, whereas Si, Ca, and Na have been removed. Plotting elements along the length of a drill-core, cutting the karnaltered exhalitic horizon, shows that the exhalites comprise potassium-rich meta-volcanic material mixed with chemical precipitates. Relative to unaltered volcanites these rocks are richer in Si, Fe, Mg, Ca, Mn, Pb and Zn, and poorer in Ti, Al, Ba, Na and K. The metamorphic mineral assemblages (ortho- and clinoamphiboles, garnet, diopside, epidote, gahnite, cordierite, staurolite, serpentine/olivine, fluorite, calcite, quartz, micas and feldspar) are developed in rocks with a bulk marly composition. |
| Quality assessment and organizational aspects of multi-element analyses of geological material with the IRl-system for routine INAA | 1988 | Bode, P.; Meerten, T.G. van | 67(2-4) | Geological research groups at the universities of Amsterdam and Utrecht obtain multi-element concentration data of their samples to a large extent by instrumental neutron activation analysis. At the Interfaculty Reactor Institute (IRI) of the Delft University of Technology, a system for routine INAA has been adapted to be used by laymen (non-specialists in radiochemistry), thus enabling geologists to carry out the analyses themselves. Much attention has been paid in developing the technique to the incorporation of quality control procedures, to ensure that the results reflect a realistic situation. Routinely, about 40-45 elements (including 9 REE) are determined with adequate accuracy. Procedures, performance and organizational aspects are discussed and the application of analytical data to geological problems in the Bergslagen region of central Sweden is briefly illustrated. |
| Note on a mid-Proterozoic stromatolite limestone, south of Grythyttan, Bergslagen, Sweden | 1988 | Boekschoten, G.J.; Raad, A.C. van der; Kenter, J.A.M.; Reymer, J.J.G. | 67(2-4) | At Grimsudden south of Grythyttan relatively well preserved limestones are present in a sequence of volcanoclastics of mid-proterozoic age. In these limestones textures were found that are characteristic for stromatolites. |
| Raman spectrometry and microthermometry data on CO2-CH4-bearing fluid inclusions in late-orogenic quartz from the Saxberget Zn-Pb-Cu-Ag deposit, Central Sweden | 1988 | Lindblom, S.; Burke, E. | 67(2-4) | |
| Deltaic coastal wetlands | 1989 | Coleman, J.M.; Roberts, H.H. | 68(1) | Modern-day deltas exist in a wide variety of settings. Despite the various environmental contrasts, all actively prograding deltas have at least one common attribute: a river supplies clastic sediment to the coast and inner shelf more rapidly than it can be removed by marine processes. The most important processes controlling the geometry and landforms in deltas are climate, water and sediment discharge and its variability, river mouth processes, nearshore wave power, tides and tidal regime, nearshore currents, shelf slope, tectonics of the receiving basin, and receiving basin geometry. Many present-day deltas are experiencing relatively large coastal landloss; this results from the complex interaction of many physical, chemical, and biological processes that operate in the natural environment and, in more recent times, the processes induced by man's utilization of this environment. All of these processes operate at different scales and magnitudes, in both time and space; some are amenable to manipulation by man, while others are essentially out of his control. Natural processes include sea level changes, subsidence and compaction, changes in deltaic sites of deposition, catastrophic events such as hurrisanes, and biologically-induced factors. Man-induced factors include dams and levees, canal dredging, and fluid withdrawal. |
| The Hudson Bay Lowland: major geologic features and assets | 1989 | Martini, I.P. | 68(1) | The Hudson Bay Lowland is a vast (325,000km2), flat (average slope 0.5m/km) physiographic region of Canada located to the southwest of James Bay and Hudson Bay. It is underlain by Paleozoic and Mesozoic rocks and bounded by Precambrian terrains. Thin Pleistocene till sheets, locally deposited on fluted terrains mantle most of the Lowland, and they are overlain by thin marine and coastal Holocene deposits which have formed during the ongoing regression from an early post-glacial sea, the Tyrrell sea. The present shores of the James Bay and Hudson Bay are but one stage of development of such regressive sequences. More than 90% of the vast emerged Lowland is covered by one of the largest cold wetlands and peatlands of the world. Up to 3-4m thick peats have developed in the last 5000 years in inland fens and raised bogs. Fresh water is the major resource of the area, both for hydroelectric power and/or irrigation on a continent wide scale. Other resources not yet fully evaluated, consist of mineral deposits on or near Precambrian inliers, hydrocarbons in the relatively thin Paleozoic sequence, and lignite, kaolin and quartz sand in Mesozoic terrains. The damage generated by any development in the area, must be carefully weighted against the worldwide importance of this vast peatland on gaseous fluxes and atmospheric balance. Furthermore the coastal zone of the Lowland is a major staging and breeding ground for polar bears, migratory birds and other species. Perhaps assurance of preservation of the still pristine natural Hudson Bay Lowland should be achieved by establishing it as an international heritage park. |
| Cyclic morphologic changes of the ebb-tidal delta, Texel Inlet, The Netherlands | 1989 | Ping, S.L. | 68(1) | Cyclic morphological changes occur in the ebb-tidal delta system of Texel Inlet (The Netherlands). This geomorphological cycle lasts about 70 years. The cycle starts with the development of a main ebb channel in the southern half of the inlet. A large ebb delta shoal forms north of this ebb channel. The shoal grows upwards into the inter- to supra-tidal zone and moves eastwards under the influence of wind and waves. The flood channel north of the shoal is forced to rotate clockwise, and it approaches the shoreline of Texel. The marginal ebb channel in the southern part of the inlet develops due to the tidal currents deflected to the south by the eastward migrating shoal and slowly rotates clockwise, forced by the small flood marginal channel that adjoins the mainland coast to the east. The cycle is completed by shoal attachment to the southern tip of Texel Island, which causes the northern marginal channel of the inlet to be buried. The eastward migration rate of the shoals is about 60-70 m per year, which involves a sediment transport rate of order of 580 to 0.64 x 106m3/year. |
| Intraplate stresses and the stratigraphic evolution of the North Sea Central Graben | 1989 | Kooi, H.; Cloetingh, S.; Remmelts, G. | 68(1) | We present results of stratigraphic modelling and quantitative analysis of subsidence data for the southern part of the North Sea Basin. Tectonic subsidence curves are given for fifteen wells in the northernmost segment of the Dutch North Sea and the southern part of the Dutch Central Graben. These curves have been supplemented with tectonic subsidence curves for eight wells from the Broad Fourteens and West Netherlands Basins. Subsidence analysis and thermo-mechanical modelling show that Late Jurassic and Early Cretaceous multiple stretching phases with a finite duration are required to explain the observed stratigraphic record. Our analysis demonstrates the important role of intraplate stresses in the evolution of these basins. The paleo-stress curve inferred from the stratigraphic modelling shows a trend with a change from tensional and neutral stresses during Mesozoic times to a stress regime of more overall compressional character during Cenozoic times. Superimposed on this long-term trend are short-term stress fluctuations. This paleo-stress curve and the associated stratigraphic record of the Dutch North Sea Basin sheds light on the record of paleo-stress measurements in the Northwestern European platform and is consistent with data on the kinematic evolution of the Tethys belt. These findings demonstrate the key-importance of tectonics and stress-induced vertical motions - related to rifting events in the northern Atlantic region and the interaction of the Eurasian and African plates - in controlling the stratigraphic evolution of the North Sea Basin. |
| Revision of the 'Late Jurassic' stratigraphy of the Dutch Central North Sea Graben | 1989 | Herngreen, G.F.W.; Wong, T.E. | 68(1) | The 'Late Jurasic' stratigraphy of the Dutch Central North Sea Graben is revised. The sediments, ranging in age from Callovian to Ryazanian, are grouped in two lithological units: the mainly non-marine Central Graben Group (with Lower Graben Sand, Middle Graben Shale, Upper Graben Sand, Puzzle Hole, and Delfland formations) and the distinct marine Scruff Group (with Kimmeridge Clay, Scruff Greensand, and Clay Deep formations). The latter two formations are new and are introduced formally. Basic palynological and micropaleontological data are included to support age assignments of various formations. Several log correlations, range charts, distribution maps, facies maps and seismic sections are given to illustrate the stratigraphic framework. Finally, a synopsis of the geological history is presented, with special attention to sea-level changes and ensuing coastal developments, illustrating the relationships with the Danish and Norwegian sectors. |
| The Netherlands during the Tertiary and Quarternary: A case history of coastal Lowland evolution | 1989 | Zagwijn, W.H. | 68(1) | The Netherlands and the adjoining southern region of the North Sea form part of a subsiding area with a complicated tectonic and sedimentary history. This area was either a shallow sea or a coastal lowland. After a compressional stage at the onset of the Tertiary, tensional forces dominated from the Oligocene onward and induced the formation of an intraplate rift system. The relationship between this system and sediment supply by rivers originating in the hinterland is discussed. In the Quaternary, depocentres shifted considerably. Here a role was played by changes in sea level due to build up of inland ice and repeated climatic changes, leading to increased sediment discharge. In the later part of the Quaternary, inland ice itself invaded the basin and reshaped the landscape. |
| Geological and geotechnical conditions of the Beaufort Sea coastal zone, Arctic Canada | 1989 | Kurfurst, P.J.; Dallimore, S.R. | 68(1) | The coastal zone of the southern Beaufort Sea and Mackenzie Delta forms an extensive area of coastal lowlands in northern Canada. This region is underlain by unstable, perennially frozen soils subjected to high rates of marine erosion and deposition. The nearshore sediments off northern Richards Island are comprised of a wedge of Holocene marine sand, silt and clay underlain by early Wisconsinan sand and clay. The geothermal regime is complex, reflecting deep permafrost conditions established during a period of terrestrial exposure and more recent marine submergence, which results in moderating ground temperatures and creation of a thick thawed layer at the sea bottom. Geotechnical problems encountered in the nearshore area include frost heave of Holocene sediments, thaw settlement related to degradation of ground ice in the early Wisconsinan sediments, and ice push and scour effects Onshore sediments consist of early Wisconsinan and older glacial, fluvial and marine sediments overlain by late Wisconsinan and Holocene, eolian and lacustrine sediments. Ground ice, which forms a significant volumetric component of the near-surface soils, occurs as pore ice, wedge ice, pingo ice and as massive bodies of segregated ice of various ages. Geotechnical problems in onshore areas include thaw settlement due to degradation of ground ice, creep of ice-rich soils and frost heave. |
| Time dependent groundwater flow under river embankments | 1989 | Bauduin, M.H.; Moes, C.J.B. | 68(1) | The Dutch Meuse - Rhine Delta mostly consists of Holocene clay and peat layers, overlying a Pleistocene sand substratum. The lowlands are below MSL, are protected against inundation by riverdikes and are mechanically drained. Time dependent variations of the river levels provoke time and distance dependent piezometric level responses in the Pleistocene sand layers. During storm surges, high piezometric pressures may reduce the bearing capacity of the embankment's foundation. Predictions of the maximum piezometric pressures are needed for safe and economic design of the dikes, taking into account the unsteadiness of groundwater flow during design storm surge. An analytical method allows to describe the piezometric response for both a tidal and step (surge) input. This method has been applied for the geo-hydrological conditions of the Meuse-Rhine delta: a pervious aquifer (Pleistocene stratum) overlain by an aquitard (Holocene layers) with time dependent leakage. The model accounts for the possible presence of a silt or mud layer between the river and the aquifer. If the calculated pressure in the sand somewhere exceeds the weight of the Holocene layers, pressure redistribution occurs and an area will be uplifted. The model can be adapted to this non-linearity and then allow to evaluate the time dependent length of the uplifted area and new piezometric levels. The model parameters can be obtained from measurements made during normal tides. |
| Toekenning van het Erelidmaatschap aan Ir B.P. Hageman | 1989 | 68(1) | ||
| Presentation of the Van Waterschoot van der Gracht medal to Dr M. Teichmüller | 1989 | 68(1) | ||
| Toekenning van de Van Waterschoot van der Grachtpenning aan Dr J. Stuffken | 1989 | 68(1) | ||
| Toekenning van de Van Waterschoot van der Grachtpenning aan Professor E. den Tex | 1989 | 68(1) | ||
| Toekenning van de Van Waterschoot van der Grachtpenning aan Dr P.A. Ziegler | 1989 | 68(1) | ||
| Coastal lowlands Symposium: Geology and Geotechnology. Preface | 1989 | Zwart, H.J. | 68(1) | |
| Late Weichselian and Holocene sedimentary history of the Leuvenumse beek valley (The Netherlands) | 1989 | Gans, W. de; Cleveringa, P.; Jagerman, R. | 68(2) | Lithostratigraphic and palynological research of the sediments in a small brook valley in the central part of the Netherlands demonstrates the existence of three sedimentary sequences. From the data four fluvial adjustments are derived and successively dated as 1) the end Pleniglacial-early late Weichselian, 2) the transition late Weichselian - Holocene, 3) the Boreal and 4) the Late Subatlantic. The fluvial adjustments are related to variations in water discharge due to climate and human impact. An attempt has been made to generalize the fluvial activity of the small drainage basins in the Netherlands since the Late Glacial |
| Palaeohydrologic conditions in the Mark River basin during the last 15,000 years | 1989 | Huybrechts, W. | 68(2) | This paper presents an outline of lithologic and morphologic developments in the alluvial environment of the Mark Basin in Central Belgium during Post Glacial times. By means of about 900 borings the spatial arrangement and stratigraphic position of palaeomorphologic features and sedimentary units in different parts of the basin was reconstructed. This, together with the radiocarbon datings, offers an insight into Holocene palaeohydrologic conditions in the Mark River floodplain. The influence of prevailing topographic and geologic conditions in the basin, and changes in external factors, such as climate and man, on the developments in the floodplain are evaluated. |
| Distribution and cycling of fine-grained sediment in the Eastern Scheldt, Southwest Netherlands | 1989 | Oenema, O. | 68(2) | Surface and core samples of sediment were taken from 3 types of mud depositional areas in the Eastern Scheldt in 1985-1986, before the completion of the Storm Surge Barrier. Total accumulation rates of clay and silt were highest (100-200 Gg yr-1) in abandoned channels. Clay and silt were also deposited in large quantities (30-80 Gg yr-1) in salt marshes, and were cycled in large amounts (200-500 Gg y-1) in mussel banks by deposition of faeces and pseudo-faeces. In the latter habitat no net accumulation occurred, because equal amounts were resuspended by wave agitation and dredging. The balance of sediment input and accumulation indicated a net seaward flux of 80-1800 Mg day-1 of clay + silt and 3-80 Mg day-1 of organic carbon through the mouth of the Eastern Scheldt. Most of the sediment probably came from eroding Holocene deposits elsewhere in the Eastern Scheldt, and smaller amounts from fluvial influx. Analysis of their elemental composition indicated that a major source of the sediments was formed by sandy deposits with clayey laminae of subrecent Dunkirk age, and a minor source was older, more clayey Calais deposits. The sedimentation rates were highest (5-15 cm yr-1) in abandoned channels near dams and dikes. In such environments, seasonal variations in sedimentation rates were clearly reflected in cyclic changes of porosity and organic carbon concentrations in the sediment. Similar seasonal changes were observed in the sediment at the surface of sandy intertidal flats. |
| Messinian palaeorelief from a 3-D seismic survey in the Tarraco concession area (Spanish Mediterranean Sea) | 1989 | Stampfli, G.M.; Höcker, C.F.W. | 68(2) | The 3-D seismic survey shot in the Tarraco concession area enables a very detailed analysis of the Messinian unconformity in that area. The revealed palaeomorphological features in combination with well data confirm that during the Messinian the sea level dropped rapidly and substantially, resulting in the erosion of a pre-Messinian shelf and slope sequence under subaerial conditions. The magnitude of the sea level drop is estimated to be about 2000m. The nature of the infill of the Messinian valleys indicates a rapid return to normal global sea level. |
| Grain fabrics of natural and experimental low-angle aeolian sand deposits | 1989 | Schwan, J. | 68(2) | This paper considers the two-dimensional grain fabrics of 23 natural and 3 experimental aeolian sand deposits. The generally low strength of the fabrics is thought to be an inherent characteristic of the investigated sediment type rather than a result of postdepositional disturbance. On a statistical basis, the 26 fabric plots can be grouped into three types of distribution patterns. In the first type, unimodal preferred orientation of elongate grains is unambiguous. In the second type, unimodal preferred orientation is either weakly developed or absent. In the third type, preferred orientation is bimodal or polymodal. The natural fabric samples are from three different exposures of Weichselian aeolian coversand. The fabric data from these sites do not contradict other available information on the paleodirection of the sand-transporting wind. The experimental fabric samples were produced in a wind tunnel. The experiments suggest that particle alignmenf by wind occurs almost instantaneously and that fabric strength does not depend on mode of deposition. |
| Late Cenozoic geohistory of Seram, Indonesia | 1989 | Smet, M.E.M. de; Sumosusastro, P.A.; Siregar, I.; Marle, L.J. van | 68(2) | Two sections in Plio - Pleistocene basin deposits were measured and systematically sampled in the southwestern part of Seram, the largest island in the northern Banda Arc, Indonesia. A geohistory analysis of field and laboratory data allows for a reconstruction of the vertical movements of the area and demonstrates that the basement of southwestern Seram was subsiding at an average rate of 50 cm/ka during the Late Pliocene - Early Pleistocene, an episode of relative tectonic quiescence, following Late Miocene compressional deformation and uplift. In the Late Pleistocene, compressional deformation and uplift was renewed but differed in style and orientation from the Late Miocene events. This history of the basins in southwestern Seram is very similar to that of the oil producing basins in the northeastern part of the island. The Late Cenozoic tectonic history of Seram can be interpreted in the frame of regional plate motions. Due to an anticlockwise rotation of the island and a relatively north to northwestward motion of Irian Jaya, the overall tectonic regime in the area gradually changed from compressional in the Late Miocene to strike-slip in the Late Pliocene. Finally, collision of Seram with the continental crust of Irian Jaya resulted in renewed compressional deformation from the Late Pleistocene onwards. |
| Acanthoscaphites varians (Lopuski, 1911) (Ammonoidea) from the Upper Maastrichtian of Haccourt, NE Belgium | 1989 | Jagt, J.W.M.; Kennedy, W.J. | 68(2) | A specimen of the scaphitid ammonite Acanthoscaphites varians (Lopuski, 1911) is described from the late Maastrichtian Vijlen Member of the Gulpen Formation as exposed in the SA Ciments Portland Liégeois (CPL) quarry at Haccourt, Liège, NE Belgium. This record constitutes an important addition to the ammonite fauna of the Maastrichtian type area. |
| Influences of structural setting on coal rank and thickness in the Grande Cache area, Alberta, Canada | 1989 | Langenberg, W.; Kalkreuth, W.; Dawson, R. | 68(2) | In addition to mapping areas of deformed coal-bearing strata, structural geological studies are used to explain coal rank variations, to predict the location of the thickened coal and to explain certain optical properties of coal. In the coalfields of the Canadian Rocky Mountains and Foothills, north of Grande Cache, Alberta, the level of coalification decreases progressively from the undeformed part of the Alberta basin towards the western edge of the Foothills. This decrease is due to a westward decrease in duration and depth of burial as a consequence of the timing of Laramide deformation across the area, indicating synorogenic coalification. Within the smaller Grande Cache area it can be shown that coalification ended after deformation and resulting uplift and erosion. The presence of optically biaxial vitrinite anisotropy may indicate the presence of a tectonic stress field during the later stages of burial and subsequent deformation. The maximum vitrinite reflectance axis is generally oriented parallel to fold axes in the area. Structurally thickened coal can be attributed to at least two structural positions: fold hinges and fold limbs. Dilation occurs at chevron fold hinges and incompetent material, such as coal, flows into these dilation zones. The resulting structure is similar in geometry to a saddle reef. Duplexes are present in fold limbs, where the roof thrust is the top and the floor thrust the bottom of the coal seam, resulting in tectonic thickening of the coal. These structurally thickened coals are important exploration targets. Prediction of structurally thickened coal by computer constructed down-plunge cross sections has proved useful in coal exploration in the Canadian Rocky Mountain Foothills. |
| Isotopic age determinations in South Norway: I. The Skår volcanic breccia, Greipstad, Vestagder | 1989 | Verschure, R.H.; Maijer, C.; Andriessen, P.A.M. | 68(2) | Two samples of the fine-grained acidic matrix of the Skår volcanic breccia about 16 km WNW of Kristiansand in Vest Agder, southwestern Norway were investigated by whole-rock K-Ar. The breccia is situated on the intersection of a WNW and a NNE trending tectonic line, associated with the NE trending 'Great Breccia', a major tectonic feature of southern Norway. The samples yielded Late Permian ages of 248 ± 15Ma and 233 ± 15Ma. This indicates that the explosive Skår volcanism was related to the period of epeirogenesis that in southern Norway gave rise to the formation of the Oslo-graben and Hardangerfjord-Graben. Possibly there is a genetic connection between the acid volcanism at Skår and periodic alkaline mafic magmatism in the whole of northern Europe and parts of northern North America during the late Palaeozoic and the Mesozoic. The alkaline magmatism in the South Scandinavian Shield during this prolonged period might be an expression of a fundamental, mainly tensional 'Basin and Range-like'tectonic regime which prevailed in the northern hemisphere after the Caledonian orogeny and which lead to the opening of the Atlantic Ocean. The acid volcanic breccia erupted at Skår could be a product of contact-anatexis of crustal material generated by intruding alkaline basic magma. |
| The thermochemical behaviour of vivianite and vivianite/metavivianite admixtures from Borne (Netherlands) and Mangualde (Portugal) | 1989 | Rodgers, K.A. | 68(2) | |
| Early diagenetic silica precipitation, in relation to redox boundaries and bacterial metabolism, in late Cretaceous chalk of the Maastrichtian type locality | 1989 | Weijden, C.H. van der; Middelburg, J.J.; Gaans, P.F.M. van | 68(2) | |
| Environmental technologies based on geochemical processes | 1989 | Schuiling, R.D. | 68(2) | The accumulation of potentially harmful substances in our environment bears a close similarity to ore-forming processes; this is particularly evident in the case of inorganic pollutants. A look at the ways in which Nature minimizes the impact of high concentrations of toxic substances on the environment can provide inspiration for environmentally sound sanitation techniques. At variance with official environmental policies in the Netherlands, but in line with the basic aims of environmental science, it is often better to leave contaminated sites untouched, than to mobilize toxic substances during sanitation, or pretend to isolate them forever from contact with the biosphere. |
| Genesis of the cliff-face near Bergen op Zoom in the southwest of the Netherlands | 1989 | Caris, J.P.T.; Thewessen, T.J.M.; Felix, R. | 68(3) | A cliff-face stretching north-south in the southwest part of the Netherlands, (from Halsteren to near the Belgium border) separates Holocene marine sediments from tidal and aeolian Pleistocene deposits. There is a difference of opinion regarding the age of the formation of this cliff-face. The main objective of this study was to verify the origin of this feature. To this end auger drilling and pollen analysis on peat was carried out. The cliff-face proved to have been formed by marine erosion during the Eemian. |
| A case study on the hydrocarbon geology of Upper Permian (Zechstein-3) carbonates in licence P6, the Netherlands' offshore. | 1989 | Poel, A.B. van der | 68(3) | Permian (Zechstein-3) carbonates in the P6 block, the Netherlands' offshore, were deposited in a subtidalintertidal-supratidal setting, in an overall shallowing-upwards mega sequence. Interpreted diagenetic events include in order of occurrence: lithification, dessication, early leaching, dolomitisation, anhydritisation, calcitisation and also late leaching, compaction/stylolitisation and late fracturation. The diagenetic sequence is related to the reconstructed burial history by plotting on a burial graph. Present diagenetic porosity (Moldic- intraparticle- vuggy- (enlarged) intercrystalline- fracture porosity) predates renewed hydrocarbon gas generation. Gas generation is continuing today. |
| Studies on swash marks and swash angles on texturally, tidally and morphodynamically-distinct beaches | 1989 | Antia, E.E. | 68(3) | This study evaluates the prospects of a new dimensional attribute of swash marks, herein referred to as swash angle, as a signature of wave-beach interaction. Results from three open Atlantic sea coasts of Nigeria indicate predominantly obtuse swash angle values. Mean swash angle values and the deviation from the mean tend to increase on beaches exhibiting fine grain sizes, elevated tidal ranges and high dissipative process signatures. The converse is the case on the microtidal, coarse-grained reflective beaches. From the obtained results and other published information, it is conceptualized that for a given beach, smaller swash angle mean and deviation would express the potential towards rapid beach mobility. On the contrary, relatively stable beaches typical of the dissipative state would reveal large swash angle and large deviation of the latter. |
| Microstructures in the Pyrenees - a tribute to Henk J. Zwart - introduction | 1989 | Eeckhout, B. van den | 68(3) | special section |
| Very low-grade metamorphism of the Seo Formation in the Orri Dome, South-Central Pyrenees | 1989 | Bons, A.J. | 68(3) | The metamorphic grade of the Seo Formation, South-Central Pyrenees, has been determined using illite crystallinity measurements. The total range of the illite crystallinity indices of the K+-saturated fraction <2 μm is 0.21-0.31 °2 ϴ and averages 0.26 ± 0.03 °2 ϴ, which indicates metamorphism in the high-grade part of the anchizone. This is in agreement with mineralogical data, such as the absence of expandable clay minerals and of metamorphic minerals such as biotite and epidote. Illite crystallinity indices of the detrital micas suggest that they were derived from igneous rocks or from rocks with at least epizonal grade of metamorphism. |
| Quantification of finite strain in the Pyrenean Slate Belt; a first assessment using Rf/Φ method | 1989 | Corstanje, R.; Klepper, C.; Rutgers, B.; Wal, I.J. van der; Eeckhout, B. van den | 68(3) | Strain analysis has been carried out on (micro)conglomeratic Cambro-Ordovician sediments from the Pallaresa area (Axial Zone of central Pyrenees). Twenty strain ellipsoids have been determined. After correction for refolding and faulting a bulk finite strain ellipsoid for the area was calculated. This ellipsoid has k-value 3.43 and low axial ratios (X/Y = 1.24, Y/Z:1.07). The ellipsoid has a long axis (X) plunging steeply NE, an intermediate axis (Y) parallel to the gently WNW plunging mean fold axis of the area, and a nearly horizontal south plunging short axis (Z). The shortening direction (Z) is normal to the steep N-NNE dipping cleavage. During deformation the sediment pile in the area must have undergone vertical tectonic thickening by factor 1.15. It is argued that this value is a minimal estimate and inhomogenous deformation must be taken into account. |
| Variscan tectonometamorphic evolution of the eastern Lys-Caillaouas massif, Central Pyrenees - evidence for late orogenic extension prior to peak metamorphism | 1989 | Kriegsman, L.M.; Aerden, D.G.A.M.; Bakker, R.J.; Brok, S.W.J. den; Schutjens, P.M.T.M. | 68(3) | Four deformation phases have been distinguished in the Cambro-Ordovician metasediments of the eastern Lys-Caillaouas massif. D1 only affected rocks of a stratigraphic unit below and Ordovician metaconglomerate horizon and is of pre-Variscan age. During D2 tight folds with steep E-W trending axial plane foliations S2 have formed, indicating N-S shortening. D3 consists of: (i) porphyroblastrotation, (ii) formation of gently dipping crenulation cleavages S3 and (iii) transposition of S2 to S3 in highest grade metamorphic rocks. D3 is interpreted as vertical shortening and horizontal extention. Both D2 and D3 are of Variscan age. D4 includes various deformation phenomena of unknown age, postdating peak metamorphism. Metamorphism started at the end of D2 and continued until after D3. Three phases have been distinguished: plurifacial regional metamorphism Ml and M3 and contact metamorphism M2 around the Lys-Caillaouas porphyritic biotite granite. This study shows that Variscan N-S shortening in the eastern Lys-Caillaouas massif was followed by metamorphism and crustal extension. Flat-lying structures overprinted steep structures during the extensional phase. Peak metamorphism was reached afterwards. |
| Deformation and metamprphism in the Trois Seigneurs massif, Pyrenees - evidence against a rift setting for its Variscan evolution | 1989 | Kriegsman, L.M. | 68(3) | Low grade metamorphic rocks in the Trois Seigneurs massif characteristically exhibit steep foliations axial planar to tight folds, indicating horizontal shortening. An older deformation phase is indicated by a considerable spread of intersection lineations with bedding on the steep foliations. The steep foliations have been folded into a kilometre-scale inclined fold, which has a crenulation cleavage subparallel to the axial plane. Rotation sense of porphyroblasts, in medium to high grade rocks, is different in each limb of this fold. The fold is argued to result from late Variscan vertical shortening and horizontal extention following crustal thickening. The massif is transected by the Cap de las Costes fault, inferred to be a strike-slip fault with 5-6 km sinistral offset. Variscan metamorphism in the Trois Seigneurs massif started after the shortening phase and reached peak temperatures after the extensional phase. It is not related to a rifting event, as proposed by Wickham & Oxburgh (1985), but to late orogenic extension after considerable crustal thickening. |
| The relationship between deformation and metamorphism in the Canigou Massif, Pyrenees: a case study | 1989 | Gibson, R.L. | 68(3) | previous interpretations of the structure of the Canigou massif have related the development of the regional foliation to tectonic emplacement of the Canigou orthogneisses within the Infracaradocian sediments (Guitard 1970, Casas 1978,Lagarde 1978). Re-investigation of the structural evolution of the massif has shown that the regional foliation (S3) is preceded by the development of a pervasive S1 foliation and localized large-scale D2 folding. D2 folds affect the contact between the Canigou orthogneisses and underlying metasediments, indicating that the orthogneisses were emplaced within the sedimentary sequence prior to the development of the regional foliation. S3 is a subhorizontal crenulation foliation subparallel to S0-S1, except locally where D2 folding results in a more discordant relationship. Regional doming of S3 is associated with post-D3 folding and mylonite development. Porphyroblast-matrix microtextural relationships indicate that the peak of Hercynian low-P-high-T regional metamorphism is synchronous with progressive development of S3. Complex Si/Se geometries indicate that deformation was inhomogeneous on a small scale. |
| Shear deformation and emplacement of the gneissic Canigou thrust nappe (Eastern Pyrenees) | 1989 | Soliva, J.; Salel, J.F.; Brunel, M. | 68(3) | The Canigou gneiss nappe is one of the most striking features developed during Variscan convergent tectonics in the Pyrenean chain. The Canigou structure is classically interpreted as a recumbent fold nappe. New data concerned with kinematic analysis of the deformation argue for the importance of thrusting tectonic imprints. Shear criteria analysis indicates that the main transport direction was towards the SW. The mylonitic shear zone described from the bottom of the Canigou gneiss is assumed to represent a main ductile thrust zone, with a magnitude of transport in excess of 30 km. |
| Calcite c-axis textures along the Gavarnie thrust zone, central Pyrenees | 1989 | Bresser, J.H.P de | 68(3) | Orientations of calcite c-axes have been measured in limestones from the eastern part of the Gavarnie thrust zone, central Pyrenees. They show preferred orientations (textures) with one or more maxima. By comparing the textures with existing experimental and theoretical data, it was possible a) to confirm the regional sense of movement along the thrust, b) to interpret a significant contribution of pure shear to the total strain in the thrust zone, and c) to recognize natural patterns which have not been reported before. It is suggested that the studied limestone samples were deformed at a temperature of about 200° C in a transitional regime with textures ranging from low to high temperature types. Specific rock properties may have governed the local predominance of a high or conversely of a low temperature type. The data, however, appear to exclude grain size as a controlling factor. |
| Evidence for pre-Variscan deformation Central Pyrenees, France | 1989 | Brok, S.W.J. den | 68(3) | |
| Neogene and pleistocene volcaniclastites of the Apennines (Italy). | 1989 | Guerrera, F.; Veneri, F. | 68(4) | Numerous volcaniclastic deposits are found interbedded in several Neogene-Pleistocene units of the Apennines. They are mostly the result of volcanic activity that was contemporaneous with sedimentation and they thus have a specific geodynamic significance. These volcaniclastites are indicative of periods of intense volcanic activity (e.g. Aquitanian-Burdigalian-Langhian), alternating with periods of lesser activity (e.g. post-evaporitic Messinian). Periods of increased volcanic activity must be attributed to important tectonic phases in the Mediterranean area. Moreover, a migration of volcaniclastic products towards the external zones of the Apennines can be observed. The composition of the pyroclastites suggests an origin from calc-alkaline magmas that were generated in volcanic arcs probably developed on continental crust. No comprehensive hypothesis on the location of the Neogene-Pleistocene effusive centres has been put forward up to now. Nevertheless, some areas, such as the Po Plain and the Tyrrhenian zone, are particularly suspicious in this respect. |
| The upper Campanian-Lower Maastrichtian chalks of the Mons basin, Belgium: a preliminary study of belemnites and foraminifera in the Harmignies and Ciply areas | 1989 | Robaszynski, F.; Christensen, W.K. | 68(4) | The Upper Campanian-Lower Maastrichtian chalks of the Mons Basin in Belgium, in ascending order, Craie de Trivières, Craie d'Obourg, Craie de Nouvelles, Craie de Spiennes, and Craie Phosphatée de Ciply, are tentatively placed in the international stratigraphic framework on the basis of preliminary studies of belemnites and foraminifera, as well as some other macrofossils. The top of the Craie de Trivières, the Craie d'Obourg, the Craie de Nouvelles are from the lower part of the Upper Campanian, and the basal 10-12 m of the Craie de Spiennes from the upper part of the Upper Campanian. The Craie Phosphatée is regarded to be from the upper part of the lower Lower Maastrichtian. Résumé. Le Campanien supérieur-Maastrichtien inférieur du Bassin de Mons est constitué du bas vers le haut des Craies de Trivières, d'Obourg, de Nouvelles, de Spiennes et de Ciply. Ces différents niveaux de craie qui ont valeur de formations sont replacés dans le cadre stratigraphique international sur la base d'études préliminaires des bélemnites, de quelques autres groupes de macrofossiles et des foraminifères. Le sommet de la Craie de Trivières, la Craie d'Obourg et la Craie de Nouvelles sont attribués à la partie inférieure du Campanian supérieur et les L0 à12mde base de la Craie de Spiennes à la partie supérieure du Campanien supérieur. La Craie Phosphatée de Ciply est considérée comme appartenant à la partie supérieure du Maastrichtien inférieur, partie inférieure. |
| Holocene palaeogeography and palaeoecology of the fluvial area near Maurik (Neder-Betuwe, The Netherlands) | 1989 | Hofstede, J.L.A.; Berendsen, H.J.A.; Janssen, C.R. | 68(4) | In the Holocene river basin ‘Het Broek' (Fig. 1) fluvial deposition of clay by six different river systems alternated with peat formation. The accumulation rate of peat in the backswamps between 8000 BP and 4000 BP was fairly constant; it averaged about 7,5 cm/century. Pollen analysis and radiocarbon dating were used to determine phases of fluvial activity. Both the lithostratigraphy and the pollen diagram reflect a number of flooding phases. Phases of fluvial deposition do not seem to be synchronous with those in the perimarine area, farther to the west. A clear decline of elm contemporaneously with a maximum in the ash values in the Early Neolithic is discussed in terms of changes in the water regime of the river and possible human interactions. |
| Neogene history of the Tabernas basin (SE Spain) and its Tortonian submarine fan development | 1989 | Kleverlaan, K. | 68(4) | The Tabernas Basin is a structural depression in the Alpine nappes of the Betic Cordilleras in southeastern Spain. From the Tortonian to the Plio/Pleistocene, sedimentation in this basin was strongly influenced by tectonic activity. At the onset of the Tortonian, basin subsidence caused submergence of an alluvial fan system and a small submarine fan complex developed in a water depth of at least 600 m. Total basin subsidence was in the order of 1200 m. Initial Tortonian submarine fan growth and evolution of fan systems has been reconstructed and is shown in 6 palinspastic maps. In the early Messinian, sediment accumulation on the fan, and basement rise caused a regressive trend. Reefs along the NW margin of the basin were part of a regional barrier reef system and muddy sediments were deposited in its centre. Prior to the development of an evaporitic phase, uplift and emergence of the eastern half of the basin took place along NW-SE trending faults. During this evaporitic phase, selenitic gymsum formed on the muddy sediments of the still submerged sea floor of the western half of the basin. At the Messinian-Pliocene boundary, folding and emergence of the sea floor coincided with the genesis of an anticlinorium in the south: this is the now emerged Sierra Alhamilla. From Pliocene onward, after a short period of subsidence, uplift prevailed contributing to the development of a southward prograding fan delta in the western part of the basin. The structural and depositional history of the basin seems to agree with its setting within a strike-slip zone. Movement along this zone is associated with the convergence of the African and Iberian lithospheric plates. |
| Neogene history of the Tabernas basin (SE Spain) and its Tortonian submarine fan development | 1989 | Kleverlaan, K. | 68(4) | Enclosure |
| A geomorphological map of the Dutch shoreface and adjacent part of the continental shelf | 1989 | Alphen, J.S.L.J. van; Damoiseaux, M.A. | 68(4) | The last decades there has been a steady encroachment of human activities into the Dutch marine environment. Knowledge about the seafloor lithology and geomorphology is imperative for further development of the Continental Shelf but also for a proper management of the shoreface, beaches and dunes, that act as a sea defence for the densily populated, low lying areas of Holland. To ensure that the coastal strip retains this function in the future, an understanding of its morphodynamics and its governing processes is of primary importance, especially in view of the projected rise in sea level. Within this framework, a geomorphological map, scale 1:250.000, has been prepared of the Dutch coastal region and adjacent part of the continental shelf which shows the distribution and characteristics of major morphological elements below the LW-line such as the shoreface, ebbdelta's with related shoals and channels, tidal ridges and sandwaves. In this paper the units identified on the map are described and their origin and behaviour is discussed. |
| A geomorphological map of the Dutch shoreface and adjacent part of the continental shelf | 1989 | Alphen, J.S.L.J. van; Damoiseaux, M.A. | 68(4) | Middle Sheet |
| A geomorphological map of the Dutch shoreface and adjacent part of the continental shelf | 1989 | Alphen, J.S.L.J. van; Damoiseaux, M.A. | 68(4) | North Sheet |
| A geomorphological map of the Dutch shoreface and adjacent part of the continental shelf | 1989 | Alphen, J.S.L.J. van; Damoiseaux, M.A. | 68(4) | South Sheet |
| A geomorphological map of the Dutch shoreface and adjacent part of the continental shelf | 1989 | Alphen, J.S.L.J. van; Damoiseaux, M.A. | 68(4) | West Sheet |
| The character of the Erkelenz intrusive as derived from geophysical data | 1989 | Bredewout, J.W. | 68(4) | In the framework of the first National Research Program for Geothermal Energy in The Netherlands, geophysical measurements were performed in an area in the Dutch province of Limburg and the adjacent part of Germany, covering the Erkelenz intrusive. Surface magnetic data confirm the magnetic anomaly known from the German magnetic maps. That anomaly had been interpreted by Bosum (1965) to be caused by a huge intrusive of basic composition (the Erkenlenz intrusive). The gravity data, those at the surface as well as those measured in the Sophia Jacoba colliery, do not show a big anomaly. This agrees better with an intrusive of acid than one of basic composition and it means that relatively high temperatures can still be expected due to radio-active heat production. The existence of high temperatures in the past could be proven by analysis of rock samples from the colliery. For recent high temperatures there are a few indications. |
| #REF! | 1989 | Ganssen, G.; Rondeel, H.E.; McGee, T.M.; Linden, W.J.M. van der; Westerhof, A.B. | 68(4) | |
| In memoriam ir. A. Hellemans | 1989 | Jordaans, J.K.H. | 68(4) | |
| Dedication to Professor Dr. Ernst ten Haaf, preface special issue on the structural geology of the Northern Appenines, Italy | 1990 | Wamel, W.A. van | 69(1) | |
| Shear zone structures and microstructures in mantle peridotites from the Voltri massif, Ligurian Alps, N.W.. Italy | 1990 | Drury, M.R.; Hoogerduin Strating, E.H.; Vissers, R.L.M. | 69(1) | In the Erro-Tobbio peridotite three generations of shear zone structures are developed in granular peridotite: peridotite tectonites, peridotite mylonites and serpentinite mylonites. Peridotite tectonites occur in a kilometre-scale shear zone developed under estimated conditions of 1100 to 1220°C and 16 ± 6 kbar, and flow stresses between 4 and 11 MPa. The deformation in this shear zone involved dislocation creep and concurrent recrystallization of olivine by a combination of subgrain rotation and extensive grain boundary migration. With decreasing pressure and temperature and increasing flow stress, spinel peridotite mylonites (T= 800-925°C, P = 6-8 kbar, σ= 93-153 MPa) and chlorite peridotite mylonites (T = 550-800°C, P = 4-6 kbar, σ = 331-786 MPa) developed in up to hundred metre scale shear zones transecting the peridotite tectonites. The mylonitic microstructures suggest that dynamic recrystallization of olivine occurred by a mechanism involving grain boundary bulging to nucleate new strain free grains. In addition, 'fluidal' microstructures dominated by pyroxene clasts with tails of fine-grained amphiboles suggest that superplastic mechanisms may have been operative in these mylonites. The sequence of tectonite shear zones followed by peridotite mylonites is inferred to result from the progressive ascent of asthenospheric peridotites during opening of the Mesozoic Piemonte-Ligurian ocean. Serpentinite mylonites, developed at temperatures of 300-550°C and pressures of about 4kbar, are observed in shear zones mostly associated with ductile overthrusting and imbrication. These structures are clearly related to nappe emplacement during Alpine collision. |
| The Lavagna and Antola Nappes in the upper Lavagna and Bisagno Valleys (N. Italy) | 1990 | Thio, H.K.; Wamel, W.A. van | 69(1) | Comprehensive structural geologic studies reveal a complex tectonic history of the Antola and Lavagna Nappes. Within the slightly metamorphic Lavagna Nappe the effect of five phases of folding have been established. The first phase (F1) is characterized by large isoclinal folds with an originally southwestern vergence. During the second phase (F2) large-scale open folding took place, whereas F3 and F4 produced folds with a northeastern vergence on a regional scale. These first four phases all produced co-axial folds with NW-SE trends. F5-folds are open and have an approximately NE-SW trend. Internal thrusting, associated with F1 and F3 has been established. After a first period of folding, the non-metamorphic rock sequences of the Antola Nappe thrusted over the Lavagna Nappe. Associated with this, thrusting within the S part of the Lavagna Nappe took place. The first four folding phases of the Lavagna Nappe and its metamorphosis were achieved prior to nappe-emplacement. The mutual stacking of the Antola and Lavagna Nappes must have taken place before the Eocene-Oligocene transition. Only F5 postdates the nappe-emplacement. |
| Folding of lithosphere in the Piemonte-Ligurian ocean | 1990 | Hoogerduin Strating, E.H. | 69(1) | Basin development in the Jurassic-Cretaceous Piemonte-Ligurian ocean as inferred from geological data is compared with a model for folding of oceanic lithosphere and subsequent flexuring due to sediment loading. According to the model, basins with a width between 130 and 160 kilometres and a relative depth ranging from 2000 to 2500 metres will develop on oceanic lithosphere with a cooling age between 35 and 55 My. These results are in good agreement with the dimensions of the Internal and External Ligurian basins, calculated from geological reconstructions. Furthermore, the model provides an explanation for the occurrence of slumps and olistostromes observed in the sedimentary record from the Aptian onwards, and for the extensive erosion on the 'Bracco Ridge', a submarine high which separated the Internal from the External Ligurian basin. |
| Application of a mechanical model to the Northern Apennines, with special reference to the effect of sea level changes | 1990 | Berg, L. van den | 69(1) | The mechanics and geometry of thin-skinned tectonic wedges are a function of the parameters top and basal slope, strength of wedge and basal layer, pore-fluid pressure and sea level. An analysis of a mechanical model, that takes these parameters into account, shows that alternating submarine and subaerial conditions can have important consequences for the stability of such a wedge. The model is applied to the Northern Apennines. It can explain multiple phases of gravitational sliding in the Ligurian scaly clay melanges. The contrasting style of deformation of different tectonic units, and temporary suppression of synsedimentary thrusting in the Romagnan sequences can also be explained by this model. It is shown that gravity spreading, induced by brittle-ductile transition, provides a mechanism which can explain the metamorphic gap at the tectonic boundary between the doubled Tuscan sequences in the Alpi Apuane, as well as the simultaneous spreading at the rear and the shortening at the front of the Northern Apennine foldbelt. |
| The structural geology and basin development of the Romagnan-Umbrian zone (Upper Savio- and Upper Bidente Valleys, N. Italy) | 1990 | Wamel, W.A. van; Zwart, P.E. | 69(1) | Combined stratigraphic and structural geologic studies in the region of the Upper Savio- and Upper Bidente Valleys lead to a re-interpretation of the Romagnan-Umbrian thrust zone, especially of the extent of the Castellaccio thrust unit. The Romagnan-Umbrian thrust zone may be characterized as a generally piggy back propagated, imbricate stack with a complex evolution. The presence of a time equivalent turbidite marker bed (= 'Contessa Bed') within all thrust units enabled the balancing and restoration of the Romagnan-Umbrian thrustzone. Theminimum amount of shortening of the 'Contessa Bed' appears to be about 48% of its original length. Folding accounted for about 49% and thrusting for about 51% of the total amount of shortening. The restoration indicates that, during the 'Contessa' event (dated as the Early Serravallian Globorotolia peripheroronda Zone: I4-14,5 Ma), the Romagnan-Umbrian turbidite basin had a minimum NE-SW width of 50km. After the 'Contessa' event, still during the Early Serravallian, an anticlinal culmination ( = the San Paolo high) formed within the Romagnan-Umbrian turbidite basin, probably generated by blind thrusting during the Serravallian and Early Tortonian. On top of the anticlinal culmination a condensed section of clayey San Paolo Marls accumulated until the Middle Tortonian (9-10 Ma). The more calcareous Veghereto Marls have been deposited on the SW dipping limb of the San Paolo anticlinal culmination. During the Middle Tortonian (9-10Ma) sedimentation in the SW part of the Romagnan-Umbrian turbidite basin was abruptly terminated by the Ligurian overthrust. Simultaneously or shortly thereafter, the Romagnan-Umbrian sequences were also intensively folded and thrusted. The Romagnan-Umbrian thrust zone developed during this main deformation phase of the area. After thrusting, a period of gentle folding, oblique-slip faulting and general uplift completed the structural geologic and sedimentary history of the studied region. |
| Palaeotectonic significance of gravity displacement structures in the Miocene turbidite series of the M. Pollo Syncline (Umbro-Marchean Apennines, Italy) | 1990 | Feyter, A.J. de; Molenaar, N.; Pialli, G.; Menichetti, M.; Veneri, F. | 69(1) | The Northern Apennines are characterized by more or less severely deformed clastic wedges which originated in elongate foredeeps. These foredeeps were generated successively at the expense of the Adriatic Foreland. A thick turbidite sequence accumulated in the Umbro-Romagnan Foredeep during the Middle to Late Miocene. The variability of this sequence indicates that sedimentation and deformation patterns migrated within individual foredeeps. Marked facies and thickness changes were caused by the successive subsidence of foredeep segments in response to ensialic shearing. Subsequent multi-level gravitational spreading resulted in the development of synformal sub-basins at a later stage of the turbidite cycle within the successive foredeep segments. The gravity displacement structures in the M. Pollo Syncline in the Umbro-Marchean Apennines support such a differentiation. Additional ensialic shearing caused the out-of-sequence evolution of some thin-skinned structures. Ultimately, these were preferentially affected by extension tectonics associated with Tyrrhenian crustal stretching. |
| #REF! | 1990 | Rondeel, H.E.; Schlager, W.; Boekschoten, G.J.; Vandenberghe, J. | 69(1) | |
| Notes on the Late Cenozoic history of the Kai Islands, Eastern Indonesia | 1990 | Marle, L.J. van; Smet, M.E.M. de | 69(2) | Field and laboratory data on Cenozoic deposits of the islands of Kai Kecil and Kai Besar provide broad age-depth constraints, but are insufficient for a detailed geohistory analysis to determine the timing, rate and magnitude of vertical movements in the eastern segment of the outer Banda Arc. Yet, a tentative reconstruction of the vertical movements of the islands could be made. On Kai Besar, lower bathyal-upper abyssal Middle-Late Eocene calcilutites and marls, in combination with Upper Oligocene and Lower-Middle Miocene middle bathyal deposits record an Eocene-Miocene passive margin fill. Kai Besar must have emerged sometime during the Late Miocene to Pliocene-Pleistocene, associated with the development of the Banda Arc thrust belt. The absence of elevated coral reefs, which are present on surrounding islands, suggests that the island is presently subsiding. On Kai Kecil, Late Pleistocene middle bathyal bioclastic turbidites and marls are nowadays situated just above sea level documenting uplift rates up to 500 cm/ka. In contrast to Kai Besar, Kai Kecil has 4-5 elevated reefs, unconformably overlying the Pleistocene core, showing that the island continues to rise. |
| 3-D Seismic interpretation and lateral prediction of the Amposta Marino field (Spanish Mediterranean Sea) | 1990 | Bouvier, J.D.; Gevers, E.C.A.; Wigley, P.L. | 69(2) | The objectives of a seismic study of the Amposta Marino field, offshore Spain, were threefold: firstly, to map the top of the main karstified reservoir (C horizon) accurately in order to identify any possibly remaining attic oil; secondly, to map and interpret a sub-horizontal, semi-continuous anomalous reflection (C2 horizon) within the karstified Montsia carbonate reservoir; thirdly, to assess the feasibility of predicting porosity in karstified reservoirs. 1. The acoustic impedance at the interface between cap rock and top reservoir can be increasing or decreasing, depending on the degree of karstification. Hence, the top reservoir reflection can be positive or negative. This interpretation problem, once recognised, could be solved and led to improvements in the structural map. 2. The synthetic seismogram, logs and drilling records of well AMB-10 indicate that the C2 horizon represents a porous karstic layer. It occurs as a semi-continuous, sub-horizontal feature around the flanks of the structure. Distribution of the C2 marker and also the reservoir performance data and geological history of the Amposta Marino field indicate that the actual porosity system in the Montsia reservoir could be the product of an originally compartmentalised porosity network (resulting from karstification) with greatly increased lateral communication as a result of subsequent mixing-zone corrosion. The C2 event is interpreted as a high-porosity layer caused by a sea level stillstand which allowed intense mixing-zone corrosion to occur. 3. The areal distribution of collapse breccia and cave development can be mapped by displaying the root mean square of the amplitude measured in a window corresponding to the karstified reservoir. Qualitatively, areas with high amplitudes correspond to the most enhanced porosity zones. 4. Although very thin compared to total reservoir thickness, enhanced porosity zones, created as a result of mixing-zone corrosion, could contain the bulk of the oil and may therefore represent an important exploration/production target. |
| The Shere lgneous Complex, Central Nigeria, geochemical constraints on the origin of peralkaline and associated granites | 1990 | Imeokparia, E.G.; Badejoko, T.A. | 69(2) | The Shere Igneous Complex comprises a sequence of metaluminous-peraluminous and peralkaline granites in the following order: (1) a central amphibole-fayalite granite, metaluminous in the core and peralkaline towards the margin; (2) a mildly peraluminous biotite granite in the east of the complex; (3) a peralkaline arfvedsonite-aegirine granite forming a peripheral ring around the central amphibole fayalite granite; (4) a peralkaline arfvedsonite-biotite granite forming a semi-circular body between (1) and (3); and (5) a peralkaline albite-arfvedsonite granite forming an outer semi-circular intrusion in the west of the complex. The peralkaline and metaluminous/peraluminous granites show some overlap of agpaitic indices, but marked dissimilarities in trace element characteristics. The amphibole-fayalite granite has high contents of Ba, Sr, Zr and low contents of Rb, Th, Y and Li. The biotite granite is enriched in Rb, Y, Th, Li, F relative to the amphibole-fayalite granite and is presumably crystallized from a differentiated magma produced by fractional crystallization of the amphibole-fayalite granite magma. The arfvedsonite-aegirine granite, the arfvedsonite-biotite granite and the albite-arfvedsonite granite are enriched in HFS elements and strongly depleted in Sr and Ba; these granites are presumably associated with a fluorine-bearing phase carrying high concentrations of HFS and other trace elements. This volatile phase has caused metasomatic alterations in surrounding rocks. The part of the arfvedsonite-biotite granite that is characterized by extreme levels of HFS elements is believed to have formed by metasomatic alteration of amphibole-fayalite granite along the contacts with arfvedsonite-biotite granite. The granitic magmas were presumably formed by partial melting of anhydrous residual crust enriched in refractory ferromagnesian and accessory minerals during a previous cycle of anatexis. The high temperatures necessary for melting this granulitic crust were provided by the emplacement of mantle derived mafic magmas into the lower crust. The extensional tectonic setting allowed small batches of granite magma to rise without substantial mixing. |
| Late Pleistocene sedimentation and landform development in western Kalimantan (Indonesian Borneo) | 1990 | Thorp, M.B.; Thomas, M.F.; Martin, T.; Whalley, W.B. | 69(2) | Widespread Quaternary alluvial sediments occur around the coastal margins of western Kalimantan. These strongly podzolised 'white sands' occur as major alluvial bodies that may be 15-20m higher than Holocene/ contemporary floodplains inland but converge and pass beneath them towards a near coastal hinge line. It is presumed that the sediments continue off-shore and correlate with previously documented 'Alluvial Complex' sequences on the submerged areas of Sundaland. Microscopic and SEM examination of quartz indicates minimum wear on most grains, and the alluvial sediments can be distinguished clearly from those of contemporary beach environments. Their extent, morphology and sedimentary characteristics indicate rapid aggradation within coastal catchments, and some formations appear to be low angle, wet alluvial fans. Radiocarbon assay indicates ages greater than 40000 RC yr BP for the sediments with 2 finite dates of 54200 +3400/-2400 RC yr BP and 51000 +2100/-1700 RC yr BP. It is concluded that they were laid down during low sea levels and by rapid erosion and deposition possibly caused by increased seasonality of rainfall, decreased total precipitation and associated ecological changes. Neogene tectonic movements may also affect their disposition. |
| The Saalian glaciation in the Dutch part of the North Sea | 1990 | Joon, B.; Laban, C.; Meer, J.J.M. van der | 69(2) | Compilation of available data from boreholes and seismic surveys in the Dutch part of the North Sea has led to a new map of Saale glacial features. The distribution of Saale sediments in this map in combination with the morphology enable a tentative reconstruction of the Saalian ice margin parallel to the Dutch coast. This suggests a revision of recent theories of Saale glacial events based on land data. |
| Variation in heavy mineral associations of Permo-Carboniferous fan sequences (Southern Germany); Their implications concerning provenance and basin evolution | 1990 | Dill, H. | 69(2) | Fan deposits from the Stockheim, Erbendorf, Weiden and Schmidgaden Basins in the immediate surroundings of the Mid-European Variscan basement contain translucent and opaque heavy mineral assemblages which have been strongly controlled by intrabasinal (volcanism, hydrothermal activity and weathering) and extrabasinal (provenance) parameters. Sediments of this marginal facies are less intensively altered by diagenesis than equivalent beds in the basin centre. Therefore, the amount and type of heavy minerals present in these depositional basins may contribute to basin and provenance analyses ofthese terrigenous fan sediments. Pyroclastic fan deposits contain smaller amounts of allogenic heavy minerals and in places they have a larger proportion of authigenic heavy minerals than found in alluvial fans. Crystal habits of zircon, apatite and anatase or mineral ratios (e.g. anatase/Fe silicate) are supplementary tools for the determination of sediment sources related to denudation of metamorphic rocks or bear a significant volcanic-derived influx. Deeply circulating waters and paleosols may be recognized on the basis of mineral transformation in the system Fe-Ti-O (giving rise to plates of anatase) and by a conspicuous depletion of particularly phosphates. Moreover, the heavy minerals in the fan deposits are an immediate response to the basement uplift in the hinterland. The history of basin subsidence, denudation of the basemement and even the P-T slope of the metamorphic source area may by inferred from the reverse order of heavy minerals discovered in the foreland. This will work well if metapsammopelitic rocks are present in the hinterland, but less well, if ultrabasic rocks occur in the source area. This procedure may successfully be used for samples from drill cores, cuttings and even samples from outcrop from fan deposits. Under these circumstances, the impact of modern weathering and soil forming processes on the heavy minerals suites has yet to be carefully established before discussing intra- and extrabasinal factors. |
| Noncryogenic deformations in Loch Lomond Stadial to Early Flandrian coversands in North Lincolnshire, England | 1990 | Schwan, J. | 69(2) | In contrast to the Late Dryas Stadial aeolian coversands in the Netherlands, there are no frost structures in their approximately coeval counterparts in north Lincolnshire, England. Faunal evidence for cold conditions in the latter category can be reconciled with the absence of cryogenic deformations by assuming that the annual snow cover was thick enough to insulate the sands from frost action. This paper discusses two types of postdepositional deformations in the north Lincolnshire coversands to which, at first glance, a cryogenic origin might be attributed. It is shown, however, that nonperiglacial processes account more adequately for their presence in these deposits. Involutions associated with a hydromorphic paleosol are due to unequal loading and slow upward percolation of ground water when the sands that underlie the contorted layer were waterlogged during some period in the past. Fissures reminiscent of frost cracks, are interpreted as tension gashes produced by a slight updoming of the clayey or shaley substrate of the coversands in the proximity of cuesta scarp-faces. |
| Additional note on the echinoid genus Cyclaster from the Late Maastrichtian of northeastern Belgium | 1990 | Jagt, J.W.M.; Michels, G.P.H. | 69(2) | The discovery of six additional specimens of the brissid echinoid Cyclaster platornatus Kutscher, 1978 in the lower part of the Vijlen Member (Gulpen Formation) as exposed at the SA Ciments Portland Liégeois (CPL) quarry near Haccourt (Liège, Belgium) enables an analysis of its range of variation. Sexual dimorphism as reflected in the size of the gonopores, which has previously been described in the literature for two species of Cyclaster, can now possibly be demonstrated for C. platornatus as well. Some remarks on the biostratigraphy and macrofauna of the Vijlen Member at this locality are added. |
| Meteorite impact, extinctions and the Cretaceous-Tertiary Boundary | 1990 | Smit, J. | 69(2) | At present the two major hypotheses to explain the mass-extinctions at the Cretaceous-Tertiary boundary (KTB) are a large meteorite impact and widespread volcanism. High resolution stratigraphy across the Cretaceous-Tertiary boundary in the Agost and Caravaca sections in Spain provides a test for these hypotheses. Hard to explain by any sort of volcanism are the shocked minerals, stishovite and the round form and distribution of microtektite remains, which are found worldwide at the KTB. It is now likely that several impacts occurred simultaneously. The low REE-abundances in the KT ejecta layer and quench crystals of clinopyroxene and other crystalline textures in the KTB microtektites betray an impact in ocean-floor basalt, whereas shocked quartz and stishovite favour a continental target. Stable oxygen and carbon isotope studies of both sections offer a glimpse of what catastrophic environmental changes may in fact have caused the extinctions. Carbon isotopes show that photosynthesis was strongly reduced at the KTB. A 8°C rise in ocean surface temperatures indicates that a greenhouse atmosphere followed the impact event. This greenhouse atmosphere may have lasted for several thousands of years. |
| Precface - Palynology, a key to climatic and geographic change - A tribute to Thomas van der Hammen | 1990 | Cleef, A.; Geel, B. van; Hooghiemstra, H.; Roeleveld, W.; Wijmstra, T.A. | 69(3) | |
| Evidence of episodic permafrost conditions during the Weichselian Middle Pleniglacial in the Hengelo Basin (The Netherlands) | 1990 | Ran, E.T.H.; Bohncke, S.J.P.; Huissteden, K.J. van; Vandenberghe, J. | 69(3) | An ice-wedge cast level, dated between ca 41,000 and 36,600 years BP. has been found in Tubantian (Weichselian) deposits near Hengelo (Twente district, Eastern Netherlands). So far, well developed ice-wedge casts of Middle Pleniglacial age have not been recorded for the Netherlands. It is argued that mean annual temperatures were near the upper limit to permit ice-wedge development. In that case substrate and hydrological conditions are critical. Sedimentary structures overlying the ice-wedge cast level point to thaw lake development. Palaeoecological evidence shows that the sequence started in open (periodically running) water. Under a declining water budget a phase with terrestrial peat sedentation was initiated which, after a short interval, culminated in an increasingly dry environment as indicated by xerophilous taxa. The ice-wedge cast level is associated with taxa indicative of bare, disturbed grounds and with the break up of a continuous vegetation cover. Subsequently a phase with (temporary) running water, predominantly standing, shallow water and a return to running water are recognized. The top of the sequence shows a vegetation which can be compared with a chionophilous arctic dwarf shrub tundra. Vegetation development could be explained in terms of changing moisture conditions, while temperature changes are of minor importance. |
| Subtropical relicts in the Pliocene flora of Brunssum (The Netherlands) | 1990 | Zagwijn, W.H. | 69(3) | Macroscopical remains of the following genera in the Early Pliocene flora found near Brunssum (The Netherlands) are described: Calamus, Hartia, Spirematospermum, Symplocos, Toddalia, Trigonobalanus, Turpinia. These genera have a subtropical character; their recent representatives occur in evergreen subtropical and tropical montane forests. Only two of them have been found in other Early pliocene deposits in Europe, but all of them have been recorded in Miocene beds in this area. The relict character of part of the Brunssum flora is discussed in relation to palaeogeographic and climatic factors. Of special interest is a comparison with a living assemblage associated with Trigonobalanus in the Andean forest of Colombia (South America). |
| A palynological study of a Holocene deposits from Grand-Bongard (Hautes-Fagnes, Belgium) | 1990 | Gotjé, W.; Wayjen, M.C.A. van; Geel, B. van | 69(3) | A peat deposit from a valley in the Hautes-Fagnes was studied palynologically. The radiocarbon-dated pollen profile spans most of the Holocene and constitutes one of the most detailed records of post-glacial vegetational changes in E. Belgium. The peat formation started near a Betula-Pinus forest and five regional pollen zones could be distinguished. The first zone is dominated by Pinus and, Betula (preboreal), the second by Corylus (Boreal) and the third by Alnus (Atlantic). The elm decline and the first signs of human influence charactetize the fourth zone (Subboreal). The fifth zone (Subatlanticum) shows maxima of Fagus and Carpinus and an obvious increase of human influence (e.g., Cerealia). The peat succession in situ took place under mesotrophic conditions as a consequence of the geographical situation of the site near the rivulet Helle. Although there has been some variation in the moisture conditions at the site, the drainage in the valley was so constant that extreme fluctuations did not occur. |
| An evaluation of the climatic conditions during the Late Quaternary in northern Greece by means of multivariate analysis of palynological data and comparison with recent phytosociological and climatic data | 1990 | Wijmstra, T.A.; Young, R.; Witte, H.J.L. | 69(3) | An analysis of the different interglacial forest phases and glacial steppe phases in the vegetation history of northern Greece, as recorded in the first 86 metres of the Tenagi Philippon core, resulted in the distinction of three forest vegetations and one steppe vegetation. From the comparison of those vegetation data with the present day occurrence of the various forest and steppe vegetations and the corresponding climatic data, an estimation of climatic conditions (temperature and precipitation) during the Late Quaternary was made. Typically, in the beginning of the interglacials an open forest vegetation characterized by Pistacia was found, indicative for warm conditions and wet summers and winters. Relatively soon summers became drier, forcing an evergreen oak forest to develop. During the second half of the interglacials deciduous forests and cool, wet conditions prevailed. At the glacial maxima a dry continental climate with cold winters accompanied a steppe vegetation. The results suggest that winter conditions are more important in determining the nature of the vegetation in the Mediterranean and that the maquis and garrigue are purely man made vegetations, as its elements occurred in different periods in the past. |
| The puzzle of Weichselian vegetation types poor in trees | 1990 | Kolstrup, E. | 69(3) | Palaeobotanical records of many Weichselian deposits indicate stands of vegetation poor in trees and with elements from a range of different environments. The scarcity of trees seems in cases to contradict the prevailing temperature regime as suggested, for example, by records deduced from beetles. Alternative explanations for the recorded combination of plant species are considered. Examples of the influence of periglacial forms and processes on vegetation are given, followed by a more speculative account of the effect of swift climatic changes during the Weichselian. Unstable environmental and climatic conditions are thought to have been particularly effective in controlling the composition of what is today considered to have been a singular combination of plant species. Unstable conditions are also thought to have played a role in hampering the development of continuous palaeobotanical records in NW-Europe. The palaeobotanical data derive from a variety of geographical environments, and as a result it is almost impossible to integrate the scattered findings into a coherent whole so as to elucidate the former ecological conditions. It is suggested that in future investigations one must look for additional possibilities of correlation, such as phases of aeolian activity, deposition of charcoal resulting from natural fires or other discernible events of restricted duration. |
| Textural characteristics of organic matter Orinoco Upper Delta | 1990 | Lorente, M.A. | 69(3) | Four subenvironments (oxbow lake, back swamp/flood basin, crevasse splay, natural levee) from the Orinoco Upper Delta plain were sampled for quantitative analysis of organic matter. Each subenvironment has been characterized on the basis of two main criteria: organic matter composition and textural characteristics. The Oxbow lake model has two main subdivisions related to the influence of the dry and rainy seasons on the organic assemblages. The rainy season assemblages are rich in light-coloured organic matter, with abundant fungal and insect remains, are usually coarse grained, and have a highly variable particle shape. The dry season assemblages are relatively poor, the organic matter is darker and the finest grain size is scarcely represented. The Montrichardia backswamp/flood basin model is also related to the flood - and the dry periods of the basin. Dry periods in the flood basin are characterized by very poor organic matter assemblages consisting of fine grains of woody and humic gels. The flood stages are characterized by a very high content of organic remains of variable composition. The crevasse splay model assemblage is characterized by a strong bimodal distribution of the grain size, and by fluctuations in the amount of organic matter preserved at different levels of the fan. The natural levee model assemblage is highly variable in the organic matter content and composition, and shows a wide range of particle grain sizes varying from medium sand to clay. |
| Late Cenozoic uplift and paleogeography of the Colombian Andes: constraints on the development of high-andean biota | 1990 | Kroonenberg, S.B.; Bakker, J.G.M.; Wiel, A.M. van der | 69(3) | An analysis of published and newly obtained data on the timing of uplift in the Colombian Andes shows that some areas were already uplifted above the (present) forest line as early as 16 Ma ago. Elsewhere early uplift data (Oligocene- Mid-Miocene) have only been obtained from elevations below 3000m. Most other areas above 3000 m reached their present altitude only after 6-4 Ma ago by more recent uplift or by the formation of stratovolcanoes on dissected planation surfaces. Accretion of the Panamanian isthmus between 7-3 Ma may have been contemporaneous with the latter, most vigorous Plio-Pleistocene uplift phase in the northernmost Colombian Andes but cannot be related to the earlier phases in the whole Andean chain. The accretion enabled immigration of holarctic species into the Andes. There is no reason to suppose a topographic interruption in the Andean Chain at the Huancabamba deflection during the Tertiary, and hence immigration of australantarctic species depended only on the presence of suitable high-Andean climatic conditions along the whole of the Andean chain. |
| A sub-glacial sediment deformation model from geotechnical and structural properties of an overconsolidated lacustro-glacial clay | 1990 | Schokking, F. | 69(3) | Sub-glacial deformation processes of ice sheets are recorded in geotechnical and structural properties of overriden sediments. Geotechnical, structural and microstructural properties were determined of Late-Pleistocene lacustroglacial clays in the northern Netherlands that were subjected to deformation by the Saalian ice sheet. From these properties a sub-glacial deformation model could be constructed of the clay sequence, depicting an extensively sheared upper zone and a lower zone that was folded, hydrodynamically consolidated and fissured during subsequent phases of ice sheet development. This sub-glacial deformation model can serve as a basis for a model of the distribution of geotechnical properties of the clays which has applications in engineering geology and geotechnical engineering. |
| On estimating the thickness of the Saalian ice sheet from a vertical profile of preconsolidation loads of a lacustro-glacial clay | 1990 | Schokking, F. | 69(3) | The consolidation history of cohesive soils can be estimated on the basis of the one-dimensional consolidation theory of Terzaghi. An effective stress profile, which existed during the steady state of the Saalian ice sheet, has been reconstructed from the results of a series of oedometer consolidation tests on a vertical sequence of Pot Clay (Marum, Province of Groningen, The Netherlands). From this effective stress profile and from geotechnical and structural properties, a fossil overburden pressure of 2100 kN/m2 could be estimated, which would have required an ice cover of at least 195 m thick. A comparison of the results of this study with geotechnical data from other locations in the northern Netherlands and a comparable research in northern Germany confirmed the regional significance of the study described in this paper. |
| #REF! | 1990 | Westerhof, A.B.; Bosscher, H.; Reymer, J.J.G.; Meer, J.J.M. van der; Reymer, J.J.G. | 69(3) | |
| Archaeomagnetic dating of a limestone kiln at Nijmegen (The Netherlands) | 1990 | Langereis, C.G.; Kars, H. | 69(4) | A kiln used for the burning of limestone was found in the town centre of Nijmegen (The Netherlands) and was sampled for archaeomagnetic dating purposes, since at the time of excavation archaeological dating materials were still absent. Samples taken from the kiln wall generally yield consistent characteristic remanent magnetizations. The mean direction is compared with the archaeomagnetic calibration curve for Britain. The result shows that the kiln is of Roman age rather than belonging to the Middle Ages. Combined with the few archaeological data found later, an age in the 4th century AD is most probable. |
| Lithostratigraphy and provenance of the Early-Pleistocene deposits in the southern Netherlands and northern Belgium | 1990 | Kasse, C. | 69(4) | An almost complete Early-Pleistocene sequence of the Tegelen and Kedichem Formation has been studied in the southern Netherlands and northern Belgium. Former Dutch and Belgian lithostratigraphic units are correlated and a new, more detailed lithostratigraphic framework is proposed. The provenance of the sediments was established by heavy mineral and gravel analysis. Rhine, Meuse and rivers from the Scheldt basin contributed their sediments to the southern North Sea basin during different stages of the Early-Pleistocene. The major importance of the rivers from the Scheldt basin in the upbuilding of the sedimentary sequence is emphasized. |
| Major lateral sediment displacement in till-sand-peat associations of the Tjonger Valley fill (the NE Netherlands) - Holocene cryoturbation? | 1990 | Meulen, S. van der | 69(4) | Attention is drawn to an extraordinary type of large-scale cryoturbation in the Tjonger Valley fill (NE Netherlands). A large lateral displacement of sediments, involving sand and till intrusion, is the most conspicuous feature. Sand intrusion has been found especially in gyttja and peat, whereas till and some loam intruded into sand. In the former case elongated ridges, some 10's x 100's metres wide, exhibit dipping layers, partly with extensive folding and some thrustplanes. Till intruded from part of the valley margin into sand layers with an abundance of flow structures and some rare thrusts. Intrusion of the sand into gyttja and peat presents opportunities to date the event. The first indications point towards an early Holocene age. Major cryoturbation was previously only known from the Pleniglacial of the last ice age in the Netherlands. Density inversions over thawing permafrost, in a watersaturated environment, are thought to have induced gravity spreading in the vast, but discontinuous layers of various compositions. The type of cryoturbatic structure encountered within deposits not only strongly varies with composition, but also with the dimensions of layers of the same composition. |
| Hydrothermal synthesis of Na-beidellite | 1990 | Kloprogge, J.T.; Eerden, A.M.J. van der; Jansen, J.B.H.; Geus, J.W. | 69(4) | Na-beidellite was hydrothermally synthesized using various starting materials at a range of P-T conditions. The best crystallized Na-beidellite was carefully investigated with XRD, SEM, TGA, MAS-NMR and IR-spectroscopy. Cell parameters are: a = 5.18 ± 0.005 Å; b = 8.96 ± 0.008 Å; c = 12,54 ± 0.011Å; V = 581.9 ± 0.5 Å3. Indexing is based on an orthorhombic cell. 29Si MAS-NMR reveal three peak positions: - 92.7 ppm (Si-OAl); - 88.4 ppm (Si-1Al); - 82.3 ppm (Si-2Al), indicating an AlIV/Si ratio of 0.106 per unit cell. The presence of small amounts of F in the hydrothermal fluid causes a significant increase in crystallinity. Na-beidellite is the only crystalline product applying a starting gel of composition Na0.7Al4.7Si7.3O22. A Na1.0Al5.0Si7O22 gel results in Na-beidellite + paragonite and gels with higher Na content produce only paragonite. |
| Geochemistry of Quaternary fluvial and eolian sediments in the southeastern Netherlands | 1990 | Moura, M.L.; Kroonenberg, S.B. | 69(4) | Bulk chemical analyses of Quaternary sediments in the southeastern Netherlands show that sands from the middle terraces of the Meuse in South Limburg are significantly lower in SiO2 and higher in almost all other analysed major and minor elements than mixed Meuse and Rhine sediments in North Limburg and adjacent areas. Within individual formations in North Limburg the Sterksel and Urk formation are charactenzed by relatively high Al, Fe, Mg, K and Rb and low Zr contents, the Kreftenheije Formation and Nuenen Group by low Rb and high Zr contents, whereas the Veghel Formation has both low Rb and low Zr contents. Principal component analysis is used to assign well-correlated element groups to individual minerals. Factor 1 (65% of the total variance) is composed of Fe, Al, Mg, K, As, Sc, Cs, Rb, Th and the LREE and is interpreted as a muscovite/goethite factor. Factor 2 (13% of the total variance), is dominated by Na, Ca, Al, Mg, K, Th and Sr and is interpreted as a feldspar factor. Factor 3 (7% of the total variance), is composed of Zr, Nb, Cr, Ti, V and Lu, elements concentrated in some stable heavy minerals. High levels of Factor 1 elements in South-Limburg sands are interpreted to be due to admixture of large amounts of shale fragments, muscovite and goethite particles. Depletion of Rb in eolian sands is interpreted to differential winnowing of micas during deflation. The concentration of many elements is also strongly grain-size dependent. Geochemical analysis is shown to provide much additional information not normally detected in routine petrographic analysis. |
| Origin of event beds in the Jurassic Çalcari Grigi' Formation, Venetian Alps, Italy | 1990 | Galli, G. | 69(4) | Three undulating, large-scale bedforms occur within a 20km wide lagoon which was probably generated by synsedimentary tectonic processes in a Jurassic shallow water rimmed platform (Trento Platform, Italy). Bedform 1 resembles hummocky cross stratification and consists of domes and troughs which display a downcurrent increase in wavelength and decrease in amplitude. Bedform 2 is composed of low-angle undulating foresets whose downcurrent structural variations over 300 m of stratigraphic exposure mimic smaller-scale climbing-wave ripple lamination. Bedform 3 consists of three large-scale stacked 'giant ripples'. Internal characteristics (shell fabrics) of bedforms reflect a complex storm action that was ineffective as sediment transport mechanism but produced an 'in situ' reorientation of shells through strong shear stress and local pressure pulses on and below the lagoonal floor. These bedforms were generated by tsunamis as evidenced by: 1) the action of surface waves; 2) a great lateral extent of exposures; 3) the restriction of bedforms to the same stratigraphic horizon (correlated by means of 'event correlation'). Bedform 1 was produced by first-order impulse-generated waves progressing discontinuously along the deepest area of the lagoon; bedforms 2 and 3 reflect bottom return flows. The trajectory system has been tentatively explained by the hydrodynamic configuration of impulse waves propagating at supercritical conditions around a lateral obstacle. |
| Strange relatives - Earth and her sibling neighbours | 1990 | Priem, H.N.A. | 69(4) | Comparative planetology has brought to light some general themes in the geological evolution of planets and planetary bodies. Particularly the study of the Moon and the Earth-like planets Venus and Mars has contributed much to the understanding of the early evolution of the Earth. All have sizes and distances to the Sun of the same order of magnitude, are primarily composed of cosmically rare silicates and metals, and underwent differentiation into core, mantle and crust. The crust is basaltic on Venus and Mars, while on the Moon the crust is anorthositic in the highlands and basaltic in the maria. Earth has, besides a basaltic crust in the ocean basins, as the only planet in the Solar System a continental crust of average dioritic composition. This continental crust owes its genesis to the interaction between ocean water, basaltic crust, and mantle dynamics. All planetary bodies suffered an intense bombardment of meteoroids early in their histories. Impacting was probably the dominant geological process in that time, but on Earth virtually no traces of the early impacts are preserved because of later geological activities. The differences in environmental conditions and geological evolution between Venus, Mars and Earth are primarily determined by differences in size (cooling rate and gravity) and distance to the Sun (solar energy input). Only Earth has a hospitable environment suitable for life - conditions that are maintained by the biosphere. On Venus infernal conditions prevail, with a surface temperature of 480°C, an atmosphere almost entirely composed of CO2, an atmospheric surface pressure of 88 bar, and no water. Very little is known about tectonic activities because of the dense sulfuric-acid cloud cover, but volcanism appears to be still active. Mars is a barren desert with extreme variations in temperature, and a very thin atmosphere with a surface pressure of 0.0064 bar almost entirely composed of CO2. Water is present as ice in polar caps and in permafrost. Both Venus and Mars possessed early in their histories copious amounts of water (and Mars possibly also life ?). Venus lost all water because of 'runaway greenhouse' conditions, while Mars probably lost most of his volatiles because of the early episode of large-scale impacting - which ravaged all planets, but was more effective on the martian atmosphere because of the planet's smaller gravity. There are no indications that plate tectonics was ever in operation on Mars, but until fairly recently (and maybe up to now) there was active volcanism, giving rise to the largest volcanoes in the Solar System. |
| Petrology and geochemistry of late Precambrian volcanic rocks of the St. David's area, Pembrokeshire, South Wales (U.K.) | 1990 | Davies, E.C.; Bloxam, T.W. | 69(4) | Late Precambrian volcanic rocks near St. David's, Pembrokeshire (U.K.) constitute a bimodal basaltrhyolite assemblage. A new structural interpretation changes the presently accepted stratigraphical succession, the main effect of which is to place the Rhosson basalts at the base rather than at the top of the sequence. The olivine bearing basalts are subaerial and are normative olivine tholeiites. They have immobile element distributions characteristic of non arc environments. Unusual types of basaltic agglomerate and lapilli tuffs are described some of which may be tuff-lavas or hot debris flows. The rhyolitic rocks comprise lavas, breccias and ash flows, the latter being reported for the first time from the Precambrian of this area. They were also subaerially erupted and the bimodal basalt-rhyolite association may be a post calcalkali phase of eruption on continental crust; possibly in an ensialic back arc environment. |
| Shear-wave splitting in shallow clays observed in a multi-offset and walk-around VSP | 1990 | Douma, J.; Helbig, K.; Schokking, F.; Tempels, J. | 69(4) | Vertical seismic profiling using shear waves showed seismic anisotropy in the shallow 'Pot-Clay' sequence in the northern parts of The Netherlands. Shear-wave splitting, a key identifier for anisotropy, was observed at various depth using a multi-offset/multi-azimuth data acquisition technique. For the first time in such investigations, a three-component geophone mounted in a penetration cone was used. This technique resulted in improved data quality. A hodogram analysis of the shear wave data showed that fissures with strike and dip as specified by geological and geotechnical data cannot explain all observations of shear-wave splitting. |
| #REF! | 1990 | 69(4) | ||
| Presentation of the Honorary Membership to Dr H.E. Rondeel | 1990 | 69(4) | ||
| Clay mineralogy in southeast Spain during the Late Miocene: climatic, paleoceanographic and the tectonic events in the Eastern Betic seaway | 1991 | Chamley, H.; Müller, D.W. | 70(1) | X-ray diffraction and electron microscope investigations were performed on late Miocene sediments of the Fortuna Basin. Results were compared to available paleogeographic data and were interpreted in terms of terrigenous sources, climate, tectonics and sea level changes. Biostratigraphic and chronologic data allow the use of clay stratigraphy in providing paleoenvironmental information. The Western Mediterranean domain was subject to periods of strong aridification as early as late Tortonian. On the land climate was dominated by subarid conditions, favouring the development of pedogenic smectites and probably palygorskite. Tectonic activity rejuvenated the region episodically, especially after the Tortonian-Messinian boundary (lower Sanel marls), at the beginning of upper evaporites deposition (marine marl/gypsum alternations of the Rambla Salada Formation), and probably when the intra-Messinian inundation started. The sea level changes appear to have been of little importance in controlling the clay sedimentation patterns in the Eastern Betic seaway during late Miocene times. |
| Methodological problems in thermoluminescence dating of Weichselian coversand and late Holocene drift sand from the Lutterzand area, E. Netherlands | 1991 | Dijkmans, J.W.A.; Wintle, A.G. | 70(1) | A thermoluminescence dating study of eolian sands was performed for methodological purposes. The twelve samples that were dated include Upper Pleniglacial and Late Glacial coversands as well as late Holocene drift sands from stratigraphically well-known, partly 14C dated exposures, along the Dinkel river in the eastern Netherlands. A new approach was used to determine the equivalent dose (ED) after previous attempts were unsatisfactory. This approach proved promising, enabling to establish an ED value with a small uncertainty. However, the present results show that most of the TL ages of the Weichselian coversands are too low by about 20-40% compared to the radiocarbon dates, although some samples do not disagree with the geological evidence. This problem has also been encountered for coversand samples from Denmark and the reason is not yet fully understood. In spite of the problems that still exist TL proved a powerful method to distinguish between eolian sands with a relatively large age difference. It is still questionable whether TL dating enables a distinction between lithostratigraphical units of the Weichselian coversands in NW Europe. |
| Tropical weathering, denundation and mineral accumulation | 1991 | Aleva, G.J.J. | 70(1) | |
| The petrology and geochemistry of Koriga iron-formation, N.W. Nigeria | 1991 | Okonkwo, C.T. | 70(1) | The Koriga iron-formation is located in the Kushaka Schist belt of north-western Nigeria. It occurs as thin intercalations in the phyllites and pelitic schists which also contain concordant bands of amphibolite. A Kibaran (ca 1100Ma) age has been suggested for the rocks of the Kushaka Schist belt which have been intruded by granitic rocks dated ca 600Ma. The iron-formation consists dominantly of silicate minerals: grunerite, spessartine-rich almandine garnet, quartz and some martite, but occassional thin, more oxide-rich bands with martite, magnetite and silicate minerals also occur. Fe2O3, (total iron content varies from 26.20 to 34.05% and SiO2 content from 46.61 to 62.51% in the silicate-rich rocks. The oxide-rich bands are richer in total iron with Fe2O3, contents of about 59% . High values of Al2O3 (3.87-9.69%) and MnO (1.30 to 7.62% characterise the Koriga iron-formation. |
| Storm deposits in the coastal region of Shanghai, the Yangtze Delta, China | 1991 | Shao Xusheng; Yan Qinshang; Xu Shiyuan; Chen Zhongyuan | 70(1) | In the nearshore area along the coast of Shanghai, from the marsh-lowland to the prodelta, a series of storm deposits is found that is relatively coarse-grained and interbedded with fine-grained fair-weather deposits. In a vertical section the proportion of storm deposits is up to 35%.The storm deposits are well preserved above normal wave base mainly due to abundant supply of sediment from the river. The storm-deposit series is characteristic of the mouth of a large river, such as the Yangtze River, having high sediment supply and accumulation rates. |
| Growth rates and population dynamics in Crassostrea cf. rarilamella from the Lower Eocene Roda Formation (southern Pyrenees, Spain) | 1991 | Martinius, A.W. | 70(1) | An oyster bed of Crassostrea cf. rarilarmella was preserved in life position in muddy estuarine sediments of Lower Eocene age in the Roda Formation, southern Pyrenees, Spain. Its population structure was studied by counting and measuring annual growth increments in the hinge plate of the oyster. The population structure is normal and indicates a time averaged death assemblage. The life table and survivorship curve show that C. cf. rarilamella had a high juvenile mortality and constant adult mortality pattern. The mean yearly decrease of the adult population was very low, as is shown by the regression coefficient. Growth line analysis revealed slower and faster growth. The cumulative growth curve does not show a gradual decrease in inclination, which confirms the interpretation of the functional shell morphology (adaptation to a muddy substrate) of C. cf. rarilamella. C. cf. rarilamella shows characteristics of an equilibrium species or K-strategist, to be expected in this sedimentological setting. |
| The Oligocene volcano-sedimentary sequence of the Dipotama Basin, N. Greece: temporal relationships between Tertiary granites and volcanics, and implications for the regional tectonic evolution | 1991 | Baker, J.H.; Liati, A. | 70(1) | The Oligocene volcano-sedimentary sequence of the Dipotama Basin, Rhodope zone, N. Greece is found unconformably overlying the Tertiary Skaloti granite along an erosional contact. The sequence comprises a thin basal conglomerate with granite and tuff pebbles in a calcitic matrix followed by lignite-bearing tuffs and distal airfall crystal and ash tuffs, with some physical reworking, overlain by an ignimbrite series. Diagenetic alteration in the volcano-sedimentary sequence is evident as calcification, while the lower part of the ignimbrite is clay-altered. The similar ages of the granite and overlying ignimbrite means that rapid uplift and erosion of about 6 km of crust occurred before subsidence allowed the development of a basin to contain the lignite-bearing sequence. The Dipotama Basin is one of a series of continental Tertiary basins covering a large part of the eastern Mediterranean, which became isolated during uplift, followed in Pliocene times by renewed inundation and a subsequent phase of uplift to produce the current mountain chain of N. Greece. Rapid uplift of thickened continental crust exhumed the Skaloti and other granites, while subsequent extensional collapse allowed the deposition of the Tertiary volcano-sedimentary sequences. |
| In memoriam Prof. ir. P.Th. Velzeboer, 1916-1990 | 1991 | Leeuwen, P. van; Roest, J.P.A. | 70(1) | |
| The Mulhacen and Alpujarride Complex in the eastern Sierra de los Filabres, SE Spain: Litho-stratigraphy | 1991 | Jong, K. de; Bakker, H. | 70(2) | The litho-stratigraphy of the Mulhacen and Alpujarride Complex, in the eastern Sierra de los Filabres, is described in detail. Well defined litho-stratigraphic units can be traced for tens of kilometres along strike, despite the complicated tectono-metamorphic history. The Mulhacen Complex comprises three thrust-sheet units, formed by crustal-scale underthrusting. The thrust-sheets are composed of a dark-coloured series of Paleozoic age, covered by light-coloured metasediments of Triassic age. The most extensively developed unit from the Mulhacen Complex is the Nevado-Lubrin unit. The clastic base of the Triassic series is covered by a sequence dominated by carbonates. These basal clastics probably represent shelf deposits in an open marine environment. The overlying carbonate sequence marks an abrupt transition to a lagoonal environment, with reef and littoral facies. This abrupt facies shift might have been caused by regional crustal extension. The Alpujarride Complex contains two tectonic units of light-coloured metasediments of Triassic age. |
| The Mulhacen and Alpujarride Complex in the eastern Sierra de los Filabres, SE Spain: Litho-stratigraphy | 1991 | Jong, K. de; Bakker, H. | 70(2) | Cross Sections |
| The Mulhacen and Alpujarride Complex in the eastern Sierra de los Filabres, SE Spain: Litho-stratigraphy | 1991 | Jong, K. de; Bakker, H. | 70(2) | Geological Map |
| Geochemistry of precambrian gneisses in the eastern part of the Oban massif, Southeastern Nigeria | 1991 | Ekwere, S.J.; Ekwueme, B.N. | 70(2) | The basement of the eastern Oban massif is composed of a wide range of texturally and mineralogically different types of gneissic rocks. Migmatitic gneisses are characterized by high contents of silica and related trace elements while granite and biotite-hornblende gneisses have relatively lower values of these elements. Geochemical variation diagrams suggest that the gneisses evolved from a calc-alkaline magma of quartzdiorite to granodiorite composition. This demonstrates that orthogneisses exist in the basement complex of Nigeria. |
| EDTA-insoluble residues from the Zechstein Ca-2 unit (Late Permian), the Løgumkloster-1 Well, Denmark | 1991 | Stentoft, N.; Frykman, P.; Rasmussen, K.L.; Koch, C.J.W. | 70(2) | EDTA-insoluble residues of carbonate rock samples from the Upper Permian Ca-2 unit of the Løgumkloster-1 well have been investigated by X-ray diffraction, scanning electron microscopy, instrumental neutron activation analysis, and magnetic measurements. The sediments have undergone severe diagenesis including dolomitization and anhydrite mineralization. Two original facies types have been recognized, an oolitic shoal facies, and a lagoonal carbonate facies. The mineralogy of the inorganic insoluble residue reflects the facies type division: the lagoonal facies contains muscovite, feldspar and quartz; the shoal facies contains a non-crystalline silicate phase, quartz, and mica. It is thought that the muscovite in the lagoonal facies is derived from weathering of exposed basement highs. The non-crystalline silicate phase in the shoal facies is thought to be a diagenetic phase precipitated at a rather late stage in the diagenetic history. |
| Distribution and composition of till on Wieringen and in the northern part of the Wieringermeer, The Netherlands | 1991 | Rappol, M.; Leeuw, B. de; Swaan, J. | 70(2) | The former island of Wieringen is part of a series of low ridges along the southern margin of the till plain in the northern Netherlands. Distribution and variations in thickness of Saalian till on Wieringen and in the surrounding area suggest that some of the low hills of Wieringen are ice-pushed ridges and that a major glaciotectonic basin is located to the south of Wieringen, in the northern part of the Wieringermeer. Compositional characteristics of till indicate the presence of at least two main till types, one in which both flint and smectite are absent and another in which these components are present. An intermediate type contains very little flint but appears to have no smectite in the clay fraction. The flint-poor till is of the Voorst type and belongs to the First Baltic Till as defined for the northern Netherlands. It is suggested that the present morphology of Wieringen shows features related to two phases of glacial overriding of the previously formed ice-pushed ridges. Firstly, ice moved in a southwestern direction, after formation of the ice-pushed ridges. During a later phase of glaciation, ice moved between Wieringen and Gaasterland in a south-southeastern direction towards the Gelderse Vallei in the central Netherlands. During the latter event, streamlined landforms on eastern Wieringen and western Gaasterland obtained their NNW-SSE orientation. These ice-flow phases can be correlated with ice movements in the northeastern Netherlands, where ice moved first in a southwesterly direction over the till plain and later in a southsoutheastern direction in the Hondsrug area. |
| Introduction - Crustal dynamics - Pathways and Records | 1991 | 70(2) | ||
| Geometries of extensional fault systems, observed and mapped on aerial and satelite photographs of Central Afar (Ethiopia/Djibouti) | 1991 | Kronberg, P. | 70(2) | Well exposed Central Afar (Ethiopia/Djibouti) offers direct observation of a wide range of extensional structures and rift morphologies, at regional and local scale. Large Format Camera satellite photography and aerial photography was used to investigate in stereo-models phenomena of progressive extensional faulting. Representative successive fault geometries and fault evolution patterns are presented and discussed. |
| Thin-section petrography of pelites, a promising approach in sedimentology | 1991 | Zimmerle, W. | 70(2) | Pelites are described mainly by their macroscopic appearance, X-ray diffraction mineralogy and chemical composition. However, these conventional methods are being increasingly supplemented by thin-section analysis. Even so-called soft-cuttings aggregates can be successfully studied in thin section after appropriate impregnation. Only by integration of the various analytical methods can pelites be fully characterized in terms of original grain size and mineralogy, present mineral composition, sedimentary fabric and history of diagenetic alteration. Thin sections of pelites from various stratigraphic levels in the FRG are briefly described: Lower Carboniferous bedded cherts, siliceous shales and tuffs; Upper Jurassic marlstones; Lower Cretaceous claystones, siliceous marlstones and tuffs; Messel oil shale (Eocene) and Eocene tuffs; Oligocene clays and tuffs. In pelites diagenetic processes such as resorption diagenesis transform the original mineral composition and alter the original sedimentary grain-size distribution. The immense diagnostic value of sedimentary as well as tectonic fabric can be exploited only by means of thin-section analysis. |
| Mass transfer in a porous medium by thermally driven fluid convection: a numerical model and its application to the Travis Peak Formation, East Texas | 1991 | Gerretsen, J.; Breeuwsma, W.H.; Boorder, H. de; Spiers, C.J. | 70(2) | The diagenetic change of porosity by long range solution-precipitation mass transfer in a freely convecting porous medium is investigated by numerical modelling. From the conservation of mass and energy, assuming Darcian flow and local chemical equilibrium, making the Boussinesque approximation and neglecting deformation effects, a set of dimensionless partial differential equations is derived. These are then transformed into a set of algebraic equations, using a central finite difference method. Solutions were obtained using an implicit Gauss-Seidel relaxation method as well as an explicit method employing direct matrix inversion plus time stepping. The coupling between fluid flow behaviour (determined by the Rayleigh number) and local mass balance is established through a linear relation between the relative change in permeability and relative change in porosity. The results obtained for steady state convection omitting solute transport effects are in good agreement with numerical and laboratory scale experiments reported elsewhere. When solution-phase transport is permitted the reservoir porosity shows an exponential change with time at rates twice those predicted using a simpler analytical approximation. The numerical model is used to evaluate the development of porosity in the Travis Peak Formation of East texas. This formation consists of well-sorted, fine-grained quartz arenites deposited in the Early Cretaceous. During the early stages of diagenesis, the average porosity decreased from25% to 10% as a result of quartz cementation. Explanations based on an influx of warm meteoric fluids are questionable because of the large fluid-to-rock ratios required. However, taking into account geological constraints on heat flux, starting permeability and layer thickness, our numerical simulations show that long range solution transfer in a freely convecting closed system may well explain the rapid decrease of porosity observed in the Travis Peak Formation. |
| Basin dynamics and sequence stratigraphy in the Calabrian Arc (Central Mediterranean); records and pathways of the Crotone Basin | 1991 | Dijk, J.P. | 70(2) | The structural and tectonostratigraphical Late Neogene development of the Crotone Basin is presented, a foreland basin in the accretionary wedge along the external side of the Calabrian Arc (Central Mediterranean). It demonstrates the role of local tectonic activity of the thrust wedge and that of regional relative sea level fluctuations on the formation of unconformity-bound depositional sequences. The tectonostratigraphic development of the basin can be divided in 4 stages: 1. a Serravalian – early Messinian Stage, characterized by a progressive enlargement of the Basin, 2. a middle Messinian – Early Pliocene Stage, characterized by intense and complex fault movements that were overprinted by the Messinian salinity crisis, 3. an Upper Pliocene - Early Pleistocene Stage, characterized by a pulsating onlap, and 4. a Late Pleistocene - Recent Stage, characterized by strong vertical movements in conjunction with the uplift of the Sila basement Massif. At the end of Stage 2 regional compression during the Mid-Pliocene Phase inverted the basin and thrust its cover towards the margins. A kinematic model is proposed whereby the evolution of the Basin was controlled by oblique sinistral movements along two confining NW-SE trending convergent crustal shear zones. Within this concept, the Middle Miocene - Early Pliocene development (Stages 1 and 2) reflects a strike-slip cycle. The sequence boundaries that belong to the Stages 1 and 3 are of remarkably similar tectonostratigraphic significance. They reflect a 'composite tectonic event' comprising an uplift/regression pulse, followed by a rapid subsidence/onlap. Each composite tectonic event is here considered to represent one growth pulse in the progressive evolution of the accretionary wedge system, while the middle Messinian - Early Pliocene phases of basin fill and tectonic inversion (Stage 2), and the Late Pleistocene - Recent uplift phase (Stage 4) reflect the increase of regional stress in the Central Mediterranean. |
| Geometric constraints on the development of shear bands in rocks | 1991 | Passchier, C.W. | 70(2) | Shear bands in ductile shear zones have been used to determine sense of shear, but they also contain information on the flow pattern and flow history in shear zones. A simple geometric analysis of two types of shear bands, S-C fabrics and extensional crenulation cleavage (ECC) fabrics, is used to delimit possible flow patterns and flow history in shear zones where such structures develop. S-C fabrics can form in bulk simple shear during the entire active period of a shear zone. Development of ECC-fabrics as observed in nature, however, is favoured by bulk extension of the shear zone as a whole. This means that such fabrics preferentially develop in an extensional tectonic setting, or in a constrictional tectonic setting during late stages of activity on ductile shear zones, when flow in the zone develops from bulk simple shear to bulk non-coaxial extension. |
| #REF! | 1991 | 70(2) | ||
| Messinian stratigraphy of the Nijar Basin (S.E. Spain) and the origin of its gypsum-ghost limestones | 1991 | Poel, H.M. van de | 70(3) | The Middle Messinian of the Nijar-Carboneras area (S.E. Spain) shows common rapid lateral transitions from thick-bedded massive gypsum to brecciated or massive limestone with voids and pseudomorphs after gypsum crystals. These 'gypsum-ghost limestones' are underlain by, and interbedded with, laminated marly sediments that contain a restricted marine microfauna attesting to oxygen-deficient conditions. Oolite-rich series of the basin margin, which include gypsiferous stromatolite and a few restricted marine fauna levels, probably constitute a lateral equivalent. Upper Messinian fine-grained laminites of the central part of the basin contain brackish fossil assemblages and numerous tongues of coarse clastic material derived from the basin margins. The gypsum-ghost limestones are interpreted to be essentially the product of two phases and types of diagenesis. Microbial sulfate-reduction during oxygen-deficient periods of the Middle Messinian first played a role in their formation. An important fresh-water diagenetic phase took place later, probably in the Late Messinian. |
| Application of a modified peel-section technique to the study of siliclastic rocks | 1991 | Cibaj, I. | 70(3) | The acetate peel section technique has been successfully used to the study of carbonate rocks. It also appears as a very helpful tool to the study of well-cemented siliciclastics: fine internal sedimentary features and paleocurrent data have been revealed from a series previously considered as monotonous and poor in sedimentary structures. |
| Model calculations on intrusive cooling and related coalification of the Peel-Erkelenz coalfield (The Netherlands and Germany) | 1991 | Erren, H.; Bredewout, J.W. | 70(3) | An analytical solution of the simplified heat equation was calculated and applied to a 3D model of the intrusion below the Peel-Erkelenz coalfield. The calculated thermal history was converted to coal ranks with an empirical integral expression. Using a least squares fit of observed coal rank data, an initial temperature of (800 + 100) °C for the intrusion was obtained. Calculated vertical coal rank gradients are comparable with those observed in the Ibbenbüren coalfield (Bramsche intrusion, FRG). A detailed 2D finite difference calculation, using the complete heat equation on a 5-layer section in the area, confirmed the analytical results. It also proved that: 1) effects of radiogenic heat production are negligible compared to cooling magma effects; 2) if the coal is remote from the magma, latent heat effects can be simplified by adding 300 °C to the initial intrusion temperature; 3) lateral and vertical variations in rock properties have negligible influence on coalification compared to cooling magma effects; a homogeneous model is therefore a good approximation. |
| The eastern Mediterranean climate at times of sapropel formation: a review | 1991 | Rohling, E.J.; Hilgen, F.J. | 70(3) | Sapropel formation in the eastern Mediterranean coincided closely with minima in the precession index. Such minima occur approximately every 21000 years. At such times perihelion falls within Northern Hemisphere summer. Minima in the precession index are characterized by intensified Indian Ocean (summer) SW monsoonal circulation, which enhanced discharge of the river Nile into the eastern Mediterranean. However, by compiling paleoclimatological data from the literature, the influence of the monsoon is shown to have reached only as far as the southern Sinai Desert. Therefore, it does not account for contemporary humid phases in the northern borderlands of the eastern Mediterranean, which seem to have been characterized mainly by increased summer precipitation. We argue that increased (summer) precipitation along the northern borderlands of the eastern Mediterranean, at times of sapropel formation, was probably due to increased activity of Mediterranean (summer) depressions. Forming predominantly in the western Mediterranean and tracking eastwards, such depressions tend to lower the excess of evaporation from the eastern Mediterranean relative to that from the western basin. Picking up additional moisture along their eastward path, such depressions also redistribute freshwater within the complex eastern Mediterranean water balance. The increase in runoff and the related flux of nutrients and continental organic matter that resulted from the increased precipitation on the northern borderlands of the eastern Mediterranean, at times of sapropel formation, presumably provided a substantial addition to that which entered the eastern Mediterranean via the Nile. |
| Conodont color alteration and microdolomite composition - implications to the Muschelkalk limestones (Upper Triassic) overlying the Upper Cretaceous intrusive body of the Vlotho Massif (Weserbergland, Northwest Germany) | 1991 | Nöth, S.; Bruckschen, P.; Richter, D.K. | 70(3) | The conodont color alteration index (CAI) and the microdolomite composition (MC) were used to evaluate the thermal diagenesis in the Upper Muschelkalk (Middle Triassic) limestones overlying the Cretaceous intrusive body of the Vlotho Massif in the southern part of the Lower Saxony Basin in Northwest Germany. The validity of these two methods is discussed. The CAI exhibits a greater accuracy at high levels of organic metamorphism, especially above temperatures of 180°C, whereas the microdolomite composition is an excellent indicator for differentiating low-temperature diagenesis. The good positive correlation between % Rm and CAI can probably be attributed to the fact that in both cases organic matter changes during diagenesis. The maximum palaeotemperature range of 300-345°C ascertained by the CAI value of 5 in sediments directly over the Vlotho Massif, lies higher than the temperatures estimated with the help of other geothermometers. |
| Deformation in the Revenue granite pluton, Mount Isa Inlier, Australia | 1991 | Passchier, C.W. | 70(3) | The Revenue granite pluton in the Mary Kathleen Zone of the Mount Isa Inlier, Queensland, has a complex internal structure due to the interference of two Early-Proterozoic phases of ductile deformation. The granite intruded into calcsilicates dated at 1780-1760Ma. A D1 shape fabric, which is present throughout the pluton, is due to intense deformation in a low angle high strain zone, probably associated with a regional phase of crustal extension. A D2-event of intense E-W shortening around 1550 Ma caused folding of the early shape fabric in the granite, and tight folding of bedding in the country rock. The present dome-shape of the pluton is mainly an effect of non-cylindrical D2 folding. |
| The structural configuration of the eastern Sierra de los Filabres, SE Spain | 1991 | Bakker, H. | 70(3) | The eastern Sierra de los Filabres is constituted of several generations of thrust sheets which were formed during entirely different tectonic events. The oldest thrust sheets are present in the Mulhacen Complex. They were formed during the first phase of penetrative Alpine deformation, Dx-1, which is related to Cretaceous continent-continent collision. The second phase of penetrative deformation Dx is also related to this collisional event. During the second phase of thrust sheet formation, Dx+1 rocks from the Alpujarride Complex were placed directly on top of the Mulhacen Complex. These thrust sheets are related to a regional phase of heterogeneous extension and crustal thinning, active during the Late Oligocene to Early Miocene. At least two subsequent phases of folding and overthrusting, Dx+2 and Dx+3 strongly modified the original superposition of tectonic units. Dx+2 deformation , characterized by strain partitioning, resulted in a detachment zone. In the northeastern part of the Sierra de los Filabres an imbricate stack was formed. During Dx+3 the detachment zone was reactivated. These movements were followed by development of low-angle extensional faults, dextral tear faults and finally a foreland dipping duplex. For the Dx+3 structures a Miocene age is suggested. Dx+1, Dx+2, and Dx+3. deformations have largely determined the present structure of the eastern Sierra de los Filabres. |
| Book reviews | 1991 | Linden, W.J.M. van der; Boekschoten, G.J.; Finlow-Bates, T.; Kleverlaan, K. | 70(3) | |
| Holocene water level development in The Netherlands' river area; implications for sea-level reconstruction | 1991 | Dijk, G.J. van; Berendsen, H.J.A.; Roeleveld, W. | 70(4) | Plotting of radiocarbon datings of samples from the base of peat layers on the flanks of fossil river dunes results in time-depth graphs that can be interpreted as curves of the local rise of the groundwater table. Combination of data from individual sites makes it possible to reconstruct groundwater gradient lines at selected moments. All gradient lines appear to consist of a steep upper part (river dominated) and a level lower part (sea level dominated). Between 6750 and 2850 BP the knickpoint between the two wandered some 10km upstream. During all of the Holocene the area east of Leerdam remained outside the direct influence of the sea. Irregularities in individual curves in the downstream area - if not caused by dating errors - may represent varying rates of MSL rise, varying tidal range and a varying floodbasin effect. For the pre-5000 BP period, assumed sea level dominance in the downstream area is not consistent with the general evidence on the position of the sea level in The Netherlands. This situation is possibly due to less tectonic subsidence in the southwestern coastal sector. |
| Quartz-based optical dating of Weichselian coversands from the eastern Netherlands | 1991 | Stokes, S. | 70(4) | Optical dates are presented for Quaternary aeolian coversand units which are separated by the Usselo Layer (Allerød Interstadial). The dates, which were generated using the sand-sized quartz fraction of the sediments, are in direct agreement with geological expectation and indicate considerable potential of the optical method for dating similar Weichselian coversand sequences throughout NW Europe. The intrinsic advantage of the optical dating method over conventional thermoluminescence (TL) dating of sediment lies in the rapidly sunlight-bleachable nature of the optical dating signal, namely optically-stimulated luminescence (OSL). This advantage over TL is demonstrated by an artificial bleaching experiment. |
| Eustatic sea level and depth of a Late Cretaceous epicontinental sea: an example from NW Europe | 1991 | Bless, M.J.M. | 70(4) | The claim that the Late Cretaceous (and more specifically the Campanian-Maastrichtian) global sea Ievel was considerably higher than that of today is partly based on the assumption that one can recognize areas which were tectonically immobile from the Cretaceous onwards. Careful examination of some of these regions in NW Europe suggests, however, that differential (inverse) warping and tilting during and/or since the Cretaceous has invalidated their use as reliable gauges for Late Cretaceous high stands. In addition, the original depth of Late Cretaceous epicontinental seas may have been much shallower than generally assumed. In the literature it is frequently suggested that the NW European flint-bearing chalk was deposited at a depth of 100 to 300 m or more. But this study shows that, for example, the Late Campanian and Maastrichtian flint-bearing chalk in the Hautes Fagnes area of NE Belgium accumulated at a depth of less than 45 to 65 m, matching the Modern deposition of coccolith ooze in the Caribbean Belize Lagoon at depths of less than 40m at places. |
| Aspects of the Late Jurassic and Cretaceous history of the Netherlands | 1991 | Burgers, W.F.J.; Mulder, G.G. | 70(4) | Three depth structure maps, two subcrop maps, two isopach maps and two structural cross-sections are enclosed. They illustrate the results of uplift and erosion and of subsequent subsidence and sedimentation that occurred in The Netherlands area during the Jurassic and cretaceous. Near the end of the Middle Jurassic, rapid sedimentation began in narrow and restricted basins after a period of uplift and erosion, known as the Mid Kimmerian tectonic phase. This sedimentation was followed by another period of uplift and erosion, known as the Late Kimmerian tectonic phase, near the beginning of the Cretaceous. Subsequent Cretaceous sedimentation started in the centres of the Upper Jurassic basins and gradually spread towards the Mid to Late Kimmerian highs. These highs were the last areas covered with sediments near the end of the Cretaceous. The Mid Kimmerian Unconformity, which can be mapped in the centres of the Upper Jurassic basins, was itself eroded in the areas of the Mid to late Kimmerian highs during the Late Kimmerian phase. Sedimentation during the Cretaceous, particularly the Late Cretaceous, was more widespread than during the Late Jurassic. Near the end of the Cretaceous, inversion and erosion took place. This erosion was strongest near the centres of the Upper Jurassic basins, where a substantial package of Cretaceous, Jurassic and locally Triassic or older sediments was eroded. This explains the present decreasing thickness of the Upper Jurassic and Lower Cretaceous sequence and of the Upper Cretaceous sediments towards the centres of the former Upper Jurassic and Lower Cretaceous basins. |
| Aspects of the Late Jurassic and Cretaceous history of the Netherlands | 1991 | Burgers, W.F.J.; Mulder, G.G. | 70(4) | Enclosure 1 |
| Aspects of the Late Jurassic and Cretaceous history of the Netherlands | 1991 | Burgers, W.F.J.; Mulder, G.G. | 70(4) | Enclosure 2 |
| Aspects of the Late Jurassic and Cretaceous history of the Netherlands | 1991 | Burgers, W.F.J.; Mulder, G.G. | 70(4) | Enclosure 3 |
| Aspects of the Late Jurassic and Cretaceous history of the Netherlands | 1991 | Burgers, W.F.J.; Mulder, G.G. | 70(4) | Enclosure 4 |
| Aspects of the Late Jurassic and Cretaceous history of the Netherlands | 1991 | Burgers, W.F.J.; Mulder, G.G. | 70(4) | Enclosure 5 |
| Aspects of the Late Jurassic and Cretaceous history of the Netherlands | 1991 | Burgers, W.F.J.; Mulder, G.G. | 70(4) | Enclosure 6 |
| Aspects of the Late Jurassic and Cretaceous history of the Netherlands | 1991 | Burgers, W.F.J.; Mulder, G.G. | 70(4) | Enclosure 7 |
| Aspects of the Late Jurassic and Cretaceous history of the Netherlands | 1991 | Burgers, W.F.J.; Mulder, G.G. | 70(4) | Enclosure 8 |
| Depositional pattern and reservoir heterogeneity of Tipam Sand-2, Lakwa Field, India | 1991 | Singh, L.; Elias Ahmed, A.; Verma, R.P.; Murthy, R.V.S. | 70(4) | This paper describes the importance of the braided channel environment for the entrapment of hydrocarbons, the porosity pattern, the reservoir heterogeneity, the sweep efficiency and the identification of bypassed oil areas, in the Miocene Tipam Sand-2 of the Lakwa Oilfield. The growth-faulted structure has an oil bearing area of 20 km2. The oil gravity varies from 20.7 to 32° API. The Tipam Sand-2 oil pool is the largest among multiple pools in the Tipam Sandstone Formation. There is a marked coincidence of the structure of the field and the thickness of the sand within its depocentre. The sandstone was deposited in a composite braided channel river system. The sand member is characterised by longitudinal and transverse bars which are flanked by marginal, abandoned and slough channel facies. The bars are covered by overbank shales of flood periods. The porosity pattern is dominated by high porosity areas within the longitudinal and transverse bars. The low porosity areas along the flanks of the structure are marked by low energy deposits. Two preferential permeability trends are parallel to the E-W running bar crests, the primary trend, and to the secondary NE-SW or accretionary trend. These areas correlate well with the well production rates, advance of waterfront and areas of better sweep efficiency. The rise in oil-water contact is controlled by reservoir rock permeability trends and oil withdrawal rates. Infill drilling electrolog data indicate a significantly differential rise of the oil-water contact from the initial oil-water contact (5-8 m), as compared to the nearby wells (10-15 m). Integrating the depositional pattern. The reservoir heterogeneity and the withdrawal rates, a reservoir zoning is attempted to identify areas of bypassed mobile oil, especially along the southern part of the structure. Watercut analysis indicates that the preferential paths are along the permeability trends. Water coning is controlled by the presence of the overbank shales, larger clearance of perforations from oil-water contact, presence of shaly sands, laminations of silt, mica and cross-bedded foreset laminae. |
| Book reviews | 1991 | Vandenberghe, J.; Kerp, J.H.F.; Boekschoten, G.J.; Campbell, A.E. | 70(4) | |
| Editorial | 1992 | Priem, H.N.A. | 71(1) | |
| Biostratigraphic control of Neogene volcanism in Sierra de Gata (south-east Spain) | 1992 | Serrano, F. | 71(1) | The chronology of the magmatic activity in Sierra de Gata is established on the basis of the study of planktonic foraminifera in sediments related to volcanites. Data were obtained from intercalated sediments, from fillings of fissures and holes in the volcanites, as well as from deposits in nearby basins, which were weakly affected by the volcanic activity. Volcanic activity began (stage A) with small submarine flows (Ao phase) intercalated in pelagic marls containing Globigerinoides bisphericus but without Praeorbulina glomerosa, which can be located at around the boundary between the N.7 and N.8 zones of Blow (uppermost Burdigalian). More significant eruptions are observed in association with sediments containing Praeorbulina glomerosa (N.8 zone, Lower Langhian) and others deposited around the FAD of Globorotalia praemenardii, which is used as marker for the Langhian-Serravallian boundary (phases A1 and A2 respectively). As regards the most important period of generalized volcanic activity in the region (stage B), sediments are found containing the Neogloboquadrina siakensis group, Globorotalia menardii and Globigerina nepenthes (N.14 zone, Upper Serravallian) and the dextral-coiling Neogloboquadrina acostaensis group (N.16 zone, Lower Tortonian and lower part of the Upper Tortonian). New volcanic emissions took place during the Late Tortonian and the earliest Messinian, but they only affect local areas of Sierra de Gata: the group of Coastal Volcanoes arose in the littoral area during the early and/or middle part of the Late Tortonian; the Rodalquilar Group developed in the central sector within the Late Tortonian-earliest Messinian interval; finally, the Carboneras lJpper Volcanites were emitted in the northern area and also in the Serrata de Níjar shortly after the Globorotalia mediterranea FAD (Early Messinian). The biostratigraphic results are compared with the radiometric ages of the volcanites, and agree well for stages A and B, and for the Coastal Volcanoes, but there is a considerable disagreement between them for the Rodalquilar Group. Radiometric datings of the Carboneras Upper Volcanoes are not available. |
| Acanthoscaphites tridens (Kner, 1848) (Ammonoidea) from the Vijlen Member (Lower Maastrichtian) of Gulpen, Limburg, The Netherlands | 1992 | Jagt, J.W.M.; Kennedy, W.J.; Burnett, J. | 71(1) | A specimen of the scaphitid ammonite Acanthoscaphites tridens (Kner, 1848) was collected in situ from the lower part of the Vijlen Member (Gulpen Formation, sensu Felder,1975b) as exposed at a building site near the Sophianum school southwest of Gulpen, southern Limburg (The Netherlands). This species has been widely quoted as an index for the lowest ammonite zone of the Maastrichtian Stage, but its precise age was poorly known. Associated nannofossils show the Gulpen specimen to come from nannofossil zone CC 24 (Reinhardtites levis Zone). A calibration of nannofossil and belemnite zones indicates it to be no older than the Belemnella occidentalis Zone (upper part of Belemnella sumensis Zone of Schulz, 1979), which is well above the base of the Maastrichtian Stage. The Gulpen specimen is thus younger than the type occurrence in the Ukraine which is in nannofossil subzone CC 23B, equivalent to the upper part of the Belemnella lanceolata Zone (upper Belemnella lanceolata to basal Belemnella sumensis Zone of Schulz, 1,979). |
| Quantification of pore geometry in carbonates using image analysis; Upper Permian (Zechstein) of Denmark | 1992 | Frykman, P. | 71(1) | Image analysis of Permian Zechstein carbonate samples has aided quantification of pore geometry parameters. Total porosity has been measured, using image analysis, from randomly selected thin sections. These porosity measurements have then been compared to core analysis measurements of the same samples. Pore surface parameters derived from the image analysis can be used to characterize mouldic porosity, and to estimate permeability. Cumulative porosity curves related to pore section size are used to group the samples in classes with different pore geometry. |
| The flow-banded rhyolite dome of San Bartolomé (Alcoroches, Guadalajara), a novelty for Spain | 1992 | Linthout, K.; Everts, A.J. | 71(1) | In the Keltiberian Massif of Nevera (SE Guadalajara, Spain) a Permian endogenous dome of flow-banded felsophyric rhyolite is recognized. Polymict, poorly-sorted, matrix-supported pyroclastica along the vent of the body indicate a gas-rich blow-out prior to its emplacement. The breccias comprise, besides fragments of paleozoic sedimentary country-rock, porphyritic phenodacite and phenoandesite, indicating the existence of less differentiated calc-alkaline subvolcanic rock in the underground. |
| Paleogeographic and climatic evolution of the Moliniacian (lower Visean) in southeastern Belgium | 1992 | Peeters, C.; Muchez, P.; Viaene, W. | 71(1) | A detailed biostratigraphical subdivision of the lower Visean (Moliniacian) in southeastern Belgium is not possible. Therefore correlations are based on the facies evolution. Based on these correlations, the paleogeographical evolution during the early Visean can be reconstructed. During the early Moliniacian, open marine subtidal limestones were deposited. Near the coast, these sediments were subsequently dolomitized and intense karstification took place under humid conditions. Basinwards, algal laminites formed in the intertidal zone. The continental interval was followed by open marine sedimentation above wave base. At the end of the early Moliniacian, beginning of the middle Moliniacian, the depositional environment became shallower. A second continental interval occurred near the Brabant Massif and a sabkha developed further to the south (i.e. basinwards) in a semi-arid to arid climate. The subsequent transgressive trend was very gradual. Middle Moliniacian sedimentation occurred in an evaporitic lagoonal and intertidal setting. The peritidal sediments contain numerous paleosol horizons, which formed under semi-arid conditions. Upper Moliniacian limestones, were deposited on a shallow open marine shelf. The paleolatitudinal position of Euramerica during the early Visean was close to the equator and normally a humid climate must have been present. The recognized semi-arid intervals are due to the large Gondwana landmass situated south of the equator, deflecting rains away from Euramerica. |
| On complex dermal elements in Loganellia species (Agnatha, Thelodonti) from the Upper Llandovery of Scotland (I.G.C.P. 328 Contribution) | 1992 | Vergoossen, J.M.J. | 71(1) | Two specialized squamation types from the Upper Llandovery of Scotland are described in detail for the first time. One type occurs mainly as fused structures here referred to as scale sets. They probably belonged to the thelodont gents Loganellia. Their morphology is discussed and ideas are put forward about their generation, function and topography. The second squamation type is here called denticulated plate, type A and denticulated plate, type B. The morphology of these plates is compared with that of the scale sets, with which they share some characteristics. The type A plates were discovered in the branchial area of a Loganellia specimen and are possibly fragments of an internal dermal cover interpreted as a complex of gill rakers. |
| εNd(T) variation in an Early Proterozoic actinolite skarn, Sweden, reflecting felsic volcanite-seawater interaction | 1992 | Valbracht, P.J. | 71(1) | Two neodymium isotopic analyses of least-altered metavolcanites from the Hjulsjö area and six analyses of albitized and actinolitized metavolcanites from Ställbergstorp farm south of Hjulsjö show variations in εNd(T) values that point to two-stage mixing involving seawater- and rock-dominated fluid-rock interaction. In a first stage felsic volcanites are albitized and leached in LREE. Some of these extremely LREE leached felsic volcanites show very negative εNd(T) values. Thus, leaching occurred by a fluid with a long crustal history, probably modified seawater containing Nd derived from an Archaean erosional area. In a second stage redeposition of LREE previously leached from the volcanic pile accompanies the formation of actinolite aggregates in the leached metavolcanite and results in an increase of εNd(T). |
| Unravelling the progressive strain-history of rocks in metamorphic areas, the example of the Somero area, SW Finland | 1992 | Konert, R.J.; Stel, H.; Reemst, P.H.M. | 71(1) | The progressive three-dimensional strain path of rocks during their metamorphic evolution and the relation between strain and structural elements were studied in the Somero area, SW Finland. All the methods used involve two basic steps: determination of two-dimensional strain ellipses on several planes and subsequent calculation of three-dimensional strain ellipsoids from the two-dimensional strain ellipses. Strain analyses were performed on: (1) deformed objects in agglomerates and xenoliths, providing finite strain values and (2) the spatial distribution pattern of cordierite and garnet porphyroblasts, reflecting F2 and F3-strain. The two types of strain markers have not been found together in one exposure. A test of the spatial distribution pattern method in terms of shape and orientation has been applied to cordierite porphoryblasts. These blasts show deformation substructures indicative of dislocation creep and have ellipsoidal shapes. Their shapes correlate closely with the results of the spatial distribution pattern method. The methods provide the possibility of obtaining strain data in metamorphic areas. |
| Comment on: the structural configuration of the eastern Sierra de los Filabres, SE Spain by H. Bakker: Geologie en Mijnbouw 70: 287-298,1991 | 1992 | Jong, K. de | 71(1) | |
| Book reviews | 1992 | 71(1) | ||
| The April 13, 1992 earthquake of Roermond (The Netherlands); first interpretation of the NARS seismograms | 1992 | Paulssen, H.; Dost, B.; Eck, T. van | 71(2) | The Roermond earthquake of April 13th,1992,was recorded by stations of the seismological NARS network located in The Netherlands, Germany, and Belgium. The data of this network allowed an accurate determination of epicenter, focal depth, origin time and focal mechanism of the event. By an arrival time inversion of P-wave onsets, the epicenter and focal depth were located at 51°10.2' N 5°58.3' E and 21 km, respectively. The relatively large focal depth of about 20 km is confirmed by travel time modelling of additional, later arriving, P-wave phases. The average crustal structure beneath the network was implicitly obtained by matching the travel time variations to the different stations. The earthquake mechanism, i.e. the direction of movement along the fault plane, is inferred by modeling the polarities and amplitudes of the various phases. The NARS data are best fitted by a dip-slip movement along a fault plane with a strike of 124° and a southwesterly dip of 70° or by dip-slip movement along the perpendicular plane with the same strike. The good agreement of the attitude of the first fault plane with that of the Peel Boundary Fault, combined with the fact that the hypocentral location plots on the downward extension of that fault, indicates that a downward movement of the Roer Valley Graben has taken place along the Peel Boundary Fault. |
| Dominant processes and sediment mobility on a sandy tidal flat: Martens Plate, German Wadden Sea | 1992 | Davis, R.A. | 71(2) | Monitoring of bedforms and depth of sediment mobility on Martens Plate in the German Wadden Sea shows that waves are more important processes than tides on a back-barrier intertidal environment subjected to tidal ranges of 3m. The tidal flat surface is wave-dominated and produces only wave or combined-flow ripples. The depth of sediment disturbance in this area is generally less than 3 cm. At the tidal channel margins, small ebb-oriented dunes are dominant. They exhibit a depth of sediment disturbance of up to 20 cm and migrate less than one wave length during a single tidal cycle. The areal extent of wave-dominated sedimentation is several times that of tide-dominated processes. Overall depth of disturbance is approximately equal to bedform height regardless of dominant processes or geomorphic location. |
| Reservoir compaction and surface subsidence resulting from oil and gas production | 1992 | Hasselt, J.P. van | 71(2) | Reservoir compaction and associated surface subsidence have been the subjects of theoretical and experimental research in Shell since the 1950's. Analytical models were developed for translating reservoir compaction to surface subsidence. The validity of these models was recently confirmed by field observations and finite element studies for the Groningen gas field in The Netherlands. Experimental methods for determining the compaction coefficient on core samples in the laboratory have been developed and refined and can now closely simulate reservoir conditions. Nevertheless, data from the Groningen field show that a discrepancy remains between the compaction coefficient measured on core material and the value derived from field observations. To resolve this discrepancy, which cannot be explained by existing compaction theories, a better understanding is required of the physical mechanisms of sandstone compaction and of the way they operate under laboratory and field conditions. Current experimental and theoretical research is aimed at the formulation of a constitutive compaction law. With such a law, predictive models that use experimentally determined rock parameters as input can be formulated for reservoir compaction. |
| Surface subsidence in The Netherlands: the Groningen gas field | 1992 | Doornhof, D. | 71(2) | In The Netherlands, surface subsidence as a result of hydrocarbon production has become more and more a subject of public interest because of the environmental and political aspects. The most pronounced case of this type of subsidence is demonstrated by the Groningen gas field situated in the north of The Netherlands. Since the start of gas production in 1963, the surface over the centre of the field has subsided by some 18 cm. To monitor reservoir compaction and surface subsidence in Groningen on a regular basis, an extensive monitoring programme was set up by the Nederlandse Aardolie Maatschappij BV, the operator in the Groningen concession. This programme includes yearly levelling surveys, measurements of shallow formation compaction (0 to 400m below surface) in 14 observation wells and in situ reservoir compaction measurements in 11 deep observation wells drilled specifically for this purpose. Prognoses of gas-production-induced surface subsidence, which are demanded by the State Supervision of Mines, are made using a three-dimensional grid block model to describe the gas-bearing reservoir and the associated aquifer. In the year 2050, when it is planned to abandon the gas field, the maximum subsidence (over the centre of the field) is calculated to be between 33 and 43cm. |
| Environment of ore formation and anchizonal metamorphism in Pb-Zn-fluorite-barite deposits of the Benue Trough, Nigeria | 1992 | Akande, S.O.; Hoffknecht, A.; Erdtmann, B.D. | 71(2) | Lead-zinc-fluorite-barite vein ore-bodies occur in the Benue Trough within the Lower Cretaceous (Albian) sequence of this intracontinental rift structure. The veins are distributed in a series of N/S and NW/SE fracture systems cross-cutting the Trough axis. Ore-hosting sediments range from deep marine carbonaceous shale in the lower Benue area to platform carbonates (middle Benue) and fluvial to deltaic sandstones in the upper Benue area. These sediments are invaded by mafic to felsic intrusives which are either pre or post-ore. Fluid-inclusion temperatures of vein minerals range from about 105°C to over 200°C and ore-fluid salinities vary from 14 to 25 equivalent weight % NaCl. Reflectance (Rm) of finely dispersed vitrinite in the ore-hosting sediments reaches up to 4.3% at vein centres in the lower Benue, decreasing to ca.2.6% at about 2km from known veins. In the middle Benue, Rm values vary from 0.9 to 1.7%. This suggests that ore-hosting shales in the lower Benue are slightly metamorphosed having been heated to an estimated temperature of about 240°C before the Santonian peak of tectonism. Illite-crystallinity indices on these shales in places suggest anchi to epimetamorphic contact aureoles adjacent to intrusive bodies. Our data suggest that the Benue ore-bodies were formed by hot, evaporitic, basinal brines set into motion by the high geothermal gradient accompanying continental rifting. Anchimetamorphic conditions were reached in shales of the lower Benue area where the largest ore-bodies occur. |
| Sedimentology and diagenesis of the ankeritized basal Zechstein conglomerate in the Campine Basin (Bree borehole, NE Belgium) | 1992 | Craen, M. de; Swennen, R. | 71(2) | The transgressive basal Zechstein conglomerate penetrated by the Bree borehole (NE Belgium) is 3.15m thick and has a polymict composition. Originally, clasts consisted predominantly of limestone, dolomite, sandstone and quartzite. Pervasive replacement by ankerite has affected the carbonate clasts, especially in the middle part of the conglomerate layer. Ankerite also forms a pore-filling cement. An origin from Fe-rich waters derived from the underiying Carboniferous clastics is indicated by the chemical and isotopic (depleted δ18O and δ13C) characteristics of the ankerite. An evolution in fluid composition due to increasing water/rock interaction is reflected in chemical and isotope variations. The preferential precipitation of both replacive and pore-filling ankerite in the middle part of the conglomerate, reflects channeling of ankerite-bearing waters in this originally highly porous and permeable part. |
| Subsurface facies analysis of the Namurian and earliest Westphalian in the western part of the Campine Basin (N Belgium) | 1992 | Langenaeker, V.; Dusar, M. | 71(2) | Geophysical wireline logs from recent boreholes were used to unravel the sedimentary history of the Namurian and earliest Westphalian in the western part of the Campine Basin. The study comprises 4 wells with petrophysical data (Merksplas, Poederlee,DZH14, DZH15) and 1 corehole (Turnhout). Paleogeographical cartoons are presented for the studied interval together with some examples of the log-response of the sedimentary sequence. The pendleian is missing in the Campine Basin. The Namurian sedimentary sequence starts with Arnsbergian to Alportian basinal mudstones. These are followed by two turbidite-fronted delta sequences which prograded towards the north into the basin. From the late Yeadonian onwards, four successive shallow water sheet-deltas developed. The upper part of the earliest Westphalian Ransart Member is formed by braided river deposits, situated underneath the Finefrau Nebenbank Marine Band. This succession corresponds very well to the Namurian sequence of a marginal part of the English Pennine Basin, the Gainsborough Trough, although the timing of the events is somewhat different. |
| Reservoir modelling of the Vlieland Sandstone of the Kotter Field (Block K18b), offshore, The Netherlands | 1992 | Jong, M.G.G. de; Laker, N. | 71(2) | The Vlieland Sandstone reservoir of the Kotter Field has significantly outperformed the original production forecast. In view of an anticipated decline of the oil production, a geological re-evaluation was carried out in 1989-1990, with the aims of contributing to increasing productivity and improving sweep efficiency. Three closely related models have been developed. The Idealised Vertical Facies Association is a sedimentological model based on core material and represents an idealised vertical sequence of genetically related sedimentary facies. The model describes an overall regressive trend, produced by the progradation of a barred shoreface sequence, which is bounded top and bottom by transgression-related erosional surfaces. Within the reservoir interval, the trend described by the Idealised Vertical Facies Association is cyclically repeated. The Field Geological Layer Model forms the synthesis of the geological knowledge to-date and presents a three-dimensional description of the reservoir resulting from the integration of core, wireline log and seismic data. It is characterized by a minimum of four stacked regressive-transgressive cycles (each representing partial development of the Vertical Facies Association) and comprises a total of thirteen, geologically distinct layers. The Field Engineering Layer Model has been developed by modification of the Geological Layer Model in order to meet the specific input requirements of a reservoir performance simulation study and to improve cost-effectiveness. Up to the end of the geological modelling study (Dec. 1990), the results of the simulation study were satisfactory. |
| Book reviews | 1992 | Woodside, J.M.; Meer, J.J.M. van der; Boekschoten, G.J.; Seyhan, E.; Linthout, K. | 71(2) | |
| Plio-Pleistocene scour hollows in the Southern Bight of the North Sea\ | 1992 | Liu, A.C.; Batist, M. de; Henriet, J.P.; Missiaen, T. | 71(3) | Scour hollows in the Belgian and French sectors of the North Sea have been studied from seismic records and borehole data. These hollows are thought to have formed by tidal scouring and fluvial erosion, as there is no evidence of any formed by subglacial scouring. The Murray Pit is filled by Neogene sediments and was probably eroded during the Early Pliocene. The remainder of the hollows are incised into the top of the Paleogene, and occur essentially within fluvial paleovalleys. They were most likely formed during phases of Late Pleistocene sea-level rise and most have been filled by Late Pleistocene marine sediments. |
| Neogene strike-slip faulting in southeastern Spain: fhe deformation of the pull-apart basin of Abarán | 1992 | Straaten, H.C. van der | 71(3) | The Abarán Basin is interpreted as a Neogene pull-apart basin that developed along an east-striking right-slip fault zone in the thin-skinned fold-and-thrust belt of the Betic foreland (External Zone). Apart from showing well known strike-slip characteristics, the fault zone is typified by drag and imbrication along subvertical faults. Considerable right-slip faulting before, during and after basin development is demonstrated by the unconformable contact between the basin and its faulted 'basement', by the formation and deformation of the basin, and by the lateral separation between basin and hinterland. The Abarán Basin shows a typical rhombic shape determined by synsedimentary faults. The fault configuration is interpreted as a releasing overstep: the northern and southern basin margin were controlled by two major right-hand stepping, east-striking right-slip faults connected by minor northwest-striking normaloblique slip faults bounding the basin in the east and the west. The progressive opening of the basin in response to the right-slip along the fault zone, generated lateral shear and extension parallel to the strike-slip basin margins throughout the sedimentation history. Right-slip led to en-echelon folds and progressive drag. Extension resulted in an overall deepening of the basin and activated normal faults. Due to movements along normal faults dipping away from the basin centre, older sediments were torn apart while being tilted. The resulting depression in the centre of the basin was subsequently filled by younger sediments that accumulated next to older deposits. Repetition of this mechanism with basinward fault progradation, generated downlapping sediment packages that step over normal faults. |
| The tectono-metamorphic evolution of the Veleta Complex and the development of the contact with the Mulhacen Complex (Betic Zone, SE Spain) | 1992 | Jong, K. de | 71(3) | Four phases of penetrative deformation (D1vel to D4vel) have been distinguished in the uppermost 0.5 km of the Veleta Complex, the lowest in the stack of four nappe complexes of the Betic Zone.-Ihe contact of the Veleta Complex with the overlying Mulhacen Complex is parallel to S2, which is the main tectonic foliation in both complexes. The rotation sense of synkinematically grown D2vel garnets and the asymmetry of preferred orientations of quartz c-axes in mylonites in the highest part of the Veleta Complex demonstrate top-to-the-west shear, pointing to a westward movement of the Mulhacen Complex. The nappe contact was folded and locally overturned during D3vel, demonstrating that the tectonic contact was formed during D2vel. During D4vel the nappe contact was reactivated as shown by concentration of extensional structures in the uppermost 20m of the Veleta Complex. It is argued that reactivation occurred during overthrusting of the Alpujarride Complex at higher structural level. Although metamorphism of the graphite-rich pelites has not resulted in characteristic mineral assemblages, the relationship between mineral growth and deformation shows that, during the early tectonic evolution, both pressure and temperature in the Veleta Complex were lower than in the overlying Mulhacen Complex. |
| Lithology and biostratigraphy of Upper Cretaceous-Paleocene carbonates in the Molenbeersel borehole (NE Belgium) | 1992 | Bless, M.J.M.; Dusar, M.; Felder, P.J.; Swennen, R. | 71(3) | The Molenbeersel well was drilled by the Belgian Geological Survey as a reconnaissance well in the Rur (=Roer) Valley Graben (NE Belgium). Paleocene and Upper Cretaceous (Upper Maastrichtian) carbonates were traversed between 1223--1283.17 m of which interval the major part was cored. A sedimentological and biostratigraphical analysis allows the recognition of three megasequences which correlate with thicker successions on the adjoining Brabant Massif, including the Maastrichtian type area. These megasequences testify to repeated flooding events on the inverted Rur Valley Block. Each of these is characterized by a basal conglomerate overlain by glauconite-rich deposits. In the upper two megasequences these deposits pass into pure calcareous strata. All deposits indicate shallow nearshore environments above storm wave base. Occasional emergence occurred as indicated by karstified horizons. Fossil assemblages belong to the boreal province with the exception of an immigration of Mediterranean organisms in the middle megasequence. This may be related to a period of tectonic relaxation of the Rur Valley Block during the Late Maastrichtian. |
| Pressure and temperature history of a low-pressure transitional granulite area, Turku, SW Finland | 1992 | Duin, J.A. van; Nieman, C.P. | 71(3) | The Turku granulite area forms the westernmost of several low-pressure granulite domains in the Svecofennian Schist Belt of southern Finland. The area shows a gradual transition from amphibolite to granulite facies metamorphism. Estimated peak metamorphic conditions, based on geothermobarometers applied to politic gneisses, metavolcanic and charnockitic rocks, are 650-680°C and 4.8 ± 0.5 kbar for the amphibolite domain, 675-725°C and 4.7 ± 0.5 kbar for the transition zone and 750 ± 50°C and 4.9 ± 0.5 kbar for the granulite domain. Prograde and retrograde mineral assemblages of pelitic gneisses indicate a 'clockwise' P-T path. On the basis of a comparison with other low-P granulite domains occurring in the same belt, namely the West Uusimaa Complex and the Sulkava area, we conclude that all three granulite domains were formed during the same thermal event in the late stage (1850-1800Ma) of the Svecofennian orogeny. The metamorphic evolution of the Svecofennides is consistent with moderate crustal thickening accompanied by additional heating through thinning of the mantle lithosphere. |
| Discussion: Late Pleistocene sedimentation and landform development in western Kalimantan (Indonesian Borneo) by M.B. Thorp et al.: Geologie en Mijnbouw 69: 133-150, 1990 | 1992 | Batchelor, D.A.F. | 71(3) | |
| #REF! | 1992 | Helmers, H.; Reijers, T.J.A.; Rondeel, H.E. | 71(3) | |
| #REF! | 1992 | 71(3) | ||
| Geochemistry of Holocene clays of the Rhine and Meuse rivers in the central-eastern Netherlands | 1992 | Hakstege, A.L.; Kroonenberg, S.B.; Wijck, H. van | 71(4) | Major and minor element geochemical analysis of Holocene clays from five borings in the Rhine and Meuse floodplains shows that Rhine deposits have less SiO2, MnO, Nb and Zr and more CaO, MgO, Na2O, P2O5, Rb and Sr than Meuse deposits. Geochemical differences between old and young floodplain clays of the Rhine are due to different granulometry and depositional regime. Multivariate statistics show that more than 70% of variance in the deposits is related to provenance and sorting during transport and deposition. Pb and Zn concentrations are correlated with organic matter content, and vegetation horizons in old floodplain deposits are naturally enriched in these heavy metals. Pb and Zn, therefore, are potential paleoclimatic indicators. Increased contents of Pb,Zn, Cr, Ba and V in young floodplain sediments dating from the last century are due to industrial pollution. |
| Redefinition of the deformation scheme of the Mulhacen Complex and implications for the relative timing of the overthrusting of the Alpujarride Complex in the Betic Zone (SE Spain) | 1992 | Jong, K. de | 71(4) | A new deformation scheme is presented for the Mulhacen Complex of the Betic Zone in southern Spain. This deformation scheme, which consists of six phases of superimposed penetrative deformation, is based on structural investigations in the contact zone with the overlying Alpujarride Complex. The newly obtained data imply that overthrusting by the Alpujarride Complex was the last major event in the deformational history of the Mulhacen Complex. |
| Large-scale polyphase deformation of a coherent HP/LT metamorphic unit: the Mulhacen Complex in the eastern Sierra de los Filabres (Betic Zone, SE Spain) | 1992 | Jong, K. de | 71(4) | This paper elucidates the large-scale polyphase deformation history of the Mulhacen Complex, the partially overprinted HP/LT metamorphic nappe complex in the Betic Zone of southeastern Spain, by tying zones of concentrated small-scale and mesoscopic deformation to large-scale structures, which could be mapped out due to excellent exposure. Small-scale structures show that progressively younger deformation was increasingly less homogeneous and became progressively more concentrated in zones. The original D1mulh- D2mulh distribution of lithologic units and main tectonic units was disrupted during subsequent polyphase deformation. During a third phase of penetrative deformation (D3mulh), S-SW vergent folding and associated S-SW ward thrusting occurred; the most intense folding and cleavage development took place in the vicinity of these thrusts. During D3mulh, a level in the top of the lowest nappe of the Mulhacen Complex acted as floor thrust of the imbrications. Mapping and structural analysis showed that during subsequent deformation this zone was reactivated and that deformation was concentrated below the detachment. The last phase of deformation (D7mulh) did not result in penetrative deformation but in approximately N-S trending subvertical faults and associated similarly oriented flexures and large-scale open folds. Tortonian sediments show that D6mulh occurred before, and D7mulh, at least partly, after their deposition. |
| Biotite crystallization temperatures and redox states in granitic rocks as indicator for tectonic setting | 1992 | Burkhard, D.J.M. | 71(4) | A T-fO2 pair is the result of solving two independent equations (for biotite and its host rock) each of which relates the two unknowns, oxygen fugacity (fO2) and temperature, with an analytically determined Fe2+/Fe3+ ratio. T- fO2 pairs, determined for a series of rock samples from localities which are spatially distributed over an intrusive are different and plot linearly in 1/T-logfO2 space. A comparison of such lines, estimated for granites from Australia, Japan and Portugal shows three major features: (1) magnetite-granites and magnetite-free ilmenite-granites cover distinct fields, (2) Australian granites have a lower oxidation state and higher biotite crystallization temperatures than granites from Japan, and (3) ilmenite-granites from Japan plot systematically in an oxygen-rich regime, that is above the NiNiO (NNO) buffer, implying that their mineral assemblage is not in equilibrium whereas ilmenite-granites from Australia plot in an oxygen-poor regime, i.e. below the fayalite-magnetite-quartz (FMQ) buffer. It is, of course, expected that magnetite-free ilmenite-granites with all Fe3+ partitioned into biotite, have an oxidation state below (FMQ). Ilmenite-granites which plot above (FMQ) must therefore have experienced oxidation upon cooling, after ilmenite and after biotite crystallization. Such an oxidation may be related to volatile water, available at temperatures below water saturation and above solidification of the rock. Because ilmenite-granites plot either below or above (FMQ) for a specific region, one may infer that this is related to a regionally low or high water content respectively. As such one can distinguish low-water regions, such as Australia and N Portugal which are recognized as non-subduction-related granites, and high-water regions, such as Japan and the Alps (Bergell) which are recognized as subduction-related granites. It is concluded that in non-subduction-related regimes the redox state of the source rock has been preserved in contrast to rocks in subduction-related regimes. |
| Evolution of the Pernambuco-Paraíba-Rio Grande do Norte Basin and the problem of the South Atlantic connection | 1992 | Mabesoone, J.M.; Alheiros, M.M. | 71(4) | The easternmost sedimentary basin of the NE Brazilian Atlantic margin shows special tectonic and sedimentary features due to the fact that it was the last link between South America and Africa. The basin is strongly influenced by the rotational separation of both continents and by the reactivation of Precambrian faultlines. The basin may be subdivided into seven subbasins which all have a homoclinal structure. The differential downwarp of the crystalline basement resulted in deeper and shallower parts that are bounded by faults. A crystalline basement high disrupts continuity between the three southern subbasins in Pernambuco and Paraíba States, and the four northern ones in Rio Grande do Norte State. Sedimentation in the basin started in about Santonian time with meandering, sometimes braiding fluvial sandstone systems passing seaward into calcareous littoral sandstones. In the Maastrichtian the sea advanced over the area. As a consequence, sedimentation in the southern subbasins began then with the accumulation of transgressive phosphorites and calciclastics from a South Atlantic source. Later, somewhat deeper-water limestones were deposited. A Paleocene regression is represented by detrital limestones and calcareous clays. Marine sediments of Maastrichtian age in the northern subbasins, which belong to the Equatorial Atlantic, are restricted to shallow-water shelf limestones which became strongly recrystallized and partly dolomitized. From the structural, geophysical, sedimentological and paleontological analyses of the basin we conclude that (1) the last link between South America and Africa was broken only at the end of the Cretaceous, (2) the sill tilted southward before its rupture, (3) the sedimentary fills north and south of the sill came from different sources, and (4) upwelling in the South Atlantic against the sill caused phosphorite deposition. |
| Discussion: Late Pleistocene sedimentation and landform development in western Kalimantan (Indonesian Borneo). Reply by the Authors | 1992 | Thorp, M.B.; Thomas, M.F. | 71(4) | Quaternary alluvia in Sundaland, as elsewhere, give a simplified picture of the complexity of eustatic, tectonic and bioclimatically driven episodes of erosion and sedimentation during the Quaternary Era. It is premature, therefore, to propose the Batchelor model of the off shore Upper Cainozoic Sundaland sedimentary sequence as a standard for the region. The W Malaysian 'Old Alluvium' includes discrete sedimentary bodies with confirmed upper Pleistocene dates making them co-eval with W Kalimantan alluvial fan terraces whose late Pleistocene age we uphold. We caution the use of humicretes and ferricretes as inter-regional chrono-stratigraphic markers. |
| Probabilistic seismic hazard assessment for The Netherlands | 1993 | Crook, T. de | 72(1) | This probabilistic seismic hazard analysis for The Netherlands is based on the catalogue of European earthquakes published by the Commission of the European Communities. The seismic hazard is assessed by applying a modified version of the McGuire program. This method uses for each seismotectonic zone a linear frequency-intensity relation, an upper bound of intensity, an average depth for large earthquakes and an azimuth-dependent attenuation. It assumes a Poisson process for large earthquakes. The annual probability versus intensity is calculated for sites at gridpoints with 7km spacing. Hazard intensity maps are presented for the annual probabilities of occurrence 0.02, 0.01, 0.005, 0.001, 0.0004 and 0.0001. A rough estimate of the error is approximately one half of an intensity unit for all probabilities. The highest seismic hazard in The Netherlands is found in the south-east with intensity VIII for a 0.0001 annual probability and is decreasing to the north-west in line with the seismicity. |
| Turbidites provide a unique opportunity to study diagenetic processes | 1993 | Middelburg, J.J. | 72(1) | The sedimentary record has always been affected by both diagenesis and changes through time in the input flux. It will be shown that distal turbidites, which are extremely uniform throughout upon emplacement, can be used to constrain diagenetic processes. Emplacement of turbidites causes the exposure of various labile and reduced components to oxic pelagic conditions. This initiates various diagenetic processes such as organic matter decomposition, element redistribution and carbonate dissolution. The influence of these processes on the sedimentary record can be obtained directly from depth profiles within initially homogeneous turbidites. The sedimentary record can provide strongly biased information when diagenetic alterations are not considered. |
| A review of Recent and fossil serpulid 'reefs'; actuopalaeontology and the 'Upper Malm' serpulid limestones in NW Germany | 1993 | Hove, H.A. ten; Hurk, P. van den | 72(1) | Serpulidae (Polychaeta) are benthic, suspension-feeding worms, mostly marine, secreting their own calcareous habitation tubes. Serpulid 'reefs' include banks deposited on shallow parts of continental shelves, and primary frame reefs at intertidal and subtidal depths. Sheltered bays harbour the largest reefs, up to a few metres in height and kilometres in length. A review of habitats with Recent serpulid mass-occurrences allows interpretation of the palaeoenvironment in which the serpulid limestones in the 'Upper Malm' (Upper Jurassic-Lower Cretaceous) of NW Germany may have been laid down. The Lower Serpulid Limestones represent concentrations of re-deposited serpulid tubes. In the Upper Serpulid Limestones ('Serpulit') the re-deposited tubes are embedded in stromatolitic algae. Both limestones were formed in lagoons fringing an inland sea. Several records of Recent and fossil 'serpulid' buildups are erroneous and can be referred to algae, vermiform 'gastropods' or non-serpulid polychaetes. Differences and similarities between calcareous tubes of serpulids and vermetids (Gastropoda) are summarized. |
| Cross-spectral analysis of two late Berriasian rhythmic limestone-marl successions in SE Spain and SE France favours orbital control | 1993 | Sprenger, A.; Kate, W.G. ten | 72(1) | The cyclicities in rhythmic limestone-marl alternations of two late Berriasian (hemi) pelagic successions are correlated. The first succession has a thickness of 42.8 m, and is situated in the northernmost Subbetic realm near Caravaca (SE Spain). It comprises the Calpionellopsis simplex subzone (D1). The second succession, with a thickness of 40.5 m, is located about 950 km to the northeast in the Fosse vocontienne near La Faurie (SE France). It starts 2 to 5 m above the base of subzone D1 and ends near its top. The carbonate contents of 740 samples of both successions were used to establish a visual correlation. A more refined correlation was established by cross-spectral analysis of the carbonate/clay ratios. Although the two sedimentation realms differ geographically and geologically, the power spectra show a remarkable resemblance at the eccentricity and precession frequencies, which is numerically confirmed by significant coherence at the 80% confidence level. The cyclicities of both, the Caravaca and the La Faurie succession, are, at least in part, orbitally controlled. |
| #REF! | 1993 | Rondeel, H.E.; Veen, A.H. van der; Silva, S. de; Hoorn, C.; Pingen, M.; Visscher, H.; Vandenberghe, J.; Meesters, A.G.C.A.; Meer, J.J.M. van der; Boekschoten, G.J. | 72(1) | |
| Introduction - Periglacial Environments in relation to Climatic Change | 1993 | Vandenberghe, J.; Schwan, J. | 72(2) | |
| Recent results of Pleistocene periglacial research in the Netherlands | 1993 | Vandenberghe, J. | 72(2) | |
| Periglacial environments and climatic development during the Early Pleistocene Tiglian stage (Beerse Glacial) in northern Belgium | 1993 | Kasse, C. | 72(2) | The climatic development of the Early Pleistocene Tiglian stage has been studied in the Tegelen Formation (Rijkevorsel, Beerse and Turnhout Members) in northern Belgium. The sedimentology, paleoecology and periglacial structures of the Beerse Member indicate the presence of a cold period (Beerse Glacial: Tiglian C4) within the warm Tiglian stage. The climatic deterioration led to a drop in sea level, which is reflected by a change in sediment provenance and sedimentary environments. Rhine supply was replaced by a local supply from central Belgium and the interglacial estuarine environment changed into a periglacial eolian sand sheet environment. Gleysols (H-Cg and Ah-Cg profiles) developed in the Beerse Member during phases of land surface stability. During the Beerse cold phase, vegetation was reduced to herbs and pine (tundra and boreal coniferous forest), indicating a mean summer temperature of about 10°C. The periglacial structures (involutions, frost cracks, initial ice-wedge casts) point to a mean annual temperature between -1 and -4°C, which is comparable with the temperature of the Weichselian Pleniglacial. |
| Saalian nivation activity in the Bosbeek valley, NE Belgium | 1993 | Gullentops, F.; Janssen, J.; Paulissen, E. | 72(2) | The geomorphological analysis of the Bosbeek valley, situated in the present-day temperate climate of Belgium, establishes that in the Saalian periglacial environment snow played a major role in shaping the landscape. It is inferred that snow banks were important for a rapid and considerable retreat of the western valley side in loose deposits. Intense snowmelt in the beginning of the short summers was responsible for the formation of a periglacial pediment between the valley side and the river floodplain. By these processes the Saalian was, at least in northeastern Belgium, the most effective glacial stage in terms of erosion. During the Weichselian, the Saalian periglacial landscape was only slightly remodelled by river incision and cover sand deposition. |
| Aspects of Weichselian Middle Pleniglacial stratigraphy and vegetation in central Poland | 1993 | Krzyszkowski, D.; Balwierz, Z.; Pyszyńsky, W. | 72(2) | The basal member of the Piaski Formation in the Bełchatów outcrop of central Poland was deposited between 43700 and 27000 BP. It consists mostly of lacustrine deposits. Its lower part contains several organic layers, fluvial sands and slope deposits. Radiocarbon-dating places the organic horizons in the Moershoofd and Denekamp Interstadials. The first of these interstadials was probably characterized by forest-tundra or scrubtundra conditions, but this needs to be confirmed since the analysed material may represent redeposited pollen. The Denekamp Interstadial was characterized by grass tundra (34000-31000 BP) and finally by discontinuous tundra of the subpolar desert (31000-27000 BP). |
| Late Plenivistulian deglaciation and the expansion of the periglacial zone in NW Poland | 1993 | Kozarsky, S. | 72(2) | In NW Poland, in the area of the last Scandinavian icesheet, periglacial phenomena occur mostly in outwash plains, till plains and pradolina terraces, and sporadically also in alluvial fans and inland dunes. Some of them contain indications of former permafrost and can be used in palaeoenvironmental reconstructions of the Late Pleistocene deglaciation. They include epigenetic and syngenetic ice-wedge casts, fossil sand-wedge polygons, ice-vein network casts and oriented icing depressions. The cryostratigraphic record of permafrost indicators and their geomorphic distribution testify to the presence of continuous permafrost or at least vast permafrost patches in the deglaciated area in NW Poland during the Late Plenivistulian and during cold spells of the Late Vistulian. |
| Periglacial environmental developments between 30 and 20 ka BP in Denmark | 1993 | Kolstrup, E. | 72(2) | A sedimentary sequence from eastern Denmark covers the time span from somewhat before 30 ka BP until 20 ka BP, based on thermoluminescence (TL) age estimates. The sequence is composed of loess and sandloess alternating with water-laid sediments in the lower part and with slope deposits in the upper part. Pollen is present in some of the layers. Integration of the evidence from this sequence with data from other north and central European localities of the same period suggests that from 30 till 20 ka BP there was much reworking of sediments by wind. The presence of slope deposits and frost-wedge casts points to (intermittent?) permafrost between about 24 and20 ka BP, and possibly also for a period between 27 and24 ka BP Although soil surface conditions were unstable, vegetation was probably present during almost the entire period; the dominant cover was herbs, grasses and sedges. |
| Mineralogy and abrasion of sand grains due to Vistulian (Late Pleistocene) aeolian processes in central Poland | 1993 | Manikowska, B. | 72(2) | The Eemian and Vistulian (= Weichselian) sedimentary fill of a closed depression and the glacigenic Saalian substratum at Kalinko as well as the Late Vistulian (= Late Glacial) dune deposits at Zamety were studied as representative periglacial sequences for central Poland. Heavy minerals and feldspars were examined by optical methods and by coloration with cobalt nitrite of sodium. Quartz grain abrasion was investigated by applying a modified Cailleux morphoscopic method and Krygowski's mechanical graniformametry. Mineralogical changes, especially a decrease in frequency of amphiboles and an increase of garnets, along with an increase of wind-abraded elements, suggest that these changes have an aeolian origin. The frequency of features which are due to aeolian activity increases progressively in Early Vistulian and Plenivistulian lake and slope deposits. The degree of transformation is highest in the sands with gravels deposited by slopewash waters and in the sands filling the Late Plenivistulian frost wedges. The degree of transformation increases markedly from about 30 000 BP onward and reaches a maximum between 20 000 and 14 000 BP. The Late Vistulian coversands and dunes consist of material that was formerly strongly transformed by wind. They do not contain more wind-abraded grains than the Late Plenivistulian non-aeolian deposits. |
| Late Quaternary chronology of the Allier terrace sediments (Massif Central, France) | 1993 | Veldkamp, A.; Kroonenberg, S.B. | 72(2) | The Late Quaternary terrace chronology of the middle Allier basin (Limagne, Massif Central, France) has been reconstructed by means of terrace (chemo)lithostratigraphy and with Th/U disequilibrium and 14C datings. The 25 m terrace level (Wb) has a Late Saalian age. The Weichselian Terrace levels Xa and Xb (20 and 10 m) contain at least four different lithostratigraphical units: one Middle Pleniglacial, two Late Pleniglacial and one Younger Dryas. The oldest Holocene ZY terrace sediments have Atlanticum ages. Timing of Allier incision and sedimentation during the Late Pleniglacial and Late Glacial appears to be mainly climate-related. Major fluvioglacial sediment fluxes from melting glaciers on the Mt. Dore and Cantal at the end of the Late Pleniglacial caused a strong rise of the Allier river bed level. This rise of approximately 20 m in the Limagne seems to have contributed to the formation of lakes like Marais de Ravel and the Grand Marais. Fluvial dynamics in the Allier basin seem to be mainly climate controlled. |
| Periglacial environments during the Weichselian Late Glacial in the Maas valley, the Netherlands | 1993 | Bohncke, S.; Vandenberghe, J.; Huijzer, A.S. | 72(2) | The sandpit at Bosscherheide, on the east bank of the Maas (= Meuse), provides a detailed record of Late Weichselian palaeoenvironmental changes. The periglacial fluvial, and aeolian processes recorded in its sediments have been studied by means of pollen, macrobotanical and thin section analyses, sedimentological observations and radiocarbon datings. The data reveal a series of processes involving rapid environmental changes, which determined the termination of the Bølling-Allerød interstadial complex. At the transition from Allerød to Late Dryas, ca 10 800 BP, large-scale floodings and deposition of suspension load took place. Prior to these floodings, a short period with (incipient) permafrost occurred. The aeolian sedimentation, leading to the formation of parabolic dunes, took place mainly between 10 500 and 10150 BP. |
| Dune dynamics and cryoturbation features controlled by Holocene water level change, Hietatievat, Finnish Lapland | 1993 | Vliet-Lanoë, B. van; Seppälä, A.; Käyhkö, J. | 72(2) | The inland dune field at Hietatievat (Finnish Lapland) is derived from an esker and accumulated during the early Holocene. A spodosol developed in a humid climate at least until the end of the Atlantic. A generalized phase of cryoturbation occurred at that time, in the absence of permafrost and in response to a higher standing water level in autumn. As a consequence of forest fires and a lowering of the water level during the Subboreal, dunes were reactivated during the Subatlantic and are still active today. The frost susceptibility of the clean sand is related to amorphous clays and organic matter accumulated by podsolisation. Cryoturbations resulting from a negative gradient of frost susceptibility (the surface horizon is less susceptible to frost heave than the subsurface) and a high standing water table evolve into hummocks during periods with a low-standing autumn water table. These hummocks develop into pseudo-convective forms (mounds with a central injection). Features observed at Hietatievat are similar to those observed in aeolian sands at the Gåsebu site (Svalbard, continuous permafrost) and are governed by the same laws of mechanical deformation. Permafrost is not a prerequisite for the development of cryoturbation. These deformations can be used as analogs for the understanding of the Late Glacial phenomena of western Europe. Holocene changes in the hydraulic regime observed through the cryopedological approach seem consistent with the results obtained by other methods. |
| The influence of periglacial activity on the remanent magnetization of sediments | 1993 | Hus, J.J.; Paepe, R.; Geeraerts, R. | 72(2) | The palaeomagnetic investigation of an ice-wedge cast in Late Pleistocene loess deposits in Belgium demonstrated that the upturned strata adjacent to the wedge have retained a stable remanence which can be used as a marker to visualize the strain. Different wedge fillings could be differentiated and identified on the basis of their remanent magnetization and magnetic susceptibility properties. Deformations due to periglacial activities easily escape observation, particularly in cores, and hence large associated anomalous magnetization directions may be erroneously interpreted as 'excursions' of the geomagnetic field. |
| Modelling of potential effects of long-term fluvial dynamics on possible geological storage facilities of nuclear waste in the Netherlands | 1993 | Veldkamp, A.; Dijke, J.J. van | 72(3) | Within the programme of investigation for suitable safe geological sites (such as salt diapirs) for long-term storage of radioactive waste (OPLA), a modelling study of long-term effects of fluvial dynamics was carried out. The model used, FLUVER, allows long-term simulations of the combined effects of climatic change, tectonism, sea level and initial relief on fluvial erosion. As an exercise, landscape development scenarios of a Rhine-Meuse type system with climate and base-level dynamics related to Milankovitch's astronomical theory, during stable, uplifting, and subsiding tectonic scenarios, are simulated and discussed. Under the assumptions that climate and base-level changes can be described with Milankovitch's theory and that tectonic activity in the Netherlands will not change considerably during the next hundred thousands of years, it can be concluded provisionally that the maximum fluvial erosion depth in the next few hundred thousand years is unlikely to exceed 100 metres and to reach a salt diapir. |
| Definition of two new members in the upper Kreftenheye and Twente Formations (Quaternary, the Netherlands): a final solution to persistent confusion? | 1993 | Törnqvist, T.E.; Weerts, H.J.T.; Berendsen, H.J.A. | 72(3) | The upper part of the Late Saalian to Early Holocene Kreftenheye Formation in the Netherlands usually consists of a relatively fine-grained, clastic bed (frequently referred to as 'loam bed'), which is generally regarded as an overbank deposit of incipient meandering fluvial systems. It was formed essentially in two phases, during the Allerød and the Early Holocene. The 'loam bed' is sometimes covered by eolian river dune deposits which have also been considered as part of the Kreftenheye Formation. Both sedimentary units have a large areal extent, a number of characteristic lithologic properties and a distinct stratigraphic position. It is shown that the 'loam bed' in a lithologic sense rarely consists of loam. The currently existing terminological confusion concerning the 'loam bed' and (to a lesser extent) the river dune deposits is caused by the mixing of lithologic, genetic, lithostratigraphic and chronostratigraphic criteria. In order to avoid further confusion, two formal lithostratigraphic units are introduced and lithologic descriptions are given for the holostratotypes of these units. The Wijchen Member of the Kreftenheye Formation essentially contains the 'loam bed'. The definition of the areally variable Wijchen Member is supported by a hypostratotype. The river dune deposits are incorporated in the Delwijnen Member. The Delwijnen Member is included in the Twente Formation because its lithologic characteristics and stratigraphic position are more similar to the Younger cover sands (Wierden Member) of the Twente Formation than to the fluvial coarse-grained deposits of the Kreftenheye Formation. |
| Geology and hydrocarbon habitat in the Arabian Basin: the Mesozoic of the State of Qatar | 1993 | Alsharhan, A.S.; Nairn, A.E.M. | 72(3) | The State of Qatar is situated in the southwestern Arabian Gulf and covers an area of about 12 000 sq km. The land portion is formed by a large, broad arch, which is part of the regional, NE-SW trending Qatar-South Fars Arch, separating two Infracambrian salt basins. The Dukhan Field on the west coast of the Qatar Peninsula, with its reservoirs in Upper Jurassic limestones, was the first oil field discovered. Since this discovery in 1940, a series of other discoveries have been made, and Qatar became a member of the Organization of Petroleum Exporting Countries (OPEC) in 1973. Hydrocarbon accumulations are widely dispersed throughout the stratigraphic column with production from Middle Jurassic to Middle Cretaceous strata. The most prolific reservoirs are in shelf carbonate sequences and minor accumulations occur in Albian clastic sediments. Seals, mainly anhydrite and shale, occur as formations of regional extent as well as intraformationally with smaller areal distributions. There are several stratigraphic intervals which contain source rocks or potential source rocks. Upper Oxfordian-middle Kimmeridgian source rocks were formed in an extensive, starved basin during a period of sea-level rise. They contain organic matter of sapropelic, liptodetrinitic and algal origin and have a total organic carbon content of 1 to 6%. Both depositional environment and tectonic evolution through geologic time have influenced sedimentary facies and stratigraphic features, which controlled reservoir, source and seal characteristics and subsequent hydrocarbon generation, migration and entrapment. |
| Relations of Hercynian metamorphism with magmatism and deformation in the Eastern Pyrenees. Implications for Hercynian evolution | 1993 | Liesa, M. | 72(3) | The Hercynian metamorphic evolution at different crustal levels of the Roc de Frausa Massif has been constrained relative to the deformation and intrusion of igneous rocks. The main deformation phase is considered to have been synchronous throughout the whole crustal section exposed. Intrusion of igneous bodies took place subsequently to deformation and overprinted the previously foliated texture of the country rocks. At shallow levels two metamorphic peaks are distinguished, viz. a regional one, synchronous with the main deformation, and a contact-metamorphic peak. At deeper levels and away from the intrusives the regional metamorphic climax is post-kinematic. Near the intrusives, the contact-metamorphic episode constituted the latest and highest temperature stage of a continuous prograde metamorphic evolution. The crustal evolution is characterized by a first compressive event at intermediate-pressure metamorphic conditions, followed by a post-tectonic event characterized by low-pressure - high-temperature metamorphism and ubiquitous magmatism. The first event is registered at shallow levels of the crust, whilst the second event is only recorded in exposures representing deeper crustal levels. The high-temperature metamorphism and magmatism could be a result of either the incorporation of mantle material into the lower crust subsequent to a thickening episode, or a subcrustal collapse of a previously thickened lithosphere. |
| Structural and paleogeographic inferences from a texture analysis of Ordovician and Silurian pelites of the Wépion borehole (Ardennes, Belgium) | 1993 | Sintubin, M. | 72(3) | A preliminary microfabric and texture analysis of shales, siltstones and a slate, collected in the Ordovician and Silurian of the Wépion borehole (Ardennes, Belgium), enables us to comment on the structural and paleogeographic significance of the Caledonian Sambre-et-Meuse massif as part of the Variscan front. The texture image in the massif only reflects a compaction strain, which is in accordance with the poorly evolved character of the fabric, in which no clear signs of a secondary cleavage can be distinguished. The shales and siltstones seem to have evolved within a shallow structural level under diagenetic circumstances. In this respect the Sambre-et-Meuse massif forms an exception with regard to the other Caledonian basement massifs in the Variscan fold-and-thrust belt in Belgium, which are all characterised by the development of a slaty cleavage in low-grade metamorphic circumstances. Such a secondary cleavage also occurs at the bottom of the Wépion borehole in the Brabant basement. |
| #REF! | 1993 | Reijers, T.J.A.; Sissingh, W.; Lankreijer, A.C.; Boekschoten, G.J.; Helmers, H. | 72(3) | |
| Presentation of the Van Waterschoot van der Gracht Medal to Prof. Dr. D.G. Price | 1993 | Kroonenberg, S. | 72(3) | |
| Alluvial architecture of the Quaternary Rhine-Meuse river system in the Netherlands | 1993 | Ruegg, G.H.J. | 72(4) | In the Rhine-Meuse river system in the Netherlands, a combination of major tectonic movements and climatic cycles (periglacial to temperate-warm, non-arid) has resulted in different sedimentation patterns on either side of the terrace intersection. Upstream of this intersection, a vertical series of river terraces was formed by the alternating processes of erosion of the valley by meandering river action and partial refilling of the valley by braided river action. The coarse-grained gravelly deposits within these terrace units show the characteristics of a braided river(Scott-type sequentional model) and reflect general aggradation during cold, i.e. glacial, stages. During interglacials, meandering rivers cut into the previously formed braided river deposits causing net sediment removal. Deposits dating from interglacials are very scarce. Downstream of the intersection, the average sedimentation rate kept up with subsidence. Sediment was supplied mostly by braided rivers during cold stages and the resulting sequences resemble the Donjek-type sequentional model. During interglacial times meandering rivers mainly caused reworking and erosion of braided river deposits from the preceding glacial stage. Meandering river deposits are more widespread than upstream of the intersection; they are interbedded between braided river deposits. Futher downstream, marine transgressions during interglacials caused the coast-related anastomosing river zone to shift upstream, sometimes as far as the present-day western Netherlands. As a consequence of the mechanism responsible for forming fluvial terraces upstream of the terrace intersection, fine-grained overbank and cut-off sediments from meandering rivers that potentially can be dated palaeontologically may be expected underneath coarse-grained 'river-terrace' deposits. |
| Sediment-petrologic characteristics of Saalian and Weichselian deposits in the Hümmling region, NW Germany | 1993 | Krook, L.; Schwan, J. | 72(4) | In the lowlands of northwest Germany, Saalian (fluvio-) glacial plateaus and ice-pushed hills are surrounded by flat and low-lying terrain consisting of Weichselian fluvial to Aeolian sands. The present work refers to the Ems-Hase fluvial basin and the adjacent part of the fluvioglacial Hümmling plateau. On the basis of heavy-mineral analyses and other data it was found that: (i) The Weichselian deposits are significantly richer in garnet and alterite than the Saalian meltwater sands which flank and underlie them in the Ems-Hase fluvial basin. It is thought that Weichselian fluvial deposition was preceded by a period of erosion related to the low sea level of the last ice age. During that phase, the ancient riversystem extended its course in upstream direction and cut down into the headwater portion of its drainage basin. As a result, the subsequent infilling of the valleys was primarily by material derived from pre-Cenozoic rocks with the share of the Saalian substrate being subordinate only. (ii) There is no significant difference in unstable-species content between fluvial and aeolian sands but for the occurrence of traces of glaucophane only in the second type. The latter feature suggests that, during the Late Weichselian Pleniglacial, deflation from the then dry part of the North Sea floor contributed to the deposition of the windborne coversands in the study area. Yet, the effect of the long-distance aeolian transport must have been slight only, and the buildup of the coversands resulted mainly from the local reworking by wind of the fluvial-sand substrate. (iii) Mineralogically, there is a distinct contrast between the fluvial sands from the northern part and those from the southern part of the study area. The pertinent heavy-mineral spectra, supplemented with previously published analyses, reveal downstream trends in the composition of the Weichselian fluvial sand. These trends reflect changes in the sediment supply from Cretaceous and older rocks in the south to thick Cenozoic beds in the north. The northern strata include shallow marine deposits of Tertiary and Pleistocene (mainly Holsteinian) age and material laid down by the Late Tertiary to Elsterian north German riversystem. |
| A seismic stratigraphic analysis of Lower Pleistocene deposits in the western Danish sector of the North Sea | 1993 | Salomonsen, I. | 72(4) | The Lower Pleistocene is well preserved in the centre of the North Sea, in contrast to the onshore sedimentary record in Denmark. In the Central Trough area the base of the Quaternary is deeper than 1000 m, and regional subsidence appears to have been uniform throughout the Early and early Middle Pleistocene. Seismic stratigraphic analysis allows subdivision of the Lower Pleistocene depositional succession in the western Danish sector into seven subunits. The seismic reflectors bounding these subunits can be correlated with seismic third-order sequence boundaries identified and mapped in the Late Tertiary and Pleistocene succession in adjacent British and German sectors. The subunits recognized in the Danish area may equal these sequences. Structure contour maps for five of the boundaries and isopach maps for three of these subunits show the position of the depocentres in the area. The main Pleistocene depocentre coincides with the axis of the central North Sea Basin. In the Early Pleistocene (Tiglian), local depocentres were also present outside this area. The sediments represented by the seismic sequences in the Dutch, British and German sectors can be related to the depositional basin of a river system draining the northwest-European continent. In addition, climatically induced changes in depositional conditions in the area have affected the sedimentation pattern. |
| Coeval genesis of pillow lava on the sea floor and under a thin cover of unlithified sediments (and associated formation of peperites) | 1993 | Assorgia, A.; Gimeno, D. | 72(4) | The Guardia Marina beach (Sardinia island, Western Mediterranean, Italy) contains outcrops of subalkaline basaltic pillow lava within a Miocene sedimentary sequence of shallow marine facies. The northern sector of the beach is characterized by the presence of feeder dikes terminating at their upper ends in antigravitative toothpaste-like massive pillows and lateral expansions of highly vesiculated and cupola-like hollow pillows. The central sector of the beach shows partially eroded pillows and pillowed dikes, as well as sandwiched layers of sediments between laterally expanded pillows. The southern sector of the beach contains well-developed pillows (intrusive with respect to the sedimentary sequence) with a clear development of peperitic lithofacies at the magma-sediment interface. The lateral continuity of the sedimentary beds suggests a coeval growth of pillows at the magma-water and magma-sediment interfaces, as well as a recurrent process of pillow-growth from feeder dikes. The multiple-rind structure in the pillows in the southern sector of the beach confirms the very shallow marine environment inferred from fossil fauna and sedimentary lithofacies. The early erosion of the pillows in the central and northern sector of the beach accounts for the proximal character of crystal-rich epiclastic layers within the calcarenitic sequence. The Guardia Marina outcrops show that pillow lava can correspond both to a subaqueous environment and to a growth of pillows under a thin layer of poorly lithified sediments. The generally accepted concept that pillow lava indicates a subaqueous environment must therefore be tested through an accurate study of the pillow-sediment interface. |
| Age and depositional environment of the Kuhfeld Beds (Lower Cretaceous) in the Alstätte Embayment (W Germany, E Netherlands) | 1993 | Herngreen, G.F.W.; Hartkopf-Fröder, C.; Ruegg, G.H.J. | 72(4) | Major parts of the Lower Cretaceous Kuhfeld Beds as present in the Alstätte Embayment, Dutch-German border area, have a marine origin and were not exclusively deposited in a limnic-terrestrial setting as previously thought. For the first time, direct fossil evidence is available. This dates the base of the formation as transitional Ryazanian- Valanginian and indicates a late Early-Late Hauterivian age higher in the formation. |
| #REF! | 1993 | Boekschoten, G.J.; Zakrzewski, M.A.; Reijers, T.J.A. | 72(4) | |
| Long-term and post-storm dynamic patterns of the subtidal rhythmic morphology along the East Frisian island coast, Germany | 1994 | Antia, E.E. | 73(1) | This report evaluates the dynamic pattern of the subtidal, longshore-rhythmic morphology along the East Frisian barrier island coast. Analysis of high-resolution sounding charts from the shoreface of Spiekeroog Island, which span a period of 37 years, leads to the following: (a) the alongshore spacing as well as the eastward increasing shore-normal orientation of the channels of the morphology were markedly constant over time; (b) the main pattern of migration of the channels was rotational about well-defined nodal points, rather than translational; (c) four rotational patterns are distinguished, two of which are symmetric, i.e. the seaward and shoreward segments (relative to a nodal point) of the channel are characterized by a similar sense (clockwise or anti-clockwise) in rotation, whereas the two asymmetric patterns display opposite rotation at both segments; (d) the sense and degree of channel rotation showed no time-dependent progression; (e) the frequency of the clockwise angular displacement > 20° was higher than that of the anti-clockwise counterpart, and (f) the Mode 1 rotational pattern, in which both the seaward and shoreward segments of the channel depict a clockwise rotation, was found to be typical of, but not exclusively associated with, storm conditions in which the storm surge height exceeded 3 m. These observations are inconsistent with the dynamic behaviour of a flow-transverse (sand wave or dune) morphology. The channels of the morphology are considered to represent channels of storm rip-currents. The regularity in the alongshore spacing of the channels suggests an edge-wave control. However the quality and type of hydrodynamic data required to verify the above assertion are presently unavailable. In the rock record, the channels would be best recognized in laterally-extensive, paleocoast-parallel vertical sections as regularly-spaced channel-fill sequences, in which epsilon crossbeds are lacking; seaward-dipping crossbeds may be widespread or rare depending on environmental conditions prior to preservation. |
| Vertical patterns of grain-size parameters of shoreface-connected ridges in the German Bight | 1994 | Antia, E.E. | 73(1) | This report evaluates the vertical variation of grain-size parameters of shoreface-connected ridges off Spiekeroog Island (German Bight). It is based on eight, 1.5 to 2 m-long, vibrocores retrieved along a single transect from successive morphozones of two ridges. The ridges are situated in water depths of 12 to 18 m, have a relief of 2 to 5 m, and are 1 to 1.5 km wide. The colour and textural composition of the ridge sediments suggest a two-fold grain-size facies. The surficial facies is mainly composed of medium to coarse-grained, relatively poorly sorted, brownish to orange-brown sands, and is usually about 60 cm thick. The subsurficial facies consists of gray-coloured fine sands with discrete occurrences of coarser sand layers that are probably storm-deposited. In general, four vertical grain-size patterns are displayed in the cores: sharp (relative to facies transition), gradational, fluctuational and homogeneous. As observed for the surficial cross-ridge pattern, the subsurface sediments of the landward flank and trough of the outer ridge are in general coarser and more poorly sorted than those of the crest and seaward flank. Similarly, the subsurface sediments of the inner ridge crest are coarser and less sorted than their counterparts from the outer ridge crest. These observations suggest that ridge sedimentation processes have always been coherent in time, even prior to the deposition of the surficial facies. The latter is considered to reflect a vertical growth of the ridges. Its origin is probably related to the present-day supply of Pleistocene sediments from the inlet channels during ebb-storm-surge conditions, rather than an in-situ reworking process. |
| An example of a kinking microfabric in Upper Pleistocene glaciolacustrine deposits from Llavorsí (Central Southern Pyrenees, Spain) | 1994 | Bordonau, J.; Meer, J.J.M. van der | 73(1) | Glacially deformed glaciolacustrine rhythmites exposed at Llavorsí in the Central Southern Pyrenees show a well-developed macroscopic crenulation lineation. Microscopic studies (thin sections and SEM) reveal a crenulation cleavage associated with very small-scale symmetrical folding and a banded extinction pattern. Combination of the thin section and SEM observations allows the reconstruction of a herringbone-like arrangement of finegrained particles or kinking microfabric. The occurrence of this microfabric can be used as a criterion for shearing, also in the absence of macroscopic observations. |
| Variations in Mesozoic-Cenozoic skeletal carbonate mineralogy | 1994 | Poel, H.M. van de; Schlager, W. | 73(1) | Literature-based estimates of Mesozoic-Cenozoic shoalwater carbonate composition indicate important changes in frequency distribution of carbonate biota that translate into changes of bulk skeletal mineralogy of the original sediments. This mineralogy was strongly dominated by metastable carbonates during the Triassic (mainly aragonite) and during the Cenozoic (aragonite and magnesian calcite). [n between these periods lies an interval of reduced metastable carbonate and consequently high calcite content. This biogenic aragonite-calcite cycle parallels the one observed in (presumably inorganically precipitated) ooids and marine cements. |
| Timing of Variscan mid-crustal shearing and batholith intrusion in the Central Pyrenees (Ariège, France) | 1994 | Bon, A.; Eeckhout, B. van den; Janzen, E.; Klepper, C.; Moerkerken, B. van; Wees, J.D. van | 73(1) | A gneiss body in the Variscan Aston massif is overlain by Cambro-Ordovician metasediments that have been intruded by a granite batholith. At the gneiss-cover contact a 1.2 km-thick zone of highly strained medium-grade metasediments occurs. The batholith is surrounded by a zone where metasediments are strained and metamorphosed due to intrusion of the pluton. This contact aureole overprints the shear zone at the gneiss-cover contact, showing deformation and retrogression of the medium-grade metasediments. This relationship reveals a younger age for batholith intrusion with respect to the formation of the shear zone at the gneiss-cover contact. This observation together with regional correlation indicates that formation of the shear zone occurred between 292 and280Ma ago. |
| Geology and hydrocarbon occurrences of the clastic Permo-Carboniferous in the central and eastern Arabian Basin | 1994 | Alsharhan, A.S. | 73(1) | The siliciclastic lower part of the Permo-Carboniferous in the Arabian Basin represents a cyclic transgressive and regressive unit, consisting of sandstones, shales and thin beds of argillaceous limestone. This unit crops out in small exposures in central and northwest Saudi Arabia, but is widespread in the subsurface of central and eastern Arabia. It is known as the Unayzah Formation in Saudi Arabia and in the western and southern Arabian Gulf region, and as the Haushi Group in Oman. The Permo-Carboniferous clastics in the Arabian Basin proved to be prospective for hydrocarbons. Oil and gas were encountered in Saudi Arabia, Qatar, the united Arab Emirates (U.A.E.) and Oman. The Unayzah Formation in the subsurface of the U.A.E. ranges in thickness from 140 to 206 m. The relatively thin upper section consists of pyritic siltstone and terrigenous mudstone with minor sandstone, whereas the lower section is dominated by a thick sequence of very fine to coarse-grained, subangular to subrounded, moderately to poorly sorted quartzitic sandstones with minor interbeds of siltstone. Minor quantities of clay minerals, plagioclase, dolomite and pyrite occur in the sandstones. The formation is interpreted to be of fluvial origin. Six lithostratigraphic units were identified in the U.A.E. Thee units have moderate to good reservoir potential, while others act as seals over these reservoirs. Porosity in the reservoir units ranges from less than I to 27%, and permeability from less than 1 to 75 md. The sediments in the U.A.E. are highly affected by diagenesis. The main diagenetic events include silica cementation (which occurs as quartz overgrowths), precipitation of illite and minor kaolinite, carbonate cementation (calcite and dolomite) filling pores around the quartz grains, and locally a partial dissolution and leaching of feldspar grains. |
| Presentation of the Van Waterschoot van der Gracht Medal to Prof. Dr. John A. Katili | 1994 | 73(1) | ||
| Errata: Age and depositional environment of the Kuhfeld Beds (Lower Cretaceous) in the Alstätte Embayment (W Germany, E Netherlands), Geologie en Mijnbouw 72: 375-391,1994. | 1994 | Herngreen, G.F.W.; Hartkopf-Fröder, C.; Ruegg, G.H.J. | 73(1) | |
| Seismotectonics and seismic hazard in the Roer Valley Graben; with emphasis on the Roermond earthquake of April 13,1992. Workshop, January 20-22, 1993, Veldhoven, the Netherlands | 1994 | Eck, T. van; Davenport, C.A. | 73(2-4) | |
| Seismotectonics and seismic hazard in the Roer Valley Graben; with emphasis on the Roermond earthquake of April 13,1992. Workshop recommendations | 1994 | Haak, H.W. | 73(2-4) | |
| Seismotectonics and seismic hazard in the Roer Valley Graben: an overview | 1994 | Eck, T. van; Davenport, C.A. | 73(2-4) | |
| Cenozoic rift system of western and central Europe: an overview | 1994 | Ziegler, P.A. | 73(2-4) | The Cenozoic rift system of western and central Europe extends over a distance of some 1100 km from the coast of the North Sea to the western Mediterranean; its southern prolongation is formed by the Valencia Trough and a Plio-Pleistocene volcanic chain which crosses the Alboran Sea and the Atlas ranges. Development of this mega-rift was contemporaneous with the Eocene and later phases of the Alpine and Pyrenean orogenies and with the evolution of the Red Sea-Gulf of Suez and Libyan-Pelagian Shelf rift systems. Evolution of the European Cenozoic rift system is thought to be governed by the interaction of the Eurasian and African-Arabian plates and by early phases of a plate-boundary reorganization that may ultimately lead to the break-up of the present continent assembly. In western and central Europe rifting commenced during the middle and late Eocene; 2040 Ma later major rift-related domes were uplifted, entailing subsidence reversals of the grabens transecting them. Uplift of the Rhenish Shield can be explained in terms of progressive mechanical and thermal thinning of the lithosphere. The Bohemian Massif Vosges-Black Forest and Massif Central arches, which are located in the periphery of the Alpine fold belt, are characterized by less pronounced lithospheric thinning; low-velocity mantle-lithosphere anomalies are observed under the Vosges-Black Forest and Massif Central domes; apart from thermal loads, deflection of the lithosphere in response to the build-up of intra-plate horizontal compressional stresses and/or to thrust-loading may have contributed to the uplift of these arches. Volcanic rocks associated with the Cenozoic rift system of western and central Europe were derived by mixing of partial melts from the convecting asthenosphere and from the mantle-lithosphere; the asthenospheric component shows similarities to the source of ocean island basalts. In the face of limited lithospheric extension, it must be assumed that the upper asthenosphere has a higher than ambient temperature and that the mantle-lithosphere is volatile-enriched. The upper asthenosphere of much of Variscan Europe is characterized by low S-wave velocities, indicating the presence of partial melts. Paleogene development of this anomaly, possibly in conjunction with a reorganization of mantle convection patterns, was accompanied by thermal weakening of the lithosphere, rendering it prone to failure in response to the build-up of intra-plate stresses. The Cenozoic rift system of Europe has many features which are consistent with a 'passive' rift system. Under the present stress regime, crustal extension is limited to the Roer Valley Graben whereas the Rhine Graben and the Massif Central are subjected to transpressional and transtensional deformation. The entire rift system corresponds to a zone of increased seismic hazard. The Massif Central and the Rhenish Shield are zones of latent volcanic activity. |
| Stratigraphy and tectonics of the Roer Valley Graben | 1994 | Geluk, M.C.; Duin, E.J.T.; Dusar, M.; Rijkers, R.H.B.; Berg, M.W. van den; Rooijen, P. van | 73(2-4) | The Roer Valley Graben is the most prominent Cenozoic tectonic feature in the Netherlands onshore, filled with up to 2000 m of predominantly Upper Oligocene to Quaternary sediments. It forms the northwestern branch of the Rhine Graben rift system. To the northeast the graben is bordered by a major faultzone, the Peel Boundary Fault, and to the southwest by a number of downstepping faults. The Roer Valley Graben developed upon pre-existing sedimentary basins of Carboniferous, Triassic to Early Jurassic and Late Jurassic age. The Cenozoic graben is structurally closely related to the Late Jurassic basin and to the area affected by inversion tectonics at the end of the Cretaceous. Differential subsidence of the Roer Valley Graben started during the Late Oligocene. Displacements along the Peel Boundary Fault were recorded from the Late Oligocene onwards. Initially the average displacement was 0.01 mm a-1, but it increased during the Quaternary to 0.8mm a-1. Fault displacements at the southwestern boundary faults of the Roer Valley Graben are smaller than at the Peel Boundary Fault. |
| Neotectonics of the Roer Valley rift system. Style and rate of crustal deformation inferred from syn-tectonic sedimentation | 1994 | Berg, M.W. van den | 73(2-4) | The Roer Valley rift system emerged since the Middle Miocene and fluvial sediments were supplied to it by the Rhine, Maas (Meuse) and local Belgian rivers. Ever since the emergence, thirty fluvial terraces of the lower Maas river have been formed due to regional uplift. Their age-altitude record shows strong evidence for an important acceleration of the tectonic activity at the end of the Pliocene (around 3 Ma), and for high-frequency oscillations superimposed on a general continuous trend. Three relaxation periods during the Quaternary were identified, the first from 1.5 to 1.2 Ma and two short ones around 5 ka BP and after 2 ka BP respectively. The reactivations, following these relaxation periods, appear to be of plate-tectonic importance. The observed accelerations in tectonic activity since the Late Pliocene through the Pleistocene to the present day, raise the question: are we at present living in a period of extremely high crustal dynamics? Floodplain positions of the rivers Rhine and Maas repeatedly changed in space and time. Strike-slip movements along the graben bounding faults explain this behaviour. The events point to punctuated changes in the stress field orientation, probably related to the interplay between Alpine and Ardennes-Rhenish Shield stress generators within the regional stress field. |
| Patterns and velocities of recent crustal movements in the Dutch part of the Roer Valley rift system | 1994 | Berg, M.W. van den; Groenewoud, W.; Lorenz, G.K.; Lubbers, P.J.; Brus, D.J.; Kroonenberg, S.B. | 73(2-4) | This article presents an integration of geomorphological and geodetic data from the area of the 1992 Roermond earthquake. A dense network of lineaments is evident from major and minor terrain features, and drainage patterns also show structural control on a kilometre scale. These discontinuous terrain lineaments, often of anastomosing character, match known fault patterns and suggest that the upper crust is subdivided into many, relatively small (up to 10 km scale) wedge-shaped blocks. The lineament distribution is consistent with patterns predicted by idealized strain ellipses. It shows a right lateral component in the motion along major faults within the Lower Rhine Embayment. The wrenching component can be related to a left-lateral motion along the Variscan Front, and a subsequent right lateral offset of the edge of the London-Brabant Massif. The analysis of a 117-years-long data set of vertical movements at 2922 geodetic bench-marks evidences significant differential movements, and corroborates the sense of relative motion given by the lineaments. |
| The stress tensor in the Rhine Graben area derived from earthquake focal mechanisms (extended abstract) | 1994 | Plenefisch, T.; Bonjer, K.P. | 73(2-4) | |
| The recent crustal stress field in Central Europe sensu lato and its quantitative modelling | 1994 | Grünthal, G.; Stromeyer, D. | 73(2-4) | A detailed pattern of trajectories of the direction of maximum horizontal crustal stresses SHmax has been derived for Central Europe sensu lato according to actual data on fault plane solutions, in-situ stress measurements, geologic fault slip determinations and geodetic information. The generalization of this direction data on maximum compressive stress in the form of trajectories shows a bending from the well-established NW-SE direction in western parts of the study area to directions of NE-SW to E-W in the eastern part. In some regions there is evidence for a more complicated pattern, e.g. apparently differing SHmax-directions in different depth horizons, stress deflections at pronounced tectonic complexes, and radial directions around the Pannonian Basin. For studying the conditions in the brittle part of the crust steady-state elastic finite-element model calculations were carried out to explain the observed stress orientations. It is shown that the simulation according to a modern plate tectonic concept leads to a pattern of main principal stress directions that is compatible with the generalized observed stress directions. More regional features were modelled by reasonable variation of elastic parameters of different lithospheric blocks. |
| The 1992 Roermond earthquake, the Netherlands, and its aftershocks | 1994 | Camelbeeck, T.; Eck, T. van; Pelzing, R.; Ahorner, L.; Loohuis, J.; Haak, H.W.; Hoang-Trong, P.; Hollnack, D. | 73(2-4) | On April 13,1992 an MW = 5.4 normal dip-slip earthquake occurred 5 km south-west of theDutch town Roermond. It was located at a depth of 17 km near the Peel Boundary Fault in the Roer Valley Graben. Belgian, Dutch, German and French seismologists installed 29 mobile seismograph stations for a period of two months after the main shock. Both the mobile and the permanent stations recorded more than 200 aftershocks. High-quality hypocentral locations were obtained for 55 aftershocks. Hypocenters that occurred in the vicinity of the main shock hypocenter coincide with one of the focal mechanism nodal planes, i.e. strike 127°, dip 70°. The Roermond earthquake also triggered seismic activity in the graben as far as 40 km to the southeast. Focal mechanisms were determined for 20 aftershocks. Out of the 14 with a predominantly normal fault solution, eight have a strike direction parallel, and six a strike perpendicular to the strike of the main event. A stress inversion using the 13 best constrained fault plane solutions of aftershocks located near the main shock hypocenter indicates a direction for the principal stress that is similar to that of the regional stress field. From our experience in analyzing the data we recommend the upgrading of the existing regional recording systems to high-dynamic range seismograph stations and the installation of a number of accelerometers in the Roer Valley Graben and its surroundings. |
| Fault-plane solutions and source parameters of the1992 Roermond, the Netherlands, mainshock and its stronger aftershocks from regional seismic data | 1994 | Ahorner, L. | 73(2-4) | The earthquake of April 13, 1992 in the border region between the Netherlands and Germany near the town of Roermond, ranges with its local magnitude of ML- = 5.9 among the largest seismic events observed in historical times in the Lower Rhine Embayment. Several hundred buildings in the area around the epicenter suffered light to moderate structural damage (intensity VII effects). The main shock was preceded about 0.2 seconds before by a foreshock of local magnitude ML = 4.8 and followed, up to the middle of May, by more than 200 aftershocks with local magnitudes up to ML = 3.8. The whole earthquake sequence has been well recorded by the dense seismic station network in the Lower Rhine Embayment and its vicinity. Based on these local and regional recordings the hypocenter locations, source parameters and focal mechanisms of the stronger events of the sequence have been determined with high precision by the Department of Earthquake Geology of the University of Cologne. The source of the main shock was located in the southwestern vicinity of Roermond, about 14 to 18 km below the surface at the depth continuation of the Peel Boundary Fault. This fault zone forms the eastern border of the Roer Valley Graben. The focal mechanism was of the extensional dip-slip type (normal fault) with the active fault plane trending in NW-SE direction (124°) and dipping steeply (at 68° to the SW). The western block (Roer Valley Graben) moved down with respect to the eastern block (Peel Horst). A diameter of the source area of 4 to 5 km has been determined from the spectral analysis of P- and SH-wave signals, using the Brune source model. The average displacement along the fault plane was approximately 21 cm, the associated static stress drop 4.4 MPa and the seismic moment 1017 Nm. The spatial distribution of the aftershocks points to a source zone which trends in the same general direction as the Peel Boundary Fault and has a total length of about 10 km. The main conclusions about the Roermond earthquake sequence fit well into the tectonic setting of the Lower Rhine Embayment and the general pattern of seismotectonic dislocations in the western and central European area. |
| Source parameters of the 1992 Roermond earthquake, the Netherlands, and some of its aftershocks recorded at the stations of the Geological Survey of Northrhine-Westphalia | 1994 | Pelzing, R. | 73(2-4) | The Roermond earthquake of April 13,1992, was recorded unclipped at four of the six stations of the Geological Survey of Northrhine-Westphalia (epicentral distances between 54 and 103 km). The local magnitude values determined from these recordings are 5.9 for stations GSH, PLH and OLF, and 6.1 for station WBS. The main shock hypocenter was located at latitude 51° 10.1’ N and longitude 5° 55.9’ E at a depth of 17.6km.The focal mechanism determined from P and SH-wave polarities and amplitude ratios is 120° for strike, 70° for dip, and - l00° for rake, which corresponds to an almost pure dip-slip movement along a normal fault. The mean seismic moment, calculated from several spectra, is 5.4 x 1016 Nm, the mean dislocation is 35 cm. Until the end of May about 80 aftershocks from the Roermond area were recorded at the stations of the Geological Survey. The main shock also triggered a series of earthquakes at the southern border of the Roer Valley Graben between Geilenkirchen and Eschweiler, about 30-45 km SSE of the main shock epicenter. The largest of these events had a local magnitude of ML = 1.7. |
| Source mechanism of the 1992 Roermond, the Netherlands, earthquake from inversion of regional surface waves (extended abstract) | 1994 | Braunmiller, J.; Dahm, T.; Bonjer, K.P. | 73(2-4) | |
| A note on the foreshock of the 1992 Roermond earthquake, the Netherlands | 1994 | Oncescu, M.C.; Camelbeeck, T.; Martin, H. | 73(2-4) | Vertical components from 12 digital seismic stations which recorded the ML = 5.8 Roermond earthquake were used to determine the position and magnitude of a foreshock using relative methods. The small shock occurred 0.19 s before and 780 m away from the main shock on its SW-dipping fault plane. The local magnitude of the foreshock is ML = 4.0, which corresponds to a seismic moment of 2.8 x1014 Nm and to a seismic energy of 4.3 x109 J. |
| The seismic activity near Aachen following the 1992 Roermond earthquake, the Netherlands | 1994 | Prinz, D.; Hollnack, D.; Wohlenberg, J. | 73(2-4) | The seismic activity following the large Roermond earthquake of April 13, 1992, was concentrated in the area of the main shock and, surprisingly, a few kilometers northeast of Aachen. The locations and source parameters of 13 earthquakes, which occurred in the Aachen area, are presented. The evaluation is based mainly on seismograms from four mobile seismograph stations of the RWTH Aachen (Rheinisch-Westfälische Technische Hochschule) which were installed close to the epicenters. Fault-plane solutions were determined for two of these earthquakes. |
| What can we learn from aftershocks? | 1994 | Scherbaum, F. | 73(2-4) | From the spatial distribution of aftershocks with respect to the regions of fault slip during the mainshock, information can be gained about the heterogeneous structure within the source volume and about the frictional properties of surrounding faults. Focal mechanisms of aftershocks reveal how stress is redistributed by large earthquakes. While analog data have mainly been used for these studies in the past, a new degree of data quality is obtained with currently available digital recording systems. In addition to the increased accuracy for the determination of purely kinematic data, waveform information can be utilized with digital data. With state-of-the-art signal processing techniques, the contributions of source, path, and site effects on the observed seismic signals can be studied. Provided these effects can be separated, aftershock signals will potentially help us to learn about the properties of fault regions in unprecedented detail. The degree of resolution which can be achieved, however will strongly depend on the number of stations and the geometry of the network employed. Depending on the special scientific problems to be addressed, optimum station geometries may vary. Modern methods in optimization theory, such as simulated annealing, have been successfully used to find optimum station distributions for aftershock monitoring. An additional aspect which has to be addressed is the problem of managing and processing aftershock data. Since high-quality digital data come at the price of huge data volumes, new strategies and concepts for data handling and signal processing have to be developed. |
| Exchange of digital seismological waveform data in Europe: status as illustrated by data collection for the 1992 Roermond earthquake, the Netherlands | 1994 | Dost, B.; Sleeman, R. | 73(2-4) | The 1992 Roermond earthquake (location 51.16°N, 5.95°E; ML = 5.8) provides a good opportunity to evaluate the current status of exchange of digital waveform data in Europe. For this purpose data are collected from broadband and short-period seismograph stations. It is the intention to publish these data on CD-ROM. The data set is evaluated on data quality, accessibility and spatial coverage of the recording stations. In order to compare signals from different stations attention has been given to the instrumentation. Evaluation shows that in contrast to broadband networks, short-period networks in north-west Europe are not prepared for an event of this magnitude. It is recommended to increase the limited dynamic range of most digital stations and to evaluate the effectiveness of the currently used bandwidth. Finally, an organized common access to the data set, as is realized for the broad-band data, is recommended for regional, short-period networks. |
| The macroseismic map of the 1992 Roermond earthquake, the Netherlands | 1994 | Haak, H.W.; Bodegraven, J.A. van; Sleeman, R.; Verbeiren, R.; Ahorner, L.; Meidow, H.; Grünthal, G.; Hoang-Trong, P.; Musson, R.M.W.; Henni, P.; Schenková, Z.; Zimová, R. | 73(2-4) | Six countries contributed to a data base covering macroseismic observations from nine countries affected by the April 13, 1992 Roermond earthquake. Despite the diversity of data sources and variety of approaches by researchers in the countries involved, particularly concerning aspects of data acquisition and intensity assignment, a clear overall-picture of the macroseismic effects could be achieved. An acceptable estimate has been made of the following parameters: macroseismic focal depth h (= 18 km), intensity attenuation α (= 0.001), the 'theoretical' epicentral intensity I0 (=7.4) and the macroseismic local magnitude (= 5.6). For further study the complete macroseismic data base is available as an ASCII-file on diskette. |
| Macroseismic effects in Germany of the 1992 Roermond earthquake and their interpretation | 1994 | Meidow, H.; Ahorner, L. | 73(2-4) | The Roermond earthquake of April 13, 1992, with a local magnitude of ML = 5.9 , belongs to the largest earthquakes which have been observed in the Lower Rhine Embayment in historical time. It was felt in central and western Europe over an area of about 600 000 km2. The German territory forms much of the eastern part of that area. The most distant reports in Germany came from Kiel (450 km), Berlin (540 km) and Munich (520 km). The epicentral intensity is observed in the German-Netherlands border region was VII on the MSK-scale. For an ML = 5.9 earthquake this I0 is unusually low as compared to other large earthquakes in the Lower Rhine Embayment. Two factors are assumed to be mainly responsible for the low epicentral intensity: (1) the focal depth which is deeper than normal, and (2) the unusually strong absorption of seismic energy by a more than 1500 m-thick layer of soft Tertiary and Quaternary sediments within the Roer Valley Graben near the epicenter. More than 2000 macroseismic reports from 600 different localities have been interpreted, resulting in detailed isoseismal maps for Germany. The following mean isoseismal radii have been determined: r7 = 6 km, r6 = 42km, r5 = 102 km, r4 = 179 km, r3 =322 km, r2 = 440 km. Based on these isoseismal radii the macroseismic focal depth has been determined with an iterative computer program based on the method of Sponheuer (1960). The uncorrected observed I0 = VII gives a focal depth of about 26 km. However, if we correct I0 for the influence of the sedimentary graben fill, resulting in a value of VII-VIII, the obtained depth is about 17 km. This corresponds better with the focal depth as determined instrumentally by various working groups. |
| Assessment of the losses caused by the 1992 Roermond earthquake, the Netherlands (extended abstract) | 1994 | Berz, G. | 73(2-4) | |
| Comparison of the macroseismic field of the 1992 Roermond earthquake, the Netherlands, with those of large historical earthquakes in the Lower Rhine Embayment and its vicinity | 1994 | Meidow, H. | 73(2-4) | The macroseismic field of the Roermond earthquake of April 13, 1992, has been compared with those of large historical earthquakes (ML ≥ 5.5) in the Lower Rhine Embayment and its vicinity: those of Düren (1755 ,1756), Tollhausen (1878), North-Brabant(1932) and Euskirchen (1951). The historical earthquakes were reconstructed and analysed mainly on the basis of contemporary historical documents. All investigated earthquakes caused at least moderate damage in their epicentral regions. While the earthquakes of Düren (1756) and Tollhausen (1878) reached the epicentral intensity VIII, the others produced only epicentral intensities between VII and VII-VIII. The mean value of the absorption coefficient α =0.002 ± 0.001 km-1 was calculated from the intensity attenuation curves. The macroseismic focal depths of the Tollhausen (1878), North-Brabant(1932) and Euskirchen (1951) earthquakes range from 9 to 8 km, whereas the Düren (1755,1756) and Roermond (1992) earthquakes occurred at a depth range from 14 to 18 km. The strongest event in historical time was the Düren (1756) earthquake. Its macroseismically determined local magnitude ML = 6.1 was slightly larger than the local magnitude of the Roermond earthquake ML = 5.9. |
| The 1992 Roermond earthquake, the Netherlands: earthquake engineering | 1994 | Bouwkamp, J.G. | 73(2-4) | An overview of the structural damage resulting from the April 13,1992 Roermond earthquake is presented. Rather than addressing the need of code requirements to enhance the structural integrity of buildings in low-intensity seismic zones such as the Roermond region, the paper addresses the effects of the basic architectural form of buildings which can dramatically affect the seismic resistance of buildings and adversely affect the possibility of structural survival. Particularly in regions of low seismicity, considering the influence of zoning and architectural layout in building design will enhance the earthquake resistance of buildings far more than could be expected through the use of earthquake design code provisions. The paper discusses the effects of design 'errors' on the potential earthquake response of buildings and offers solutions to improve the seismic performance. |
| Observations of damage ratios to buildings in the epicentral region of the 1992 Roermond earthquake, the Netherlands (extended abstract) | 1994 | Pappin, J.W.; Coburn, A.R.; Pratt, C.R. | 73(2-4) | |
| Loading of foundation piles during the1992 Roermond earthquake, the Netherlands | 1994 | Luger, H.J.; Meijer, P.; Brinkman, J. | 73(2-4) | In order to assess the influence of the 1992 Roermond earthquake on a piled foundation, a pile and the interacting mass of the supported structure were modelled. The model represents a typical pile in the Maasniel area of Roermond, the Netherlands. Results indicate that piles are subjected to significant loading. Popular belief that wind-loading conditions in the Netherlands impose higher loads on the foundation piles than an earthquake like the one in Roermond is not correct. Especially bored (in-situ fabricated) pile types may be loaded beyond their elastic range. Recommendations for verification and improvement of the model are given. |
| Attenuation of seismic ground motion due to the L992 Roermond earthquake, the Netherlands (extended abstract) | 1994 | Berger, N. | 73(2-4) | |
| Strong ground motion computation of the 1992 Roermond earthquake, the Netherlands, from linear methods using locally recorded aftershocks | 1994 | Gariel, J.C.; Horrent, C.; Jongmans, D.; Camelbeeck, T. | 73(2-4) | The strong earthquake (ML = 5.8) on April 13, 1992 near Roermond (the Netherlands) is the largest for the area in the last 50 years and has affected a highly urbanized and industrialized region. Unfortunately, no strong motion records were retrieved in the epicentral area. However, a temporary network was installed by the Belgium Royal Observatory a few hours after the mainshock and more than 100 aftershocks were recorded by digital stations. These aftershock records are used to reconstruct the ground motion in the epicentral area during the mainshock. Two different techniques have been considered, namely the empirical Green's function method and the convolution technique. Using the former one, it is shown that, in the epicentral area, peak acceleration reached values between 0.57 and 1.75 m/s2. Acceleration values two times larger are obtained using the deconvolution technique. |
| Local ground motion variations observed in the region of Roermond, the Netherlands, from aftershocks of the April 1992 earthquake | 1994 | Horrent, C.; Jongmans, D.; Camelbeeck, T. | 73(2-4) | The Roermond earthquake of April 13, 1992 (ML = 5.8) was felt in the proximity of the epicentre with different intensity in the Netherlands, Germany and Belgium. Within a few hours after the main shock, a temporary network of seven stations was installed in the epicentral area. About 200 aftershocks were recorded by these stations and also by the Belgian permanent network. The aftershock records in the graben exhibit large differences in ground motion, which may result from the source mechanism. However, significant amplifications were observed at some sites for very different earthquake locations. These results suggest that site effects have played a significant role in the ground motion. They are supported by spectral ratio computations between the signals recorded in the graben and at a reference bedrock station. |
| Accelerometer recordings of the 1992 Roermond earthquake, the Netherlands, and ground motion simulations using the empirical Green's function method | 1994 | Helm, J.A.; Bour, M.; Hoang-Trong, P. | 73(2-4) | A telemetered digital three-station network at Soultz-sous-Forêts in NE France (280 km SE of Roermond) recorded the ML = 5.8 mainshock of the Roermond earthquake on April 13, 1992 and also the ML = 3.6 aftershock at 01:06 UTC, April 14,1992. Using the empirical Green's function method the ground motions recorded during the mainshock are modelled from the recording of the aftershock. This method is used to calculate a maximum ground acceleration of 0.17 m/s2 (peak-to-peak) at a site in the Rhine Graben where the observed maximum ground acceleration was 0.18 m/s2. The recordings from the three stations show a variation in the amplitude of peak-to-peak ground acceleration for the three sites, from 0.027 m/s2 at a rock site on the edge of the Upper Rhine Graben to 0.18 m/s2 at a station on sediments in this graben. |
| Geotechnical consequences of ground motion: hazard perspectives | 1994 | Davenport, C.A. | 73(2-4) | Following the 13 April 1992 Roermond earthquake, areas of the Netherlands experienced severe shaking and suffered ground failures, particularly ground cracking, sand injections, and shallow local landslips. Such phenomena are well documented in historical case histories of large earthquakes in many areas of the world: famous examples of widespread failure are reviewed and the key phenomena identified, e.g. Assam (1899) and Alaska (1964). The geotechnical conditions and consequences resulting from strong ground motions are emphasized and important applications in earthquake hazard assessment are discussed in the context of readily available literature. Liquefaction and kindred state changes leading to mass failure, settlement, and flow-slide behaviour are considered for cases of water-saturated sandy and silty deposits. A simple classification is required to facilitate discussion of strong motion domains; these being nearfield, proximal farfield, and distal farfield. Volume changes, dewatering and displacement patterns provide insights into hazard assessment applications, amongst which three are considered: (i) intensity scaling effects, with a scheme appropriate to north-west Europe, (ii) in situ measurement by Standard and Cone Penetration Tests (SPTs and CPTs), and (iii) palaeoseismology. The potential of finding palaeoliquefaction phenomena in the southern Netherlands is considered to be high in the vicinity of certain faults. The importance of palaeoseismology is evaluated with relevant world-wide research perspectives regarding palaeoliquefaction. Recommendations are given to encourage research initiatives. |
| Liquefaction and the 1992 Roermond earthquake, the Netherlands | 1994 | Nieuwenhuis, J.D. | 73(2-4) | The scanty information available on liquefaction phenomena during the Roermond earthquake does not allow firm conclusions on the technical significance of these phenomena. However, speculations based on applied mechanics principles justify a few conclusions on what happened and what did not happen. First, the presence of fracture vents and sand boils agrees well with the estimated earthquake magnitude ML = 5.8-5.9; second, the rare occurrence of sand boils and the absence of visible settlements indicate that liquefaction was not an important phenomenon during the earthquake; third, damage of farms due to liquefaction seems absent. This observation is in agreement with the theoretical analysis of responses of the farm foundations to liquefaction. If the area affected by liquefaction had exceeded some 1% of the total area, significant damage would have been detectable. The low ground water tables during the time of the earthquake have most probably prevented extensive damage. |
| Liquefaction potential and dewatering injection structures at Herkenbosch: field investigations of the effects of the 1992 Roermond earthquake, the Netherlands | 1994 | Davenport, C.A.; Lap, J.M.J.; Maurenbrecher, P.M.; Price, D.G. | 73(2-4) | Near-surface soils in the southern Netherlands include fine sands with, in some areas, a watertable at shallow depth. A reconnaissance study undertaken in 1987 to ascertain the potential for a liquefaction hazard in areas south of Eindhoven revealed a high liquefaction potential in the area around and to the south of Roermond. The earthquake of 13 April 1992 caused sand eruptions to occur in numerous locations in the vicinity of Roermond. This study focuses on sand fissures and mounds located to the south of Herkenbosch, between the town and the River Roer. Excavations revealed extensive disturbance of clay and silt deposits down to confined saturated sand deposits at depths of several metres below the surface. Extensive ground cracking, with or without sand extrusion, occurred over an area of circa 0.5 km2. Pit and trench excavations permitted detailed mapping and sampling of over 30 m of sand-injected fissures. The evidence indicates that ground cracks were injected, almost passively, by sand entrained within water, driven upwards following liquefaction of the previously confined sand. Groundwater conditions are such that sand volcanoes and spring pits developed at the bottom of the deeper excavations. |
| Safety of dikes and embankments in the Netherlands with special reference to earthquakes | 1994 | Lindenberg, J.; Calle, E.O.F.; Vrouwenvelder, A.C.W.M. | 73(2-4) | The protection against flooding is an important topic in the Netherlands. Based on statutorily defined sea and river levels which have to be withstood, safety is expressed as an acceptable annual probability of flooding for each area protected by water-retaining structures. This hazard assessment considers primarily the basic threat of extreme high water levels alone or in combination with (specific) storm conditions. However, combinations of high water levels with unrelated damaging events may also contribute to the total flooding hazard. This paper describes the general approach for the assessment of the possible combined failure mechanism leading to the scenario 'flooding due to earthquake-induced damage'. Based on the results of simplified slope stability calculations, the conclusion is drawn that the contribution of this scenario to the total probability of flooding is exceedingly small for the lower river region of the Netherlands. |
| Influence of the 1992 Roermond earthquake, the Netherlands, on shallow foundations | 1994 | Meijers, P.; Loger, H.J.; Lange, H.G. de | 73(2-4) | This paper considers the influence of the strong ground motion due to the Roermond earthquake on soil behavior and shallow foundations. As no local strong ground motion acceleration record was available, a synthetic record has been used. The procedure used to obtain this synthetic acceleration record is explained. The stratigraphy of the shallow subsoil is briefly described and results of a short literature review on densification of soils are presented. Finally, an estimate is made of the settlement of shallow foundations at one site (Maasniel area) in Roermond, due to the strong ground acceleration induced by the earthquake. From this estimate we conclude that shallow foundations, designed according to Dutch building codes, will generally not suffer excessive settlement values under earthquake loading comparable to that which occurred in Roermond on April 13,1992. |
| Earthquake-triggered landslides at the Brunssummerheide, Limburg, the Netherlands : preliminary studies following the 1992 Roermond earthquake | 1994 | Alkema, D.; Mosselman, M.; Paulussen, I. | 73(2-4) | Two landslides occurred at the Brunssummerheide during, or shortly after the main shock of the 1992 Roermond earthquake. The Brunssummerheide is located 25 km south of the epicentre. An earthquake can reduce the stability of a hillslope in three ways: firstly, the ground acceleration from seismic waves forms an additional destabilizing force; secondly, the shear strength may be reduced by an increase of the pore pressure, and thirdly, an earthquake may cause the breaking of small cohesive bonds between soil particles, thus reducing the overall cohesion. Slope stability back-analyses were carried out to reconstruct the forces and processes during the event. Peak ground accelerations as predicted by empirical attenuation relationships are insufficient to cause instability of the slopes. It is concluded that an increase of at least 100% in the pore pressures was required to destabilize the two hillslopes. |
| Technical note on the 1992 Brunssummerheide landslide in Limburg, the Netherlands | 1994 | Maurenbrecher, P.M.; Price, D.G.; Verwaal, W. | 73(2-4) | The 1992 Roermond earthquake caused two landslides in Brunssummerheide park, South Limburg, the Netherlands. The larger of the two slides is within the area of a large slide which happened in 1955. This area consists of loose, reworked, uniformly graded, fine quartz sands in overall gently sloping ground with a gradient of 1 in 5. At the foot of the slope the ground is wooded and approximately level, with groundwater almost at the surface. The severe and varied tilting of the trees in this area indicates horizontal movement and upward bulging of the soil. High water tables persist and springs in the area are the source of the Roode Beek, a tributary of the Maas River. Swampy and even quicksand conditions exist. The smaller landslide also occurred in a slope with a swampy area at its foot. Other slopes not associated with swampy areas were not affected by the earthquake. The association of loose, reworked and water-saturated sands with slope failure suggests that the slope failures may have taken place by liquefaction of these sands removing support from the toe of the slope. This paper presents a description of the failed slope; a detailed discussion of the probable cause of failure awaits further research. |
| Radon behaviour in mineral spring water of Bad Brambach (Vogtland, Germany) in the temporal vicinity of the L992 Roermond earthquake, the Netherlands | 1994 | Koch, U.; Heinicke, J. | 73(2-4) | The correlation between the Vogtland micro earthquakes and the fluctuations of 222Rn concentration in spring water and soil air has been investigated in the Saxon State Spa of Bad Brambach for more than three years. In contrast to the soil air, spring water shows significant radon anomalies at the time of about 50% of the earthquakes or earthquake swarms (ML < 4, epicentral distance < 50 km). The 1992 Roermond earthquake has confirmed for the first time that it is possible to register an anomaly effect in Bad Brambach related to seismic wave motion from earthquakes with larger epicentral distances. Recent investigations have shown that CO2 outgassing due to tectonic processes may act as a gas lift for radon. A model conception and first results of continuous radon and CO2 measurements in spring water are presented. |
| Using expert opinion for assessing seismic hazard in low-seismicity areas | 1994 | McGuire, R.K. | 73(2-4) | The uncertainty in seismic hazard is especially important in regions of low seismicity where empirical observations alone do not constrain the locations and characteristics of future seismicity. In these regions, subjective judgment, properly defined and documented, must be used to quantify the uncertainty in earthquake occurrences and ground motion. A project to use expert opinion to quantify uncertainties has been conducted in the eastern United States, revealing several important rules that such studies must follow. These are that the judgments and documentation must be firmly based and justified on a scientific plane, that diversity among experts must be resolved if it is caused by misunderstanding or miscommunications, and that the earth scientists themselves must be involved in the development of the procedures to quantify and document expert opinion. |
| Seismic hazard assessment for the Lower Rhine Embayment before and after the 1992 Roermond earthquake | 1994 | Rosenhauer, W.; Ahorner, L. | 73(2-4) | A regional probabilistic seismic hazard analysis for the Lower Rhine Embayment was published by the authors in 1975 and updated in 1984 as part of a comprehensive study for the former Federal Republic of Germany and adjacent regions. The seismic zones of the lower Rhine Embayment were found to belong to the most active in western and central Europe. This contribution presents the modifications required after the occurrence of the Roermond earthquake of April 13,1992. New frequency-magnitude curves λ(> M) are derived as the essential quantitative input, applying the generalized Gumbel distribution for magnitude extremes. Completion of the former data for the years l980-1992 leads to distinct changes of λ(> M) in the seismic zone in which the epicenter of the Roermond earthquake is situated. Revised frequency-intensity curves λ(> I) are computed with the Monte-Carlo simulation techniques using code PSSAEL developed earlier by the authors. Only small changes are found. For example, an intensity (MSK) I = VII is now expected at Roermond for future events with a probability of 4.9.10-4/year instead of 2.4.10-4/year. The regional seismic risk is illustrated by two recomputed hazard maps of the Lower Rhine Embayment. |
| Earthquake hazard for Roermond, the Netherlands | 1994 | Crook, T. de | 73(2-4) | The frequency-intensity and the frequency-magnitude relations are calculated from the observed tectonic earthquakes in the Netherlands. The obtained mean return periods for an intensity VII and a magnitude 5.8-5.9, like the 1992 Roermond earthquake, are estimated to be 132 years and 1000 years or more respectively. The influence of the recent Roermond earthquake on the existing seismic hazard intensity maps for the Netherlands is negligible. The earthquake hazard for the town of Roermond is evaluated |
| Historical seismicity of the lower Rhine and Meuse valleys from 600 to 1525: a new critical review | 1994 | Alexandre, P. | 73(2-4) | The historical seismicity of eastern Belgium, Netherlands Limburg and the northern Rhineland should be entirely revised. Going back to sources contemporaneous with the events, we have been able on the one hand to eliminate the false data appearing in traditional catalogues, and on the other hand to elaborate a new critical catalogue of 22 earthquakes which occurred in this area for the period from the earliest known records up to 1525. Special attention has been paid to the large shocks of June 11, 1395 and August 23, 1504. |
| Fission-track analysis: principles, methodology and implications for tectono-thermal histories of sedimentary basins, orogenic belts, and continental margins* | 1995 | Andriessen, P.A.M. | 74(1) | Fission tracks, formed by natural fission of 232Th,235U and 238U, are damage zones in the crystal lattice. The decay constants of the first two isotopes are so small that, for all practical purposes, all fission tracks are derived from fission of 238U. The spontaneous fission-track (FT) density is proportial to the elapsed time and the uranium content. The latter parameter is determined by irradiation of the sample with thermal neutrons, causing the 235U-isotope to fission. A new set of induced fission tracks is made and the induced FT density is proportional to the amount of uranium, because the 235U/238U ratio is constant. FT dating is commonly performed on volcanic glass and accessory minerals such as apatite, zircon and sphene. Compared to other radiogenic age determinations, FT apparent ages are systematically younger, except for rocks that cooled rapidly such as volcanics and shallow-depth intrusives. Laboratory experiments show that fission tracks are not stable at high temperatures. This provides an explanation for the comparatively young FT ages and at the same time, opens a new important field of application: FT analysis as a geochrono-thermometer. Within a mineral-specific temperature range, fission tracks begin to anneal until they are completely erased at the high temperature boundary. The temperature, at which total annealing occurs, depends on the timescale of the heating event and the chemical composition of the mineral. Data from drill holes confirm the laboratory experiments over geological timescales. For apatite it is possible to establish an annealing zone for spontaneous fission tracks under geological time-temperature (T-t) conditions. Annealing is temperature-dependent and as the process progresses the length of the fission track shortens. This results in a reduction of the spontaneous track density and hence in a decrease of the FT age. The apparent age, single-age grain distribution, FT mean length and length distribution are diagnostic of the temperature histories of rocks. Recent advances in understanding annealing kinetics of fission tracks in apatite permit computer modelling of age and length parameters for given T-t pathways. FT analysis thus constitutes a powerful and unique tool for the reconstruction of thermal, uplift and subsidence histories, and also for provenance studies of sediments. Particularly in hydrocarbon exploration, the applicationof fission tracks to the study of thermal and burial histories has proven the unique ability of the method in understanding the formation and evolution of sedimentary basins. FT analyses are also used for studying uplift, exhumation, unroofing, denudation and erosion histories of basement rocks. These parameters are important for our understanding of tectonic processes and for numerical modelling studies, because they constrain temperature histories in diverse geological settings like subduction and collision zones, extensional areas of continental breakup during rifting, and intra-plate settings. |
| A transition from a braided to a meandering channel facies, showing inclined heterolithic stratification (Late Weichselian, central Netherlands) | 1995 | Makaske, B.; Nap, R.L. | 74(1) | An excavation near Deest (Land van Maas en Waal, central Netherlands) offered an opportunity to study sedimentary structures near the top of the Late Weichselian Kreftenheye Formation in two point bar sequences showing different lithofacies. The sandy point bars rest on gravelly braided river deposits (facies 1). The older point bar sequence (facies 2) was formed by a small-scale channel and is characterized by clayey lateral accretion surfaces, indicated by inclined heterolithic stratification (IHS). This point bar sequence has features indicative of variable discharge during deposition during a transitional stage from a braided to a meandering channel pattern. The younger point bar sequence (facies 3) was formed by a larger channel that incised the braidplain and is thought to represent a fully developed meandering channel pattern. IHS was not found in these deposits. Point bar formation at the study location ceased during the Allerød or early Younger Dryas when the meandering channel was abandoned. The fill of this residual channel (facies 4) consists of gyttja, peat and (humic) clay. Finally, the point bars and the residual channel were covered by floodbasin deposits of Holocene meandering river systems (also facies 4) which consist predominantly of clay. |
| The role of erosion and deposition in the construction of alluvial fan sequences in the Guadix Formation (SE Spain) | 1995 | Viseras, C.; Fernández, J. | 74(1) | A study is made of a Pliocene alluvial fan in the Guadix Basin (Betic Cordillera, Spain). On the basis of the characteristics of the sequences and the position of the Arroyo de Gor section within the fan, a model is proposed to explain the sequential trends, taking into account the importance of the erosional processes associated with lateral displacement according to a pendular pattern of a fluvial system made up of a trunk channel and lateral, secondary channels. Lateral migration of channels in a constant direction is a consequence of the preferential attachment of bars to one bank, as shown by recent systems. Change in the direction of migration is caused when channels reach the basin margin or the opposing slope of an adjoining fan. This can also occur if tilting towards the centre of the basin takes place. According to this model, a marginal position in a fan would be recognised by a series of fining and thinning upward (FU + ThU) sequences delimited by clear erosion surfaces. The backsets of the bars accumulated in the channels invariably dip towards the centre of the fan. A central position is characterised by a higher number of FU + ThU sequences not reaching completion at the top (and, therefore, with a lower proportion of overbank facies). The backsets dip alternately in opposite directions. This model may also be used for the evolution of the sediment supply/subsidence ratio in a particular zone of a basin. |
| Fish remains from the Aptian near Bentheim, Germany | 1995 | Lambers, P.H.; Boekschoten, G.J. | 74(1) | The remains of two fossil fishes from the Lower Aptian of the Bentheim area, north-western Germany, are described. A fragment of a large pectoral fin is identified as Pachycormidae indet. It is the first report of a Lower Cretaceous pachycormid in Europe and extends the geographic range of pachycormids to Germany. A trunk of a small teleost fish is identified as Clupeomorphaindet. This extends the range of Lower Cretaceous clupeomorphs to north-western Germany. |
| Triassic-Miocene paleogeography and basin evolution of the Subbetic Zone between Ronda and Málaga, Spain | 1995 | Meer, F. van der | 74(1) | During the Triassic, continental and supratidal environments prevailed in the north of the Ronda-Málaga region whereas intertidal and shallow marine environments characterize the south. From the Jurassic up to the Miocene, the Ronda-Málaga region was the scene of shallow marine environments in the north and open or deeper marine environments in the south. The Miocene reveals rapidly changing paleo-environments. During the Aquitanian a submarine fan system developed with clastic supply from an emerged area in the north. In the Burdigalian, deformation started to the south of the study area and depositional patterns completely reversed, now showing detritus supply from an emerged area in the south. The entire area emerged during Langhian and Serravallian times and several local extension basins developed in the Tortonian. Backstripping analysis reveals four phases of accelerated subsidence related to extension in the Mesozoic: Anisian-Ladinian (241-235Ma), Norian-Hettangian (223-203Ma), Callovian-Tithonian (161-146Ma), and Cenomanian-Turonian (97-89Ma). These phases can be correlated with tectonic events in the Central Atlantic Ocean. The Tertiary subsidence record shows a change from slow to rapid subsidence in the Late Oligocene and Early Miocene related to a change from extensional to compressional tectonics. Throughout the Middle and Late Miocene and the Pliocene, strike-slip tectonics resulted in local extension and compression giving rise to renewed basin development. The paleogeographic reconstructions together with subsidence analysis allow to discuss the tectonostratigraphic evolution of the Ronda-Málaga region within the framework of western Mediterranean plate tectonics. |
| Pre-Hercynian magmatism in the Eastern Pyrenees (Cap de Creus and Albera Massifs) and its geodynamical setting | 1995 | Navidad, M.; Carreras, C. | 74(1) | In the Eastern Pyrenees Hercynian massifs, basic and acid magmatic associations occur in metasedimentary series of probable Cambrian Late Precambrian age. Basic magmatic rocks occur in the lower part of the metasedimentary series as metagabbros and metabasalts derived from low-Ktholeiites and quartz-tholeiites. They are characterized by low niobium and thorium contents (< 5 ppm) and their multi-element and REE patterns are flat. They are interpreted as fractionated E-MORB mantle partial melts. Acid magmatic rocks are: 1) Metarhyolites and dacitic metatuffs intercalated at different levels in the series. They are characterised by low to moderate niobium and thorium contents (7 -12 ppm). Their multi-element patterns are analogous to those of crustal melts, and the REE patterns are characteristic of progressively fractionated calcalkaline magmas. These rocks are derived from aluminous calcalkaline crustal magmas. 2) Rhyolitic metaporphyries mainly in the upper part of the series, although thin sills are also present in the lower part. These rocks are highly impoverished in incompatible and REE elements and display low titanium, phosphorus and strontium contents. Their REE patterns are flat with a significant europium anomaly. The rocks represent highly differentiated aluminous calcalkaline crustal magmas. 3) A quartz-monzonitic metaporphyry sill in the lowest part of the series. It represents a meta-aluminous magma with alkaline affinity and, although its incompatible element patterns are analogous to those of the metavolcanics, its REE patterns are more fractionated and exhibit a stronger impoverishment in HREE. The assemblage of acid rocks can be ascribed to a magmatic episode developed by crustal partial melting and likely also to subsequent differentiation. The interbedded acid and basic volcanics in the lower part of the series suggest that both magmatic events overlapped in time, although no genetic connection exists since the acid and basic rocks are of crustal and mantle origin respectively. The magmatism probably took place in a continental back-arc basin. |
| Classification of gem deposits of Sri Lanka | 1995 | Dissanayake, C.B.; Rupasinghe, M.S. | 74(1) | Approximately 25% of Sri Lanka's landmass is gem-bearing. Most of the gem deposits are located in restricted zones (approximately 15000 sq km) within the area occupied by rocks of the Highland/Southwestern Complex . Over 90% of Sri Lanka's gem mining is from secondary placer deposits that can be classified as sedimentary gem deposits of residual, eluvial and alluvial types. Primary or in-situ gem occurrences are located mainly in contact-metamorphic zones comprising of skarn and calcium-rich rocks. Corundum occurrences have also been found in aluminous-rich, silica-deficient metasedimentary formations. Gem minerals that are frequently found in pegmatites within the Highland/Southwestern Complex include corundum, zircon, beryl, quartz varieties, feldspar and chrysoberyl. A special feature of many secondary gem deposits of Sri Lanka is their location on morphotectonically controlled sites. |
| Organic matter assemblages from recent sediments of the Tacarigua coastal Iagoon (northern Venezuela) | 1995 | Rull, V. | 74(2) | Sediments of the Tacarigua coastal lagoon in northern Venezuela are rich in organic material. The lagoon and its sediments are therefore important as a modern-day analog for the interpretation of palynofacies assemblages in clastic sediments that formed in tropical coastal environments. Samples representative of the most important subenvironments of the lagoon were collected and prepared with standard palynological methods. The organic materials were analyzed in terms of biological origin, source area and textural characteristics. The analytical results were evaluated with standard statistical techniques. Based on Principal Components Analysis (PCA) six sample groups are differentiated. Sample groups A and B are very rich in humic gels and they represent the western part of the lagoon in which sedimentation largely reflects the influence of the River Guapo. Sample group C contains both humic gels and degraded plant material. Group C represents the central part of the lagoon where sedimentation is influenced both by the River Guapo and the lagoon mouth. Sample group F contains sub-equal percentages of degraded algal and/or bacterial material, humic gels and degraded plant material. Group F is representative of the eastern part of the lagoon where autochthonous sedimentation is important. Sample groups D and E which have a high percentage of degraded algal and/or bacterial material, are representative of sediments that were laid down in close proximity to mangrove vegetation. In view of the varied character of the organic assemblages in these modern lagoonal deposits, the interpretation in environmental terms of similar fossil assemblages is complex and requires a careful consideration of all the evidence. |
| The Mesozoic and Cenozoic of the Malaguide Complex in the Mátaga area: a Paleogene olistostrome-type chaotic complex (Betic Cordillera, Spain) | 1995 | Serrano, F.; Sanz de Galdeano, C.; Delgado, F.; López-Garrido, A.C.; Martín-Algarra, A. | 74(2) | This paper analyses the stratigraphic disorganization of the Mesozoic and Cenozoic in the Malaguide Complex of the Málaga area and concludes that this disorganization was caused by gravitational tectonics, which arranged most of the Meso-Cenozoic in olistostrome-type chaotic masses. The deformations occurred between the Middle Eocene and the latest Oligocene. The paper also reports the presence of up to now partially unknown Eocene sediments, deposited in lagoonal environments. Finally, for the first time, the existence around Málaga of sediments belonging to the Upper Oligocene - Aquitanian Ciudad Granada Group and the Lower Burdigalian Viñuela Group is shown. |
| Late Cretaceous sedimentation and tectonic inversion, southern Netherlands | 1995 | Gras, R. | 74(2) | The Late Cretaceous in northwest Europe is characterised by general sealevel rise, leading to extensive platform carbonate sedimentation of the Chalk Group, and by tectonic inversion, as witnessed by uplift and erosion of the Late Jurassic to Early Cretaceous basins. The Roer Valley Graben in the southern Netherlands was uplifted and eroded in the Late Cretaceous. The inversion was accomplished by the reverse rejuvenation of the graben-bounding faults. On the adjacent horst blocks northeast of the graben, the Maasbommel High and the Peel Horst, a section of the Late Cretaceous Chalk Group has been preserved. Analysis of the Late Cretaceous chronostratigraphy and facies of well Maasbommel-l on the Maasbommel High shows that the high occupied a marginal position in the basin in Cenomanian times, and a basinal position during the Turonian to Early Santonian. A pulse ofclastic influx in the Late Santonian to Early Campanian marks the onset of the reverse rejuvenation of the graben-bounding Peel Boundary Fault and the uplift of the Roer Valley Graben relative to the Peel Horst and Maasbommel High. The inversion ceased in the Late Maastrichtian, when large parts of the graben were flooded and a condensed sequence of post-inversion Chalk Group sediments was deposited regionally. |
| U-Pb zircon ages of metatuffites and Older Granite from the Tunaberg area, SE Bergslagen, Sweden | 1995 | Dobbe, R.T.M.; Oen, I.S.; Verdurmen, E.A.T. | 74(2) | Two U-Pb zircon datings of metatuffites from the lower and upper unit of the metavolcanosedimentary sequence in the Tunaberg area, SE Bergslagen, Sweden, yield an age of 1871 ± 7 Ma for the metatuffite in the lower unit and an age of 1836 ± 9 Ma for the metatuffite in the upper unit. An Older Granite in a folded, composite granite-basite sheet that is intrusive in the upper metavolcanosedimentary unit contains zircons with cores that are apparently inherited from older crust; the U-Pb zircon age of 1912 ± 29 Ma obtained for this Older Granite must be discarded as the intrusion age of this granite. The maximum age of intrusion of the pre-main folding composite sheet of Older Granite and metabasite is constrained by the 1836 ± 9 Ma age of the upper volcanosedimentary unit. The deposition of the southern Bergslagen metavolcanosedimentary sequence in the Tunaberg area occurred in the period 1.88-1.83 Ga, i.e. a somewhat later and much longer period than the deposition period of the 1.89-1.88 Ga western Bergslagen volcanosedimentary sequence. |
| Orogenesis, a time odyssey | 1995 | 74(2) | ||
| Preface - Orogenesis, a time odyssey | 1995 | 74(2) | ||
| Introduction - Orogenesis, a time odyssey | 1995 | Zwart, H.J. | 74(2) | |
| Precambrian orogenesis: was it really different? | 1995 | Passchier, C.W. | 74(2) | Identification of macro-tectonic regimes responsible for development of orogenic or mobile belts becomes increasingly difficult with age. Especially Precambrian mobile belts are difficult to interpret because of a lack of 'far-field data' such as palaeogeographic reconstructions and palaeomagnetic data from contemporaneous oceanic crust. Nevertheless, most Precambrian mobile belts can be fitted into actualistic macro-tectonic models of orogenesis involving destructive plate margins. Archaean granite-greenstone areas are an exception in that they are difficult to fit to such actualistic models. One possible explanation is that they partly developed in a setting which is different from modern macro-tectonic regimes. A granite-greenstone area in the Yilgarn Craton, Western Australia, is presented as an example of unusual geometries in such a setting. |
| Southern Uralides and Variscides: comparison of their anatomies and evolutions | 1995 | Matte, P. | 74(2) | The Uralides and the Variscides are two Palaeozoic orogenic belts located on the eastern and south-western borders of the East-European Precambrian craton (Russo-Baltica), respectively. Both belts have common characteristics (nappe tectonics, opposite vergences on both sides) and have been formed within roughly the same time-span (500-270 Ma for the Variscides, 500-230 Ma for the Uralides). Nevertheless they exhibit striking differences in shape, preservation of ophiolites and island arcs, grade and type of metamorphism, and erosion level, which reflect different accretionary histories. The Variscides were formed by collision of large continental blocks involving major continental stacking and thickening, which resulted in strong heat production and related high-temperature metamorphism, crustal melting and late-orogenic denudation. The Uralides were formed by accretion of island arcs and micro-continents against a large East-European continent, associated with much lower heat production, low-temperature, high-pressure metamorphism, restricted crustal melting and minor erosion. |
| The Betic Cordilleras (SB Spain). Anatomy of a dualistic collision-type orogenic belt | 1995 | Biermann, C. | 74(2) | The first of three main tectonic events in the orogenic evolution of the Betic Cordilleras of southern Spain involved crustal subduction during the Late Cretaceous. It included the stacking of nappes in a deep crustal environment, accompanied by HP-metamorphism and polyphase ductile deformation. It has only been recorded in the nappes of the Internal Zone of the Betic Cordilleras and took place after a Middle Jurassic initial phase of rifting and break-up of a Triassic and Early Jurassic carbonate platform. The second phase in the development of the orogenic belt starts with an important regional phase of extension in Late Oligocene-earliest Miocene time. Crustal thinning during this extensional phase and updoming of the subcrustal lithosphere in the Betic-Alboran domain resulted in heating of the extended crust. Heating has been recorded in the metamorphic nappes of the Internal Zone. Extension of the Betic-Alboran domain resulted in low-angle normal faulting in the nappe pile of the Internal Zone. In the Early Miocene an abrupt transition from regional tension to compression is responsible for the final thrusting of elements of the Betic nappe complex towards the passive continental margin of the Iberian plate. This 'final emplacement' of the nappes marks the beginning of Neogene thin-skinned deformation in the External 7nne. In the Internal Zone, continuing convergence between the African and Iberian plates, resulted in strike-slip deformation from the latest Burdigalian onwards. Deformation in the eastern Internal Zone during this third tectonic phase is mainly characterised by basin subsidence and basement uplift in a strike-slip controlled regime under changing orientations of the main compressive stress. Theoretical lithospheric strength profiles predict differences in lithospheric strength between the eastern and western Betic Cordilleras, caused by differences in thermal structure and crustal thickness of the lithosphere. These differences are an inherited effect of the Late Oligocene-earliest Miocene extensional phase that influenced in particular the eastern part of the Betic Cordilleras. In the western Betic Cordilleras tectonic modelling predicts bending of the lithosphere and development of the Guadalquivir foreland basin under the load of the nappes, emplaced during the Early Miocene. In the eastern Betics lithospheric strength was restricted to the brittle upper crust, resulting in brittle strike-slip deformation and the development of pull-apart basins and basement uplifts. |
| Discussion: Alluvial architecture of the Quaternary Rhine-Meuse river system in the Netherlands, by G.H.J. Ruegg, Geologie en Mijnbouw 72: 321-330,1994 | 1995 | Törnqvist, T.E. | 74(2) | |
| Discussion: Alluvial architecture of the Quaternary Rhine-Meuse river system in the Netherlands. Reply by the Author | 1995 | Ruegg, G.H.J. | 74(2) | |
| Deep seismic reflections in the Netherlands, an overview | 1995 | Duin, E.; Rijkers, R.; Remmelts, G. | 74(3) | A project to study deep crustal structures was carried out by the Geological Survey of the Netherlands between 1986 and 1993. In this period deep seismic data were acquired on- and offshore the Netherlands. The data consist of stacked normal-incidence seismic lines with recording times of up to 16 s and wide-angle measurements. Interpretations show that the crust is composed of a transparent upper part and a reflective lower part. The base of the reflective zone coincides with the Moho discontinuity. The seismic lines cross several basins. The Roer Valley Graben was modelled with a pure-shear McKenzie model. The Mesozoic basins in the southern North Sea seem to have originated from pure-shear movements with an additional simple-shear component. The Moho depth map shows that the crust is thinner beneath the basins and thickens beneath the highs. |
| Late Weichselian and Holocene fluvial palaeogeography of the southern Rhine-Meuse delta (the Netherlands) | 1995 | Weerts, H.J.T.; Berendsen, H.J.A. | 74(3) | During the Late Weichselian, climatic changes induced the formation of a two-fold terraced braided-river plain that was formed by precursors of the rivers Rhine and Meuse in the central Netherlands. The older (and higher) terrace is Pleniglacial. It is partly covered by river dunes and coversand of Younger Dryas age. The younger (and lower) terrace originated during the Younger Dryas. Sealevel rise during the Holocene forced the rivers to aggrade since the Early Atlantic. Since then, avulsions have led to a complicated palaeo-channel pattern in which Rhine and Meuse precursors still can be distinguished. River avulsions occurred predominantly during three periods; between 5000 and 4000 BP, around 3000 BP, and around 1800 BP. These periods ofincreased avulsion frequency have also been found in the northern and central parts of the delta. Rivers were essentially meandering, but in the western part of the area anastomosing rivers existed before 3000-4000 BP. Some Meuse distributaries also have an anastomosing pattern around circa 2000 BP, although they show lateral accretion, and have a rather high width/thickness ratio (40-60). Meander wavelength increased considerably in the Middle Ages. This reflects an increase in peak discharge. |
| Compositional variation of detrital garnets in Quaternary Rhine, Meuse and Baltic River sediments in the Netherlands | 1995 | Tebbens, L.A.; Kroonenberg, S.B.; Berg, M.W. van den | 74(3) | Electron microprobe analysis of detrital garnets from Quaternary Rhine, Meuse and Baltic River sediments in the Netherlands area is used to trace back the provenance and relative contributions from different source lithologies in each drainage basin. In the Late Pliocene, high-grade metamorphic almandine- and pyrope-rich garnets from the Vosges and Black Forest dominate the Rhine garnet suite. With the onset of the Pleistocene, the Alpine Foreland Molasse is connected to the Rhine drainage area, supplying grossular- and probably also spessartine-rich garnets. The connection of the Aare and other Alpine tributaries to the Rhine in the Middle Pleistocene (Menapian-Bavelian) finally introduces large amounts of almandine-rich garnets derived from high-grade regionally metamorphosed inner Alpine source lithologies. The garnet suite of the Meuse sediments almost entirely consists of spessartines and Mn-rich almandines. They are derived from Mn-rich low-grade metamorphic pelites of the Libramont anticlinal region and the Stavelot Massif in the Ardennes. A small association of Mn-poor almandines is ascribed to a Vosges supply from before the capture of the Upper Meuse by the Moselle. The Baltic River garnet assemblages are characterized by a wide compositional spectrum, indicative of a large differentiated source area. The almandine- and pyrope-rich garnets are most likely derived from the extensive Fennoscandian Shield, while the spessartine-rich specimens are thought to originate from the mid-German Variscan massifs. |
| Conodont alteration in Devono-Carboniferous dolomites from southern Belgium | 1995 | Helsen, S. | 74(3) | Conodonts from selected Frasnian and Tournaisian dolomites in southern Belgium have Colour Alteration Index (CAI) values of 3.0-4.5 or 6.0-7.0. The textural alteration of these conodonts includes various features. Most striking are the subhedral apatite crystals that surround the conodont denticles. Furthermore, fields of apatite crystals, irregular apatite envelopes and apatite pseudomorphs after calcite occur on the conodont surfaces. The higher CAIs as well as the textural alteration are probably related to dolomitization processes. Phosphates may have been supplied by decomposition of organic matter or by ascending saline fluids. |
| Dutch Younger Dryas research | 1995 | 74(3) | ||
| Introduction - Dutch Younger Dryas Research | 1995 | Troelstra, S.; Hinte, J.E. van | 74(3) | |
| Between Diluvium and Deluge: the origin of the Younger Dryas concept (extended abstract) | 1995 | Joosten, J.H.J. | 74(3) | |
| The Younger Dryas in the marine record (extended abstract) | 1995 | Ganssen, G. | 74(3) | |
| The climate of the Younger Dryas in the Netherlands (extended abstract) | 1995 | Vandenberghe, J. | 74(3) | The Younger Dryas is to be considered as a biostratigraphic zone which in the Netherlands started 10900 (radiocarbon) years ago and ended 10200 BP. It is subdivided in two parts. The first half(up to 10 500 BP) is characterized by severe, continental conditions which resemble those at the end of the Pleniglacial; a permafrost was present. The second half shows milder conditions as a transition to the Holocene; permafrost disappeared at about 10500 BP. |
| Younger Dryas cooling and fluvial response (Maas River, the Netherlands) (extended abstract) | 1995 | Kasse, C. | 74(3) | |
| Younger Dryas deposits of the Tjonger Valley fill in the NE Netherlands (extended abstract) | 1995 | Meulen, S. van der | 74(3) | |
| Palynological investigations of Younger Dryas sediments in the northern Netherlands (extended abstract) | 1995 | Mook-Kamps, E. | 74(3) | |
| Human occupation of the southern Netherlands during the Younger Dryas (extended abstract) | 1995 | Deeben, J. | 74(3) | |
| A short review of the Younger Dryas in the Eastern Mediterranean area (extended abstract) | 1995 | Bottema, S. | 74(3) | |
| The Younger Dryas-Sapropel S1 connection in the Mediterranean Sea (extended abstract) | 1995 | Troelstra, S.; Hinte, J.E. van | 74(3) | |
| The Younger Dryas climatic event in the Cordillera de Talamanca, Costa Rica (extended abstract) | 1995 | Islebe, G.A.; Borg, K. van der; Hooghiemstra, H. | 74(3) | |
| Preliminary palynological results on the Pleistocene-Holocene transition, Seram Trench, offshore Irian Jaya, lndonesia (extended abstract) | 1995 | Kaars, S. van der | 74(3) | |
| Historical overview of lithostratigraphic research on the Upper Cretaceous of southern Limburg, the Netherlands | 1995 | Felder, W.M. | 74(4) | A historical overview is presented of the (litho)stratigraphic studies into the Upper Cretaceous deposits in southern Limburg (the Netherlands), the type area of the Maastrichtian. From 1860 onward, a workable lithostratigraphy has been available for these deposits. At present, a division including four formations and 23 members is being used. |
| An Early Oligocene oil seepage at the southern rim of the North Sea Basin, near Leuven (Belgium) | 1995 | Riessen, E.D. van; Vandenberghe, N. | 74(4) | A prominent chocolate-coloured horizon at the top of the Kerkom Sand (Oligocene, Tongeren Group) near Pellenberg in the Leuven area (Belgium), has traditionally been interpreted as the illuvial zone of a podsol type soil. Observed features however are equally compatible with an origin as an oil-saturated reservoir sand. In fact, organic geochemical analyses indicate strongly that a fossil oil seepage is the most likely interpretation. The time of oil impregnation may be related to an important tectonic re-arrangement, which started at the very end of the Eocene, and probably triggered the leakage and migration of oil from traps in the southwest of the Netherlands. The oil migrated through porous sands up the gentle northern flank of the Brabant Massif, guided by clayey seals till it reached the surface. The presence of a fossil oil seepage in the Leuven area, means that possible traps, downdip of the Pellenberg outcrop, may contain accumulations of oil. |
| Introduction - Geology of gas and oil under the Netherlands | 1995 | 74(4) | ||
| Synopsis: Petroleum geology of the Netherlands - 1993 | 1995 | 74(4) | ||
| preface Petroleum Geology of the Netherlands 1993 | 1995 | Kroonenberg, S.B. | 74(4) | |
| Synopsis: Petroleum geology of the Netherlands - 1993 | 1995 | 74(4) | ||
| Resources and resourcefulness | 1995 | Moody-Stuart, M. | 74(4) | |
| The role of oil and gas in the Dutch energy policy | 1995 | Dessens, C.W.M. | 74(4) | |
| New oil and gas - Technology leads the way | 1995 | Halfon, J. | 74(4) | |
| Natural gas in the Netherlands: exploration and development in historic and future perspective | 1995 | Breunese, J.N.; Rispens, F.B. | 74(4) | The discovery in 1959 of the giant Groningen gas field with reserves of 2750 billion (109) cubic metres (bcm) triggered a strong revival of the hydrocarbon exploration in the Netherlands. Over the last decades, the country has proven to be a very prolific hydrocarbon province, particularly for natural gas. Supported by the favourable exploration climate, exploration efforts have been generally at a high and sustained level. Well over 250 gas accumulations have been discovered throughout the stratigraphic column in various plays. Field sizes range from medium (of the order of 50 bcm) down to very small (2 bcm or less). The total initial reserves in these fields are around 1150 bcm. A mature stage of exploration has now been reached in many areas. Within a few years virtually all production acreage and large parts of the exploration acreage in the Netherlands will have been covered with 3D seismic. The introduction of 3D seismic has led to an improvement of exploration drilling efficiency and to increased technical success rates. Moreover, the application of 3D seismic has indicated additional prospectivity undetected before. It provides a major opportunity, and challenge, for finding incremental reserves. On the development side, nearly all large and medium-size gas fields have, or shortly will, come on stream. However, the majority of the relatively large number of small and marginal fields is still undeveloped. The challenge here is to reduce economic limits by further expansion of the infrastructure and application of modern marginal-field development technology. |
| #REF! | 1995 | 74(4) | ||
| Feasibility of retrieval of radioactive waste from a salt-mine repository: an overview | 1996 | Broek, W.M.G.T. van den; Heilbron, H.C.; Menken, M.J.V. | 75(1) | Two options for permanent disposal of radioactive waste in rock salt are distinguished: the salt-mine repository and the deep boreholes and cavity combination. Of these, the salt-mine repository is treated in some detail. The results of a feasibility study of waste retrieval from a salt-mine repository are reviewed. This study was carried out in the framework of the 'OPLA’ research programme of the Netherlands. Three disposal concepts have been considered: a modification of a concept for permanent disposal, a concept incorporating thick-walled overpacks and a concept which involves cased boreholes. Circumstances that may influence the retrieval operation (e.g. salt temperature, and volume and weight of overpacks) are taken into account. As a conclusion, it appears technically feasible to retrieve radioactive waste from a salt-mine repository, provided that the period between disposal and retrieval is not longer than a few hundred years. |
| A seismic zoning map conforming to Eurocode 8, and practical earthquake parameter relations for the Netherlands | 1996 | Crook, T. de | 75(1) | A zoning map for earthquake intensities and a relation between intensity and design ground acceleration are presented, conforming to Eurocode 8, the European earthquake building code. For the southeast of the Netherlands, reduced or simplified seismic design procedures may be used. For the remainder of the country, where expected intensities are very low, the provisions of Eurocode 8 need not be observed. From the Netherlands data set, the linear frequency-magnitude relation for the tectonic earthquakes is re-calculated. A correlation between intensity and magnitude is determined and compared with similar relations in California and Germany. The radius of perceptibility estimated from the local magnitude is more accurate than that estimated from the maximum observed epicentral intensity. This radius is substantially greater in the Netherlands than in California for the same epicentral intensity. The maximum expected earthquake for the Netherlands is estimated at about 6 ¼ local magnitude. |
| Paleomagnetic dating and effects of Weichselian periglacial processes on the magnetization of Early Pleistocene deposits (southern netherlands, northern Belgium) | 1996 | Kasse, C. | 75(1) | Early Pleistocene deposits of the Dutch-Belgian border area between Breda and Turnhout have been dated with paleomagnetic methods. Two normal polarity subzones in the sedimentary sequence are identified as the Olduvai and Jaramillo subchrons. The magnetozones are compared with the early Pleistocene pollenzones which are based on ecological changes reflecting Quaternary climatic variations. The Olduvai subchron was identified in pollenzones Tiglian C4 and C5 and the Jaramillo subchron in pollenzone Bavelian Bv3b. Late Pleistocene Weichselian periglacial processes clearly influenced the remanent magnetization of the early Pleistocene deposits. Melting of the icerich topzone of the Weichselian permafrost apparently modified the original remanence and led to complete remagnetization of the upper part of early Pleistocene clay beds. |
| The stratigraphical position of the Edegem Sands Member (Berchem Formation, Miocene) in its type area at Wilrijk (N Belgium), based on planktonic foraminifera | 1996 | Hooyberghs, H.J.F. | 75(1) | The glauconitic and fossiliferous Edegem Sands Member of the Berchem Formation (Miocene) in northern Belgium contains 25 different taxa of planktonic foraminifera. The presence of Globorotalia kugleri and Globigerinoides primordius allows to assign an Aquitanian age (Early Miocene) to the member. More accurately, this presence allows a correlation with Biozone N4, defined in tropical regions by Blow (1969,1979). |
| Palinspastic reconstruction of Permo-Carboniferous basins involved in Alpine deformation: the Erill Castell-Estac basin, Southern Pyrenees, Spain | 1996 | Soriano, C.; Martí, J.; Casas, J.M. | 75(1) | Permo-Carboniferous rocks are located in the lower thrust sheets of the Alpine antiformal stack in the Central Pyrenees. In order to study the geometry, distribution of facies, thickness and dynamics of Permo-Carboniferous basins, a detailed knowledge of Alpine tectonics is required, which has not always been taken into account by previous authors. This paper follows a different approach to the study of these basins. The Alpine structural units bounding the Permo-Carboniferous series of the eastern part of the Erill Castell-Estac basin have been mapped in detail, as a first step in this palinspastic restoration. This procedure has allowed: 1) to define some Alpine thrusts as inverted Permo-Carboniferous normal faults, 2) to constrain the age of several Permo-Carboniferous faults, 3) to differentiate the area studied as a volcano-tectonic depression, independent of the western part of the Erill Castell-Estac basin, and 4) to establish the paleogeographic position of the Permo-Carboniferous series and the minimum dimensions for the part of the basin studied. |
| Lower Carboniferous stratiform iron-manganese mineralizations (Rheinisches Schiefergebirge, Germany): products of submarine hydrothermal activity and diagenetic manganese redistribution | 1996 | Huckriede, H. | 75(1) | Lower Carboniferous iron-manganese ores of volcanic-sedimentary origin occur in the eastern part of the Rheinisches Schiefergebirge (Germany). Major constituents are rhodochrosite, bementite, hematite, and quartz. The ores are only weakly metamorphic and exhibit excellently preserved primary textures and fossils. Metamorphic equivalents of these ores are the manganese deposits of the Iberian Pyrite Belt. Most strikingly, the iron-manganese ores show a clearly developed zonation. Positions of former hydrothermal vents are indicated by chert mounds which are intersected by vertical pipes of coarse-grained hematite. The chert mounds are covered and surrounded by beds of fine-grained hematite. Manganese ore forms the distal part of each deposit. The formation of the ores was controlled by complex interactions of hydrothermal activity, intrusive and extrusive volcanism, formation of intramagmatic sulphide ores as well as diagenetic redistribution of certain elements: SiO2, copper, nickel, and iron were mobilized due to hydrothermal alteration of basic subvolcanic intrusive rocks. Copper and nickel were mostly re-deposited as sulphides within the intrusives, whereas manganese, iron, and SiO2 were transported by hot convecting waters to the sea floor. Here, SiO2 and the dissolved metals were precipitated by mixing with oxygenated sea water. Subsequently, manganese was separated from iron by diagenetic reactions. Enrichments of cosmic spherules and conodonts indicate that this process required a long time. |
| Rb-Sr and Sm-Nd geochronology and isotope geochemistry of Central Iberian metasedimentary rocks (Portugal) | 1996 | Tassinari, C.C.G.; Medina, J.; Pinto, M.S. | 75(1) | Rb-Sr and Sm-Nd isotopic data are reported for 27 samples of fine-grained metasediments from five different localities of the Slate Greywacke Complex of the Central Iberian Zone, Portugal. Over most of the area, Rb-Sr whole-rock isotope systematics yields a 440 to 400 Ma time interval, which is considered to correspond to an important metamorphic episode. Initial 87Sr/86Sr ratios of most Variscan granitoids from northern Portugal together with the Sr isotopic evolution curves for all studied metapelites, show that the latter are not suitable main sources for these granitoids. Sm-Nd depleted-mantle model ages and whole-rock Sm-Nd isochron ages provide values of 1.35 to 1.25 Ga, which may correspond to the average age of the mantle-extraction of the sources of the sediments. These data provide evidence that metamorphism of greenschist facies does not induce Nd isotopic rehomogenization in fine-grained sediments. The Sr and Nd isotopic signatures of the analysed metasediments (Sri = 0.7090 to 0.7170; and εNd (430) = -2.6 to -4.18) suggest derivation from young continental crust, and deposition probably in a tectonically passive setting. |
| Discussion: The Betic Cordilleras (SE Spain). Anatomy of a dualistic collision-type orogenic belt, by C. Biermann, Geologie en Mijnbouw 74: 167-182,1995 | 1996 | Vissers, R.L.M. | 75(1) | |
| Discussion: The Betic Cordilleras (SE Spain). Anatomy of a dualistic collision-type orogenic belt. Reply by the Author. | 1996 | Biermann, C. | 75(1) | |
| Discussion: Triassic-Miocene paleogeography and basin evolution of the Subbetic Zone between Ronda and Málaga, Spain, by Freek van der Meer, Geologie en Mijnbouw 74: 43-63, 1995 | 1996 | Martín-Algarra, A.; López-Garrido, A.C.; Sanz de Galdeano, C.; Martín-Martín, M. | 75(1) | |
| Discussion: Triassic-Miocene paleogeography and basin evolution of the Subbetic Zone between Ronda and Málaga, Spain. Reply by the author. | 1996 | Meer, F. van der | 75(1) | |
| Miocene shallow-water deposits of the northern Apennines: a stratigraphic marker across a dominantly turbidite foreland-basin succession | 1996 | Amorosi, A. | 75(4) | Lower-Middle Miocene shallow-water deposits commonly occur in the piggy-back-basins sequence of the northern Apennines thrust-belt. In contrast, such deposits are restricted to small bodies of reduced lateral extent in the adjacent foredeep succession. Lateral tracing of major unconformities across the two different structural domains allows reconstruction of a common sedimentary evolution for the study area, through the identification of three depositional sequences with an internal arrangement in systems tracts, generally showing lack or scarcity of lowstand deposits. A regional unconformity, marking the erosional truncation of the underlying turbidite deposits, constitutes the base of sequence S1 (Upper Burdigalian). Above mixed carbonate-siliciclastic, shallow-water facies (transgressive systems tract, TST), sequence 51 exhibits a progradational stacking pattern of outer-shelf to inner-shelf and nearshore facies (highstand systems tract, HST). The unconformable lower boundary of sequence S2 (Lower Langhian) is the base of transgressive, glaucony-rich, tide- and storm-influenced nearshore arenites (TST). The maximum flooding surface, showing local concentration of glaucony, records the sharp change from marginal marine arenites to highly bioturbated shelf deposits (HST). A generalized drowning of shelves during the Late Langhian-Early Serravallian is documented by rapid transition to coarse-grained siliciclastic deposits and deepwater marls (sequence S3). Tectonics appear to have exerted a major control on sedimentation, especially at the onset of sequence S1 and during deposition of sequence S3. Conversely, a possible eustatic control may apply for sequence S2. |
| Timing of deformation in the Malaguide Complex of the Sierra Espuña (SE Spain). Geodynamic evolution of the Internal Betic Zone | 1996 | Martín-Martín, M.; El Mamoune, B.; Martín-Algarra, A.; Martín-Pérez, J.A.; Serra-Kiel, J. | 75(4) | New biostratigraphic data on calcareous nannoplankton and larger foraminifera of the Tertiary of the Malaguide Complex in the Sierra Espuña area show the presence of previously unknown Upper Eocene sediments. The timing of the deformation in the Malaguide Complex of the Sierra Espuña area is analysed, and a Late Oligocene to Late Aquitanian age is proposed for the main deformation |
| The Cenozoic fill of the North Sea Basin (UK sector 56-62° N), a seismic stratigraphic study with emphasis on Paleogene massflow deposits | 1996 | Veeken, P.C.H. | 75(4) | Seismic stratigraphic study techniques allow to recognize several Cenozoic sedimentary cycles in the central and northern part of the North Sea area (UK sector), and to deduce their depositional history. Large-scale sedimentation patterns are illustrated with emphasis on Paleogene massflow deposits, forming important hydrocarbon-bearing reservoirs. Five regional unconformities form the bases of five depositional sequences (DS). These sequences can be subdivided into systems tracts in which seismic lithofacies units are outlined, calibrated by 76 wells. The base of DS-1 (Paleocene-Early Eocene) reflects the change from predominantly pelagic carbonates to clastic deposition. Within DS-1, prograding slope systems are present. Fan-delta systems supplied clastics to the shelf, whilst in the coastal area prograding deltas, swampy lakes and barrier complexes existed. Base-of-slope sand-prone sediments were laid down as slope-front fills, in submarine fan mounds and in parallel-bedded basinfloor deposits. Massflow sedimentation is dominant in the deeper parts of the basin. Axial basinfloor transport is indicated by the mound geometry and abnormal tichkness of the bottom sets. A volcanic pulse is expressed by a volcano-clastic seismic marker. In DS-2 (Eocene-Early Oligocene) a slope system fringed the western margin of the basin. Massflow sedimentation continued; sources and depocentres are correlatable to those active in the Paleocene. Subordinate input sources existed in the Norwegian sector. The base of DS-3 (Late Oligocene-Middle Miocene) is onlapped by fine-grained marine deposits. Sediment thickness increases basinwards. Rapid sedimentary loading of underlying shales prevented proper dewatering, causing plastic deformation and under-compaction. In DS-4 (Late Miocene-Early Pleistocene) sediment input from the east increased. DS-5 (Quaternary) shows that sediment supply from the south-southwest became more significant. |
| Belemnella (Belemnella) cf. praearkhangelskii Naidin, 1964 from the Member at Altembroeck (NE Belgium, Early Maastrichtian) | 1996 | Keutgen, N. | 75(4) | Biometrical analysis of a Belemnella faunule of 264 specimens from interval 0 of the Vijlen Member as exposed at Altembroeck (NE Belgium) shows that most specimens belong to Belemnella (Pachybetemnella) sumensis Jeletzky, 1949, the belemnite index of the early part of the late Early Maastrichtian. Belemnella (Betemnella) cf . praearkhangelskii Naidin, 1964 is restricted to a single level (Bm2). In NW Germany this species is confined to a narrow interval characterizing the middle sumensis Zone. lt is concluded that the Bm2 level at Altembroeck is of special importance for long-distance correlation between the Vijlen Member and the Maastrichtian in NW Germany. In the Altembroeck section, belemnite guards are enriched at certain levels. The belemnite accumulations probably developed as a result of stratigraphic condensation. |
| Diagenesis-related differences in isotopic and elemental composition of late Campanian and early Maastrichtian inoceramids and belemnites from NE Belgium: palaeoenvironmental implications | 1996 | Elorza, J.; García-Garmilla, F.; Jagt, J.W.M. | 75(4) | Late Campanian and early Maastrichtian inoceramid bivalves and belemnite rostra from three sections in the Liège and Limburg provinces (Belgium) are analysed petrologically and geochemically. Oxygen isotope ratios indicate that the early Maastrichtian material has been more affected by diagenesis than the late Campanian specimens, but data for belemnites do support the cooling trend from the late Campanian to the early Maastrichtian. Late Campanian and early Maastrichtian mean palaeotemperatures are deduced to have been lower than12.5 and 11.3 °C, respectively. Enrichment and depletion of elements, including rare-earth elements, and the generalised bright red-yellowish cathodoluminescence colour indicate cation-sensitive mobilisation processes during diagenesis. |
| Strain analysis in the Axial Zone of the Variscan basement of the Pyrenees | 1996 | Capellà I Solà, I. | 75(4) | The structural zonation in the Axial Zone of the Pyrenees, in which an infrastructure and a suprastructure are distinguished, can be correlated with a variation in the orientation of the principal strain axes. The deformation associated with the main foliation in the infrastructure is accommodated heterogeneously. Computed strain ellipsoids in gneisses show an apparent flattening strain (k= 0.29), which is in contrast to the apparent constrictional forms of pebbles in adjacent layers. Strain values in the suprastructure indicate an apparent flattening strain (k = 0.36) of low magnitude (Rxy = 1.36 and Ryz = 2.01), which can be taken as representative of the bulk finite strain throughout that domain. The trend of the X-axes is roughly E-W parallel to the fold axes in the infrastructure, whereas it is NW to N-plunging and at a wide angle to the ESE-WNW trending folds in the suprastructure. The Z-axes are steeply plunging in the infrastructure and almost horizontal in the suprastructure. Strain patterns in each of the two structural domains are suggested to be associated with different tectonic events. Between the infrastructure and the suprastructure, a transition zone exists where both domains grade into one another. |
| The influence of host-rock composition on the colour alteration of Namurian conodonts from Belgium | 1996 | Helsen, S. | 75(4) | The thermal alteration of Namurian conodonts of Belgium from existing stratigraphic collections has been examined and reviewed, their colour alteration indices (CAIs) being mapped. Comparisons with CAIs from Dinantian strata and with vitrinite reflectance data not only suggest little hydrocarbon potential for the Namurian in Belgium, but also indicate that the colour alteration of most Namurian conodonts has been influenced by their organic-rich host-sediments. Possible causes for this additional alteration, such as irradiation by natural radioactive decay of authigenic uranium, are discussed. |
| #REF! | 1996 | 75(4) | ||
| The Geulhemmerberg Cretaceous/Tertiary boundary section (Maastrichtian type area, SE Netherlands); an introduction | 1996 | Brinkhuis, H.; Smit, J. | 75(2-3) | |
| The Cretaceous/Tertiary boundary in the Maastrichtian type area (SE Netherlands, NE Belgium); a historical account | 1996 | Jagt, J.W.M.; Felder, W.M.; Dortangs, R.W.; Severijns, J. | 75(2-3) | In view of the renewed interest in the Cretaceous/Tertiary (K/T) boundary in the type area of the Maastrichtian Stage, a historical account is presented of the litho- and biostratigraphy of the strata below and above this boundary, as well as the position of the boundary itself. Localities exposing uppermost Maastrichtian and lowermost Palaeocene deposits are reviewed and for some of them, including the recently discovered Geulhemmerberg site, lithologic logs are provided. |
| Sedimentological aspects of the K/T boundary at Geulhemmerberg, Zuid Limburg, the Netherlands | 1996 | Roep, T.B.; Smit, J. | 75(2-3) | Traditionally, the K/T boundary in Zuid Limburg is placed at the Hardground of Vroenhoven between the Maastricht and Houthem Formations. The finding in the Curfs quarry and Geulhemmerberg of possible Paleocene microfossils below this hardground in a coarse-grained, well-bedded calcarenite unit with thin clay intercalations or clay pebbles excited new interest in the mode of deposition of this unit. The latter fills an irregular paleorelief, developed as a heavily burrowed hardground (Hardground of Berg en Terblijt), marking a hiatus at the top of the Maastichtian calcarenites. In galleries in the Geulhemmerberg, the fill of this paleorelief consists of a thinning-up and fining-up sequence of 1) coarse-grained fossil hash with thin clay intercalations, 2) debrisflow-like coarse calcarenites, 3) well-laminated HCS-like calcarenites, and 4) alternating clay and calcarenitic flaser-bedding. The inferred process of infilling is episodic storm-wave activity in ca 20-40 m waterdepth. The scarcity of burrowing in the unit below the traditional K/T boundary in an otherwise heavily burrowed section of Maastrichtian and Paleocene calcarenites, and the preservation in the unit of delicate sedimentary structures and relatively thick clay layers point to extraordinary sedimentary circumstances. These are difficult to explain, but not incompatible with deposition shortly after the Chicxulub impact. |
| Microfacies analysis of Cretaceous/Tertiary boundary sections in the quarries Geulhemmerberg and Curfs, SE Netherlands | 1996 | Zijlstra, J.J.P.; Brouwers, M.H.M.P.; Brinkhuis, H.; Boer, P.L. | 75(2-3) | Detailed thin-section microfacies analysis reveals the temporal and spatial variation of the depositional and early diagenetic conditions of the upper part of the Meerssen Member of the Maastricht Formation, now considered to span the Cretaceous/Tertiary (K/T) boundary, at Geulhemmerberg and Curfs (Maastrichtian type area, SE Netherlands). The precession- induced cycles of the Meerssen Member have been formed due to periodic variations of hydrodynamic energy and of deposition rate. Their genesis is similar to that of other precession-induced cycles encountered in the underlying Maastrichtian and Campanian carbonates. The microfacies distribution shows that the calcarenitic Geulhemmerberg sediment has been deposited under higher hydrodynamic energy conditions and in deeper water than the coeval sediments of quarry Curfs. The microfacies is locally characterised by dissolution features that may have been produced by percolating meteoric water during syn-sedimentary exposure. We propose that the intercalated clay layers, despite their open marine microfossil assemblage, were deposited under conditions of very low wave energy in very shallow marine depressions that were only affected during storms. |
| Late Maastrichtian and Early Palaeocene index macrofossils in the Maastrichtian tyoe area (SE Netherlands, NE Belgium) | 1996 | Jagt, J.W.M. | 75(2-3) | The uppermost Cretaceous and lowest Palaeocene in the type area of the Maastrichtian yield several macrofossils which can be used as index species in correlations with northern and southern Europe. For a macrofossil zonation of the uppermost Maastrichtian, coleoid and ammonoid cephalopods and inoceramid bivalves are of prime importance, while biozonations for the lowermost Palaeocene rely particularly on echinoid and asteroid species. On coleoid and ammonoid evidence, the type Maastrichtian is coeval with the uppermost Maastrichtian as interpreted in the Tethyan realm (Bay of Biscay sections in particular) and the North Temperate realm (NW and NE Europe). The occurrence in the lower part of the Geulhem Member (Houthem Formation) of distinctive, exclusively Early Danian echinoderm species suggests that the entire Lower Danian of the Danian type area is represented in the Maastricht area, and that what is considered to be the uppermost part of the underlying Meerssen Member (Maastricht Formation) represents the equivalent of the Early Danian 'Cerithium Kalk' in Denmark. |
| Early Danian benthic foraminiferal community structures, Geulhemmerberg, SE Netherlands | 1996 | Kuhnt, W. | 75(2-3) | Benthic foraminiferal assemblages from eight clay-layers within a relatively thick section of the lowermost Paleocene (planktonic foraminifera P0 Zone) at the Geulhemmerberg, SE Netherlands, were examined for changes in abundance and species composition. The lower clay layers (A to D) are characterized by peculiar benthic foraminiferal assemblages with high numbers of small spiral forms which resemble modern epifaunal phytodetritus-feeding communities, that are well adapted to a food-limited environment in which much of the nutrient input is seasonally or erratically pulsed. Another distinct assemblage with high numbers of small, infaunal morphotypes such as Tappanina selmensis, Reussella ex gr. europaea, buliminids and bolivinids characterizes the upper part of the succession (clay layers E and F). This assemblage exhibits striking similarities to modern assemblages in areas with enhanced organic-matter export flux rates resulting in increased food supply for benthic organisms and slightly dysaerobic conditions at the sea floor. The occurrence of these 'high-productivity' benthic foraminiferal assemblages coincides with a marked increase in Thoracosphaera çalcarcous dinoflagellate cysts and may indicate an important phase in the recovery of the marine ecosystem after the collapse of the food web at the Cretaceous/Tertiary boundary. |
| Calcareous benthic foraminifera across the Cretaceous/Tertiary boundary in the Geulhemmerberg (SE Netherlands) | 1996 | Witte, L.; Schuurman, H. | 75(2-3) | Recently, a section comprising the Cretaceous/Tertiary boundary was discovered in an underground quarry at the Geulhemmerberg, South Limburg, the Netherlands. A series of samples collected from these strata were analysed for their calcareous benthic foraminiferal contents. Upper Maastrichtian and indifferent Upper Maastrichtian to Lower Paleocene species were found to be the most common elements throughout the sequence and no drastic faunal changes have been observed. Extremely rare inner-neritic Paleocene elements, however, enable a tentative identification of the position of the system boundary between samples G2A and G2B. Slightly higher in the section, an increase in palaeo-water-depth is inferred from the first occurrence of the mid-shelf species Tappanina selmensis |
| Planktic foraminifera in the Cretaceous/Tertiary boundary clays of the Geulhemmerberg (Netherlands) | 1996 | Smit, J.; Zachariasse, W.J. | 75(2-3) | In the Geulhemmerberg section across the Cretaceous/Tertiary (K/T) boundary, planktic foraminiferal assemblages were found only in the basal Paleocene clay layers. These layers are interpreted to correspond to the planktic foraminiferal P0 Zone because Paleocene planktic foraminifers do not occur yet, whilst Paleocene nannofossil and dinoflagellate assemblages are already present. This is consistent with the K/T boundary clays (P0 Zone) of El Kef in Tunisia and of Agost and Caravaca in Spain, in which Paleocene species are also absent. The planktic assemblages of the clay layers have a low diversity, comparable to P0 planktic assemblages from the Nye Kløv section in Denmark. Heterohelix globulosa (Ehrenberg) dominates the assemblages. Excellent preservation of the planktic foraminifers, and anomalously high planktic foraminifer percentages (P/(P+B) = 53.3%) provide compelling arguments for survivorship of at least five generalist Cretaceous taxa into the basal Paleocene P0 Zone, as shown earlier at Caravaca, El Kef and Nye Kløv. However, due to the lack of planktic faunas in under- and overlying sediments, it is impossible to infer whether the planktic foraminiferal faunas in the P0 Zone clay-Iayers have changed, or are impoverished compared to Upper Maastrichtian faunas |
| Palynology of the Geulhemmerberg Cretaceous/Tertiary boundary section (Limburg, SE Netherlands) | 1996 | Brinkhuis, H.; Schiøler, P. | 75(2-3) | The newly found, relatively complete section across the Cretaceous/Tertiary (K/T) boundary in the Geulhemmerberg caves contains rich and well-preserved palynological assemblages. Stratigraphically diagnostic dinoflagellate cysts indicate that the lower part of the Geulhemmerberg succession represents the latest Maastrichtian and that an early Danian age may be assigned to sediments overlying the Berg en Terblijt Horizon, notably on the basis of the appearance of Senoniasphaera inornata. On the basis of quantitative palynological analysis, the sediments are interpreted to represent relatively marginal marine, inner neritic conditions, with nearby landmasses providing important terrestrial input. Almost all terrestrial palynological elements are most probably derived from Bryophyta (mosses). Their sudden proliferation at the K/T boundary may be associated with increased transport from the coastal plain, and/or it may reflect a major change in the terrestrial ecosystem at K/T time. Changes in the palynomorph distribution are probably mainly caused by differing hydrodynamical conditions, possibly combined with slightly varying waterdepths and/or the introduction of restricted marine conditions. |
| Calcareous dinocysts from the Geulhemmerberg K/T boundary section (Limburg, SE Netherlands) | 1996 | Willems, H. | 75(2-3) | Calcareous dinoflagellate cyst (calcdinocyst) associations from the Cretaceous/Tertiary (K/T) boundary section of the Geulhemmerberg comprise 31 morphotypes in total. In addition, two incertae sedis organisms, morphologically related to the genus Bonetocardiella, occur. In the uppermost Maastrichtian and lowermost Danian, the quantitatively dominant calcdinocysts are Pithonelloideae, nearly exclusively Pithonella sphaerica, accompanied by up to 1.4% Bonetocardiella spp. In the uppermost Maastrichtian, Pithonella and Bonetocardiella make up the entire association. They are joined by Obliquipithonelloideae and Orthopithonelloideae in the lowermost Danian. Most calcdinocyst species (22 of the 31, species) appear to survive the IIT boundary event(s), while eight species first appear above the boundary. The distribution of the Obliquipithonelloideae and Orthopithonelloideae is related to the lithofacies. With up to 18 species, the diversity is highest in the clay layers, notably in the A, B, C and E clays. In these layers, the number of orthopithonelloids increases in comparison to the obliquipithonelloids. The cyclic diversity distribution of calcdinocyst morphotypes may possibly be attributed to sea-level changes, with maxima correlating to the diversity maxima as found in the A, B, C and E clays. |
| Calcareous nannoplankton of the Geulhemmerberg tK/T boundary section, Maastrichtian type area, the Netherlands | 1996 | Romein, A.J.T.; Willems, H.; Mai, H. | 75(2-3) | Light-microscopic analysis of the calcareous nannoplankton of the Geulhemmerberg section indicates the presence of the Late Maastrichtian Nephrolithus frequens Zone and the Early Danian Biantholithus sparsus Zone, separated by a hiatus encompassing the earliest Danian. SEM analysis, however, indicates the presence throughout the section of Neobiscutum romeinii, N. parvulum and small forms of Cruciplacolithus primus, taxa reported so far only from the Early Danian. If these are in situ, a Danian age for the whole Geulhemmerberg section cannot be excluded. |
| Paleomagnetism of the Geulhemmerberg K/T boundary section, the Netherlands | 1996 | Langereis, C.G. | 75(2-3) | Paleomagnetic samples of six clay layers from an interval containing the Cretaceous/Tertiary (K/T) boundary in the Geulhemmerberg cave show only normal polarities, contrary to the expected reversed directions. The unique preservation of the sediment makes it unlikely that the normal polarities are an overprint through weathering or that the acquisition of the remanence has been delayed by post-depositional diagenetic formation of magnetite. Possibly, the normal polarities are the result of a relatively short relaxation time of the magnetic minerals which would cause the magnetic domains to realign with the present-day field, a process which would occur without affecting the preservation. |
| Stable isotope (δ18O, δ13C) records across the Cretaceous/Tertiary boundary at Geulhemmerberg, southern Netherlands | 1996 | Schmitz, B.; Speijer, R.P. | 75(2-3) | The stable isotopic (δ18O, δ13C) records for bulk samples and well-preserved, monospecific, benthic foraminiferal samples show no or only small variations across the Cretaceous/Tertiary (K/T) boundary at Geulhemmerberg, southern Netherlands. The site represents an inner shelf environment, where calcarenites and clay layers formed. Comparisons with previously established isotopic records from Danish K/T boundary sections, where significant isotopic changes (2-3 °C cooling and 1.5‰ negative δ13C shift) occur in the basalmost P0 Zone, indicate a small hiatus at the base of the Danian at Geulhemmerberg. This is consistent with other data, such as absence of a strong Ir anomaly and shocked quartz. The oxygen-isotopic values of planktonic, mid-depth-dwelling Heterohelix globulosa foraminifera, recovered from two early Danian Geulhemmerberg clay layers, are similar to, or more positive than the benthic values from the same layers. The origin of these apparently anomalous water-column ð18O gradients is enigmatic. The inverted gradient may reflect sporadic development of an unusual water-mass stratification, such as the occurrence of an upper water mass with a slightly lower (1-2‰) salinity and with a few degrees lower temperature than bottom water. Alternatively, it may reflect different provenance areas of the planktonic and benthic foraminifera during turbulent conditions, while storm and back-wash deposits formed. Overall, the whole-rock and benthic oxygen-isotopic records across the Geulhemmerberg section indicate fully marine (> 33‰) conditions throughout. |
| Molecular palaeontology of the earliest Danian at Geulhemmerberg (the Netherlands) | 1996 | Yamamoto, M.; Ficken, K.; Baas, M.; Bosch, H.J.; Leeuw, J.W. de | 75(2-3) | Organic compound distributions in extracts of three selected clay samples from the lowermost Danian section at Geulhemmerberg were analysed in order to enhance the understanding of the depositional environment immediately after the Cretaceous/Tertiary (K/T) boundary. A highly dominant C40:2 ethyl ketone is identified. This compound is probably derived from specific, highly abundant non-coccolithophorid Prymnesiophyte algae which may already have been present in late Maastrichtian times. Fatty acids as well as their randomly oxidized hydroxy- and keto counterparts are also abundant. These compounds probably indicate bacterially transformed biochemicals of terrestrial origin, although they are probably not derived from the Bryophyte moss spores abundantly present in these sediments. Their distributions are, however, strikingly similar to those of fatty acids in Antarctic soils. ω16-, ω17 -, and ω22- keto- and hydroxy fatty acids with highly specific distribution patterns and a clear even over odd carbon number preference are thought to be of marine origin. The biochemical relationships between these compounds and the C40:2 ethyl ketone suggest that they may originate from the same algae. This presence of highly functionalized organic compounds demonstrates the extreme immaturity and excellent preservation of the unique Geulhemmerberg K/T boundary sediments. |
| Neutron activation analysis of trace elements in the Geulhemmerberg Cretaceous/Tertiary boundary section, SE Netherlands | 1996 | Smit, J.; Rocchia, R. | 75(2-3) | The Geulhemmerberg K/T boundary section was analysed for (trace) elements by instrumental neutron activation analysis (INAA). Twenty-seven elements were detected in almost all of the 22 samples. Another seven elements were above detection limit in only a few samples, and four elements were below the detection limit in all samples. Anomalous Ir levels have not been found in any sample. However, when Th-normalized, there is an indication for higher concentrations of Ir (and Cr) just below the K/T boundary, possibly due to downward diffusion. The distributions of most trace elements can be explained by the alternation of layers of clay and almost pure limestone in the section, and by the lithophile, chalcophile or siderophile character of the elements. Strontium, usually correlating positively with Ca and CaCO3, correlates negatively with Ca in the Geulhemmerberg section. The relatively high values of Sr in the clay-layers indicate that these layers were shielded from diagenesis. The La/Ce ratio is lower in the clay than in the limestone layers. This may reflect dysoxic conditions in seawater during the deposition of the clay layers. The La/Yb ratio is low in the uppermost Maastrichtian, and high in the basal Danian. An enrichment of Co and Fe at the Berg en Terblijt hardground can be explained by the presence of iron encrustations. |
| Strontium-isotope stratigraphy of the type Maastrichtian and the Cretaceous/Tertiary boundary in the Maastricht area (SE Netherlands) | 1996 | Vonhof, H.B.; Smit, J. | 75(2-3) | The comparison of a detailed 87Sr/86Sr. profile through the Maastrichtian of the ENCI, Curfs and Geulhemmerberg quarries in the Maastrichtian type area with a Late Maastrichtian to Early Danian seawater 87Sr/86Sr curve of the Bidart (France) and El Kef (Tunisia) sections provides a useful chronostratigraphy for these quarries. The best fit yields an accumulation rate of ~ 10 cm/ka for the upper 30 m of the Maastrichtian in the composite Curfs and ENCI section. Apparently, despite diagenetic alteration, the fossils from the Curfs and ENCI quarries partly retained their original seawater 87Sr/86Sr values. 87Sr/86Sr analyses of well-preserved heterohelicids in the Geulhemmerberg E-clay support the suggested Early Danian age of this clay. They also support the suggestion that the planktic foraminifer Heterohelix globulosa survived the Cretaceous/Tertiary boundary event(s) for some 5 to 50 ka. |
| The Geulhemmerberg Cretaceous/Tertiary boundary section (Maastrichtian type area, SE Netherlands); summary of results and a scenario of events | 1996 | Smit, J.; Brinkhuis, H. | 75(2-3) | Integration of sedimentological, biostratigraphical, geochemical and paleomagnetic analyses of the recently discovered marginal marine Cretaceous/Tertiary (K/T) boundary section in the Geulhemmerberg caves (Maastrichtian type area, Limburg, SE Netherlands) resulted in a depositional model of the succession, placing the results in a global K/T boundary perspective. The proposed depositional scenario involves 1) deposition of marginal marine Upper Maastrichtian calcarenites and formation of a paleo-relief (proto-hardground, Berg en Terblijt Horizon), 2) deposition of latest Maastrichtian calcarenites, 3) K/T storm or hypercane-related 'washing' of the paleoshelf, and removal of latest Maastrichtian and earliest Danian sediments, including removal of an Ir-bearing layer, and 4) storm-induced filling of the paleodepressions in the Late Maastrichtian paleorelief by calcarenites and K/T boundary clays during early P0 Zone times of decreasing storm intensity. Only the distributions of calcareous nannoplankton and ammonites do not fully match this scenario, since early Tertiary nannofossils have been reported from below the Berg en Terblijt Horizon and, at a nearby outcrop, ammonites from just above it. Their distribution patterns across the K/T boundary in the area require further study. We conclude that there is an unprecedented expanded earliest Tertiary succession in Limburg, containing a wealth of information about the first hundreds of years following the mass-extinction event at the K/T boundary. |
| Faulting history at the eastern termination of the High Atlas Fault (Western High Atlas, Morocco) | 1997 | Sintubin, M.; Nefly, M.; Rijpens, J.; Zegbroek, B. van | 76(3) | At its eastern termination, the High Atlas Fault in the Western High Atlas in Morocco, consists of a splay of three faults. In the interjacent fault blocks, Neo- and Paleoproterozoic basement, forming the northernmost extremity of the NW-African Craton, is cropping out. The Precambrian basement witnesses a long history of brittle deformation starting at the end of the Pan-African Orogeny. A subsequent episode of normal faulting can be related to the development of a Hercynian basin along the northern passive margin of the cratonic promontory. With regard to the main tectonic activity in the Western High Atlas, basically two models exist: one emphasising block tectonics reflecting Mesozoic rifting followed by Alpine uplift and inversion, the other emphasising Late Paleozoic dextral wrench tectonics. The analysis of the fault activity along the splay faults reveals a predominantly Alpine history, consisting of the Triassic development of the 'Atlas Rift' along the axialzone of the orogen, followed by uplift and inversion. The Late Jurassic to Cenozoic fault activity took place in a sinistral transpressive regime and was partitioned over the three splay faults. Dextral strike-slip fault activity could not be demonstrated in the fault blocks nor along the splay faults. Therefore the faults were probably not involved in Late Paleozoic dextral wrench tectonics. |
| Sequence stratigraphy based on microfacies analysis: Mfamosing Limestone, Calabar Flank Nigeria | 1997 | Reijers, T.J.A.; Petters, S.W. | 76(3) | Field observations and petrographic analysis allow a sequence-stratigraphic interpretation of the intensely karstified Albian Mfamosing Limestone Formation in the Calabar Flank of the south-eastern Niger Delta. Main criteria for this interpretation are the presence of siliciclastic intercalations, of prominent hardgrounds, of characteristic microfacies including stromatolites and of phreatic and vadose diagenetic patterns. These criteria enable the recognition, from bottom to top in the type section of the Mfamosing Limestone, of a late phase in the formation of a highstand systems tract and of a flooding surface followed by a lowstand systems tract in which erosional features have been developed locally. The succession is topped by a transgressive systems tract. Some of these units and key sequence-stratigraphic boundaries have been traced into other outcrops in the area. In their identification within the heavily karstified outcrops, petrography overprints and vertical sequence patterns play a significant role. A sedimentation model explains the areal differences in development. Siliciclastic shedding influenced the carbonate system. Time-equivalent carbonate bodies occur on either side of the opening South Atlantic Ocean |
| Quantitative analysis of top-seal capacity: offshore Netherlands, southern North Sea | 1997 | Spain, D.R.; Conrad, C.P. | 76(3) | Sealing characteristics of the caprock to the Main Buntsandstein reservoir sands in the P blocks in the Dutch offshore are assessed based on a core from the P15 well. The core which represents the Main Buntsandstein, Solling, Röt, and Muschelkalk interval has been analyzed using standard geologic and petrophysical techniques including mercury-injection capillary-pressure tests. The caprock to the Main Buntsandstein reservoir sands consists of anhydritic and/or dolomitic sandstone to argillaceous siltstone, silty shale, and dolostone. Early emplacement of nodular anhydrite followed by cementation and replacement by anhydrite, dolomite, and siderite has resulted in tight, submicroporous pore geometries which act as good to excellent seals. Capillary entry pressures of the best caprock lithologies are such that gas columns of the order of 300 m could potentially be trapped. The actual column height in P15 is about 1,25 m as indicated by RFT data. The presence of significant gas accumulations in the Main Buntsandstein in the P12,P14, P15, P18 and adjoining Q8 and Q16 blocks suggests that the P15 top-seal quality may be representative for that area. |
| High-resolution sequence stratigraphy of the Lower Triassic 'Buntsandstein' in the Netherlands and northwestern Germany | 1997 | Geluk, M.C.; Röhling, H.G. | 76(3) | Detailed log correlations of the largely fluvio-lacustrine Lower Triassic 'Buntsandstein' (Late Permian-Early Anisian), carried out on 80 wells in the Dutch onshore and offshore areas, can be linked to northwest-German high-resolution sequence stratigraphy. The correlations show that cyclic sedimentation occurred in large parts of the basin. Seven 1st-order sequences are recognised, namely the Main Claystone, Rogenstein, Volpriehausen, Detfurth, Hardegsen, Solling and Lower Röt Sequences. They are overlain by the lower part of the Upper Röt-Lower Muschelkalk Sequence. Distinct sequence boundaries have been identified at the bases of four sequences: Volpriehausen, Detfurth, Solling and Upper Röt. The higher-order sequences consist of fining-upwards cycles with a thickness of up to tens of metres. The sequences are laterally persistent and have a characteristic expression on gamma-ray and sonic logs. In the Lower Buntsandstein, they display a uniform character throughout most of the area, with only minor differences in thickness or lithology. NNE-oriented lows and swells were formed during deposition of the Volpriehausen, Detfurth and Hardegsen Sequences. Uplift prior to the deposition of the Solling Sequence caused deep erosion on the swells in the basin and minor erosion in the lows. The high-resolution sequences probably represent alternating, relatively wet and dry climatic periods, with a periodicity of about 100000 years. An analysis of the sequences suggests that their reduced thickness on the swells is mainly the effect of erosion. This is supported by analyses of the accumulation patterns and rates. |
| A Pan-African core complex in the Sinai, Egypt | 1997 | Blasband, B.; Brooijmans, P.; Dirks, P.; Visser, W.; White, S. | 76(3) | In the late Precambrian history of the Wadi Kid area in the Sinai, Egypt, two deformation phases are clearly recognized. The first phase, D1 (pre-620 Ma), produced a steep regional foliation, axial planar to upright F1 folds, in rocks of a lower-greenschist grade. This compressional phase of deformation is interpreted in terms of subduction in an island-arc setting. The second phase, D2 (post-620 Ma), is mainly expressed by the widespread development of sub-horizontal mylonitic zones with a total thickness of 1.5 km. Shear sense indicators give a consistent regional transport direction to the northwest, with local indications of reversal to the southeast. This event is associated with regional LP/HT metamorphism, indicative of high thermal gradients. Because of the LP/HT metamorphism, the change in geochemical nature of the granitoids, and the orientation of the dykes, we interpret the mylonitic zones as low-angle normal shear zones related to core-complex development during an extensional event with the transport reversal being induced by doming. We postulate that orogenic collapse was responsible for the transition from the D1 compressional phase to the D2 extensional phase. |
| Chlorite geothermometry and the temperature conditions at the Variscan thrust front in eastern Belgium | 1997 | Zhang, Y.; Muchez, P.; Hein, U.F. | 76(3) | |
| Coalification anomalies induced by fluid flow at the Variscan thrust front: A numerical model of the palaeotemperature field | 1997 | Lünenschloss, B.; Bayer, U.; Muchez, P. | 76(3) | |
| Analysis of paleomagnetic data: a tribute to Hans Zijderveld. Introduction | 1997 | Dekkers, M.J.; Langereis, C.G.; Voo, R. van der | 76(1-2) | |
| Low paleosecular variation at the equator: a paleomagnetic pilgrimage from Galapagos to Esterel with Allan Cox and Hans Zijderveld | 1997 | Rochette, P.; Ben Atig, F.; Collombat, H.; Vandamme, D.; Vlag, P. | 76(1-2) | McFadden and Merrill (1995) suggested that the paleosecular variation (PSV) measured by the angular scatter of the virtual geomagnetic pole is minimal at the equator and should be smaller during a superchron than during the last 5 Myr. We revisited a key site of the 0-5 Ma database, the Galapagos archipelago, studied by Allan Cox in the early sixties. We obtained 79 sites with reliable mean directions on four islands (San Cristobal, Floreana, Santa Cruz and Pinzon), showing a larger proportion of transitional data than Cox (16 instead of 6%), because the sampling was concentrated on the Brunhes-Matuyama transition as delimited by Cox. This dataset allowed us to test the statistical method of Vandamme (1994) to separate PSV from transitional data. We obtained an angular scatter value of 11.2° (9.9-12.9°), instead of 16.8° for an a-priori rejection angle of 40°, compared with the 12.7° predicted from the global compilation (McFadden et al. 1991). Studies of sequences of lava flows are quite scarce in the Permian Kiaman Superchron, and the Esterel volcanics with their subequatorial paleolatitude are a good candidate to test the above prediction. We confirm the quality of the original data of Zijdeweld (I915) and we improved the mean direction from one site. We also used new geological and geochronological data: Ar/Ar ages point to the period 264-278 Ma for a totally reversed volcanic sequence, in agreement with an ending of the Kiaman Superchron at 262-268 Ma. The extremely low angular scatter obtained (4 to 8°, depending on data selection) confirms the prediction, but an alternative interpretation invoking a post-volcanic Permian remagnetization is discussed. |
| Paleomagnetism of the Esterel rocks: a revisit 22 years after the thesis of Hans Zijderveld | 1997 | Vlag, P.; Vandamme, D.; Rochette, P.; Spinelli, C. | 76(1-2) | For his PhD. thesis, Zijderveld (1975) studied the paleomagnetism of the Permian Esterel rocks (southern France). High-quality thermal and alternating-field demagnetization diagrams were interpreted to determine the direction of the characteristic natural magnetization. For the Esterel volcanics, a mean direction of Dec = 206.5°,Inc = -23°, α95 = 5.7°, k = 112 was found for this magnetization. The dispersion in this mean is remarkably low. Only the declination of the Reyran Rhyolite in the Reyran River quarry clearly deviated from this mean. This deviating direction is not found in our samples, taken at the same site. As many faults occur in this quarry, it is suggested that Zijderveld sampled this rhyolite on a small rotated block. To verify whether the small dispersion in the mean paleomagnetic direction of the Esterel rocks has a geomagnetic or a rock-magnetic origin, two conglomerate tests were carried out. One of these might be interpreted as positive. The results of the other conglomerate test (Agay Formation) are ambiguous: four of the six measured boulders show directions close to the mean paleomagnetic direction of the Esterel rocks. Rock-magnetic measurements show that the remanence is carried by a magnetite and a hematite fraction. The low dispersion in the paleomagnetic directions, the conglomerate tests, and hematite as remanence carrier suggest that the characteristic remanence in the Esterel volcanics was not instantaneously acquired during cooling, but might be affected by remagnetization due to weathering. |
| Automated AF- de magnetization on the 2 G-Enterprises through -bore, cryogenic magnetometer | 1997 | Giddings, J.W.; Klootwijk, C.T.; Rees, J.; Groenewoud, A. | 76(1-2) | Since the early sixties, alternating field demagnetization (AFD) has been a standard laboratory technique for demagnetizing rocks to expose the multicomponent structure of their natural remanent magnetization (NRM). In the majority of AFD implementations, however, the procedure remains as labour-intensive as ever. The implementation that we have developed at the Australian Geological Survey Organisation, automates the procedure or AFD based on the static method, and results in significant productivity and efflciency gains without compromising data quality. A properly formulated procedure for static AFD may be the only method of retrieving higher-coercivity components of natural remanence in samples prone to developing gyroremanence at higher alternating fields (AFs). Our AFD environment comprises: a 2G-Enterprises through-bore, cryogenic magnetometer; 2G AF-coils and control equipment; and personal computer software, developed by us, to control all procedural aspects for a complete AFD of a sample including, importantly, a counteracting procedure to neutralize the effects of gyroremanence build-up at higher AFs. With our system, AFD of 8 samples/day, each of 20+ steps, requires only 20 min of user attention compared with a full day for conventional systems. |
| New paleomagnetic results from the Aegean extensional province | 1997 | Haubold, H.; Scholger, R.; Kondopoulou, D.; Mauritsch, H.J. | 76(1-2) | Various Oligocene formations from NE Greece (ignimbrites from the Medousa area, rhyolites from Zagradenia, granodiorites from Elatia) show discordant paleomagnetic signatures, in each case indicating small cw (clockwise) rotation and also inclination flattening. Marls from Pithion were partly remagnetized in a present-day field. Samples that contain ancient magnetization components also indicate small cw rotation and inclination flattening. However, the magnetization of andesites from Peplos reflects a considerably larger rotation, likely owing to local tectonics. In the context of previous work in the area, these results are used to propose a subdivision of NE Greece into four structural zones of distinctive rotational behaviour (from east to west): sites in zone 1, east of the Kavala-Xanthi-Komotini fault (KXK), show various cw and ccw (counterclockwise) rotation angles owing to complex kinematics resulting from the interaction of the KXK and the north-Anatolian fault zone. However,zone 2,between the KXK and the Strymon valley, is structurally homogeneous (~10° cw rotation). The paleomagnetic signature of the Vertiskos massif (zone 3) implies a larger (> 30°) cw rotation, whereas sites in the Vardar basin (zone 4) contain a paleomagnetic signature similar to that of zone 2. This suggests a motion of the Vertiscos massif, a meta-ophiolitic nappe, relative to underlying strata. Indeed, zones 2 and 4 may be parts of the same structural unit which underlies this nappe. |
| Palaeomagnetic data of late Cretaceous rocks from Sumba, Indonesia; the rotation of the Sumba continental fragment and its relation with eastern Sundaland | 1997 | Wensink, H. | 76(1-2) | Sumba island forms part of a continental fragment, located near the transition of the Sunda Arc to the Banda Arc. It lies within the forearc region, between the active volcanic arc to the north and the Java Trench to the south. Palaeomagnetic studies of Cretaceous (late Albian-early Campanian) Lasipu sediments revealed a mean characteristic remanence (ChRM) direction with D=42.5°,I=-23.0°,and α95 =6.1°, indicating a palaeolatitude of 12° S. This ChRM is, most likely, a secondary magnetization, possibly caused by the intrusion of the 65-Ma-old Tanadaro granodiorite. This granodiorite gave a mean ChRM direction with D = 44.7°, I = -16.3°, and α95 = 12.2°, pointing to a palaeolatitude of 8.3° S. Eastern Sundaland with Borneo, west and south Sulawesi, and Sumba formed one continental unit in the late Mesozoic, most likely attached to the southeast Asian mainland. Borneo and west and south Sulawesi underwent large counterclockwise (CCW) rotations since the Jurassic with ~ 45° during the Cretaceous, and ~ 45° during the Palaeogene. The Sumba microcontinent, most likely, became detached from eastern Sundaland soon after deposition of the Lasipu sediments. Palaeomagnetic data show that Sumba underwent subsequent clockwise (CW) rotations of up to 96°: 53° between 82 and 65 Ma, and 38° between 65 and 37 Ma. Since the late Eocene, only small rotations occurred. The data indicate that eastern Sundaland, including Sumba, remained close to the equator since the Jurassic. CW rotations occurred in Sundaland both in the north (Indochina) and in the west (Sibumasu) as a consequence of the India - Eurasia collision. The same sense of rotation is seen further east in Sulawesi's East Arm and the Philippine Sea plate. Eastern Sundaland (Borneo and west Sulawesi) with CCV/ rotations is being trapped between these CW rotating plates. |
| How far between Iran and Eurasia was the Turan plate during Triassic-Jurassic times? | 1997 | Lemaire, M.M.; Westphal, M.; Gurevitch, E.L.; Nazarov, K.; Feinberg, H.; Pozzi, J.P. | 76(1-2) | Calc-alkaline volcanic deposits from the south-west of the Turan plate, near the city of Turkmenbasi (40°00’N, 52°58tE) in Turkmenistan, were studied paleomagnetically. These rocks have been affected by a greenschist-facies metamorphism, possibly of regional extent, that has been K/Ar-dated as 200 to 227 Ma old. A low-blocking temperature component (D = 349° ,l = 64°), close to the present field direction and probably of viscous or recent chemical origin, was isolated by a negative fold test at three sites. The mean direction of a high-blocking-temperature component isolated at 15 sites, mainly carried by magnetite, is scattered before and after tectonic correction and is therefore difficult to interpret. A group of seven sites with low inclinations before and after tectonic correction was isolated. The mean inclination of these sites (31 ± 8°), syn-folding or post-folding, corresponds to a paleolatitude of 17 ± 8° which is lower than the conventional Eurasian paleolatitudes for post-Permian times. The paleomagnetic data from the Turan and Iran plates constrain this low paleolatitude to the Late Triassic and Jurassic period. This requires a shortening of at least 7° between the Turan plate and Eurasia during this time. |
| Palaeomagnetism of three dyke swarms in Nansen Land, north Greenland (83° N) | 1997 | Abrahamsen, N.; Bengaard, H-J.; Friderichsen, J.D.; Voo, R. van der | 76(1-2) | Three basic dyke swarms of post-Ellesmerian (post-Early Carboniferous) age in Nansen Land (83° N, 43° W) are still not dated numerically, but cross-cutting relationships show Group 1 to be older than Group 2, while Group 3 is the freshest and likely the youngest. Group 1 (the most northerly swarm) strikes N-S; Group 2 NW-SE, and Group 3 (the most southerly swarm) E-W. From more than 200 dykes 234 specimens from 28 sites were investigated palaeomagnetically. Group 1 dykes show unexpected shallow inclinations with a cleaned mean direction of (Dm, Im) = (151°, -5.8°), N = 7, k = 18.5, α95 = 13.9°. They show hydrothermal alterations, some remagnetization by lightning, and the low inclination indicates a low palaeo latitude. The palaeopole is (Plat, Plon) = (8.9° S, 14.0° W) with (dp, dm) = (7°, 14°), and is close to the North American Early Carboniferous mean pole, suggesting a syn- or early late-tectonic dyke injection. The polarity is reverse. Groups 2 and 3 of presumed Cretaceous or Tertiary age show dominantly normal and reverse polarities, respectively. Their mean directions per polarity are well grouped, with (Dm, Im) = (-30.6°, 76.7°), n = 13, k = 191.4, α95 =3.9°, and (Dm, Im) = (133.4°, -76.7°),n = 10, k = 87.5, α95 = 5.9°, respectively. They are antipodal within 95% significance, and combining both swarms gives (Dm, Im) = (-37.5°, 76.8°), n = 23, k = 124.3, α95 = 2.7°, corresponding to a mean pole of (Plat, Plon) = (70.0° N, 185.1° E) with (dp, dm) - (4.7°,5.0°), for which the spline of Late Cretaceous-Tertiary poles for all Greenland indicates a palaeomagnetic age of 57 ± 10 Ma. This pole (in present-day coordinates) is very close to the Late Cretaceous North American pole, in accordance with the fact that Greenland belongs to the North American craton, and that the two younger swarms are essentially postdating the opening of Baffin Bay. |
| Paleomagnetism of Carboniferous sediments from the West Sudetes (SW Poland) | 1997 | Kadzialko-Hofmokl, M.; El-Hemaly, I.A. | 76(1-2) | The studied Carboniferous flysch and molasse sediments from the Intra-Sudetic Basin correspond to the period from Middle Visean to Early Autunian. Main magnetic minerals carrying the natural remanent magnetization (NRM) are goethite, magnetite, maghemite and hematite, all usually secondarily formed and/or remagnetized due to several tectonometamorphic events. In most samples several NRM components were isolated. One of them is usually a Jurassic-Triassic overprint. Some others define the Westphalian-Early Permian segment of the declination and inclination trajectory for the Sudetes calculated according to the reference apparent polar wander path for the Baltica plate. The Sudetic path is slightly shifted to the east compared to the reference path, suggesting the possibility of independent movements of the Sudetes during this time. The majority of isolated NRM components are secondary and related to the Sudetic orogenic phase and later tectonometamorphic activity. |
| The Late Carboniferous to Late Triassic segment of the apparent polar wander path of lberia | 1997 | Osete, M.L.; Rey, D.; Villalaín, J.J.; Juárez, M.T. | 76(1-2) | A palaeomagnetic study has been carried out at 16 well-dated sites from four areas in central Spain (southeastern Iberian Massif and western Iberian Ranges) in order to constrain the Late Carboniferous to Late Triassic segment of the apparent polar wander path (APWP) of lberia. 322samples (218 with useful results) were collected from andesitic rocks at Atienza (287 ± 72 Ma) and from Triassic continental red beds at Molina de Aragón (Anisian-Ladinian), Afcaraz (Ladinian-Carnian), Alcázar de San Juan (Ladinian-Carnian) and Cuevas de Ayllón (Carnian-Norian). Comparison of the palaeomagnetic results from the western Iberian Ranges and from the Iberian Massif indicates that the investigated area of the Iberian Ranges forms part of Stable Iberia. The palaeomagnetic poles obtained in this study and a revision of previous palaeomagneÍic da|a, discarding poles obtained from areas of doubtful stability, show together a gradual and consistent change in latitude and longitude resulting in a coherent segment of the APWP for the Late Carboniferous to Late Triassic time span. |
| Late Cenozoic magnetostratigraphy (11 - 0 Ma) of the Dongshanding and Wangiiashan sections in the Longzhong Basin, Western China | 1997 | Li, J.J.; Fang, X.M.; Voo, R. van der; Zhu, J.J.; Niocaill, C.M.; Cao, J.X.; Zhong, W.; Chen, H.L.; Wang, J.; Wang, J.M.; Zhang, Y.C. | 76(1-2) | A paleomagnetic study of the 510-m-thick Wangjiashan section of Late Miocene and Pliocene terrestrial sediments reveals a fairly complete reversal record with ages from 1,1 to 1.8 Ma. The magnetostratigraphy of the Dongshanding section, located nearby, reveals a partially overlapping reversal record with ages from 2.2 to 0 Ma, and facilitates correlation of the Wangjiashan section with the global polarity time scale. A new stratigraphic division of the Wangjiashan section replaces the name Linxia formation by five new formation names, based on lithologic variation and mammalian fossil finds. The new formations and their magnetostratigraphically determined ages are: Dongshan Formation (c.1.75-2.6 Ma), Jishi Fm. (c. 2.6-3.6 Ma), Hewangjia Fm. (4.5-6.0 Ma), Liushu Fm. (6.0-7.6 Ma), and Dongxiang Fm. (7.6-c. 12 Ma). The Neogene stratigraphy and fossil mammals suggest that the nearby part of the Tibetan Plateau experienced a persistent denudation during the Late Miocene and Early Pliocene, but that it was uplifted more rapidly at about 3.6 Ma. |
| Palaeomagnetic and rock-magnetic study of a Pliocene volcanic section in southern Georgia (Caucasus) | 1997 | Goguitchaichvili, A.T.; Sologachvili, D.Z.; Prévot, M.; Calvo, M.; Pavlenichvili, E.S.; Maissuradze, G.M.; Schnepp, E. | 76(1-2) | Twenty-six basaltic flows were sampled for a paleomagnetic and rock-magnetic study of the Tchuntchka section in the Akhalkalaki volcanic region in southern Georgia (Caucasus). Three to five samples from each flow were subjected to thermal or alternating-field demagnetization. The upper part of the section yields normal (D = 355.5°, I=54.2°,N= 17, α95=2.5°, k=226),and the lower part reversed polarity directions (D= 180.3°, l= - 59.4,° N = 8, α95 = 4.8°, k = 135). An anomalous direction was found in one flow in the upper part (D = 118.5°, I = - 77.3°). Rock-magnetic experiments show that the remanence is carried in most cases by magnetite or low-Ti titanomagnetite. The fraction of grains with a multidomain magnetic structure does not seem to be important. The remanence carried by such grains is removed only partly by low-temperature demagnetization. A tentative magnetostratigraphic correlation between the 3.8-Ma-old Thoki and Tchuntchka sites is proposed. |
| Late Permian magnetostratigraphy on the eastern Russian platform | 1997 | Gialanella, P.R.; Heller, F.; Haag, M.; Nurgaliev, D.; Borisov, A.; Burov, B.; Jasonov, P.; Khasanov, D.; Ibragimov, S.; Zharkov, I. | 76(1-2) | The Late Permian is characterized palaeomagnetically by the transition from the long-lasting Permo-Carboniferous reversed polarity superchron (PCRS; also called: Kiaman reversed superchron) to the subsequent Permo-Triassic mixed polarity superchron, often called Illawarra mixed polarity superchron. Many discussions have been devoted to the exact time of the onset of the Illawarra reversals. Apparently contradictory data have been obtained from magnetostratigraphic sediment successions formed in different environments in many regions of the world. These sediments have been dated using classical geological or palaeontological correlation methods without the possibility of absolute age control because volcanogenic materials are missing. Application of the local or regional stratigraphic schemes leads to difficulties and apparent diachronous age estimates of the end of the PCRS. This paper shows that in agreement with earlier investigations, the continental red beds of the Upper Permian Tatarian stage on the eastern Russian platform record the Kiaman/Illawarra boundary. The Illawarra reversal sequence measured in a type section at the Volga river can be correlated well with the corresponding polarity pattern found in the Tethyan realm if one assumes a longer duration of the Tatarian than previously suggested. |
| Archaeomagnetic dating of seven archaeological fireplaces in the Netherlands | 1997 | Hoof, A.A.M. van; Langereis, C.G.; Joosten, I.; Thijssen, J.R.A.M.; Nijhof, E.; Groenendijk, H.A.; Eynde, G.R.M. van den | 76(1-2) | The palaeomagnetic directions of seven Dutch fireplaces are compared with the archaeological age estimates which range from the first to the 17th century AD. A comparison with the British master curve of secular variation for archaeomagnetic dating results in a refinement of the archaeological age estimates in two cases, while four other archaeological age estimates can be confirmed. For one fireplace only one sample is reliable, resulting in a very poorly defined archaeomagnetic age of 2 to 3 centuries younger than the expected age (i.e. late Middle Ages). On the other hand, accepting the archaeological age estimates, the palaeomagnetic directions can contribute to the database that is used to construct the British secular-variation master curve. We applied the classification grades proposed by Tarling & Dobson (1995) which range from unreliable (grade 1) to reliable (grade 5). Three fireplaces have grades 5, one has grade 4, one grade 3, one grade 1 and for one case no grade was assigned. |
| Environmental magnetism: an introduction | 1997 | Dekkers, M.J. | 76(1-2) | In environmental magnetism, the properties of magnetic minerals are used as proxy parameters for many purposes. Examples are paleoclimate analysis, paleoceanographic studies, provenance studies of sediments, studies of anthropogenically-induced pollution, and archeological investigations. Mineral-magnetic techniques are sensitive, require little sample preparation, are rapid, often grain-size indicative, and usually non-destructive. These techniques involve 'bulk' properties which makes them complementary to geochemical micro-analytical techniques. Measurements include the field- and temperature-dependence of various types of induced and remanent magnetizations. Mineral-magnetic methods are continuously being improved. The underlying causal relations between observed mineral-magnetic properties and the processes that led to those properties, are becoming increasingly better understood, and the extended use of such properties as proxy parameters for many processes is foreseen. The following environmental magnetic applications are reviewed: the analysis of paleoclimatic variations in loess and other sediment types, the untangling of sedimentary features in piston cores, and the interpretation of the anthropogenic impact on the environment, in archeological studies and in studies of present-day pollution. The pathway between the provenance area and depositional site is shown to have a crucial impact on the magnetic properties. |
| A geochemical record of Late Cenozoic sedimentation history in the Southern Netherlands | 1998 | Huisman, D.J.; Kiden, P. | 76(4) | A sediment-geochemical study was performed on unconsolidated Upper Cenozoic siliclastic sediments from an area in the south of the Netherlands. Glauconite-rich sediments (Breda Fm) show high K contents and low Ba/K ratios. Major shifts in sediment composition as a result of changes in the Rhine system and of shifts between Rhine and Scheldt provenance, as known from heavy-mineral studies, are also recorded in changes in the grain-size dependent variations between Al, Na and K. Pleistocene Rhine sediments (Tegelen Fm) show higher Na contents than Pliocene Rhine sediments (Oosterhout and Kiezeloöliet Fms) and Scheldt-derived material (Kedichem Fm), probably as a result of larger contents of sodic plagioclase. Scheldt-derived sediments show low K/Al ratios as a result of a smectite-dominated clay-mineralogical composition and low contents of micas, whereas Rhine-derived sediments have high K/Al ratios which reflect an illite-kaolinite-dominated clay mineralogy and higher contents of muscovite. The presence of siderite causes high Fe contents in the Tegelen Fm in the east of the area, suggesting a freshwater depositional environment. Increased Mg contents in the siderite-bearing sections of the Tegelen Fm and in parts of the Oosterhout and Kiezeloöliet Fms are probably caused by the presence of minor amounts of dolomite. Localized high concentrations of (pyrite-) S are not only found in the marine Oosterhout Fm and the estuarine Tegelen Fm, but also in the fluviatile Kiezeloöliet and Kedichem Fms, which indicates at least minor marine transgressions during their deposition. |
| New raninid crabs (Crustacea, Decapoda, brachyura) from the late Maastrichtian of the Netherlands | 1998 | Fraaye, R.H.B.; Bakel, B.W.M. van | 76(4) | Three new raninid crabs, Lyreidina pyriformis gen. n., sp. n., Raniliformis chevrona sp. n., and Raniliformis prebaltica sp. n., are described from the Maastrichtian type area (SE Netherlands). The new genuslyreidina is the third member within the subfamily Lyreidinae Guinot 1993, and the first anterolateral-spines-lacking representative from the Cretaceous. The evolutionary development of the genus Raniliformis Jagt, Collins & Fraaye (1993) seems to include a continuous lineage occlusa-prebaltica-baltica. R. chevrona is considered as an offshoot. |
| Burial history and thermal evolution of Westphalian coal-bearing strata in the Campine basin (NE Belgium) | 1998 | Keer, I. van; Ondrak, R.; Muchez, P.; Bayer, U.; Dusar, M.; Viaene, W. | 76(4) | A 1D-modelling program has been applied to reconstruct the burial and thermal histories of two exploration boreholes, KB172 and KB174, located in the Campine Basin. The results show differences in geological histories. The coalification of the Westphalian A and B strata in KB174 (0.66-0.98% Ro) was pre-Permian. Calculated maximum temperatures, based on borehole data and vitrinite reflectance, regional thicknesses and a heat flow of 84 mW/m2 during the Late Westphalian, range from 110 °C at the top to 175 °C at the bottom of the Westphalian cored in this borehole. The high coalification (0.85-1.30%Ro) of the Westphalian C and D strata in KB172 could be the result of the deposition of ~2500 m of Upper Permian to Middle Jurassic sediments in combination with elevated heat flows (71-80 mW/m2). Two coalification periods, i.e. Late Westphalian and Middle Jurassic, are suggested for this borehole. The simulated maximum temperatures range from 130°C at the top to 175 °C at the bottom of the investigated Westphalian C and D. The differences in the burial and thermal histories of both boreholes can be related to the activity of the transversal Donderslag Fault, a major structural element in the Campine coalfield, and the Roer Valley Graben. |
| Mobility of rare-earth elements and copper during shear-zone-related retrograde metamorphism | 1998 | Jong, G. de; Rotherham, J.; Phillips, G.N.; Williams, P.J. | 76(4) | In Mid Proterozoic crystalline rocks of the Mount Isa Inlier, around Cloncurry, Australia, 2000 km2 of alteration and brecciation are the product of high-temperature (> 450 °C) concentrated saline solution activity. During retrogression, this fluid was locally responsible for mobility of V Y Nb and light rare-earth elements (15 x enrichment). Copper and S were leached during alteration and this may have been a significant source of components in nearby Cu-Au deposits. Similar rare-earth-element behaviour has been observed in the hematite breccias which host Cu-sulfides at the giant Olympic Dam Cu-Au deposit |
| Diapirism synchronous with regional deformation and gold mineralisation, a new concept for granitoid emplacement in the Southern Cross Province, Western Australia | 1998 | Dalstra, H.J.; Bloem, E.J.M.; Ridley, J.R.; Groves, D.I. | 76(4) | The Southern Cross Province in the Archean Yilgarn Block of Western Australia comprises large dome-shaped granitoid bodies surrounded by narrow greenstone belts. Determination of the emplacement mechanism of these domes is fundamental for understanding the tectonic history of this region. Many structures in the greenstone belts show trends which reflect their tectonic relationships with the granitoid domes. Some of these structures host large gold occurrences. The domes have concentric foliation patterns, both within the granitoids themselves, and in the neighbouring greenstone belts. The smaller domes only have radial mineral lineation patterns in their wall rocks, but the largest dome, the Ghooli Dome, has also a tangential pattern. The prevailing gentle dip of the foliation in the centre of this dome and the abundance of greenstone xenoliths suggest that the present exposures are close to its roof. Geothermometry and geobarometry on mineral assemblages in the Ghooli granitoid and its xenoliths show that its crystallisation temperature was just above 700 °C at a relatively high pressure of 4.3 to 6.2 kbar. These P-T conditions are higher than those inferred for peak metamorphism in the greenstones. Therefore, this granitoid must have been emplaced initially at crustal levels deeper than the maximum burial of the greenstones which flank the dome. The Ghooli Dome has a SHRIMP U-Pb zircon age of 2691 ± 7 Ma. Diapiric rise of the granitoid plutons taking place in a regional compressive tectonic regime is considered to be the most likely mechanism for the final emplacement of these bodies into their host rock at about 2636-2620 Ma. This concept is preferred over the alternatives because it best reconciles the calculated P-T data, the observed structural patterns, the presence of pegmatites and aplites in the host rock, and the orientation of the mineral-bearing structures. |
| Schürman Symposium on the Early Archaean. Introduction | 1998 | Priem, H.N.A. | 76(4) | |
| Tectonic evolution of the Eastern Pilbara, Australia (Extended abstract) | 1998 | White, S.H.; Zegers, T.E.; Haaften, W.M.; Kloppenburg, A.; Wijbrans, J. | 76(4) | |
| Archaean growth structures in the Pilbara, Australia (extended abstract) | 1998 | Nijman, W. | 76(4) | |
| 40Ar/39Ar and U-Pb dating in the eastern Pilbara, Australia; temporal constraints on structural and metamorphic events between 3.5 and 2.8 Ga (extended abstract) | 1998 | Zegers, T.E.; Wijbrans, J.R.; Nelson, D.R.; White, S.H. | 76(4) | |
| The late Archaean and early Proterozoic: what happened next? (Extended abstract) | 1998 | Passchier, C.W. | 76(4) | |
| Evolution of the northeastern Kaapvaal craton and the central Limpopo belt, South Africa, based on single-zircon ages (extended abstract) | 1998 | Kröner, A.; Jaeckel, P.; Brandl, G.; Nemchin, A.A.; Pidgeon, R.T | 76(4) | |
| Accretion and stabilisation of the Archaean Zimbabwe Craton (extended abstract) | 1998 | Dirks, P.H.G.M. | 76(4) | |
| Early Archean processes: evidence from the South African Kaapvaal craton and its greenstone belts (extended abstract) | 1998 | Wit, M.J. de | 76(4) | |
| #REF! | 1998 | 76(4) | ||
| Subareal terminoglacial fans I: a semi-quantitative sedimentological analysis of the proximal environment | 1999 | Zieliński, T.; Loon, A.J. van | 77(1) | Fans formed under subaerial terminoglacial (previously called 'ice-contact') conditions have several characteristics that differ from those formed under other conditions. Twenty-five such fans in NE Poland were investigated to model the dominant genetic processes involved. These fans show, as do other types, a proximal, a middle and a distal environment. The present study deals with the proximal environment. The fans date from the last, i.e. Weichselian or Vistulian, glacial. The proximal terminoglacial fan comprises abundant gravelly sediments, resembling the glacial deposits from which they were derived. Three facies, each subdivided into two subfacies, can be distinguished; these are dominated by mass flows, unchannelised flows, and stream (= channelised) flows, respectively. The characteristics of the facies are described and illustrated. It is concluded that the irregular supply of water by the nearby ice masses dominates the sedimentary processes. |
| Seismic stratigraphy of the Mesozoic and Cenozoic in Northern Belgium: main results of a high-resolution reflection seismic survey along rivers and canals | 1999 | Batist, M. de; Versteeg, W.H. | 77(1) | This paper presents the results of high-resolution reflection seismic surveys carried out between 1989 and 1996 along rivers and canals in northern Belgium. The seismic data penetrate down to 900 m in the sedimentary cover or to the Paleozoic basement. The reflection response of the acoustic basement provides clear indications with regard to the top of the Paleozoic: crystalline basement and Lower Paleozoic metasediments and volcanics of the London-Brabant Massif and NE-dipping Devonian and Carboniferous strata. The subhorizontal Mesozoic and Cenozoic sedimentary cover comprises 20 unconformity-bound seismic units: 5 in the Cretaceous and 15 in the Cenozoic. Based on borehole information, these units are correlated with lithostratigraphically defined formations or groups. Some of the unit-bounding unconformities are of regional importance. They are attributed i) to eustatic sea-level changes causing regional flooding during the Late Cretaceous or incision of deep valleys during the Late Oligocene and Late Miocene, ii) to regional tectonic tilting between Late Eocene and Early Oligocene, or iii) to a combination of eustasy and tectonics causing valley incisions during the Lutetian. Faults of the Roer Valley Graben have offset different stratigraphic levels by sometimes considerable amounts (up to 230 m in the Oligocene to Quaternary succession). Although the main tectonic phase took place during the Miocene, the activity has varied considerably through time, and also from fault to fault. Most faults seem to have a 10 to 30-m displacement since the Late Pliocene. |
| Oligocene to middle Miocene basin development in the Vélez Rubio Corridor - Espuña (Internal-External zone boundary; Eastern Betic Cordilleras, SE Spain) | 1999 | Geel, T.; Roep, T.B. | 77(1) | The Vélez Rubio Corridor and the area northwest of the Sierra Espuña are located on the Internal-External Zone Boundary. The External Zone is represented by the Southern Subbetic, the most basinward part of the former passive margin of Iberia, the Internal Zone by its unmetamorphosed highest unit, the Malaguide Complex, tectonically underlain by the metamorphosed Alpujarride Complex. During the Oligocene and Aquitanian, the Southern Subbetic was the locus of slope deposition with northeastern provenance of detritus. In the Malaguides of the Espuña, the detritus of Lower Oligocene transgressive conglomerates and Middle Oligocene fan deltas indicates Sardinian proximity. The Upper Oligocene to lower Aquitanian Ciudad Granada and Pliego formations of the Malaguide Complex, carrying exclusively Malaguide detritus, were deposited in grabens within the Malaguide realm during an extensional rifting phase. The Malaguides, still far removed from the Subbetic, underwent major thrusting during the Aquitanian. Of the sedimentary units found between the Internal and External Zones, the oldest unit (the allochthonous Aquitanian Solana formation) was deposited in submarine fans outside the Subbetic or Malaguide realms proper, but in close connection with the latter. The Internal Zone collided with the External Zone in the early Burdigalian with concomitant disruption of the Southern Subbetic slope. On the suture, a deep basin was formed and fitted in by the Burdigalian Espejos formation carrying detritus from the Subbetic and from the Malaguide and Alpujarride Complexes. In the late Burdigalian, the Subbetic was thrust southward over the Espejos formation, thus double-sealing the collisional contact. During the latest Burdigalian to Langhian, new basins were formed along the Internal-External Zone Boundary and within the Southern Subbetic. The onset of strike-slip faulting caused shoaling and uplift of these basins. Onset of a new pattern of strike-slip faulting induced the formation of a new suite of basins during the Tortonian, e.g. the Lorca Basin. |
| Petrography and geochemistry of septarian carbonate concretions from the Boom Clay Formation (Oligocene, Belgium) | 1999 | Craen, M. de; Swennen, R.; Keppens, E. | 77(1) | The septarian carbonate concretions from the Boom Clay (Belgium) consist mainly of authigenic minerals such as micrite (< 70% bulk volume) and pyrite framboids (~ 3%).These mineral phases occur between detrital grains and fossils. The septarian cracks are lined with calcite, which is sometimes covered with pyrite. The preservation of delicate sedimentological features in the concretion matrix (hardly compacted faecal pellets, burrows and uncrushed shells) points to an early origin of the concretions. Systematic geochemical variations from concretion centre to edge suggest that growth continued during shallow burial. The δ13C values (-17.5 to 20.5 ‰) of the concretionary carbonate show that bacterial sulphate-reduction processes were dominant. Sulphate-reduction-derived HCO3- was diluted by marine-related HCO3-, derived from dissolved bioclasts. A slight enrichment in δ13C during growth is caused by the decreasing influence of sulphate reduction because of the progressive closure of the diagenetic system due to shallow-burial compaction. The δ18O values (-0.5 to +1.0‰) of the concretionary carbonate point to a marine origin. The slightly 18O -depleted signature with respect to time-equivalent marine-derived carbonate relates to the incorporation of an 18O -depleted component, originating from sulphate and organic matter. The slight decrease in δ18O during growth relates to an increasing influence of this component and to a decreasing influence of seawater-derived oxygen during early diagenesis. |
| Conodont colour alteration indices (CAI) of Upper Ordovician limestones from the Iberian Peninsula | 1999 | Sarmiento, G.N.; García-López, S.; Bastida, F. | 77(1) | Conodont colour alteration index (CAI) data in Upper Ordovician rocks from several areas of the Variscan domain in the Iberian Peninsula indicate conditions ranging from diagenesis to low-grade metamorphism. In most of the areas, where studies using other indicators, such as illite crystallinity (IC) or vitrinite reflectance are lacking, the CAI method has permitted a preliminary estimation of the metamorphic grade. In the Almadén syncline (Central-Iberian Zone), where IC studies are available, the thermal conditions inferred from CAI data agree with those obtained by the IC method. In the Puertollano-Almuradiel syncline, the thermal interval obtained primarily from fluid inclusions (270-370°C) overlaps considerably with that obtained from CAI data (180-340°C). In general, cleavage in rocks is present in anchizonal or epizonal conditions, whereas in diagenetic conditions with CAI ≥ 2.5, cleavage is scarce. The conodont texture changes with increasing metamorphism, and apatite recrystallization appears in general with CAI ≥ 5. Variation of CAI values within a single sample and/or within short stratigraphic distances observed at several localities is due to hydrothermal activity. |
| Discussion: Oil seepage or fossil podzol? An Early Oligocene oil seepage at the southern rim of the North Sea Basin, near Leuven (Belgium) by E.D. van Riessen & N. vandenberghe, Geologie en mijnbouw 74: 301-312 (1996) | 1999 | Buurman, P.; Jongmans, A.G.; Kasse, C.; Lagen, B. van | 77(1) | |
| Discussion: Oil seepage or fossil podzol? An Early Oligocene oil seepage at the southern rim of the North Sea Basin, near Leuven (Belgium). Reply by the authors | 1999 | Riessen, E.D. van; Vandenberghe, N. | 77(1) | |
| Rpresentation of the van Waterschoot van der Gracht Medal to Prof. A.J. Pannekoek and Prof. J.L.R. Touret | 1999 | Pannekoek, A.J.; Touret, J.L.R. | 77(1) | |
| Applications of remote sensing in geology. Preface | 1999 | Meer, F. van der; Kosters, E.C.; Fraikin, S.J. | 77(2) | |
| Geological remote sensing in aerospace and time. Introduction | 1999 | Reeves, C.V. | 77(2) | The more one considers the earth sciences these days, the more one realises that any view that falls short of global runs the risk of being short-sighted. This article sketches the position of remote sensing in geology following several points of observation: 1) Earth scientists are not blind but when it comes to geology are we not all blind? 2) We all come to whatever particular earth science problem we have to tackle with a background of scientific knowledge. 3) Interpretations are ephemeral. Our specialist windows each bring us a partial view of the hidden subsurface. If we are wise we share our fields of expertise so that the earth sciences can best deliver their potential benefits to global society. |
| Multi-sensor data fusion for the detection of underground coal fires | 1999 | Zhang, X.M.; Cassells, C.J.S.; Genderen, J.L. van | 77(2) | The spontaneous combustion of coal causes widespread underground coal fires in several countries, amongst which is China. These coal fires cause serious environmental, economic and safety problems. In northern China, the coal fires occur within a wide region stretching 5000 km east-west and 750 km north-south. Remote sensing therefore provides an ideal tool for monitoring this environmental hazard over such a large and remote area. As part of a research project to detect, measure, monitor and extinguish these coal fires, this paper describes a remote-sensing based multi-sensor data-fusion methodology for detecting the underground fires. The methodology is based on fusing a variety of satellite-based image types (optical, thermal, microwave) together with airborne data (optical and thermal infrared) and ancillary data sources such as geological and topographic maps. The results of the remote-sensing data fusion are presented, using pixel-based, feature-based and decision-based fusion approaches |
| The influence of neo-tectonics on river patterns in Bangladesh; a preliminary study based on Landsat MSS imagery | 1999 | Seijmonsbergen, A.C. | 77(2) | Bangladesh is part of the active foredeep depression south of the Himalayan collision zone, bordering the Indian plate. Seismic activity is common both in the mountain chain and in the Ganga plain reaching into the basin of the Bay of Bengal and forming the counterpart of the uplifted Himalayan chain. Erosion, sedimentation, river migration and transport within the Jamuna (Brahmaputra) river system are therefore not only controlled by processes on the Earth's surface, but are also the result of a balance between fast and continuing deposition versus geological subsidence and uplift. An attempt is made to correlate the behaviour of the Jamuna river to neo-tectonic movements, as interpreted from Landsat MSS imagery using available literature. From the imagery covering the period 1916 to 1987, supervised and unsupervised classifications of bands 5 and 7 were made. The 1978 and 1986 images revealed the most useful classifications and yielded pronounced differences in colour variation for visual interpretations of geological lineaments and terrain units. The Jamuna riverbed can be divided into compartments, limited by faults. |
| Imaging spectrometry for geological remote sensing | 1999 | Meer, F. van der | 77(2) | Without use of imaging spectrometry, imaging of the Earth's surface from aircraft and from spacecraft is hampered by the low spectral resolution and limited number of spectral bands, typically less than 10 bands of 100 to 200 nm width. Imaging spectrometry in remote sensing concerns the acquisition of image data in many narrow (< 40 nm wide) contiguous spectral bands with the ultimate goal of producing detailed spectral reflectance curves for each pixel in the image. Many minerals and rocks have unique spectral signatures with characteristic absorption features that are 20 to 40 nm wide. Imaging spectrometers allow to depict these narrow features and thus map surface mineralogy based on spectral image characterization. This paper gives a review of imaging spectrometry and addresses the following topics: airborne and spaceborne systems available, spectral and geometric data preprocessing, atmospheric correction, techniques for thematic data analysis, and applications in the field of geological remote sensing. In the final section a case study is described where imaging spectrometer data is used for mapping surface mineralogy in a hydrothermal alteration system, thus guiding gold exploration. |
| Spectral mixture analysis for mapping land degradation in semi-arid areas | 1999 | Tromp, M.; Epema, G.F. | 77(2) | Spectral mixture analysis (SMA) is an image-processing technique used for the analysis of airborne hyperspectral remote-sensing data which consist of a large number of spectral bands, typically over 100. In this paper the possibilities are examined of using SMA for the analysis of Landsat Thematic Mapper satellite data with only six bands in the visible to shortwave-infrared wavelength. 'We use data from a semi-arid area in the Sanmatenga province of Burkina Faso, an area known to experience land-degradation problems. In SMA, we assume that pixels in an image consist of one or more homogeneous (uniform in character) or pure surfaces, the so called end-members. The endmembers were derived from the image data on the basis of specific image characteristics. Field data was collected to describe the characteristics of these end-members in terms of land cover, soil and degradation phenomena. The end-members derived from the image analysis, although statistically pure in terms of image spectral characteristics, prove to be mixtures at a field scale. This lack of purity is explained by the nature of semi-arid areas which is more heterogeneous than that of most other areas. The SMA yielded cover percentages for the end-members from which an unsupervised classification was made. Comparison of the classification with the results of SMA shows that the latter provides information on the amount and spatial distribution of land characteristics such as land degradation. |
| Deformation measurements using SAR interferometry: potential and limitations | 1999 | Klees, R.; Massonnet, D. | 77(2) | Most applications of Synthetic Aperture Radar (SAR) make only use of the amplitude information in just one image. Interferometric SAR (InSAR) makes use mainly of the phase measurements in two or more SAR images of the same scene, acquired at two different moments and/or at two slightly different locations. By interference of the two images, very small slant-range changes of the same surface can be inferred. These slant-range changes can be related to topography and/or surface deformations. InSAR thus has the potential of mapping centimeter-scale ground displacements over a region many tens of kilometers in size at a resolution of a few meters making it one of the most promising space-geodetic techniques for monitoring Earth's surface deformations. The goal of this paper is to discuss some of the potential new applications of InSAR for the monitoring of deformations, and to show its major limitations. Some potential new applications of InSAR related to surface-change detection including earthquake and crustal studies, the monitoring of volcanoes and anthropogenic effects, and the monitoring of glaciers and ice sheets are presented. The discussion on the limitations of InSAR for surface-change detection focuses on atmospheric perturbations and the problem of temporal decorrelation. |
| Background of ground-penetrating radar measurements | 1999 | Kruk, J. van der; Slob, E.C.; Fokkema, J.T. | 77(2) | CharacterizaÍion of the shallow subsurface (0.25 to 10 m) is of growing importance for engineering activities. solutions of environmental problems, and archaeological investigations. Ground-penetrating radar (GPR) is an appropriate technique considering the depth range of interest, the strength of electric and magnetic contrasts between different subsurface layers and buried objects, and the required resolution. GPR surveys can detect subsurface structures by recording electromagnetic reflections from discontinuities. The detectability of objects and the delineation of subsurface structures increases with increasing wave velocity and conductivity differences between the object and its surroundings or between adjacent layers. However, unwanted reflections from objects above the surface influence the images. Shielded antennas can be used to avoid strong reflections from these objects. The data thus obtained are, however, more difficult to interpret. The fundamentals of GPR and two different acquisition setups for a GPR system are discussed. Basic interpretation tools for travel-time and velocity estimation are described, and finally, case studies are presented, followed by conclusions. |
| Applications of remote sensing in geology. Appendix | 1999 | Reeves, C.V. | 77(2) | |
| Climate change and coastal evolution in Europe | 1999 | Groot, T.A.M. de; Orford, J.D. | 77(3-4) | |
| Pleistocene and Holocene aeolian facies along the Huelva coast (southern Spain): climatic and neotectonic implications | 1999 | Zazo, C.; Dabrio, C.J.; Borja, F.; Goy, J.L.; Lenzine, A.M.; Lario, J.; Polo, M.D.; Hoyos, M.; Boersma, J.R. | 77(3-4) | The stratigraphic relationships, genesis and chronology, including radiocarbon dating, of the Quaternary sandy deposits forming the El Asperillo cliffs (Huelva) were studied with special emphasis on the influence of neotectonic activity, sea-level changes and climate upon the evolution of the coastal zone. The E-W trending normal fault of Torre del Loro separates two tectonic blocks. The oldest deposits occur in the upthrown block. They are Early to Middle Pleistocene fluviatile deposits, probably Late Pleistocene shallow-marine deposits along an E-W trending shoreline, and Late Pleistocene and Holocene aeolian sands deposited under prevailing southerly winds. Three Pleistocene and Holocene aeolian units accumulated in the downthrown block. Of these, Unit 1, is separated from the overlying Unit 2 by a supersurface that represents the end of the Last Interglacial. Accumulation of Unit 2 took place during the Last Glacial under more arid conditions than Unit 1. The supersurface separating Units 2 and 3 was formed between the Last Glacial maximum at 18 000 14C yr BP and ca. 14 000 14C yr BP, the latter age corresponding to an acceleration of the rise of sea level. Unit 3 records wet conditions. The supersurface separating Units 3 and 4 fossilised the fault and the two fault blocks. Units 4 (deposited before the 4th millennium BC), 5 (> 2100 14C yr BP to 16th century) and 6 (16th century to present) record relatively arid conditions. Prevailing wind directions changed with time from W (Units 2-4) to WSW (Unit 5) and SW (Unit 6). |
| Lateglacial climate change and coastal evolution in western Jura, Scottish Inner Hebrides | 1999 | Dawson, A.G.; Smith, D.E.; Dawson, S.; Brooks, C.L.; Foster, I.D.L.; Tooley, M.J. | 77(3-4) | The geomorphic and sedimentological evidence for former sea-level changes in the exposed coastline of western Jura shows a clear coastal response to past changes in climate. In particular the rapid and high-magnitude climate changes associated with the onset and termination of the Younger Dryas appear to have been accompanied by major changes in coastal response. In western Jura, the temperate climate of the Lateglacial Interstadial was associated with beach-ridge deposition, with the earlier part of this period being associated with larger ridges than the latter. By contrast, the cold climate during the Younger Dryas appears to have been dominated by frost processes, sea-ice development and rapid rates of coastal erosion of bedrock. Cold-climate shore erosion of bedrock appears to have ended suddenly at the close of the Younger Dryas. |
| Evidence for Late Pleistocene and Holocene sea-Ievel, neotectonic and climate control in the coastal zone of northwest Portugal | 1999 | Granja, H.M. | 77(3-4) | The coastal zone of northwest Portugal can be subdivided into two geomorphological sectors: Sector 1, between the Minho River and the town of Espinho, where the coastal segments consist of estuaries, sandy and shingle beaches with rocky outcrops, and Holocene dune systems (foredunes and some migrating dunes with blow-outs). The estuaries and the foredunes in particular are very degraded by human activities. Sector 2, between Espinho and the Mondego Cape, where coastal lagoons and Holocene dune systems (foredunes, parabolic and transverse dunes) occur. This study deals with the macroscale, i.e. 100-1000 years, forcing by sea-level changes and neotectonic activity on the one hand, and mesoscale, i.e. 1-100 years, forcing by climate fluctuations on the other hand, on these (palaeo-)environments. It is shown in particular that sea-level changes and neotectonic activity play a dominant role in the evolution of the coastal zone since the Late Pleistocene. Sediment starvation on the shoreface is postulated to be one of the major causes for coastal erosion since at least the 15th century. The mesoscale role of climate is difficult to assess at the present stage of knowledge, mainly because of overprinting by the macroscale evolution of the coast. However, data on estuarine saltmarsh evolution in sector 1 point towards discrete changes in storminess, while the development of Medieval dune systems in sectors 1 and 2 are attributed to the Little lce Age or, alternatively, to human occupation of the dune areas. |
| Sea level, climate change and coastal evolution | 1999 | Shennan, I.; Tooley, M.; Green, F.; Innes, J.; Kennington, K.; Lloyd, J.; Rutherford, M. | 77(3-4) | Analyses of geomorphologically contrasting sites in Morar, NW Scotland, describe the forcing mechanisms of coastal change. Isolation basins (i.e. basins behind rock sills and now isolated from the sea following isostatic uplift) accumulated continuous marine and freshwater sediments from c.12 to 2 ka BP. Raised dune, marsh and wetland sites register breaching, migration and stability of dunes from c. 9 to 2 ka BP. High-resolution methods designed to address issues of macroscale and microscale sea-level changes and patterns of storminess include 1-mm sampling for pollen, dinocyst and diatom analyses, infra-red photography, X-ray photography and thin-section analysis. The data enhance the record of relative sea-level change for the area. Major phases of landward migration of the coast occurred during the period of low sea-level rise in the mid-Holocene as the rate of rise decreased from c. 3 to < 1 mm/year. Relative sea-level change controls the broad pattern of coastal evolution at each site; local site-specific factors contribute to short-term process change. There is no record of extreme events such as tsunami. Within a system of dynamic metastable equilibrium, the Holocene records show that site-specific factors determine the exact timing of system breakdown, e.g. dune breaching, superimposed on regional sea-level rise. The global average sea-level rise of 3 to 6 mm/yr by AD 2050 predicted by IPCC would only partly be offset in the Morar area by isostatic uplift of about 1 mm/yr. A change from relative sea-level fall to sea-level rise, in areas where the regional rate of uplift no longer offsets global processes, is a critical factor in the management of coastal resources. |
| Sequence stratigraphy of Holocene incised-valley fills and coastal evolution in the Gulf of Cádiz (southern Spain) | 1999 | Dabrio, C.J.; Zazo, C.; Lario, J.; Goy, J.L.; Sierro, F.J.; Borja, F.; González, J.A.; Flores, J.A. | 77(3-4) | This first sedimentary interpretation of two incised-valley fills in the Gulf of Cádiz (southern Spain), which accumulated during the last fourth-order eustatic cycle in response to fluvial incision, changes of sea level, and correlative deposition, relates the filling of the estuarine basins and their barriers with four regional progradation phases, H1 to H4. The cases studied are the wave-dominated Guadalete, and the mixed, tide and wave-dominated Odiel-Tinto estuaries. The sequence boundary is a type-1 surface produced during the lowstand of the Last Glacial period ca. 18 000 14C yr BP. No fluvial lowstand deposits were found in the area. Due to rapid transgression the valley fills consist of transgressive and highstand sediments. The maximum landward advance of the estuarine barriers occurred ca. 6500-6000 14C yr BP during the maximum of the Flandrian transgression, but there is no evidence of sea level rising appreciably above the present. A large part of the estuaries was filled during Hr (ca. 6500-4400 14C yr BP) but ravinement by shifting tidal inlets destroyed most of the coeval barriers. During the H2 phase (ca.4200-2550 14C yr BP) sedimentation was favoured by arid conditions and concentrated in the axial estuarine zones and the barriers. Between H2 and H3 prevailing winds changed from W to WSW, increasing spit growth to the east and south-east. Progradation of bay-head deltas and flood-plains during H3 (ca. 2300-800 14C yr BP) and H4 (500 yr ago to the present) further reduced the accommodation space in the largely-filled valleys, and sediment by-passed the estuaries and accumulated in the estuarine barriers as fast-growing spits. Arid conditions and increasing human activity have caused rapid coastal modifications. |
| The sedimentary record of recent (last 500 years) environmental changes in the Seixal Bay marsh, Tagus estuary, Portugal | 1999 | Freitas, M.C.; Andrade, C.; Moreno, J.C.; Munhá, J.M.; Cachão, M. | 77(3-4) | The inner Tagus estuary is essentially a sedimentation basin that receives cohesive sediment from terrestrial, marine, biological and anthropogenic sources. Three short cores from one site in a marsh area of this estuary (Seixal Bay) were analysed for sedimentary, geochemical and micropalaeontological contents (benthic foraminifera and nannoplankton). The length of the cores represents about half a millennium of sedimentation. Textural analysis suggests a highly uniform mud sedimentation for most of the cores but geochemical, mineralogical and micropaleontological results indicate climatic and environmental changes and anthropogenic disturbance. Three Foraminifera zones were identified. The lower part of the lower zone indicates sedimentation in an open channel or a lower domain of an exposed high-energy sandflat. Sediments of the upper part of the lower zone and of the middle zone were deposited in a lower-energy environment, probably associated with a sheltered, vertically aggrading mudflat located within the Seixal Bay. Biological and mineralogical indicators suggest that periods of total or partial closure of this bay occurred. Clay minerals indicate that drier and colder conditions prevailed in the lower half of this zone evolving gradually to a wetter and warmer environment towards the top. The upper zone indicates persistence of low-energy sedimentation and evolution towards the present salt-marsh conditions. Anthropogenic pollution is clear in geochemical proxies at the top of the sedimentary column and was used for dating purposes. |
| Saltmarsh deposition and its relationship to coastal forcing over the last century on the north-west coast of Ireland | 1999 | Wheeler, A.J.; Orford, J.D.; Dardis, O. | 77(3-4) | The mesoscale (time) control of annual storm-surge activity on quasi-annual saltmarsh (tidal marsh) deposition is studied from two estuarine saltmarshes on the high-energy NW coast of Ireland. Both saltmarshes exhibit a cliffed edge where maximum sedimentary variation is expressed in the form of lamination. Sections were logged and characterised by lithofacies based on grain-size determinations. Sections dated using Cs and Pb determinations indicated deposition records of decadal to century scale (c. 0.5 cm a-1). Linear multiple regression explains (p < 0.05) half the variation of the deposition rate by annual coastal forcing (surge frequency and magnitude) and sediment modes (coarse silt to clay). Further variability in deposition rate is partially reflected in the non-linear response between forcing and deposition that is affected by mesoscale (30, 11 and 5-year) periodicities in forcing. Increased annual surge activity appears to be associated with a coarsening of, and reduction in annual deposition. A relationship between annual deposition rate and fractal dimension of surge timing (i.e. the clustering of surge events) is identified. |
| A microfaunal and sedimentary record of environmental change within the late Holocene sediments of Boca do Rio (Algarve, Portugal) | 1999 | Hindson, R.; Andrade, C.; Parish, R. | 77(3-4) | The foraminifera and ostracods observed in a late Holocene sedimentary sequence within a fluvial valley at Boca do Rio in the coastal zone of the western Algarve, Portugal, reveal a general, though not smooth transition from marine to fluvial conditions. The relative influence of these two environments appears to depend on the degree of permeability of the barrier system at the coast. Optically stimulated luminescence dates and palaeoecological information obtained from the sequence suggest that barrier formation may be related to changes in climate and/or patterns of ocean current circulation. An unusual deposit rich in sand and gravel found within the otherwise mud dominated sequence has been dated at AD 1801 ± 76 years. This deposit contains foraminifera and ostracods which indicate marine conditions, and which contrast markedly with the brackish-water, estuarine assemblages found in the mud deposits. The rapid transition in the foraminifera and ostracod assemblages indicates a shortlived coastal flooding, which may represent the tsunami associated with the Lisbon earthquake of AD 1755. The variations in the foraminifera and ostracod assemblages also suggest subsidence during the earthquake, with uplift having occurred in the period since then. |
| Micro- to mesoscale evolution of beaches in response to climatic shift: observation and conceptual modelling (Brittany, France) | 1999 | Regnauld, H.; Binois, S.; Fouqué, C.; Lemasson, L. | 77(3-4) | In the framework of the European project 'Climate change and coastal evolution in Europe', the microscale (< 1 year) morphological evolution of beaches in Brittany (W France) has been monitored for some years and linked to immediate forcings, the first one being tides (with a 13-m tidal range), and the second storm intensity. For the same sites, a mesoscale (decades) evolution was reconstructed from air photographs and historical data. The evolution is forced first of all by human activities, and secondly by climatic shift: wind direction changes and average wind velocity evolution. These results were used to build and calibrate a model of coastal behaviour. The model is based on a simple sediment cell (input - transit - output) and simulates the movements of volumes of sands under successive morphodynamic processes. Each of these processes is modelled (in terms of volume exchanges) and parameterized by the relevant atmospheric element. Thus, the model is not deterministic but simulates different probabilities for atmospheric events and morphological response. The model runs for one year and produces realistic sediment accumulation values and coastal retreat rates. When run for half a century, results are also quite comparable to the field data. Storm frequency changes appear to be an important element for the evolution, but the main and first forcing is the availability of sediment. |
| Contemporary process controls on the evolution of sedimentary coasts under low to high energy regimes: Western Ireland | 1999 | Duffy, M.J.; Devoy, R.J.N. | 77(3-4) | Sedimentary environments, representative of the Irish west coast, have been studied to examine their responses at the microscale (10-1-100 yr). This was achieved using a variety of techniques, including grain-size analysis, measurement of accretionary responses and radiometric dating. Monthly elevation monitoring of silt-dominated marshes shows an annual pattern in sediment accumulation. This reflects two processes: a) winter accretion attributable to storm events, and b) summer consolidation and contraction of the marsh sediments. Together, the results suggest that intertidal sedimentation is likely to be dominated by episodic processes, primarily storms. Examination of the tidal regime shows a weaker than expected influence of hydroperiodicity on intertidal accretion, although this influence remains distinctive, as expressed by a landward textural fining. Storms were also identified as of major importance in the functioning of higher-energy sandy coastal systems, again having a largely accretional influence, primarily through aeolian transport. Erosion at such study sites is probably controlled by the attainment of a critical threshold surface elevation, or by exceptional storm action, or a combination of both. The linking of microscale sedimentation rates with those at the meso- to macroscale, and assessment of their importance for coastal functioning, is difficult due to the geological averaging effect of the sedimentary record. Human impacts on this coast in historical times are large but difficult to quantify. |
| Climate shifts and coastal changes in a geological perspective. A contribution to integrated coastal zone management | 1999 | Groot, T.A.M. de | 77(3-4) | This Special Issue deals with the impact of climate change on western European coastal systems. Notwithstanding the inherent problems of studying geological data in terms of climate shifts, the results show that on the meso and the macroscale of time, climatic forcing is a major drive for coastal change. However, its impact is largely influenced by other factors. Sediment availability plays a dominant role in the evolution of coastal systems and it can be considered one of the most important thresholds at the land-ocean interface. Sea-level changes are expected to have a significant impact on most European coasts. There is particular concern for the tidally influenced flats and marshes, and for those coastal areas known to have already a net sediment deficit and to be threatened by erosion. Areas where isostatic uplift has countered sea-level rise until now, are expected to become subject to coastal erosion in the near future under an accelerated sea-level rise scenario. The sensitivity and vulnerability of coastal systems to climate shifts is shown to be largely controlled by storm magnitude and fetch. A particular case of vulnerability is the impact of tsunamis. Finally, the consequences of human interference have been demonstrated in many cases. The implementation of geoscientific studies for rational, comprehensive and cost-effective strategies on a regional or national level of integrated coastal zone management is reviewed. |
| Presentation of the Van Waterschoot van der Gracht Medal to Dr S. Jelgersma | 1999 | 77(3-4) | ||
| Late Cretaceous - Early Tertiary sedimentation and tectonic inversion in the southern Netherlands | 1999 | Gras, R.; Geluk, M. | 78(1) | Analysis of the Upper Cretaceous stratigraphy of the Peel Block reveals the basin development of the block to have been influenced by both the inversion of the Roer Valley Graben and Central Netherlands Basin, and the overall Late Cretaceous transgression. Sediments of Santonian to Danian age were deposited on the block. These sediments are compared with the detailed lithostratigraphy of southern Limburg, where Late Cretaceous strata are exposed. Four successions can be recognised in southern Limburg. The two oldest successions, the Santonian Oploo Formation (new name, proposed in the present contribution) and the mainly Early Campanian Vaals Formation, are restricted to the central and northern parts of the block. These siliciclastic formations were deposited under the influence of inversion of the Roer Valley Graben and the Central Netherlands Basin, as well as under the influence of a rising sea level. Towards the north, sands of the Oploo Formation grade into marls and chalks of the Ommelanden Formation. The two youngest successions comprise the largely Late Campanian to Maastrichtian Gulpen and Maastricht Formations and the Danian Houthem Formation. These chalk formations were deposited under the influence of regional subsidence during a sea-level highstand. Subsequent to deposition of the Houthem Formation, a regional regression triggered a change from shallow-marine carbonate to paralic siliciclastic deposition. |
| The fractal geometry of tidal-channel systems in the Dutch Wadden Sea | 1999 | Cleveringa, J.; Oost, A.P. | 78(1) | Horton's hierarchical and fractal analysis of channel circumference reveals that tidal-channel systems in the Dutch Wadden Sea have similar branching patterns. Channel systems have the same characteristics as three- to four-times branching networks. The branch lengths of these channels decrease logarithmically. The channel systems can be regarded as 'statistical self-similar fractal' networks, considering the natural variability in branch lengths and channel positions. Branching of channels does not continue below the 500 m scale. The channel-system circumference length is logarithmically related to the tidal prism and drainage area. The similarity of the channel systems, regardless of their size, relative amount of intertidal flats, and tidal amplitude, points to a self-organising nature. All processes depend on the feedback between morphology and hydrodynamics. At first sight, the channel systems can be regarded as an ebb-driven drainage network, governed by erosion. However, flood-dominated net sedimentation occurs in large parts of the drainage basins and modifies the ebb-driven network. The complex interaction of hydrodynamic and morphodynamic processes in tidal basins limits the applicability of process-based models. Behaviour-oriented modelling has a wide applicability and can be improved using the fractal geometry as the dynamical equilibrium morphology. The fractal-network geometry can also be used for stochastic reconstructions of fossil tidal-channel systems, when only limited observations are available. |
| Doniflagellate cyst stratigraphy and depositional history of Miocene and Lower Pliocene formations in Northern Belgium (southern North Sea Basin) | 1999 | Louwye, S.; Coninck, J. de; Verniers, J. | 78(1) | The occurrence of organic-walled dinoflagellate cysts (dinocysts) in the Diest Formation, a largely decalcified succession with a poor fossil content, and in the adjacent strata of Lower Miocene and Lower Pliocene formations, allowed a biostratigraphic evaluation of these deposits and an assessment of the hiatus between the lithostratigraphic units. The Diest Formation was deposited during Tortonian - Messinian times. Dinocyst biozones defined in the North Sea region and the U.S.A. East Coast are recognised within the Diest Formation, although environmental factors seem to have influenced the presence of some key zonal species in the shallow-marine deposits of northern Belgium. The two members of the Diest Formation studied, i.e., the Dessel Sands and the Diest Sands, appear to be strongly diachronous. The depocentre was located in the Campine area during the early Tortonian and shifted to the area north of Anfwerp during late Tortonian to Messinian times. The age assessment provides a correlation of the sequence boundaries of Haq et al. (1987) at the top of the Diest Formation with SB 5.5. |
| Cleavage/fold relationships in the Silurian metapelites, southeastern Angelo-Brabant fold belt (Ronquières, Belgium) | 1999 | Debacker, T.N.; Sintubin, M.; Verniers, J. | 78(1) | The presence of convergent cleavage fans in folded Silurian pelitic deposits along the southern extremity of the Brabant Massif has commonly been considered as an indication for a polyphase deformation history. Recent field work on the classic section at Ronquières shows, however, that all the structural elements can be explained by a single progressive deformation, taking place at gradually higher structural levels. This deformation is considered to have occurred at the time of the Acadian orogeny. The section under study contains a fold train of five gentle to open first-order folds, unconformably overlain by gently S-dipping Givetian rocks. Although the Silurian turbidite deposits are predominantly pelitic, the folds are characterized by convergent cleavage fans. The trend of the cleavage fan axes remains constant in the various folds throughout the section. In contrast, the trend of the fold hinge lines gradually changes along the section from a clockwise relation with the cleavage fan axis in the northern part (anticlockwise cleavage transection) towards an anticlockwise relation in the southern part (clockwise cleavage transection). Individual fault/fault intersections have a constant trend throughout the section, parallel to the cleavage fan axes and the mean fold hinge line. Small kink bands and small transverse joints reflect the same structural trend. The coaxial disposition of the structural elements seems at first sight incompatible with the presence of both clockwise and anticlockwise cleavage-transected folds. This disposition may, however, be explained by an enechelon periclinal nature of the fold train, possibly formed in a slightly constrictional deformation environment |
| Middle to late Devonian basin evolution in the Rügen area, NE Germany | 1999 | McCann, T. | 78(1) | The Middle to lower Upper Devonian succession of the Rügen Depression in NE Germany consists of largely clastic sediments, whereas the Upper Devonian deposits are mixed carbonate and clastic. Petrographic and geochemical data suggest that the sediments were deposited in a cratonic or recycled setting. Deposition was largely confined to a fault- bounded basin, located between two structural highs. During the Devonian, the Rügen area underwent evolution from a continental and marginal marine area during the Eifelian-early Frasnian to a deeper marine environment during the late Frasnian-early Famennian. By the latest Famennian, an open-shelf carbonate facies environment was established. |
| Subareal terminoglacial fans II: a semi-quantitative sedimentological analysis of the middle and distal environments | 1999 | Zieliński, T.; Loon, A.J. van | 78(1) | Twenty-five fans in NE Poland, formed under subaerial terminoglacial (previously called 'ice-contact') conditions, were investigated to model the dominant genetic processes involved. These fans show, as do other types, a proximal, a middle and a distal subenvironment. It is found, however, that the characteristics of these subenvironments as present in subaerial terminoglacial fans differ in several respects from those in fans formed under other climatic conditions. The present study deals with the middle and distal subenvironments. These appear to be much less complex than the proximal subenvironment in this type of fan. The middle terminoglacial fan comprises two sandy facies, characterized by unchannelized transport (mainly sheet floods) and stream flows. The distal terminoglacial fan is characterized by one (sandy/silty) facies, resulting from unchannelized currents and from settling in ephemeral ponds; braided streams play a secondary part in this fan subenvironment. The characteristics of the middle and distal fan subenvironments are described and illustrated, as is the facies from the distal subenvironment. Their vertical and lateral relationships are presented in a facies model. |
| Geochemical, and stable and radiogenic isotope records in Devonian and Early Carboniferous carbonates from Valle de Tena, central Pyrenees (Spain): evidence for their diagenetic environments | 1999 | Subías, I.; Yuste, A.; Fanlo, I.; Fernández-Nieto, C.; González López, J.M. | 78(1) | Mineralogical, textural and geochemical investigations were made to determine the post-depositional evolution of Devonian and Early Carboniferous carbonates from Valle de Tena. The carbonate association is made up of low-Mg calcite, which occurs as micrite, spat cements, neomorphic patches and spar filling veinlets. Non-stoichiometric dolomite and ankerite occur as cements (dolomite also as replacements) in the Middle Devonian, post-dating calcite types. All these phases pre-date tectonic stylolites, indicating compaction after stabilization of the carbonate minerals. Strontium concentrations indicate that Early Devonian and Early Carboniferous micrites initially precipitated as aragonite; Middle and Late Devonian micrites precipitated as high-Mg calcites. Both precursors were diagenetically stabilized to low-Mg calcites through interaction with meteoric waters in phreatic environments. Trace elements in dolomite and ankerite indicate precipitation from Sr-enriched meteoric water. All studied carbonates, except Middle Devonian limestones, precipitated in reducing environments, which favoured- incorporation of Fe and Mn. Late calcite generations precipitated from more saline waters than micrites. Light δ18O values in micrites suggest alteration mainly in meteoric-phreatic environments. The dolomites and ankerites precipitated from more 18O-depleted fluids than the calcites, suggesting a greater contribution from meteoric waters. Variations in δ13C of micrites represent primary secular trends, according to published δ13C variations. The δ13C oscillations within each succession probably relate to sea-level oscillations. Strontium isotopes also point to a meteoric origin of diagenetic fluids. Model calculations suggest that O and Sr isotopes equilibrated between calcites and fluid at relatively low water/rock ratios, whereas C isotopic signatures are inherited from limestones. |
| Palaeokarst and rauhwacke development, mountain uplift and subaerial sliding of tectonic sheets (northern Sierra de los Filabres, Betic Cordilleras, Spain) | 1999 | Orozco, M.; Molina, J.M.; Crespo-Blanc, A.; Alonso-Chaves, F.M. | 78(1) | The rauhwackes near Serón in the northern Sierra de los Filabres (S Spain), previously considered as true tectonic breccias, are reinterpreted on the basis of sedimentological, geomorphological and geometrical evidence as subaerial or nearly subaerial sedimentary deposits. Channel fills, parallel lamination, cross-lamination, graded bedding, sedimentary clastic dykes and other sedimentary structures and features occur in the rauhwacke body. These sedimentary rocks correspond to continental deposits of alluvial and karstic origin deposited over a karstified erosional surface of Nevado-Filabride marbles. Although no fossils have been found in the rauhwackes, a Tortonian age for these rocks is suggested on the basis of structural arguments and lithostratigraphic data from the nearby Almanzora basin. The rauhwackes were buried by slabs of Alpujarride rocks that gravitationally slid over them during the uplifting of the Sierra de los Filabres. |
| Microstructures associated with static and dynamic recrystallization of Carrara marble (Alpi Apuane, NW Tuscany, Italy) | 1999 | Molli, G.; Heilbronner, R. | 78(1) | The present contribution summarizes the first results of a study focusing on microstructures from Alpi Apuane marbles. Its aim is both an analysis of the evolution of the metamorphic complex recorded in marbles and the supply of basic material for process-oriented studies on calcite microstructures due to natural deformation. Quantitative analysis of the variations of statically recrystallized microstructures suggest a relationship with the peak metamorphic temperatures. Previously unrecognized post-thermal peak shear zones, showing overprint microstructures typical of grain-boundary migration and dynamic recrystallization, are described; they document the natural deformation of Carrara marble. |
| A tribute to Bert Boekschoten - Introduction | 1999 | Vergoossen, J.M.J.; Lambers, P.H. | 78(2) | |
| Bert Boekschoten: a biographical sketch | 1999 | Lambers, P.H. | 78(2) | |
| Evolution: disjunct degeneration of immunological determinants | 1999 | Marin, F.; Gillibert, M.; Westbroek, P.; Muyzer, G.; Dauphin, Y. | 78(2) | The dissolution of calcified invertebrate skeletons releases an elaborate mixture of proteins, glycoproteins and polysaccharides. These 'skeletal matrix' macromolecules are thought to play a major role in calcification and were widely used for phylogenetical studies. We tested the reactivity of water-soluble macromolecules from a wide range of invertebrate skeletons with two antisera raised against the shell matrix of the bivalve, Pinna nobilis. Projections of our results on the phylogenetical tree of Starobogatov (1992) show for the first time that, during evolution, antigenic determinants may degenerate in some stocks while they remain intact in others. The phylogenetic implications of these patterns of disjunct degeneration are discussed. |
| Corals as speaking stones | 1999 | Borel Best, M. | 78(2) | Corals are animals living in shallow seas (where they may form coral reefs) or in the deep sea. Because they fossilize well, these 'stones' inform us in detail about the geological past; not only about the history of the Earth as a whole (rotation, tectonics, sea-level changes), but also about past local environmental conditions in the sea. Joint research of marine biology and marine geology can therefore solve many questions about our changing world, and can be used to discover what factors cause deterioration of living coral reefs. |
| Making fire in the Stone Age: flint and pyrite | 1999 | Stapert, D.; Johansen, L. | 78(2) | Flint implements with rounded ends, excavated at several Late Palaeolithic sites in Denmark and the Netherlands, are described and interpreted as strike-a-lights used in combination with pyrites. Experiments were carried out; the use-wear traces on the experimental pieces are similar to those occurring on the prehistoric specimens. It is concluded that the pyrite technique for fire production most probably predated wood-on-wood techniques, both in Europe and Greenland. |
| Flying high: on the airborne dispersal of aquatic organisms as illustrated by the distribution histories of the gastropod genera Tryonia and Planorbarius | 1999 | Wesselingh, F.P.; Cadée, G.C.; Renema, W. | 78(2) | The actual and fossil distribution patterns of the aquatic gastropod genera Tryonia and Planorbarius indicate that avian dispersal was an important dispersal mechanism in the geological past. Combining the distribution histories of these genera with ecological data on modern relatives provides insights into the process of dispersal of aquatic taxa in general. Avian dispersal of aquatic taxa is facilitated by a variety of factors, including mass occurrence in resting/foraging places of migrating birds, ways to attach to the birds and to overcome desiccation during flight, as well as easy reproduction from a single specimen when introduced into a new habitat. The uncertain taxonomical status of aquatic organisms, as well as biased preservation and sampling, provide serious drawbacks for understanding the importance of aerial dispersal. |
| Anomiid (bivalve) bioerosion on Pleistocene pectinid (bivalve) shells, Rhodes, Greece | 1999 | Bromley, R.G. | 78(2) | A trace fossil, Centrichnus eccentricus, was found beneath a saddle oyster (Anomia ephippium) that was preserved undisturbed on its substratum (a shell of Pecten jacobaeus), at the site of attachment of the calcified byssus. |
| Euthecosomatous gastropods (Mollusca: Heterobranchia) from Buton (SE Sulawesi, Indonesia), with notes on species from Viti Levu, Fiji; systematics, biostratigraphy | 1999 | Janssen, A.W. | 78(2) | Pteropoda (Mollusca, Gastropoda, Euthecosomata) described by Beets (1943, 1950,1953) from the alleged Late Miocene/Early Pliocene asphaltic deposits of Buton (SE Sulawesi, Indonesia) are revised. The following species are distinguished: Styliola subula (Quoy & Gaimard, 1827), Cavolinia bituminara (Beets, 1953), Cavolinia mexicana(Collins, 1934), Cavolinia vendryesiana (Guppy, 1873)and Diacria mbaensis Ladd, 1934. A comparison with the Fiji pteropod associations suggests a Miocene (Tortonian to Messinian) age for the Indonesian faunules. Pteropod species described by Ladd (1934) from Viti Levu (Fiji Islands), are revised in an appendix. Five species are distinguished, viz. Creseis acicula (Rang, 1828) (?), Cavolinia gypsorum (Bellardi, 1873), C. mexicana, C. rewaensis (Ladd, 1934) and Diacria mbaensis Ladd, 1934. The presence of Cavolina gypsorum dates this association as Miocene (Tortonian-Messinian). |
| Numerical distribution of Santonian to Danian corals (Scleractinia, Octocorallia) of Southern Limburg, the Netherlands | 1999 | Leloux, J. | 78(2) | The stratigraphical occurrence of 35 known species from the Upper Cretaceous and Danian of Southern Limburg is presented based on existing collections and newly collected material. Corals are relatively rare, except in the Meerssen Member of the Maastricht Formation. Two faunas were recognised in the Meerssen Member: a fauna dominated by Cyclolites cancellata at the base of this member - which coincides with the sequence boundary of the third-order sequence cycle TA1.1 of Haq et al. (1988) - and a fauna dominated by mushroom-shaped and encrusting colonies at the top of the transgressive systems tract of the same sequence cycle. |
| Ophiuroid diversity in the type area of the Maastrichtian Stage | 1999 | Jagt, J.W.M. | 78(2) | With the exception of holothurians, all Late Cretaceous (Campanian-Maastrichtian) and Early Palaeogene (Danian) echinoderms from the extended type area of the Maastrichtian Stage are currently being revised. In addition to a handful of taxa described previously in the literature, many new genera and species of brittle star and basket star (Ophiuroidea) have been recognised in recent years. In fact, the study area is one of the very few regions in the world that have yielded diverse ophiuroid faunas of latest Cretaceous age. Of note also is the fact that many of the new taxa are based on more or less complete specimens, i.e., discs preserving (portions of) arms, making generic assignment much more reliable. The various ophiuroid groups recognised are briefly discussed and selected specimens are illustrated in order to document the diversity. Formal descriptions will be published elsewhere. Ophiuroid taxa described by Berry (1938), as based on poorly preserved material from the Late Maastrichtian of the area, are briefly commented upon. |
| The oldest tylosaurine mosasaur (Reptitia; Lacertilia) from the Late Cretaceous of Belgium: Hermann von Meyer (1860) revisited | 1999 | Mulder, E.W.A.; Mai, H. | 78(2) | A mosasaurid parietal from the Late Cretaceous of Belgium, originally described by Von Meyer (1860), turns out to be assignable to the tylosaurine Hainosaurus cf . bernardi Dollo 1885. A small sediment sample, extracted from the bone, was analysed for coccoliths and revealed its early Late Campanian age. This is thus the earliest record of a tylosaurine mosasaur from Belgium. |
| The actinopterygian fish fauna of the Late Kimmeridgian and Early Tithonian ‘Plattenkalke' near Solnhofen (Bavaria, Germany): state of the art | 1999 | Lambers, P.H. | 78(2) | An overview is presented of the actinopterygian fishes from the Late Jurassic (Late Kimmeridgian and Early Tithonian) 'Plattenkalke' near Solnhofen (Solnhofen lithographic limestone), Bavaria, Germany. The fish fauna is very diverse, with the palaeonisciform Coccolepis, halecostomes such as Lepidotes, Heterostrophus, three genera of macrosemiids and six genera of pycnodontiforms, halecomorphs including two genera of caturids, two genera of amiids, Ophiopsis, 'Furo', Ionoscopus, Brachyichthys, Callopterus, Liodesmus, ?Lophiurus, five genera of pachycormids, three genera of pholidophorids, Pleuropholis, two genera of aspidorhynchids and eleven genera of basal teleosts. Although several groups have been subject of revision, most of the fauna remains poorly known. Study of this rich fauna will provide a lot of information on the phylogeny and interrelationships of halecostome fishes. |
| Late Silurian fish microfossils from an East Baltic-derived erratic from Oosterhaule, with a description of new acanthodian taxa | 1999 | Vergoossen, J.M.J. | 78(2) | Fish microfossils were extracted from an erratic. The taxa from the rich microvertebrate fauna of late Pridolian (latest Silurian) age (P punctatus Zone) are listed. A full description is given of two new Gomphonchus taxa, G. mediocostatus and G. boekschoteni. On the basis of old and new material, 'Gomphonchus hoppei' is redescribed, interpreted as a porosiform poracanthodid, and assigned to Gomphonchoporus gen. nov. This interpretation ecessitates redefinition of the Poracanthodidae VERGOOSSEN 1997 to include scales without a pore-canal system. The type genus, Poracanthodes, is redefined to include only punctatiform poracanthodids sensu Vergoossen 1997. Discovery of previously undescribed scale forms of the type species, P. punctatus BROTZEN 1934, results in an extended diagnosis for this biozonal index fossil. A new poracanthodid genus, Radioporacanthodes, is erected for the porosiform poracanthodids sensu Vergoossen 1997, with type species R. porosus (BROTZEN) 1934 s.s. Brief palaeontological and distributional comments on other microvertebrate taxa from the list are included, as well as a section on the biostratigraphical and correlational implications of the present and similar faunas from erratics for the East Baltic standard succession. |
| Proceedings of the Third European Workshop on Vertebrate Palaeontology (Maastricht, May 6-9, 1998): Preface | 1999 | Jagt, J.W.M.; Lambers, P.H.; Mulder, E.W.A.; Schulp, A.S. | 78(3-4) | |
| Colin Patterson (1933-1998): a major vertebrate palaeontologist of this century | 1999 | Bonde, N. | 78(3-4) | |
| A new Cenomanian ichthyofauna from southeastern Morocco and its relationships with other early Late Cretaceous Moroccan faunas | 1999 | Cavin, L.; Dutheil, D.B. | 78(3-4) | A new ichthyofauna from southeastern Morocco, comprising five forms, is briefly discussed. The faunal composition differs from the Early Cenomanian Kem Kem and Early Turonian Goulmima assemblages, but is close to that from Jebel Tselfat. We propose a Late Cenomanian age for the new fauna and that from Jebel Tselfat. The evolution of these fish assemblages shows the Moroccan fish faunas to have been related to those from South America until at least the Early Turonian. Central Tethyan influence on faunas seems to have been restricted to a short period of time during the beginning of the Late Cenomanian transgressive phase. |
| Late Silurian fish microfossils from Helvetesgraven, Skåne (southern Sweden) (I). | 1999 | Vergoossen, J.M.J. | 78(3-4) | The fauna from a Late Silurian residue sample from Övedskloster (Skåne) is listed. It comprises scales of 'Agnatha' (rare osteostracan scales, and the thelodonts Thelodus parvidens,'T. traquairi', T. sculptilis, T. admirabilis, and 'Loganellia cuneata') and of Gnathostomata (the acanthodians Nostolepis striata, Gomphonchus sandelensis, Poracanthodes? lehmani sp. nov., and Poracanthodes cf. punctatus, tesserae of the head and other specialized elements of the squamation; and the osteichthyan Andreolepis hedei). This fauna is considered to be as old as, or slightly younger than that from the complex of sedimentary rocks along the Anglo-Central Urals margin of the Laurussian continent affected by the Ludfordian A. hedei Event. This event marks the transition between the hedei and sculptilis Zones of the Microvertebrate Standard Zonation and can be correlated with the snajdri Conodont Interval Zone. The evidence favours a simultaneous palaeogeographical appearance of the punctatiform and porosiform poracanthodid acanthodians within the Baltica region of Laurussia. |
| Transatlantic latest Cretaceous mosasaurs (Reptilia, Lacertilia) from the Maastrichtian type area and New Jersey | 1999 | Mulder, E.W.A. | 78(3-4) | Cranial and postcranial elements of the mosasaurid reptiles Mosasaurus hoffinanni Mantell 1829 and Plioplatecarpus marshi Dollo 1882 from the Maastrichtian type area, and of Mosasaurus maximus Cope 1869 and Plioplatecarpus depressus (Cope 1869) from New Jersey are compared. Views held by previous authors are discussed. It is concluded that these European and North American taxa are conspecific. |
| New latest Cretaceous microvertebrate fossil assemblages from the Haţeg Basin (Romania) | 1999 | Grigorescu, D.; Venczel, M.; Csiki, Z.; Limberea, R. | 78(3-4) | Late Cretaceous terrestrial ecosystems in southern Europe are relatively poorly known, although much progress has been made during the past decade, principally with regard to the microvertebrate components of these ecosystems. The Maastrichtian terrestrial deposits of the Haçeg Basin, at the easternmost end of the South European archipelago and well known for reptilian fossils (e.g., turtles, crocodilians, pterosaurs and dinosaurs), have been thoroughly screened during the past five years. Important microvertebrate assemblages, both quantitatively and qualitatively speaking, were found at Pui (Sînpetru Formation), Tuştea and, particularly, Vălioara (Densuş-Ciula Formation). Several new taxa are noted here for the first time for the Haţeg Basin, including gars, discoglossids, albanerpetontids, scincomorphan and anguimorphan lizards; dromaeosaurids and multituberculates are confirmed. Most of the microvertebrate remains are poorly preserved and precise systematic assignment has proved difficult. The Haţeg fauna appears to be primitive and endemic, with a Neopangean core composition, and suggests a composite palaeobiogeographic origin for the Late Cretaceous European ecosystems, confirming conclusions reached in studies of the larger vertebrates. |
| A possible azhdarchid pterosaur from the Crato Formation (Early Cretaceous, Aptian) of northeast Brazil | 1999 | Martill, D.M.; Frey, E. | 78(3-4) | The partially articulated, distal portion of a left wing finger of a pterosaur from the Crato Formation of northeast Brazil has a T:shaped cross-section to the second and third phalanges. This cross-sectional shape is one of several characters diagnostic of the pterodactyloid pterosaur family Azhdarchidae (Unwin &. Lu 1997). Until now, this family of pterosaurs was known exclusively from the Late Cretaceous. The specimen described here may be the first recorded azhdarchid from the southern hemisphere and the earliest recorded member of the family. |
| A long-necked pterosaur (Pterodactyloidea, Azhdarchidae) from the Upper Cretaceous of Valencia, Spain | 1999 | Company, J.; Ruiz-Omeñaca, J.I.; Pereda Suberbiola, X. | 78(3-4) | Fragmentary remains, including cervical vertebrae and limb bones, of a large pterosaur from the Upper Cretaceous of Tous, province of Valencia (Spain), are described. The material was recovered from lacustrine beds in the upper part of the Calizas y Margas de Sierra Perenchiza Formation, which is probably Maastrichtian in age. Six fragments of vertebrae allow a reconstruction of the anatomy of the mid-series cervicals of the animal. The general morphology of the cervical vertebrae is closely similar to that of the long-necked Azhdarchidae. Compared to other azhdarchids, the Valencia pterosaur shows minor differences from the genera Azhdarcho and Quetzalcoatlus, and is here provisionally referred to as Azhdarchidae indet. A wingspan of about 5.5 m is calculated by comparison with other known azhdarchids. This is the second azhdarchid pterosaur described from the Iberian peninsula. It confirms the wide distribution of this group of large pterosaurs at the end of the Cretaceous. |
| The smallest of the largest: a new look at possible dwarfing in sauropod dinosaurs | 1999 | Jianu, C.M.; Weishampel, D.B. | 78(3-4) | Franz Baron Nopcsa recognised that the Late Cretaceous titanosaurid sauropod from Transylvania, Magyarosaurus dacus, was much smaller than the better known sauropods from the Upper Jurassic of the United States and even from Late Cretaceous deposits elsewhere in the world. In keeping with his biogeographic interpretations, Nopcsa viewed this difference as a consequence of body-size effects via island habitation. We present a preliminary reevaluation of Nopcsa's claims and their heterochronic consequences using two approaches, viz. (1) regression analysis of humeral data as a means of establishing patterns in body size among titanosaurids, and (2) optimization of humeral data onto titanosaurid cladograms to evaluate evolutionary trends within the clade. Our regression analysis is based on twenty species distributed among fourteen genera of neosauropods and uses length and midshaft mediolateral width of the humerus of presumed fully adult forms, and of growth samples that consist of postnatal to adult individuals. Linear regression analysis suggests that, among adult neosauropods, M. dacus appears to be represented by the smallest individuals; that M. dacus humeri appear to be more similar to those of subadults than to adults of other taxa; and that this 'juvenile' morphology may constitute dwarfing in M. dacus by paedomorphosis. In order for these regressions to reflect their evolutionary context more fully, we also present optimisation analyses of humeral form within Titanosauroidea. Although many aspects of the phylogeny of this clade are relatively poorly resolved, preliminary results of our analyses are consistent with the conclusion that M. dacus was a heterochronic dwarf. |
| A primitive euhadrosaurian dinosaur from the uppermost Cretaceous of the Ager syncline (southern Pyrenees, Catalonia) | 1999 | Casanovas, M.L.; Pereda Superbiola, X.; Santafé, J.V.; Weishampel, D.B. | 78(3-4) | New hadrosaurid material is recorded from Fontllonga (Ager syncline, province of Lleida), in the Catalonian Pyrenees, comprising a dentary with part of the dental battery recovered from Late Maastrichtian strata (Tremp Formation), close to the presumed Cretaceous/Tertiary boundary. This hadrosaurid is more derived than is Telmatosaurus transsylvanicus from the Haţeg Basin (Romania) , but lacks a number of features that diagnose the clade Hadrosaurinae plus Lambeosaurinae. It is attributed to the Euhadrosauria on the basis of the following synapomorphies: dentary teeth not recurved distally, narrow dentary crowns, and denticles not supported by subsidiary ridges. The phylogenetic relationships of the best-known iguanodontids and hadrosauroids are evaluated using mandibular and dentary tooth characters. On the basis of a cladistic analysis, the family of Hadrosauridae is diagnosed by more than 29 dentary tooth positions, parallel-sided vertical furrows formed by dentary alveoli, and absence of caudal secondary ridges. Within Hadrosauridae, successive sister-groups of Hadrosaurinae plus Lambeosaurinae are the Fontllonga taxon and Telmatosaurus. The clade Hadrosaurinae plus Lambeosaurinae is characterised mainly by a coronoid process inclined rostrally and by the absence of secondary ridges on dentary crowns. The Fontllonga find suggests the diversity of European hadrosaurids at the end of the Cretaceous to have been greater than previously thought. Moreover, the primitive character of European hadrosaurids as compared to western North American and Asian relatives may be explained in terms of geographical isolation during the Late Cretaceous. |
| Dinosaur remains from the type Maastrichtian: an update | 1999 | Weishampel, D.B.; Mulder, E.W.A.; Dortangs, R.W.; Jagt, J.W.M.; Jianu, C.M.; Kuypers, M.M.M.; Peeters, H.H.G.; Schulp, A.S. | 78(3-4) | Isolated cranial and post-cranial remains of hadrosaurid dinosaurs have been collected from various outcrops in the type area of the Maastrichtian stage during the last few years. In the present contribution, dentary and maxillary teeth are recorded from the area for the first time. Post-cranial elements comprise a newly collected, fragmentary, large right metatarsal III and a broken ?right humerus, recently recognised in the collections of Teylers Museum (Haarlem). Unfortunately, none of these remains can be identified to species level. The available material suggests, however, that more than one taxon of non-lambeosaurine hadrosaurid and a possible euhadrosaurian are represented. Most of the new finds are stratigraphically well documented, which means that they may be linked to the recently published sequence-stratigraphic interpretation of the type Maastrichtian. Dinosaur remains recorded previously from the Maastrichtian type area are tabulated. |
| Theropod dinosaur diversity and palaeobiology in the Wealden Group (Early Cretaceous) of England: evidence from a previously undescribed tibia | 1999 | Naish, D. | 78(3-4) | A robust, partial right tibia of a theropod dinosaur (Natural History Museum London collections, BMNH R9385) is described for the first time. The specimen was collected at Hastings, Sussex (England) in the last century, and is among the oldest known of English Wealden Group theropods. It represents a tetanuran theropod that may have been about 3 m in total length, and is distinct from all currently known Wealden theropods for which tibiae have been described. The present specimen is significant palaeobiologically in exhibiting a series of theropod tooth marks on its caudal surface, indicating predation or scavenging by another theropod. |
| Lithornithid birds (Aves, Palaeognathae) from the Lower Palaeogene of Denmark | 1999 | Vedding Kristoffersen, A. | 78(3-4) | An incomplete sternum and imprints of a right part pelvis and an associated left femur from the uppermost Palaeocene/lowermost Eocene (Fur Formation) of Denmark are assigned to the extinct palaeognath bird order Lithornithiformes Houde 1988, and to the single described family thereof, the Lithornithidae. Morphological features indicate that both individuals were adult birds, smaller than Lithornis cf . nasi, which is represented by an incomplete humerus from the largely contemporaneous, marine Olst Formation in Denmark, and corresponding in size to the smallest known lithornithid, Lithomis hookeri. Lithornithiformes, common in the Palaeocene and Eocene of North America and Europe, were terrestrial birds capable of flight whose remains are often found in aquatic sediments. Both the depositional environment in which the Danish lithornithids were found, and the associated faunal components suggest that the birds were not transported by rivers. Some of the lithornithid species inhabiting NW Europe may have lived and foraged along the shores of the North Sea Basin. |
| New remains of Pleistocene Ovibos moschatus from Germany and its geographic and stratigraphic occurrence in Europe | 1999 | Raufuss, I.; Koeningswald, W. von | 78(3-4) | All remains of Pleistocene muskoxen from central and western Europe are attributable to a single species, Ovibos moschatus. Its occurrence was restricted mainly to the area north of the Pyrenees and Alps, covering lowlands and mountain areas up to 1600 m. In the Middle Pleistocene, Ovibos occurred in a cold phase, well before the Elsterian, and again during the Saalian and Weichselian. In the Late Pleistocene, Ovibos co-occurred with other faunal elements indicative of severe continental climatic conditions during the early and late Weichselian. During the middle Weichselian, the genus seems to have retreated. A list of European localities that have yielded Ovibos moschatus, inclusive of geographical references, is provided. |
| A new phase in the journal's history | 2000 | Smit, J.; Wong, T.E.; Kasse, C.; Loon, A.J. van | 79(1) | |
| The Holocene evolution of the barrier and the Back-barrier basins of Belgium and the Netherlands as a function of late Weichselian morphology, relative sea-level rise and sediment supply | 2000 | Beets, D.J.; Spek, A.J.F. van der | 79(1) | Flooding of the southern part of the North Sea occurred between 9000 and 8000 BP when the rate of relative sea-level rise was on the order of 0.7 cm per year for the Dover Strait Region and 1.6 cm per year for the area north of the Frisian Islands, forcing the shoreline to recede rapidly. When relative sea-level rise decelerated after 7000 BP for the Belgian coast and 6000 BP for the central Netherlands coast, sediment supply by the tidal currents balanced the creation of accommodation space in the estuaries and other back-barrier basins. Consequently, the barrier started to stabilize, and the tidal basins and their inlets silted up. Between 5500 and 4500 BP the Belgian coastal plain changed into a freshwater marsh with peat accumulation, and the same happened 500-1000 years later in the western provinces of the Netherlands. The E-W running barrier/back-barrier system of the Frisian Islands in the northern Netherlands stayed open until today, however, because of lower sediment supply. The period between 4000 and 2000 BP was relatively quiet due to the strong deceleration of the rate of sea-level rise; peat cushions developed behind the barriers, which were straightened by erosion of the headlands. Major and often catastrophic flooding occurred in the Middle Ages, when the estuaries in the southwestern part of the Netherlands formed. About 226 (± 15%) x 109 m3 sediment, mostly sand, is stored in the barriers and back-barrier basins of the Netherlands, 70% of which was deposited prior to 5000 BP. About 10% of the stored sediment is estimated to be of alluvial origin. Most of the sediment is derived by the erosion of the Pleistocene basement during recession of the barriers, but tide-induced cross-shore transport from the North Sea forms an additional source for the barriers and back-barriers of the west-facing coast of the Netherlands. |
| Late Permian (Zechstein) carbonate-facies maps, the Netherlands | 2000 | Geluk, M.C. | 79(1) | The Late Permian Zechstein carbonates in the Southern Permian Basin were deposited under marine conditions. The carbonates form part of a largely progradational infill, with a gradual northward facies shift. The paleogeography of the Zechstein carbonate deposits has been reviewed recently on the base of well data, cores and publications. This has resulted in three updated maps of the carbonate units. These maps reflect the increase in knowledge of the palaeogeography of the Zechstein as a result of several decades of subsurface exploration. It is found that deposition of the carbonates was controlled by various factors, i.e., rifting during deposition of the basal Zechstein, sea-level fluctuations and basin subsidence. This resulted in an overall E-W orientated facies distribution in the Zechstein carbonates, and in the gradual northward shift of the various facies belts in time. Reefs in the Z1 Carbonate Member and off-platform highs and turbidites in the Z2 Carbonate Member have been identified as potential future exploration targets. |
| Modelling the hydrocarbon generation and migration in the West Netherlands Basin, the Netherlands | 2000 | Balen, R.T. van; Bergen, F. van; Leeuw, C. de; Pagnier, H.; Simmelink, H.; Wees, J.D. van; Verweij, J.M. | 79(1) | The hydrocarbon systems of the Mesozoic, inverted West Netherlands Basin have been analyzed using 2-D forward modelling. Three source rocks are considered in the modelling: Lower Jurassic oil-prone shales, Westphalian gas-prone coal deposits, and Lower Namurian oil-prone shales. The Lower Namurian hydrocarbon system of the basin is discussed for the first time. According to the modelling results of the Early Jurassic oil system, the oil accumulations were filled just after the main inversion event. Their predicted locations are in agreement with exploration results. Modelling results of the Westphalian gas system, however, show smaller and larger sized accumulations at unexplored locations. The gas reservoirs were filled during the Late Jurassic-Early Cretaceous rifting phase. Results of modelling of the Lower Namurian oil system indicate that gas formed by secondary cracking of the oils can have mixed with the Westphalian coal-derived gas. Such a mixing is inferred from geochemical analyses. The existence of a Lower Namurian hydrocarbon system in the West Netherlands Basin implies that hydrocarbons are possibly trapped in the Westphalian and Namurian successions. These potential traps in the basin have not yet been explored. |
| Fracture networks in Rotliegend gas reservoirs of the Dutch offshore: implications for reservoir behaviour | 2000 | Gauthier, B.D.M.; Franssen, R.C.W.M.; Drei, S. | 79(1) | Fracture systems of Rotliegend gas fields in and at the margins of the northern Broad Fourteens Basin in the Dutch offshore are described in terms of orientation, frequency, origin and type, and in relation to larger-scale structures. First, fracture data collected from core and image logs have been corrected to account for the bias related to the l-D sampling. Second, these results were integrated with data on fracture cements and diagenesis in order to assess the timing of the fracture network development. On the basis of their regional extent three phases of fracturing and four orientation trends can be distinguished in the basin: (l) at Triassic times and related to early diagenesis and burial, NW-SE to NNW-SSE and NE-SW to ESE-WNW particulate shear fractures developed; (2) during the Mid-Kimmerian and related to the main burial stage, shear-related and dilational-shear-fault-related fracturing occurred parallel with larger-scale faults; (3) during the Cretaceous and related to uplift, NW-SE and NE-SW joints propagated; a regional joint system developed outside the Jurassic rift basin, preferentially oriented E-W to ESE-WNW; these joints have not been dated accurately. The fault-related shear fractures tend to compartmentalise the reservoirs, whereas the regional joints tend to enhance reservoir flow properties. These fracture systems are thought to play a negative or positive role, respectively, but only in fields with poor reservoir quality. Consequently, in such cases small-scale fractures should be taken into account in held development planning. |
| Composition and genesis of rattlestones from Dutch soils as shown by Mössbauer spectroscopy, INAA and XRD | 2000 | Loef, J.J. van | 79(1) | The chemical and mineralogical composition of rattlestones found near the main Dutch rivers has been studied by Mössbauer spectroscopy, INAA and XRD. Rattlestones are concretions of iron, formed in an environment of lateral iron accumulation, under the influence of periodical oxidation, around a fine core of ferruginous sediments, mainly clay and sand. The core has shrunk and detached itself from the mantle around it. 57Fe Mössbauer spectroscopy was applied to identify the iron oxides, among which goethite is predominant. The goethite crystallinity was investigated by measuring its magnetic properties and its crystallinity which is poorest at the outer side of the stone. The latter is confirmed by the broadening of the different X-ray reflections. In addition, illite and vermiculite were identified by XRD; these clay minerals were found mainly in the core. The elemental composition was determined by INAA. The iron content in the mantle is about 50% by weight and gradually decreases outwards, while the core contains 2-15% Fe by weight. Differences between rattlestones from the Middle Pleistocene East of the Meuse river and those from the Late Pleistocene North of it are the absence of lepidocrocite and a richer mineralogy in the former. It is concluded that the rattlestones are formed around a fine clayey core. Groundwater supplied the iron and other (trace) elements for the genesis. It is unlikely that rattlestones are the result of oxidation of siderite. |
| A seismological motivated survey of blasting activity in the northern Rhine area | 2000 | Hinzen, K.G.; Pietsch, S. | 79(1) | Discrimination between quarry blasts and earthquakes has gained importance due to signature of the Comprehensive Test Ban Treaty. In this context, large chemical explosions are significant. In the routine analysis of data from local seismograph networks, discrimination between smaller blasts and micro-earthquakes is not always clear. Many quarries are in operation and blasts far outnumber natural earthquakes in the highly industrialized northern Rhine area. We compiled a list of active quarries in the Northern Rhine Area and mapped their locations. We then created a database from a questionnaire sent out to all quarries on the list. From the 33% of questionnaires that were returned, we discerned some representative values for the main blasting parameters and explosive consumption. In the study area of 72,000 km2, approx. 21,000 blasts are fired per year (80 per working day). Most of the blasts (72%) have total explosive charges between 400 and 4500 kg. Shots with charges above 10 tons are rare (20-30 per year). Some 80% of the blasts are ripple-fired with a nominal firing time interval of 20 ms. Based on empirical amplitude vs. distance curves from vibration control measurements, a relation between maximum charge weight per delay time, L (kg), and a 'quarry blast' magnitude, MQB, is derived: MQB = 0.6•log10(L) + 0.131. Using this relation and extrapolating the database from the questionnaire shows that for magnitudes between 1 and 2, blasts occur 200-250 times more frequently than micro-earthquakes in the Northern Rhine area. |
| Wedge equilibrium in fold-and-thrust belts: prediction of out-of-sequence thrusting based on sandbox experiments and natural examples | 2000 | Nieuwland, D.A.; Leutscherm, J.H.; Gast, J. | 79(1) | Thrust tectonics are dealt with on the basis of primarily experiments focusing on the dynamics of a developing thrust belt and on understanding and predicting normal-sequence and out-of-sequence thrusting. Field examples are presented in addition to the examples of sandbox-model experiments. The results have improved the insight into thrust-belt-forming mechanisms; the validity of the conclusions is supported by natural examples. The experimental program was aimed at examining the effect of changes in a selection of key parameters in thrust tectonics on the geometry and the successive phases in the development of thrust sheets. Sandbox experiments were used to analyse the effects of basal friction, detachment lithology, basement relief and syntectonic sedimentation. Multilayer experiments were performed to simulate the effects of ductile detachment lithologies. It was found that a thrust belt's cross-sectional geometry is formed in a dynamic process during which the wedge may develop from subcritical through critical to supercritical and back to critical again. The process is illustrated with sandbox experiments, analyzed by time-lapse computed tomography scans and in-situ stress measurements. On the basis of the sandboxmodel results and the natural examples, we conclude that a critical examination of the boundary conditions of a fold-and thrust belt and of changes in these conditions during the deformation process enables predictions about the geometry and kinematics of the thrust belt. |
| Subaerial terminoglacial fans III: overview of sedimentary characteristics and depositional model | 2000 | Zieliński, T.; Loon, A.J. van | 79(1) | A general model is presented for the small type of fans (not to be confused with sandurs) that develop subaerially in the zone immediately before an ice front. These fans have in common with other fans that a proximal, a middle and a distal subenvironment - with distinctly different sedimentary facies - can be distinguished. The characteristics of these fans differ in several respects, however, from those formed under other conditions, particularly by the high proportion of mass-flow deposits in the proximal part, by the relative scarcity of fine particles in the middle fan, and by the relatively uniform character of the sediments in the distal fan. The special character of this type of fan is ascribed to the interaction of a continuously changing distance between the ice front and the fan (as a result of alternating phases of ice advance and ice retreat), its position that may be surrounded by ice for a large part, and the irregular supply of debris-laden meltwater that comes sometimes even in the form of more or less catastrophic floods. Due to the fact that terminoglacial fans have a good preservation potential only during phases of ice retreat, these fas tend to show a slight fining-upward tendency. The slope of terminoglacial fans tends to be more gentle (rarely over 2-5°) than that of fans formed under different conditions. |
| Provenance of coarse ice-rafted detritus near the SE Greenland margin | 2000 | Linthout, K.; Troelstra, S.R.; Kuijpers, A. | 79(1) | The provenance of coarse-grained ice-rafted detritus has been studied, based on material collected from the SE Greenland margin. The sediment was sampled by a 1.5 m3 video-grab from 1256 m water depth. The fraction > 1 cm was macroscopically investigated and a thin-section analysis was made. The results clearly show that East Greenland north of the Denmark Strait is the source region of the material sampled. The main provenance is from areas adjoining Kangerdlugssuaq Fjord, Blosseville Kyst, Scoresby Sund, Kong Oskar Fjord, and Kejser Franz Joseph Fjord. It can thus be demonstrated that significant ice-stream activity and iceberg calving occurred there. Present-day iceberg production is mainly concentrated to the Scoresby Sund, but the other areas apparently represent locations of larger ice-stream activity during periods prior to the Holocene. More generally, it can be concluded that southerly surface-water flow similar to the present East Greenland Current must also have occurred prior to the Holocene. Although either North America (Canada) or Scandinavia - or both - are generally referred to as important regions for the provenance of ice-rafted detritus, we conclude that (East) Greenland may have been an important source for (late) glacial North Atlantic ice-rafted detritus production as well |
| Geochemical mapping in the Kingdom of the Netherlands: Introduction | 2000 | Gaans, P.F.M. van; Vriend, S.P. | 79(4) | |
| Spatial prediction of the variability of Eary Pleistocene subsurface sediments in the Netherlands - Part 1: Heavy minerals | 2000 | Huisman, D.J.; Weijers, J.P.; Dijkshoorn, L.; Veldkamp, A. | 79(4) | We investigated the spatial variability of the heavy-mineral composition in the Early Pleistocene fluviatile Kedichem Formation in the Netherlands in order to meet the demand for more information about subsurface sediment composition. We first determined the spatial extension and thickness of the sediment body, then used Fuzzy clustering techniques on a database containing approx. 2000 heavy-mineral counts from the Kedichem Formation to map the spatial extension of the various sediment provenances within the formation. Three clusters could be discerned, one representing a combined Meuse-Scheldt source, the other two representing a mixed Rhine-Baltic source. We made slice maps at several depths through the formation, and plotted the cluster memberships. The maps show an overall dominance of the Meuse-Scheldt source in the south of the Netherlands, whereas the Rhine-Baltic source occurs mainly in the central Netherlands. The methods employed show that it is possible to map and study the 3-D variation in heavy-mineral composition and hence sediment provenance in the Dutch subsurface with the use of simple statistical and visualization techniques. |
| Spatial prediction of the variability of Eary Pleistocene subsurface sediments in the Netherlands - Part 2: Geochemistry | 2000 | Huisman, D.J.; Weijers, J.P.; Dijkshoorn, L.; Veldkamp, A. | 79(4) | We started a geochemical mapping campaign in the Early Pleistocene fluviatile Kedichem Formation in the Netherlands in order to meet the demand for more information about subsurface sediment compositions. Geochemical data were collected during a sampling campaign, and about 600 samples from the Kedichem Formation were analyzed. By linking the geochemical data with lithological classifications from the TNO-NITG borehole database, we established a geochemical prediction model. Elements were divided into classes according to their geochemical behaviour in relation to lithological parameters. For each of the classes, we combined lithological groups in to groups with relevant geochemical differences. By calculating for each element the average composition in each of these groups, we were able to predict the geochemical composition of subsurface sediments by 'translating' the spatial lithological data from the TNO-NITG borehole database into geochemical data. We visualized this model by calculating and interpolating the average composition of horizontal slices of the Kedichem Formation. The model performance is fairly good, although it has a tendency to underestimate extreme values. |
| Natural compositional variation of the river Meuse (Maas) suspended load: a 13 ka bulk geochemical record from the upper Kreftenheye and Betuwe Formations in Northern Limburg | 2000 | Tebbens, L.A.; Veldkamp, A.; Kroonenberg, S.B. | 79(4) | Unambiguously pristine and largely unpolluted sediments from the Late Weichselian and Holocene infìllings of the Meuse residual channels in northern Limburg (the Netherlands) have been sampled to determine the natural compositional variation of the river's suspended load. Bulk geochemical and granulometric analyses demonstrate that about 70% of the variation can be ascribed to hydrodynamic mineral sorting. Clay- and fine silt-sized phyllosilicates are the most important deterministic features, hosting the bulk of Al2O3,TiO2, K2O, MgO and trace element variability (notably Ba, Cr, Ga, Rb and V). Quartz is abundant in the fine and coarse sand fractions. Na2O and the Zr-Nb-Nd-Y quartet relate to albitic feldspars and hearvy minerals, respectively, in the coarse silt fraction. The granulometry should therefore be quantified if geochemical baseline data for a particular geological unit or region are drawn up and for the evaluation of potentially polluted sediments. Although provenance has not changed, the composition of Meuse sediments cannot be considered constant over a time frame of 1000-10,000 years, due to climatic change. Weathering of phyllosilicates in both interstadial and interglacial soil environments and changing relative source-area contributions alter the detrital clay-mineral supply to raise the Al2O, and lower the K2O and MgO contents in holocene Meuse sediments. Early diagenetic siderite and vivianite formation in gyttjas causes relative accumulations of Fe2O3, MnO, P2O5 Co, Ni and notably Zn above the phyllosilicate background values. These accumulations are natural and show that sediments with elevated trace metal contents are not necessarily polluted. Very earlyatmospheric pollution in relation to ore mining and smelting activities in the Roman era, however, probably caused elevated Pb contents in Subatlantic humic clays and peat samples, long before the historic pollution of the Industrial Revolution started. The Al2O3, Fe2O, and CaO contents are used to predict the trace-element values as a function of sample granulometry, siderite/vivianite and lime content, respectively. As such, they can provide a sound basis for environmental researchers to determine baseline values of heavy metals in bulk samples of fine-grained fluvial sediments. |
| Heavy-metal pollution of the river Rhine and Meuse floodplains in the Netherlands | 2000 | Middelkoop, H. | 79(4) | The embanked floodplains of the lower Rhine river in the Netherlands contain large amounts of heavy metals, which is a result of many years of deposition of contaminated overbank sediments. The metal pollution varies greatly between the various floodplain sections as well as in vertical direction within the floodplain soil profiles. The present contribution describes the key processes producing the spatial variability of the metal pollution in floodplain soils: (1) spatial patterns of the concentrations and deposition of Cd, Cu, Pb and Zn during a single flood, which have been determined from samples collected after a high-magnitude flood event; (2) the pollution trends of the lower Rhine over the past 150 years, which were reconstructed on the basis of metal concentrations in sediments from small ponds within the floodplain area. During the flood the largest metal depositions (0.03 g/m2 Cd, 0.7 g/m2 Cu, 1.1 g/m2 Pb and 5.0 g/m2 Zn for the Rhine) occurred along the natural levees, decreasing to about one third of these values at larger distance from the river. Deposition of heavy metals occurred since the end of the nineteenth century. Periods of maximum pollution occurred in the 1930s and 1960s, when Cu, Pb and Zn concentrations were about 6-10 times as high as background values. The resulting metal distribution in the floodplain soil profiles is illustrated by means of typical examples. Maximum metal concentrations in floodplain soils vary from 30 to 130 mg/kg for Cu, from 70 to 490 mg/kg for Pb, and from 170 to 1450 mg/kg for Zn. The lowest metal pollution is found in the distal parts of floodplain sections with low flooding frequencies, where average sedimentation rates have been less than about 5 mm/a. The largest metal accumulations occur in low-lying floodplain sections where average sedimentation rates have been more than 10 mm/a. |
| Provincial soil-quality monitoring networks in the Netherlands as an instrument for environmental protection | 2000 | Busink, E.R.V.; Postma, S. | 79(4) | Since 1991, several provinces in the Netherlands have put much effort in establishing soil-quality monitoring networks. The purpose of these networks is to provide insight in the trends in (geochemical) soil quality, on which new policies for environmental protection can be based, such as restrictions in certain landuse types and cleaner production processes. The soil quality networks are yet too young to serve this goal. Monitoring efforts are concentrated on micro- and macro-elements, particularly in the top layer of the soil (mainly heavy metals and PAH) as well as phreatic groundwater (mainly nitrares and phosphates) in the various regions of a province. The regional soil-quality monitoring networks focus explicitly on diffuse environmental pollution in the rural areas, which means that sample sites influenced by soil pollution caused by local sources are excluded. Regional differences in soil quality in the rural areas are primarily caused by chemical and physical differences in the natural soil composition and by differences in deposition loads (direct and indirect). Hydrological conditions can also exert a large influence, particularly for nitrate leaching. This leads to three major criteria which the network design is based upon: (1) soil type, (2) landuse (assumed to be representative for deposition), and (3) groundwater tables. Subregions are formed by combining these criteria. Subregions are considered to be more or less homogeneous at a regional scale with respect to the criteria named. Within each region, a pre-calculated number of sites, based on variability of present concentrations, have been sampled and the sample material has been analyzed. Descriptive statistical parameters could thus computed; they are the base for the geochemical soil mapping of the individual, homogeneous subregions. A recent evaluation of all operational soil-quality monitoring networks shows that these networks are effective instruments to gain insight into the differences in quality of the soil and the phreatic groundwater between the various regions. The understanding of these differences and the processes that caused them provide the provincial authorities with valuable information for policy making and environmental management. The evaluation also reveals differences in network designs, mostly due to local differences in physical-chemical properties and political choices. It can be concluded from the first results of the networks that the relative high loads of zinc and copper, caused by spreading manure on the farmlands in areas of intensive agricultural landuse, have led to notably higher concentrations of these elements in the top layer of the soil compared to more natural lands like forested areas. The fact that the intensive agricultural landuse is mainly situated on relatively highly permeable sandy soils results in high nitrate concentrations in the phreatic groundwater, up to concentrations far beyond EG drinking-water target levels. First monitoring results signalled several environmental problems of which most of the policy makers were already aware, but could not quantify. Delineation of the most vulnerable areas and/or areas with unacceptably high loads and quantification of concentrations of different elements enable regional governments to take appropriate measures. The soil-quality monitoring networks will focus in the coming years on the effectiveness of the measures taken in the various areas. Efforts are being made to integrate the relatively new soil-quality monitoring networks and the longer existing groundwater-quality monitoring networks to achieve a better understanding of the (bio)geochemical cycling processes. Tuning the individual regional soil-quality monitoring networks of the various provinces will enable the provision of additional information about soil quality at a larger scale. |
| Designing efficient sampling schemes for reconnaissance surveys of contaminated bed sediments in water courses | 2000 | Brus, D.J.; Jansen, M.J.W.; Haan, W.F. de | 79(4) | A method for designing efficient sampling schemes for reconnaissance surveys of contaminated bed sediments in water courses is presented. The method can be used in networks of water courses, for instance to estimate the total volume of bed sediment of a defined quality class. The water courses must be digitised as arcs in a Geographical Information System. The method comprises six steps: (1) stratifying the water courses; (2) choosing a variogram; (3) calculating the parameters of the variance model; (4) choosing a compositing scheme; (5) choosing the values for the cost-model parameters; and (6) optimizing the sampling scheme. The method is demonstrated with a survey of the main water courses in the reclaimed areas of Oostelijk Flevoland and Zuidelijk Flevoland. |
| Construction of maps for soil recycling in regional infrastructural works integrating soil-quality laws | 2000 | Lienen, F. van; Frapporti, G.; Stein, A. | 79(4) | A soil-quality map is at present an important tool to integrate laws on soil quality with regional infrastructural works. Basic data are commonly available, but soil quality is an indicator that has to be derived from these data, including site-specific environmental standards. We propose three geostatistics-based methods for the comparison of interpolated contaminant concentrations and standards. The study is illustrated by data from a part of the Betuwe railroad transect, which extends over 12 km in the western Netherlands. As it turns out, a useful procedure is to combine interpolated contaminant concentrations with interpolated threshold values. |
| The groundwater quality of Aruba, Bonaire and Curaçao: a hydrochemical study | 2000 | Sambeek, M.H.G. van; Eggenkamp, H.G.M.; Vissers, M.J.M. | 79(4) | Groundwater resources on the Caribbean Islands of Aruba, Bonaire and Curaçao are limited and of poor quality. The groundwater of the islands is brackish, due to both seawater mixing and the semi-arid climate of the islands. Two hundred and thirty water samples were collected to relate chemical variations in the groundwater of the three islands to the underlying differences in geology, and to define the natural versus anthropogenic influences. Both the chemical and isotopic (δ18O, δD, and δ37Cl) compositions of samples were determined. Several geochemical processes are recognised in the chemistry of the groundwater samples. The most important processes are calcite dissolution, cation exchange, silicate weathering and potassium fixation. In (sub)urban areas anthropogenic influences affect the groundwater quality: high nitrate concentrations were measured. Infiltrating domestic and agricultural (waste)water replenishes the aquifer, and has a desalinization effect on the groundwater quality. This phenomenon is primarily seen on Curaçao, the most populated island. Oxygen and hydrogen isotopic compositions of groundwaters from Curaçao and Bonaire show that the samples are either meteoric water, or are affected by evaporation or seawater mixing. No distinction could be made between the last two processes. Only a few samples were measured for the Cl-isotope composition; all showed that no physical processes have taken place. |
| Aruba - a geochemical baseline study | 2000 | Oever, F. van den | 79(4) | A stream-sediment survey was carried out for the island of Aruba. Concentrations in stream sediments represent the abundance of chemical elements in the drainage basins. A geochemical atlas was created from the collected data and natural background values were established. Cluster analysis and pattern recognition techniques were used to gain a better understanding of the data set. Two cluster models were selected to study the various geochemical controls on the sediments and to establish a spatial basis of environmental-quality settings for the development of future environmental policies. The first cluster model was suitable to recognize in some detail the reflection of the geology on the geochemistry of the stream sediments. The second, coarser cluster model stressed the importance to distinguish between the two main lithological units of the island when instituting natural background values. Not one uniform value per element is valid, but the value depends on the lithology. |
| The semi-arid environment of Curaçao: a geochemical soil survey | 2000 | Vries, A.J. de | 79(4) | A geochemical soil survey was carried out on the island of Curaçao in October 1992 as part of an overall geochemical characterization of the three Leeward islands of the Netherlands Antilles. The aim of this soil survey was to provide systematic geochemical data of the rural soils of Curaçao for characterisation, geochemical mapping and environmental application. A total of 122 samples was collected from the topsoils (upper 0.1 m) within a rectangular grid (2 km2). All samples were sieved to a grain size of < 2 mm and analysed for 24 elements by ICP-AES, after decomposition with hot aqua regia. A small, selected set of soil samples was subjected to a more extensive study of soil properties. It appears from statistical data interpretation of the chemical compositions with techniques like non-linear mapping and cluster analysis that the topsoils of Curaçao can be divided into six homogeneous groups (soil types) with contrasting chemical signatures. Labelled according to their dominant geology soil process or most striking characteristic, these soil types are defìned as follows: sandy limestone soil type, Midden Curaçao soil type, arid/calcareous soil type, basal West soil type, agriculture-influenced soil type, and the basalt East soil type. Geochemical contour maps were made that provide a basis for environmental issues on the island. Finally, background levels (baseline data) were derived from the chemical soil composition of several elements, taking into consideration the correlation with the Fe or Al content of these soils. The defined baselines can be used to establish background values for future soil surveys. |
| Abiotic landscape and vegetation patterns in the Netherlands during the Weichselian Late Glacial | 2000 | Hoek, W.Z. | 79(4) | The Late Glacial landscape of the Netherlands was a landscape with changing geomorphology and vegetation. Glacial, eolian and fluvial processes in the time before the Late Glacial initially had formed the main landscape types that still existed during the Late Glacial. In these landscape types, geomorphological processes persisted, particularly during intervals when the vegetation cover was discontinuous. Vegetation development initiated soil formation and stabilised the substratum. On the other hand, the abiotic landscape influenced vegetation development, and particularly vegetation patterns. The Late Glacial vegetation patterns, changing in time, have been reconstructed on the basis of a palynological database containing the data from over 250 pollen diagrams from the Netherlands. Patterns of vegetation and abiotic landscape appear to compare to each other in many instances, indicating the close interrelationship between vegetation and the abiotic landscape. |
| The Eemian - local sequences, global perspectives: introduction | 2000 | Kolfschoten, T. van; Gibbard, P.L. | 79(2-3) | |
| The Eemian stage in the Netherlands: history, character and new research | 2000 | Bosch, J.H.A.; Cleveringa, P.; Meijer, T. | 79(2-3) | A historical outline of the Eemian research in the Netherlands is presented as an introduction to recent research in the type area. At the end of the 19th and during the first part of the 20th century, Eemian sediments were recognized because of the presence of lusitanian and mediterranean mollusc species. From 1930 onwards, pollen analysis made it possible to identify also non-shell-bearing deposits and to equate them with the Eemian. At the same time this technique proved a valuable tool for understanding the vegetation development during this interglacial. Pollen zonation offered a unique possibility for the correlation of terrestrial sequences in North-West Europe. The type area of the Eemian, near Amersfoort, was described by Harting in 1874 and was comprehensively restudied by Zagwijn (1961). A pollen zonation was introduced as a standard for the Netherlands, allowing the correlation of pollen records from both marine and non-marine depositional environments. This enabled a more detailed temporal resolution, resulting in a better understanding of the distribution of the various environments in the type area. In the northern and central parts of the Netherlands, the identification of the marine sequence was, apart from the occurrence of the specific mollusc fauna, facilitated by the presence of a till of Saalian age underlying the Eemian deposits. The presence of deep glacial basins in these areas enabled the deposition and preservation of a complete Eemian record in a marine setting. Sediment accumulation in the basins began immediately following deglaciation at the end of the Saalian. The Eemian type sections at Amersfoort are situated near the margin of one of these basins. Recent research of the Eemian focused on the integration of lithostratigraphic evidence and information on the sedimentary environment as derived from diatoms, dinoflagellates, foraminifers, molluscs and pollen. |
| Late Saalian and Eemian deposits in the Amsterdam glacial basin | 2000 | Gans, W. de; Beets, D.J.; Centineo, M.C. | 79(2-3) | During its maximum extension, the Saalian ice cap reached into the central Netherlands, where glacier tongues excavated over 100 m deep basins in the unconsolidated Middle and Early Pleistocene sediments. The basins are filled by relatively thick successions of Late Saalian, Eemian and Weichselian sediments. The fiIl of the Amsterdam glacial basin is among the best known and studied in the Netherlands. The Late Saalian sediments consist mainly of warves and ill-bedded clays and silts with, along its southern margin, influxes of sands from the surrounding ice-pushed ridges. During deposition of these sediments, the Amsterdam basin formed part of a large lake extending into the present North Sea. Draining of this lake at the end of the Late Saalian left small, shallow pools at the site of the glacial basins. Late Saalian and Eemian sediments are probably separated by a short break, although sedimentation may have been continuous in the deepest part of the basin. The Eemian deposits consist in main lines of a thin, diatom-rich sapropel at the base, overlain by an up to 30 m thick clay-rich sequence covered by a wedge of sand that measures more than 20 m in the northern part of the basin and that peters out southwards. As appears from the fauna, most of the clays were deposited in a lagoonal setting shielded behind a threshold and/or barrier. The rate of sediment supply was low so that lagoonal conditions were maintained over a long timespan. Sands derived from the surrounding ice-pushed ridges and transported by longshore drift and tidal currents formed a spit at the northern margin of the basin, which moved southward after eustatic sea-level rise stabilized and the lagoon was filled by clay. Loading of this clay-rich sequence by the spit and its washover fans induced subsidence, however, because of compaction, so that marine conditions were maintained until after the Eemian highstand. Fluvial and eolian sediments of Weichselian age, locally reaching a thickness of almost 10 m, eventually levelled the Amsterdam glacial basin. |
| Stratigraphy and integrated facies analysis of the Saalian and Eemian sediments in the Amsterdam-Terminal boderhole, the Netherlands | 2000 | Leeuwen, R.J.W. van; Beets, D.J.; Bosch, J.H.A.; Burger, A.W.; Cleveringa, P.; Harten, D. van; Herngreen, G.F.W.; Kruk, R.W.; Langereis, C.G.; Meijer, T.; Pouwer, R.; Wolf, H. de | 79(2-3) | The Amsterdam glacial basin was a major sedimentary sink from late Saalian until late Eemian (Picea zone, E6) times. The basin's exemplary record makes it a potential reference area for the last interglacial stage. The cored Amsterdam-Terminal borehole was drilled in 1997 to provide a record throughout the Eemian interglacial. Integrated facies analysis has resulted in a detailed reconstruction of the sedimentary history. After the Saalian ice mass had disappeared from the area, a large, deep lake had come into being, fed by the Rhine river. At the end of the glacial, the lake became smaller because it was cut off from the river-water supply and eventually only a number of shallow pools remained in the Amsterdam basin. During the early Eemian (Betula zone, E1), a seepage lake existed at the site. The lake deepened under the influence of a steadily rising sea level and finally evolved into a silled lagoon (late Quercus zone, E3). Initially, the lagoon water had fairly stable stratification, but as the sea level continued to rise the sill lost its significance, the lagoon becoming well mixed by the middle of the Corylus/Taxus zone (E4b). The phase of free exchange with the open sea ended in the early Carpinus zone (E5), when barriers developed in the sill area causing the lagoon to become stratified again. During the Late Eemian (late E5), a more dynamic system developed. The sandy barriers that had obstructed exchange with the open sea were no longer effective, and a tidally-influenced coastal lagoon formed. The Eemian sedimentary history shown in the Amsterdam-Terminal borehole is intimately connected with the sea-level history. Because the site includes both a high-resolution pollen signal and a record of sea-level change, it has potential for correlation on various scales. Palaeomagnetic results show that the sediments predate the Blake Event, which confirms that this reversal excursion is relatively young. The U/Th age of the uppermost part of the Eemian sequence is 118.2 ±6.3 ka. |
| The Eemian stratotype locality at Amersfoort in the central Netherlands: a re-evaluation of old and new data | 2000 | Cleveringa, P.; Meijer, T.; Leeuwen, R.J.W. van; Wolf, H. de; Pouwer, R.; Lissenberg, T.; Burger, A.W. | 79(2-3) | In order to obtain a better understanding of the infilling of the Saalian glacial basins during the Eemian, particularly following the recent research in the Amsterdam Basin (Terminal borehole), it was necessary to re-investigate the type locality of the Eemian at Amersfoort. Both published and unpublished data from various biota (diatoms, foraminifers, molluscs, ostracods, pollen) provide new information on the changing sedimentary environments during the Eemian. Although the organic and clastic sediments of the infilling represent nearly all the pollen zones, the sedimentary sequence at Amersfoort is discontinuous: four breaks at least are recognised at the type locality. The successive sedimentary environments and the breaks in the record are linked with the transgression of the Eemian sea, the topographic position at the margin of an ice-pushed ridge, and the changes in hydrodynamic conditions. Local conditions, such as a sandy sea bed, shallow water and a reduced water exchange near the North Sea margin, influenced the salinity of the basin. Rib counts of Cerastoderma edule shells indicate a higher salinity at the end of the Taxus (E4b) and the beginning of the Carpinus (E5) zones than that present in the modern North Sea. Local conditions were responsible for the higher salinity following the climate optimum. During the Abies phase (the later part of regional pollen zone E5), the sea level had already fallen. The change from eutrophic peat growth (with Alnus and Salix) to an oligotrophic Ericaceae/sphagnum community at the end of the Eemian resulted from the change from a marine to a fresh-water environment, probably coherent with a deterioration of the climate. |
| The Eemian interglacial in the North European plain and adjacent areas | 2000 | Turner, C. | 79(2-3) | Many small deposits of Eemian age, including the stratotype, are found right across the North European plain. In adjacent areas, this interglacial is known by local names such as Ipswichian (Britain), Luhe or Ribains (France), Riss-Würm interglacial (Alps) and Mikulinian (Poland and Russia). It correlates primarily with MIS 5e of the deep-sea stratigraphy, though boundaries may not be exactly the same. Basins containing Eemian sediments rest directly on morainic deposits of all three Saalian ice advances, which must all, therefore, fall within MIS 6. Indicator species of both plants and animals suggest that mean July temperatures in the early-temperate part of the interglacial were warmer than during the Holocene. For many years, palynologists have recognised a very uniform succession of temperate tree acme pollen zones and a substantial late-temperate expansion of Carpinus as hallmarks of this interglacial across much of northern Europe. In southern England, however, deposits with a similar pollen signature are being recognised on stratigraphic and palaeontological grounds as characterising not only the Ipswichian but also the previously poorly-defined interglacial stage correlating with MIS 7. High Carpinus values are known from these latter sites and from the Le Bouchet interglacial of the French Massif Central, also clearly correlated with MIS 7. Thus stratigraphic confusion and misinterpretations may have occurred at supposedly Eemian/Ipswichian sites unrelated to the glacial stratigraphy or to deep continuous records. The uniformity and rapid development of Eemian vegetational successions may be ascribed to (1) rapid warming and the lack of any late-glacial climatic oscillation on the scale of the Younger Dryas, (2) the development of an open marine connection in the first half of the interglacial from the English Channel across the North and Baltic Seas to the White Sea and the Arctic Ocean, and (3) the occurrence of Saalian per-glacial refugia for Carpinus, not only in the Balkans but also on the Iberian peninsula, permitting much more rapid northward colonisation of Europe during this interglacial. The question of climatic events within the Eemian is far from settled. Not only is the ice-core evidence ambiguous and awaiting further clarification, but the scale and synchroneity of proposed events at different continental sites in both northern and southern Europe show no clear pattern at present; clearly there is a need for more detailed investigation and interpretation. Likewise there is ongoing debate about the duration of this interglacial and its detailed correlation with the deep-sea core record and events within the North Atlantic Ocean. |
| The Riss-Würm interglacial from West to East in the Alps: an overview of the vegetational succession and climatic development | 2000 | Drescher-Schneider, R. | 79(2-3) | The vegetational and climatic developments during the Riss-Würm interglacial in the area on the northern flank of the Alps are reviewed. Reforestation seems to have begun over the whole region with a dwarf-shrub and ensuing shrub phase, leading to birch and/or pine woodland. The rise in summer temperatures, which δ18O values suggest to have been a two-stage event, permitted the immigration and expansion of more demanding trees (elm, oak, lime, ash, ivy, hazel, yew, etc.). Following the thermal maximum, which took place during the hazel and yew biozones, hornbeam dominated the forests in the alpine foreland, whilst fir/spruce forests formed the dominant vegetation at sites closer to the Alps or at a higher altitude. A marked climatic deterioration can only be recognised towards the end of the interglacial, which led to extensive spruce/pine and, finally, almost pure pine forests. |
| A review of the occurrence of Corbicula in the Pleistocene of North-West Europe | 2000 | Meijer, T.; Preece, R.C. | 79(2-3) | Shells belonging to the bivalve gents Corbicula occur commonly in Pleistocene interglacial deposits in NW Europe. These have usually been identified as C.fluminalis, a modern species described from the Euphrates river, although the veracity of this specific attribution remains equivocal. Corbicula has nowadays a southern distribution, and laboratory studies indicate that it is thermophilous. It is also tolerant of brackish water, one of several attributes that make this an effective colonizer. In NW Europe, Corbicula is known from the Lower Pleistocene but is absent from the Cromerian Complex, occuring again in the three interglacials following the Anglian/Elsterian. It appears to be unknown from the last interglacial, except as derived fossils. |
| The climatic significance of coleopteran assemblages from the Eemian deposits in southern England | 2000 | Coope, G.R. | 79(2-3) | Assemblages of fossil coleoptera (beetles) have been obtained from eight sites in southern England that date from the early phase (Pinus - Quercetum mixtum - Corylus pollen assemblage zone) of the Eemian (Ipswichian) interglacial Stage. Altogether 294 different species have been identified from these sites. They represent a wide spectrum of habitat requirements; terrestrial, aquatic, carnivorous and phytophagous species and many more with subtle dependences of specialist biotopes. Almost all of them live today in central and southern Europe and some are restricted to regions well south of the British Isles. By using mutual climatic range methods, the thermal climate of the early phase of the Eemian Interglacial has been estimated quantitatively, showing that mean July temperatures were about 4°C above those of southern England today. Mean winter temperatures were not much different from those nowadays. This phase was probably the thermal maximum of the Eemian Interglacial. Precipitation levels are difficult to quantify but were adequate to maintain flowing rivers in England throughout the year. These results are in agreement with the presence of other fossils, both plants and animals, in the same deposits. |
| The Eemian mammal fauna of central Europe | 2000 | Kolfschoten, T. van | 79(2-3) | The knowledge of the Eemian fauna of central Europe is based on the fossil record from a number of sites located in the eastern part of Germany. The faunas with different deer species as well as Sus scrofa, Palaeoloxodon antiquus, Stephanorhinus kirchbergensis and Glis glis indicate a forested environment alternating during the climatic optimum of the Eemian s.s. with areas with a more open environment inhabited by species such as Cricetus cricetus, Equus sp. (or Equus taubachensis), Equus hydruntinus and Stephanorhinus hemitoechus. Characteristic for the Rhine valley fauna are Hippopotamus amphibius and the water buffalo (Bubalus murrensis);both species are absent in the eastern German faunas with an Eemian age. Taking into account the short period of time covered by the Eemian s.s., the amount of data on the Eemian mammalian fauna is remarkably large. There is, however, still an ongoing debate on whether the stratigraphical position of a number of faunas are of Eemian or 'intra-saalian' age. Furthermore, there are faunal assemblages or stratigraphically isolated finds referred to the Eemian without indisputable evidence. This is particularly the case in the Rhine valley, where most of the socalled Eemian fossils come from dredged assemblages. The picture of the evolution of the Eemian fauna and its geographical variation is consequently still incomplete. |
| The relevance of the Eemian for the study of the Palaeolithic occupation of Europe | 2000 | Speleers, B. | 79(2-3) | The relevance of a study of the Eemian occupation of Europe lies largely in the discussion on the environmental tolerances of early humans and in the limits encountered during the reconstruction of Palaeolithic habitats. The traditional vision is reviewed; then follows a discussion of Gamble's studies (1986, 1987) in which he postulated an absence of human occupation in North-Western Europe during the Eemian. Gamble's explanatory models and the reactions to his work are presented. Finally, the relation is considered between the distribution pattern of sites, the former dispersal of early humans across the European landscape, and the implications of this evidence for hypotheses of environmental tolerances of Palaeolithic humans. |
| The Mikulino (= Eemian) mammal faunas of the Russian Plain and Crimea | 2000 | Markova, A.K. | 79(2-3) | During the last decades a considerable amount of data on mammals from Mikulino (=Eemian) deposits of rhe central and southern parts of the Russian Plain has been produced. Mammuthus primigenius (the early type), Palaeoloxodon antiquus (the advanced form), Arvicola ex gr. terrestris, Eolagurus cf. luteus and Lagurus cf. lagurus characterize this period. The so-called 'Shkurlatian mammal assemblage' was distinguished on the basis of a number of Eemian faunas. The age of the mammal localities was established by using various geological and palaeontological evidence, together with the results of palaeomagnetic studies and absolute dating. The evolutionary level of the diagnostic species allows correlations between localities from different parts of the Russian Plain that have varying taphonomical conditions. The mammal- and malacofauna of the Mikulino Interglacial can also be used as a basis for correlations between the Karangat marine strata of the Black Sea and the continental deposits (alluvial sediments of the second terrace of the Sudost' River and the Salyn phase of the Mezin fossil pedocomplex (see Dodonov et al., this volume). Forest, forest-steppe and steppe zone landscapes have been reconstructed for the central and southern parts of the Russian Plain on the basis of the Eemian faunas. |
| Last-interglacial record from central Asia to the northern Black Sea shoreline: stratigraphy and correlation | 2000 | Dodonov, A.E.; Tchepalyga, A.L; Mihailescu, C.D.; Zhou, L.P.; Markova, A.K.; Trubikhin, V.M.; Simakova, A.N.; Konikov, E.G. | 79(2-3) | The records of the last interglacial in several palaeogeographical zones and various sedimentary environments from Central Asia to the Black Sea shoreline are presented. The last interglacial is characterized in the study areas by a two- or three-unit stratigraphical complex with both terrestrial and marine formations. Finds of significant small mammalian remains, together with a characteristic mollusc fauna in the Karangatian marine sediments, provide key levels for biostratigraphical correlation between the marine and continental deposits. New U/Th dates allow the correlation of the Karangatian transgression with δ180 substage 5e. |
| Pedosedimentary evolution of the last interglacial and eary glacial sequence in the European loess belt from Belgium to central Russia | 2000 | Haesaerts, P.; Mesrdagh, H. | 79(2-3) | For more than one century, the textural B-horizon of the last interglacial soil and its cover deposits have been standing out in Europe as an important pedostratigraphic marker. The complexity of this horizon was well illustrated since the seventies, though its pedological and stratigraphic significance remained doubtful. Macro-, meso- and micromorphological data gathered by the authors at various key-sites in Europe and the sequential correlation principle have resulted in a better understanding of the high complexity of the pedosedimentary and stratigraphical evolution of the last interglacial and early glacial loess succession. The present study identifies four megacyclic pedosedimentary intervals that show a general trend towards dry and continental climatic conditions. A consistent correlation exists between pedosedimentary evolution and vegetation, as recorded in the Grande Pile pollen record. The picture obtained in the present study is similar for both the Western and the Eastern European loess palaeosol successions. The so-called 'last interglacial soil', with three major soil-forming processes, belongs to the Eemian and Saint- Germain I (MIS substages 5e and 5c), whereas the humiferous sediments and soils on top are linked to Melisey II, Saint-Germain II and Ognon I (MIS substages 5b and 5a).The overlying loess, colluvial sediments and humiferous soils that end the palaeosol succession belong to the Ognon II and III interstadials; they record the onset of the early Pleniglacial (MIS stage 4) characterized by a significant increase in aeolian sedimentation. |
| The Eemian interglacial in Sweden, and comparison with Finland | 2000 | Robertsson, A. | 79(2-3) | The current status of knowledge concerning the Eemian interglacial in Sweden is surveyed, and comparisons are made with northern and western Finland. The course of shore displacement is fragmentarily known for Sweden, since brackish-marine sediments have been identified, on the basis of diatom analysis, at only few sites. In Finland, on the other hand, a shore displacement curve has been constructed for the Eemian Baltic Sea in Ostrobothnia, central western Finland. The vegetation history is summarised for the southernmost part of Sweden, and can be correlated with that documented in Denmark. For the central part of Sweden, information is sparse, but the composition of the forests has been outlined for most of the interglacial, although information on regional pollen assemblage zones E3 and E4 (early-temperate substage) are mainly missing. A more complete picture of the interglacial vegetational history is known from Ostrobothnia in Finland. The thermophilous indicators Viscum, Ilex, Hedera and Osmunda grew far North during the Eemian. Corylus and Carpinus expanded much further to the North than during the Holocene. In Swedish and Finnish Lapland, the vegetation history is similar except that Larix was common in Finland during the Eemian, but its presence has so far not been confirmed in Sweden. Eemian deposits relocated during the Weichselian glaciation contain pollen and diatoms that can be used for reconstruction of the Eemian environment. No clear indication of a rapid climatic deterioration during the Eemian has been found so far in either Swedish or Finnish sequences. |
| Marine late Saalian to Eemian environments and climatic variability in the Danish shelf area | 2000 | Seidenkrantz, M.; Knudsen, K.L.; Kristensen, P. | 79(2-3) | The marine Eemian (marine oxygen-isotope substage 5e: MIS 5e) is represented by shallow-water deposits in southern and western Denmark, while relatively deep-water environments occurred to the north and north-east, where complete interglacial successions seem to be present. We present an overview of the marine Eemian deposits in Denmark, and discuss in more detail indications of climate variability, both for the late Saalian and within the Eemian. |
| Direct land/sea correlation of the Eemian, and its comparison with the Holocene: a high-resolution palynological record off the Iberian margin\ | 2000 | Sánchez Goñi, M.F.; Turon, J.L.; Eynaud, F.; Shackleton, N.J.; Cayre, O. | 79(2-3) | High-resolution pollen, dinocyst and isotopic profiles covering the marine isotope stage 5 (MIS 5) are presented from core MD952042 (Tagus abyssal plain, 37°47'N, 10°09'W). Both marine and terrestrial proxies indicate the occurrence of a Bølling-Allerød-Younger Dryas-like event at the beginning of MI substage 5e. The terrestrial Eemian stage coincides with both the lightest oxygen isotope values of substage 5e and the heavier ones approaching the 5e/5d transition. Accordingly, the Eemian is not equivalent to MI substage 5e, as the Holocene is not equivalent to MIS 1. Remarkably, both pollen and dinocyst data reflect the same climatic pattern on land and ocean, and they evidence a succession of climatic events that the isotope signal does not identify. The Eemian began with a Mediterranean vegetation that was gradually replaced by Eurosiberian formations indicating a change from Mediterranean to oceanic climates. In the middle of the Eemian, warming conditions were interrupted by an event corresponding to a slight cooling resulting from an increase in precipitation over land and ocean. Finally, a warming trend characterised the last phase of the Eemian. The occurrence of small climatic changes during this interglacial is inconsistent with the dramatic variability suggested by the GRIP ice-core record |
| Vegetation variability in Greece during the last interglacial | 2000 | Tzedakis, P.C. | 79(2-3) | The extent of regional variability in vegetation development in mainland Greece during the last interglacial is considered. Three pollen sequences - Ioannina (northwest Greece), Tenaghi Philippon (northeast Greece) and Kopais (central Greece) - all located in different environmental settings, extend into the last interglacial. Examination of the vegetation histories of the three sites during the last interglacial reveals the influence of local climatic conditions with closed mixed forests in the northwest, becoming progressively more open and less diverse farther to the east and south. All three sequences contain a number of similar trends, however, in the expansion of certain taxa. In addition, they also show the presence of a two-step late glacial interval, a short episode of forest reduction in the second part of the interglacial and a final small expansion of tree populations at the very end of the interglacial. Comparison with other European records shows a number of common features, but also suggests differences consistent with the particular environmental setting of the Greek sites. |
| Preface Groningen 40 years special issue | 2001 | Graaff, W.J.E. van de | 80(1) | |
| Groningen, 40 years, a special issue | 2001 | Dronkert, H. | 80(1) | |
| Groningen, 40 years, a special issue. Dinner Speech and conference wrap-up | 2001 | Oele, J.A. | 80(1) | |
| Gas: source of prosperity | 2001 | Jorritsma-Lebbink, A. | 80(1) | |
| Groningen field, past, present and future | 2001 | Roels, H.J.M. | 80(1) | |
| Groningen, Gasunie and the gas market | 2001 | Verberg, G.H.B. | 80(1) | |
| Non-Groningen gas supplies for Western Europe | 2001 | Mellbye, P. | 80(1) | |
| Past, present and future of the gas market in the North Sea region | 2001 | Quinn, A.C. | 80(1) | |
| Groningen in the European context | 2001 | Burgos, C. | 80(1) | |
| Gas: government and market | 2001 | Hulst, N. van | 80(1) | |
| Groningen - its impact on European society | 2001 | Lubbers, R.F.M. | 80(1) | |
| The petroleum industry in the Netherlands - its setting and possible future | 2001 | Alblas, L.D. | 80(1) | The setting and possible future of the petroleum industry in the Netherlands is briefly discussed. The result of a risk assessment shows, that the Dutch hydrocarbon province can be divided in low, medium, high and very high-risk areas for new capital investments. The assets of operators in the Netherlands have been evaluated on exploration, production, storage and pipeline potential, now and in the future. Despite the presence of potential new plays, exploration activities are expected to decrease in the near future. Despite the possible development of marginal fields, which will be not adding major reserves, the production reserves will decrease in the next 10 - 15 years and many fields will be abandoned. However storage, pipeline infrastructure and gas marketing are expected to increase in the future, mainly because of the liberalisation of the Dutch gas market. |
| Exploration activities in the Netherlands and North-West Europe since Groningen | 2001 | Glennie, K.W. | 80(1) | Once the great size of the Groningen Field was fully realized late in 1963, exploration in the southern North Sea was a natural development as the reservoir bedding dipped westward. The origin of that bedding was not certain, one possibility, dune sands, led immediately to a program of desert studies. Licensing regulations for Netherlands waters were not finalized until 1967, offshore exploration beginning with the award of First Round licenses in March 1968. In the UK area, the Continental Shelf Act came into force in May 1964, paving the way for offshore seismic, the first well being spudded late in that year. The first two wells were drilled on the large Mid North Sea High; both were dry, the targeted Rotliegend sandstones being absent. Then followed a series of Rotliegend gas discoveries, large and small, west of Groningen, so that by the time exploration began in Netherlands waters the UK monopoly market was saturated and exploration companies were already looking north for other targets including possible oil. The Rotliegend was targeted in the earliest wells of the UK central North Sea even though there had already been a series of intriguing oil shows in Chalk and Paleocene reservoirs in Danish and Norwegian waters. These were followed early in 1968 by the discovery of gas in Paleocene turbidites at Cod, near the UK-Norway median line. The first major discovery was Ekofisk in 1969, a billion-barrel Maastrichtian to Danian Chalk field. Forties (1970) confìrmed the potential of the Paleocene sands as another billion barrel find, while the small Auk Field extended the oil-bearing stratigraphy down to the Permian. In 1971, discovery of the billion-barrel Brent field in a rotated fault block started a virtual 'stampede' to prove-up acreage awarded in the UK Fourth Round (1972) before the 50% statutory relinquishment became effective in 1978. Although the geology of much of the North Sea was reasonably well known by the end of the 1970s, new oil and gas reservoirs continued to be discovered during the next two decades. Exploration proved the Atlantic coast of Norway to be a gas and gas-condensate area. The stratigraphic range of reservoirs extended down to the Carboniferous (gas) and Devonian (oil), while in the past decade, forays into the UK Atlantic Margin and offshore Ireland met with mixed success. During this hectic activity, Netherlands exploration confirmed a range of hydrocarbon-bearing reservoirs; Jurassic oil in the southern Central Graben, Jurassic-Cretaceous oil derived from a Liassic source mainly onshore and, of course, more gas from the Rotliegend. German exploration had mixed fortunes, with no commercial gas in the North Sea and high nitrogen content in Rotliegend gas in the east. Similarly in Poland, where several small Zechstein oil fields were discovered, the Rotliegend gas was nitrogen-rich. The discovery of some 100 billion barrels of oil and oil equivalent beneath the waters of the North Sea since 1964 led to an enormous increase in geological knowledge, making it probably the best known area of comparable size in the World. The area had a varied history over the past 500 million years: plate-tectonic movement, faulting, igneous activity, climatic change, and deposition in a variety of continental and marine environments, leading to complex geometrical relationships between source rock, reservoir and seal, and to the reasons for diagenetic changes in the quality of the reservoir sequences. Led by increasingly sophisticated seismic, drilling and wireline logging, and coupled with academic research, the North Sea developed into a giant geological laboratory where ideas were tested and extended industry-wide. |
| Forward prediction of aeolian systems using Fuzzy logic, constrained by data from recent and ancient analogues. | 2001 | Hern, C.; Nordlund, U.; Zwan, K. van der; Ladipo, K. | 80(1) | Aeolian sands are the main reservoir rock in some of the largest gas fields, such as the Shell-Exxon Groningen Field, operated by NAM. Although aeolian reservoirs have been studied for many years, there is still room for improvement in the predictive modeling of such reservoirs. A pilot project with this objective was initiated by SIEP B.V. in 1997, together with Heriot-Watt University in Edinburgh, UK and with Uppsala University, Sweden, to evaluate the factors influencing aeolian systems, and to formulate a forward model using 'fuzzy logic'. The project was initiated to develop a fuzzy system for generic modeling of Aeolian architectures. The key aims were to be able to predict the type, amount and distribution of major facies in generic aeolian systems and specifically to model regional-scale architecture in the sub-surface. Fuzzy rules and sets, which defined the behaviour of aeolian systems, were constructed and used to modify the pre-existing fuzzy modeling software which had been designed for shallow and deep marine systems. The modeling procedure used input data appropriate to the Rotliegend climate, and was validated by comparing the resulting models, in terms of thickness and spatial distribution of facies types, to well data from the Upper Rotliegend interval of the Lauwerszee Trough area, NE Netherlands (Figures 1 &.2). |
| The distribution of the Pre-Westphalian source rocks in the North German Basin - Evidence from magnetotelluric and geochemical data | 2001 | Hoffmann, N.; Jödicke, H.; Gerling, P. | 80(1) | For the first time this project attempts to directly correlate magnetotelluric and geochemical data with the aim of creating a model on the regional distribution of potential pre-Westphalian source rocks deposited in marine environments in the North German basin. Analysis of the magnetotelluric data shows, that there is a deep good conductor at the north-eastern fringe of the North German basin around the islands of Rügen and Usedom and on the mainland north east of the Anklam Fault. Through integration with seismic data and the offshore well G14 the conductor can be correlated with the Cambro-Ordovician candinavian Alum shales. To the south an adjoining area approximately corresponding to the depo-centre of the Rotliegend basin lacks a deep good conductor. Therefore it can be assumed that a regional distribution of comparable source rocks is unlikely. Another excellent and important conductor starts to the south west of the Lower Elbe Line extending along the Dutch-German border into the North Sea, and into the Münsterland. Its place in the local stratigraphy has not been adequately established. It is most likely that this good conductor corresponds to the black shales of the Early Namurian and the Dinantian, which is the case in the boreholes Münsterland 1 and Pröttlin 1 for example. In this paper they are collectively called Rhenohercynian. Alum shales. On the Dutch-German border a transition into the "Bowland Shale" facies or equivalents is to be expected. It cannot be ruled out that even stratigraphically older black shales, possibly from the Cambro-Ordovician could contribute to the high integrated conductivity ofthe deep good conductor. The evidence of highly conductive layers in the deep subsurface poses the question whether these layers could be potential source rocks for the gases in the north German gas fields. This question can be answered with a clear yes. Gas and isotope geochemical studies on gases from producing Rotliegend deposits have shown that Rhenohercynian Alum shales have been a significant source for these fields. This will be illustrated in detail using the gas fields from the production province "Ems Estuary" as an example. |
| Tertiary sedimentary development of the Broad Fourteens area, the Netherlands | 2001 | Wong, T.E.; Parker, N.; Horst, P. | 80(1) | The Broad Fourteens Basin is a NW-SE trending Mesozoic structural element that was affected by inversion movements during the Late Cretaceous (Subhercynian Phase) and Early Tertiary (Laramide Phase). Since the overlying Tertiary section of this area is relatively little studied, a multi-disciplinary investigation was initiated using both seismic and well data. The present study is the first phase of that project and deals exclusively with the stratigraphical framework and sedimentary development based on well logs from approximately forty wells. The Tertiary sedimentary section in this area (maximum thickness up to approximately 800 m) consists of siliciclastic rocks that generally correlate well with the established lithostratigraphical framework of the Netherlands. However, the highly variable thickness of these lithological units, illustrated by isopach maps for all units, reflect the intricate pattern of sea level movements, differential vertical movements and the ensuing erosion, that took place in this tectonically active area. Well P06-02, one of the most complete sections in the center of the area, was selected for detailed biostratigraphical analysis to support further stratigraphical subdivision and correlation. This yielded information on both the distribution pattern of various lithological units and the influence of large, partly global, events during basin development. It is concluded that application of detailed sequence stratigraphy in the study area is very problematic and only 2nd and some 3nd order cycles could be recognized. |
| Integrated gas field development: The Anjum story | 2001 | Hollman, F.J. | 80(1) | In contrast to oil field development, gas field development requires tight integration of subsurface, surface and economic issues due to the difficulty of storing surplus produced gas and the large effect of the back-pressures in a surface network on the individual well performance. As a major gas supplier the Shell Group, and in particular NAM, has extensive experience in this field. The gas production from onshore fields in the North Friesland area is a recent NAM development. A 10 million cubic meter per day LTS gas treatment installation located near the village of Anjum came on stream in 1997 . Production initially started from 3 wells in 2 fields to deliver gas to the Gasunie grid at Grijpskerk. The total area comprises 10 fields and 4 remaining prospects and is planned to be fully developed by the year 2001, using wet gas pipelines to route the production to either the Anjum LTS installation or the Grijpskerk SilicaGel installation. The Rotliegend reservoirs in this part of the Netherlands are very heterogeneous and require a more detailed subsurface simulation than feasible with the standard NAM tool for gas field development (GENREM). In addition, the area is close to the Waddenzee and based on extensive ecological research, NAM uses a stringent, self-imposed ecological constraint, whilst evaluating the development plans for this area. Detailed subsidence studies have been run using subsidence-modeling tools, which run under a software user-interface called FrontEnd, an in-house development by the Shell Group. Also running under this interface is an application for gas field development called Gas Field Planning Tool (GFPT). GFPT combines a detailed subsurface simulator with a surface simulator using a development planning module, which handles economic and operational aspects of the integrated model. Lastly, the interface gives access to a powerful command language and a mathematical toolbox, which can be used to define almost any missing functionality. Making use of the flexibility offered by the FrontEnd interface and with help from available expertise in RTS (Shell Rijswijk), an integrated GFPT model was built, which not only incorporates operational and economic constraints, but also does optimization and subsidence analysis. The model is used to evaluate all development options and scenarios for this area in a consistent manner. Therefore, all proposed development plans are optimized within all applied constraints whether they are related to surface, subsurface, economic, or environmental aspects. Production history and well performance are very close to those predicted by these detailed models, which will allow accurate prediction of future field performance and subsidence. |
| Gas field planning tool | 2001 | Berkel, J. van; Kaymak, U.; Kulawksi, G.; Weisenborn, T.; White, M. | 80(1) | Gas Field Planning Tool (GFPT) was developed in 1990 by the Shell Group of Companies to fill the need for a tool for gas field planning and development using deterministic subsurface and surface models. Main initiators were Shell Canada, NAM (the Netherlands), Shell Expro (UK) and BSP (Shell Brunei), as these companies are major gas producers. Shell Companies now have several years experience with using the GFPT. Application ranges from simple single field models to corporate-level models with a large number of gas reservoirs and wells. Shell companies now using GFPT models are Shell Expro (UK), BSP (Brunei), SSB (Malaysia), Shell Canada, SPDC (Nigeria), SDA (Australia), Woodside (Australia), PDO (Oman), NAM (the Netherlands), New Business Development (e.g. Lunar Project) and in future also Shell Egypt. NAM currently has a GFPT model for the Anjum field in Friesland and for the Ten Arlo field in the north of Holland. GFPT is currently being migrated to an HFPT (Hydrocarbon Field PlanningTool), which can also be used for planning of condensate, oil and water developments and for control of hydrocarbon compositions in the network using PVT de-lumping at the well head (e.g. for LNG plants) and optimisation techniques (linear, non-linear or based on bean-back lists). |
| Value Analysis: Capturing Total Cost of Ownership reduction opportunities in E&P projects | 2001 | Schans, E. van der; Lijssel, J.W.N. van; Steenderen, P. van | 80(1) | Value Analysis is a powerful tool to increase the value of a capital investment project and to capture cost saving opportunities. It is a method conceived during WorldWar II and frequently used on infrastructure projects, especially in the USA. The Value Analysis process typically consists of a well prepared 3 to 5 day workshop with focus on generating ideas to improve the current engineering concept. Emphasis is on screening all proposals in order to identify the most promising ideas. The workshop results in a number of proposals to modify the existing engineering concept. Stork Engineers & Contractors have used the Value Analysis method on several projects as well as in proposals for Engineering, Procurement and Construction (EPC) projects in the Exploration and Production (EP) industry. Typical results of Value Analysis led to a decrease of Total Cost of Ownership by some 10 to 30%. A well facilitated Value Analysis workshop also leads to mutual trust and understanding between the parties involved. A key element in a Value Analysis is (re)definition of the proposed functionality of a project. This is done through challenging the existing technical concept by increasing this functionality or by meeting this functionality at a lower cost. |
| The concession Groningen: A lawyer's view | 2001 | Taverne, B.G. | 80(1) | The discovery in 1959 of natural gas in a well drilled by the Nederlandse Aardolie Maatschappij (NAM) near Hoogezand, Gemeente Slochteren, a town in the Province of Groningen, led to the development and establishment of major natural gas production in the Netherlands. This important industrial development could not have started and the necessary investments would not have been made by the industry if not in accordance with the then applicable Napoleonic Mining Law of 1810 a concession had been applied for and granted allowing to exploit this discovery. From this point of view, admittedly a lawyer's view, the award of the concession, which was named Groningen, should be considered to be the actual starting point for the aforesaid development. On 1 July 1961 NAM submitted its application for a concession based on its Slochteren discovery and with this submission the negotiations started between the Netherlands government on the one side and NAM and its two shareholders, viz. Shell and Exxon, on the other side, on the terms and conditions to be incorporated in the applied for concession. On the government's side attention was focused on two aspects: how to integrate the natural gas discovered into the economy of the country and how to involve the State in the production and disposal thereof. From the outset the government intended, that the State's interests should be represented by the Staatsmijnen in Limburg (State Mines) in order to give this coal mining enterprise a future outside and independent from its ailing coal mining business in the Province of Limburg. To this end the government arranged for State Mines to enter into a maatschap (partnership) with NAM. In this partnership State Mines would get a 40% participating interest, leaving 60% for NAM. The concession would be granted to NAM, but the latter would be obliged to produce the natural gas reserves contained within the concession for the account and responsibility of the partnership. The partnership would be managed by State Mines with a 50% voting right and by NAM's two shareholders each with a 25% voting right. In the deed of concession, which was granted on 30 May 1963, if is stipulated, that any natural gas not needed by the concessionaire for its own operations should be sold to a corporation to be designated by the Minister and the articles of association of which would require the latter's approval. This corporation, named the NV Nederlandse Gasunie (the Gasunie), was established on 6 April 1963. Its shareholders were (and still are) State Mines (now Energie Beheer Nederland (EBN)) with, a 40% shareholding interest, the two shareholders of NAM, each with a 25% interest, and the State itself with a 10% interest. The Gasunie is allowed to realise from its business of buying, transporting and selling natural gas an after tax profit of NGL 80 million per year. Any surplus revenues are transferred to NAM (the transfer sum) in payment of the gas delivered by NAM. The concession area comprises about 2,970 square km, covering the territory of the Province of Groningen and the territorial waters adjacent to the Province. The concession area includes part of the Waddenzee, an area in respect of which special environmental/zoning rules and regulations are in force. As a matter of fact any exploitation of the gas reserves situated in that area is ruled out, at least for the foreseeable future. The concession area also includes an area described as the Common Area in the Supplementary Eems I Dollard Agreement of 14 May 1962. Under the terms of this Agreement natural gas produced from the gas reserves situated in the Common Area had to be shared with German concessionaires. NAM was appointed the operator for implementing the provisions of the Agreement. A certain varying amount of subsidence is experienced throughout the concession area. In this matter the partnership agreed to compensate, up to a certain financial limit, third parties which incurred costs or suffered damage in connection with said subsidence. |
| Subsidence, tremors and society | 2001 | Gussinklo, H.J.; Haak, H.W.; Quadvlieg, R.C.H.; Schutjens, P.M.F.M.; Vogelaar, L. | 80(1) | The province of Groningen is flat and level, lying at an elevation close to sea level. The area is intensely cultivated and water table levels are a matter of concern. When the size of the Groningen gasfield was recognized in the sixties, it was realized, that substantial subsidence might occur at the surface affecting a large area. Intensive studies were performed over time to predict future subsidence. These studies are supported by theoretical and experimental research in Shell since the 1950's concerning reservoir compaction and related surface subsidence. To monitor reservoir compaction and surface subsidence on a regular basis, an extensive monitoring program was set up by NAM. The program comprises leveling surveys, GPS measurements, measurements of shallow formation compaction and in-situ reservoir compaction. In Groningen weak earthquakes have occurred since 1991 at irregular intervals. A multidisciplinary study from 1991-1993 on the relationship between gas production and earthquakes in the northern part of the Netherlands, combined with further studies concluded, that under certain circumstances these earthquakes may result from gas production. Monitoring is carried out through a seismic observation network with borehole sensors and locally installed accelerometers. Because of the expected impact of subsidence induced by gas production on surface water management, an Agreement was concluded between the Province of Groningen and NAM. In line with the 1983 Agreement the 'Commissie Bodemdaling' was founded, in which both NAM and the Province of Groningen are represented. On the basis of NAM predictions and actual measurements this Committee determines, what measures are to be taken to prevent, minimize or to correct for effects of gas production induced surface subsidence. |
| Four decades of Groningen production and pricing policies | 2001 | Correljé, A.F.; Odell, P.R. | 80(1) | This paper deals with production and pricing policies for the Groningen gasfield. It will provide an evaluation of the past and a view to its future in a liberalized European gas market. The lifelong production potential and high productivity of the Groningen gasfield is unique. The extremely low-cost field is also unique in the sub-optimal manner in which it has been exploited over the whole of its forty year life to date. Its initial monopolistic situation in the West European energy economy created an opportunity for its development to be limited to production levels, whereby super-normal profits were generated on high value sales at the cost of consumers' welfare. The breach in the monopoly, through competition from Soviet gas, readily able to undercut Groningen prices, posed a serious threat both to unit values and market expansion. Fortunately the fortuitous 1973/4 international oil supplies and pricing crisis restored Groningen's fortunes. Following the upward price adjustments for foreign sales, the stage was set for achieving high company profits and massive government revenues. Dutch society in a broader sense benefited only indirectly through government tax expenditures. Again, energy consumers' welfare gains were ignored. This remains the essence of the situation, pending agreement on the introduction of the liberalized market to meet EU directives. Currently the Dutch gas regime and policy objectives are being adjusted to the requirements of operating in a liberalized market. These changes recognize: first, the invalidity of the government's long-held fears for gas scarcity in such a way, that the earlier steps to restrict both foreign and national sales have been abandoned, and second, the need to reinstate Gasunie as an active, rather than a passive, player in the European gas market, in which other participants have subverted Gasunie's earlier dominance. The second part of the paper will examine, whether and how these changes can be reconciled with the core elements of the Dutch gas policy i.e. state and private revenues, co-ordination of supply and production, the 'small fields policy' and the balancing role of the Groningen field. The liberalization of the European gas market, together with changes in the pattern of supply and demand and stated Dutch policy objectives of energy policy may give rise to conflicts between the interests of the Dutch State, the owners of the field and, again, the consumers. |
| Environmental conditions and paleowind directions at the end of the Weichselian Late pleniglacial recorded in aeolian sediments and geomorphology (Twente, Eastern Netherlands) | 2001 | Huissteden, K.J. van; Schwan, J.C.G.; Bateman, M.D. | 80(2) | The Late Weichselian Pleniglacial wind regime in the eastern Netherlands is reconstructed by means of landform and sedimentological analysis. This analysis involves aeolian and fluvial landforms in the Dinkel river valley in the Twente region. The aeolian deposits considered here date from the Last Glacial Maximum (approximately 22 ka) to the start of the Bølling Interstadial at 14.7 ka. A major event in this period is the formation of a cryoturbation level caused by permafrost degradation, overlain by an erosional hiatus dated between 21 and 17 ka. Both features are attributed to a period of warmer and moister climate, causing permafrost degradation and erosion by surficial runoff. Thereafter aeolian activity prevailed under relatively arid conditions. A deflation surface was formed, the Beuningen Gravel Bed. This deflation surface is present in many Weichselian sections in the Netherlands and the adjacent parts of Belgium and Germany. The deflation occurred concurrently with deposition of coversand at other places. The morphology of the coversand-landscape in the Dinkel valley was controlled by the relief of the pre-existing floodplain and the wind pattern. Coversand ridges consisting of low dunes accumulated near the margins of the active channel belt. Relatively thick sand sheets occur in the leesides of the ridges, thin sand sheets are found at greater distance. Mainly westery sand-transporting winds operated during winter and summer. In winter aeolian deposition occurred by frequent and strong easterþ winds also. On the smallest, local scale, the pattern of deposition was determined by the topography and moisture of the receiving surface. Coversand deposition came to an end with the formation of a sand sheet under relatively warm and less arid conditions. Coversand deposition continued into the Bølling Interstadial; colonization of the coversand surface by vegetation probably has been delayed by nutrient-poor conditions. |
| The climate in The Netherlands during the Younger Dryas and Preboreal: means and extremes obtained with an atmospheric general circulation model | 2001 | Renssen, H. | 80(2) | The shift from the cold Younger Dryas phase to the relatively warm Pre-boreal at ~11.5 thousand years BP occurred within 50 calendar years and represents a clear example of rapid climate warming. Geologists and palaeo-ecologists have extensively studied the impact of this shift on the environment in The Netherlands. The global atmospheric general circulation model of the Max-Planck-Institute for Meteorology is applied to perform simulations of the Younger Dryas and Pre-boreal climates. Here detailed results are presented for the grid-cell representing The Netherlands, providing quantified estimates of climatic means and extremes for both periods. The results suggest that the Younger Dryas climate was characterised by cold winters (temperatures regularly below -20°C) and cool summers (13-14°C), with a high inter-annual variability, strong fluctuations in temperature, frequent storms and snowfall from September to May. The Pre-boreal climate was a 'continental' version of present-day climate, with cooler winters, warmer summers (-2'C difference) and more snowfall, but lower wind speeds. Also, the Pre-boreal climate was wetter than the present and Younger Dryas climates. The main driving factors were the low temperatures of the partly sea-ice covered N Atlantic Ocean and the insolation that was very different from today, with more incoming solar radiation during summer (+30 W/m2) and less during winter (-10 W/m2). The presented detailed results could be valuable for interpreting palaeo-environmental records and for modelling studies on sedimentological processes during the Late Quaternary. |
| Vertebrate track bed stratigraphy of the Röt and basal Lower Muschelkalk (Anisian) of Winterswijk (East Netherlands) | 2001 | Diedrich, C. | 80(2) | The 35.5 m thick Anisian section of the Winterswijkse Steen- en Kalkgroeve (Eastern Netherlands) comprises the Upper Röt (Upper Röt Claystone Member) to the basal Lower Muschelkalk (Oolith Member). In the section 15 terrestrial or marine influenced parasequences are recognized. A fourth order sequence shows the increasing marine influence. New marker beds, ten vertebrate track beds, three bone beds and cephalopod remains have been documented. This enabled correlation to other sections in NSI Germany. The tracks found in the Winterswijkse Steen- en Kalkgroeve at the boundary Röt/Lower Muschelkalk are linked to the oldest known vertebrate skeleton remains of the Germanic Basin. It is the first time that the exact stratigraphic position of these vertebrate remains has been established. In the terrestrial influenced section of the Winterswijkse Steen- en Kalkgroeve, the well preserved vertebrate track ways and vertebrate fauna will be of international importance and will provide new data of the Triassic carbonate tidal flat megatracksite concept and reptiles living in this environment. |
| FT-IR and Raman microscopic study at 293 K and 77 K of celestine, SrSO4, from the middle triassic limestone (Muschelkalk) in Winterswijk, The Netherlands | 2001 | Kloprogge, J.T.; Ruan, H.; Duong, L.V.; Frost, R.L. | 80(2) | This paper describes the Raman and infrared spectroscopy of SrSO4 or celestine from the Muschelkalk of Winterswijk, The Netherlands. The infrared absorption spectrum is characterised by the SO42-modes v1 at 991 cm-1, v3 at 1201, 1138 and 1091 cm-1, and v4 at 643 and 611 cm-1. An unidentified band is observed at 1248 cm-1. In the Raman spectrum at 293 K the v1 mode is found at 1000 cm-1 and is split in two bands at 1001 and 1003 cm-1 upon cooling to 77 K. The v2 mode, not observed in the infrared spectrum, is observed as a doublet at 460 and 453 cm-1.The v3 mode is represented by four bands in the Raman spectrum at 1187, 1158, 1110 and 1093 cm-1 and the v4 mode as three bands at 656, 638 and 620 cm-1. Cooling to 77 K results in a general decrease in bandwidth and a minor shift in frequencies. A decrease in intensities is observed upon cooling to 77 K due to movement of the Sr atom towards one or more of the oxygen atoms in the sulfate group. |
| Laser-diffraction and pipette-method grain sizing of Dutch sediments: correlations for fine fractions of marine, fluvial, and loess samples | 2001 | Buurman, P.; Pape, T.; Reijneveld, J.A.; Jong, F. de; Gelder, E. van | 80(2) | To evaluate correlations between silt and clay fractions determined by pipette method and laser diffraction, samples from Dutch fine marine, fluvial, and loess deposits were analysed by both methods. For fluaial deposits, correlations for fractions 50 μm were excellent (R2 > 0.95), those for 2-4, 4-8, 16-32 and 32-50 μm were satisfactory (R2 = 0.80 - 0.95), while that for the fraction 8-16 μm had an R2 of only 0.68. For marine deposits, correlations for 50 μm were in the same range, but those of all other fractions except 8-16 μm were lower. In the loess samples, correlations for all but the 8-16 μm fraction were unsatisfactory. Laser diffraction gave 42% of pipette clay in marine samples, and 62% in fluvial and loess samples if regressions are forced through 0. Sand fractions detected by laser diffraction were 107% of the sieve fraction in marine samples, and, 99% in the fluvial samples. Correlations for fractions smaller than reference size are generally better than those for individual size fractions. Both the 2 μm and the 50 μm boundary cause problems in the comparison. The first because of platy shape of clay minerals, and the second due to both a change in method in the pipette/sieving procedure, and to non-sphericity of particles. Apparently, correlations for clay- and silt-size fractions obtained by pipette method and laser diffraction will be different for each type of sediment. |
| The atlas of structural geometry: a digital collection of 25 years of analogue modelling | 2001 | Nieuwland, D.A.; Nijman, M. | 80(2) | |
| Preface Evaluation of the potential for large earthquakes in regions of present day low seismic activity in Europe | 2001 | Camelbeeck, T.; Galadini, F.; Meghraoui, M.; Berg, M. van den | 80(3-4) | |
| Late Tertiary fault activity in the southwestern boundary fault system of the Roer Valley Graben | 2001 | Sintubin, M. | 80(3-4) | The Bree Uplift is a particular structure in the direct footwall of the southwestern graben boundary fault system of the Roer Valley Graben, which has been firstly recognized at the base of the Cretaceous. To date fault activity around the Bree Uplift has been confined to the Subhercynian (late Cretaceous) inversion event or considered fading out during Tertiary times. The revision of the existing geological data reveals that the Bree Uplift can still be recognized on the top-Tertiary map. This infers at least a late Tertiary activity, suggesting continuous fault activity in the graben boundary fault system not only on the major boundary faults but also on different splay faults, bounding individual fault blocks. |
| Plio-Pleistocene fault pattern of the Feldbiss fault system (southern border of the Roer Valley Graben, Belgium) based on high resolution reflection seismic data | 2001 | Dusar, M.; Rijpens, J.; Sintubin, M.; Wouters, L. | 80(3-4) | A high-resolution reflection seismic survey was carried out in 1999 over the Feldbiss fault system, the southern border of the Roer Valley graben, in Belgium. Six profile-lines with total length of. 13982 m provided information on the 40-600 m depth range, covering Lower Pleistocene to Miocene strata with special emphasis on the Plio-Pleistocene Kieseloolite formation. Data quality depends on near-surface conditions and on degree of deformation in some fault zones, with better results for seismic detonator sources compared to vibroseis sources. The new data confirm the segmented character of the fault system with occurrence of fault bends, relay ramps and branching of overlapping fault sequences, testifying of the strong tectonic activity during the lower Pleistocene. Antiform structures along the Bichterweerd scarp, relaying the Feldbiss to the Geleen fault in the Meuse valley, are presented as a model for the Tertiary evolution of the Bree Uplift. |
| Morphometric analysis of active normal faulting in slow-deformation areas: examples in the Lower Rhine Embayment | 2001 | Camelbeeck, T.; Martin, H.; Vanneste, K.; Verbeeck, K.; Meghraoui, M. | 80(3-4) | We studied the applicability of classical scarp degradation modelling to active normal faults in the Lower Rhine Embayment. Our quantitative analysis was conducted on the frontal Bree fault scarp (Feldbiss fault) in Belgium and the Peel fault scarp near the city of Neer in the Netherlands. Vertical offset and diffusion age of these scarps have been modelled from elevation profiles across the studied faults using the diffusion equation. For that purposer a computer-program (profil2000) has been written, providing a sensitivity analysis of the determined parameters in function of the spatial repartition of the elevation measurements along the considered profiles. The results of this morphometric analysis have been validated by a comparison with the geologic record of the tectonic activity observed in the trenches excavated at the sites where the measurements have been conducted. We conclude that the modelling can only be applied to study tectonic activity since the Last Glacial Maximum (±14-19 kyr BP) because the surface expression of older paleoearthquakes in unconsolidated Late Pleistocene sediments has been erased by the strong erosive phase that occurred at the end of this glacial period. Even for Holocene scarps, morphologic dating seems very difficult because man-made perturbations destroyed surface evidence of the very recent fault activity in many sites. Nevertheless, we estimate that an appropriate value for the mass diffusivity constant for ~ 1 -m-high scarps in the investigated region is 0.002 to 0.010 m2/yr. On the other hand, vertical offsets can be determined with a good precision. These amount to respectively ~1 m and 1,3 m since the Last Glacial Maximum on the Feldbiss fault in Belgium and the Peel fault near Roermond in the Netherlands. |
| Results of Analysis of Digital Elevation Models Used Site Selection for Paleoseismological Investigations at the Rurrand Fault | 2001 | Hinzen, K.G.; Reamer, K.; Rose, T. | 80(3-4) | Topographic and morphologic models based on detailed Digital Elevation Models (DEM) of the Rur Graben, in particular a 33 km section of the Rurrand Fault, proved to be essential in preliminary investigations for the site selection of a trench for detailed paleoseismological investrgations. The entire DEM in the 33 km Jülich-Düren area displayed as a color-shaded terrain map clearly illustrates the main features of the eastern border fault of the Rur Graben. As investigations concentrated on the 8 x 6 km Stetternich-Hambach section of the Rurrand fault, the use of contoured topographic, gray-shaded terrain and terrain slope maps helped delineate the main features of the surface fault expression. On the basis of topographic profiles constructed from the DEM, no fault scarp could b |
| Geophysical investigations across the Peel boundary fault (The Netherlands) for a paleoseismological study | 2001 | Demanet,D.; Evers, L.G.; Teerlynck, H.; Dost, B.; Jongmans, D. | 80(3-4) | In preparation of the first paleoseismic trenching in the NE border of the Roer graben (the Netherlands), site selection was carried out. Combining geological and seismological information and using existing aerial photographs, seismic reflection and geodetic levelling data, it was decided to focus on the Peel boundary fault near the village of Neer. Detailed information on the exact location of the fault was obtained through geophysical techniques, mainly ground penetrating radar (GPR) and resistivity measurements. GPR data unambiguously showed the flexuring and offset of reflectors affected by the fault. Performing eleven GPR profiles along strike allowed to obtain a 3D picture of the fault, laterally extending the information given in the trench. |
| The Caboneras Fault Zone (southeastern Spain) revisited with Ground Penetrating Radar - Quaternary structural styles from high-resolution images | 2001 | Reicherter, K.R.; Reiss, S. | 80(3-4) | The Carboneras Fault Zone (CFZ) represents an active set of sinistral strike-slip faults in the Betic Cordilleras of southeastern Spain. It constitutes a major segment of the 'Trans-Alboran shear zone' during the Cenozoic, striking NE-SW. The CFZ separates the Cabo de Gata Block (Neogene volcanics) against Neogene basinal sediments and the metamorphic basement of the Alpujarride Complex. Three sites along the CFZ were examined with Ground Penetrating Radar techniques. Radar surveying was complemented by structural studies. Shallow-depth high-resolution imaging of Tyrrhenian beach terraces exhibited both vertical and minor horizontal offsets in the Rambla Morales site in the south. A sinistral strike-slip fault associated with minor thrust faults in a positive flower structure was detected in the middle segment along the La Serrata ridge, sealed by a caliche of late Pleistocene age (> 10 ka). The Playa de Bolmayor section yielded sub-surface evidence for several faults probably related to recent activity of individual fault strands. Our results suggest a distributed tectonic activity of the CFZ during the Late Quaternary. |
| Paleoseismological investigations at the Rurrand fault, Lower Rhine Embayment | 2001 | Lehmann, K.; Klostermann, J.; Pelzing, R. | 80(3-4) | From 1998 to 2000, we have studied the evidence for large paleoearthquakes at the Rurrand Fault. This fault represents the eastern border of the Roer Valley Graben, which is the tectonically most active region in the Lower Rhine Embayment. The purpose of our paleoseismological studies is to enlarge the seismicity data base for this region beyond instrumental records and historical reports using indications of surface-faulting events from stratigraphic conditions at active faults. Larger time spans considered in the earthquake catalogue will enable a more reliable statistical analysis which is required for seismic hazard assessment. Based on analyses of geological data and geomorphologic investigations, detailed geophysical surveying was carried out along the southern Rurrand Fault segment for the selection of a site appropriate to paleoseismological studies. Mapping of physical parameter contrasts with seismic reflection, VES, ERT, and GPR measurements along fault-crossing profiles inferred position and near-surface structure of the fault. At the site promising the best conditions, a trench was excavated across the fault near the city of Jülich, Germany. Within a depth of about 4 m, the Rurrand Fault was exposed in an about 50 m-wide system of faults and fault zones, affecting the stratigraphic sequence with various displacement characteristics and amounts of throw. According to heavy mineral analyses, the deposition time of most the exposed sediment strata was assigned to Pliocene and Lower Pleistocene time. These geological units are covered by loess layers deposited through solifluction processes during the Weichselian glacial, i.e. some tens of ka B.P., or - with lower probability - during the Saalian glacial. Several faults which had also affected the loess reflect younger fault activity. However, clear paleoseismic features were not observed in the trench, thus an unambiguous proof of the occurrence of coseismic fault displacements could not be furnished. Recently, differential subsidence due to drainage takes place in the surroundings of the nearby opencast mining. An amount of some 0.35 m, concentrated in a very narrow lateral zone, has been observed during the last 40 a at about 1 km distance from the trench position. To date, the subsidence could not be clearly located in the trench exposure. Results from geodetic levelling campaigns will help to determine the offset residuals and to gain better insight into the ruling displacement processes at the Rurrand Fault. |
| Paleoseismological analysis of the Rurrand fault near Jülich, Roer Valley graben, Germany: Coseismic or aseismic faulting history | 2001 | Vanneste, K.; Verbeeck, K. | 80(3-4) | A first trench has been excavated for paleoseismological analysis in the German part of the RoerValley graben, which has experienced several historical earthquakes with a maximum intensity up to VIII on the MSK-scale. The trench has exposed the Rurrand fault as a complex fault zone with at least five separate, SW-dipping, normal fault strands displacing an early Pleistocene terrace of the Rhine river by more than 7 m. The major part of the observed deformation was produced during or after deposition of an overlying unit of stratified loess of middle Weichselian to probably Saalian age. The faulting history is shown to be episodic, with different fault strands active at different times. Growth faulting that would be indicative of continuous, aseismic fault motion has not been observed. Our stratigraphic control is not sufficient to constrain the timing and to provide evidence of the coseismic nature for each observed fault displacement. However, two units of structureless, gravelly loess are interpreted as the result of extensive solifluction triggered by two large surface-rupturing events. This is suggested by the position of these units, which is controlled by the main faults, and by their remarkably young age (< 400 cal. BC), indicated by radiocarbon and OSL datings and by the presence of historic brick fragments. At least two faults show moderare activity that is even younger. Our interpretation is not in agreement with earlier hypotheses that ongoing vertical movements of circa 1 mm/a in the German part of the Lower Rhine graben are the result of aseismic fault creep, but is in line with the results of similar investigations on the southwestern border fault of the Roer Valley Graben in Belgium, which demonstrates the need for further paleoseismological research in this region. The Rurrand fault is presently experiencing aseismic slip on its superficial portion, induced by extensive groundwater lowering for mining purposes. This ongoing deformation seems to be expressed in the trench as diffuse bundles of anastomosing cracks extending up to, and in some cases even into the plough zone, rather than as sharp fault planes which are typical of older, tectonic fault movements. |
| The Deposition History of the Coversands along the Bree Fault Escarpment, NE Belgium | 2001 | Frechen, M.; Vanneste, K.; Verbeeck, K.; Paulissen, E.; Camelbeeck, T. | 80(3-4) | The coversands along the Bree fault escarpment, NE Belgium, were investigated by a combined dating approach including infrared optically stimulated luminescence (IRSL), thermoluminescence (TL) and radiocarbon methods. Four trenches were excavated cutting the fault scarp near the village of Bree in northeast Belgium. Altogether 17 luminescence samples and seven radiocarbon samples were investigated in order to set up a more reliable and precise chronological frame for the local coversand stratigraphy and the timing of Late Quaternary earthquake events. The chronological results indicate at least five accumulation periods for the coversand units in the area of interest. The oldest coversands were deposited during Saalian or Early Weichselian followed by coversands deposited during the Early and/or Middle Weichselian. At least three coversand units can be distinguished for the time span of the Late Weichselian to Holocene. Significant TL age underestimation of more than 20% compared to IRSL was found for samples from Trench 4. Most of the IRSL age estimates are in agreement with radiocarbon dates from the same section. |
| Late Quaternary fault movements in the Mt. Baldo-Lessini Mts. Sector of the Southalpine area (northern Italy) | 2001 | Galadini, F.; Galli, P.; Cittadini, A.; Giaccio, B. | 80(3-4) | Paleoseismological investigations have been performed at Mt. Baldo and in the Lessini Mts. in order to collect quantitative data on the activity of minor faults showing geomorphic evidence of recent activation. The 4.5-km-long, NNE-SSW trending Naole fault was responsible for the formation of a narrow depression at the top of Mt. Baldo, bordered by a continuous bedrock (carbonate) fault scarp to the west. The extensional activity along this minor fault is probably due to gravitational deformations (lateral spreading) in response to the warping of the Mt. Baldo anticline. A 1.5-km-long graben is instead related to the 2.5-km-long, NNW-SSE trending Orsara fault (Lessini Mts.) which was responsible for the formation of bedrock (carbonate) fault scarps. This minor fault is part of a complex structural framework made of few-km-long faults which show evidence of Quaternary activity. Two trenches have been excavated across the Naole fault which showed the occurrence of displacement events subsequent to 17435-16385 BP (cal. age) and probably prior to 5455-5385/5330-5295 BP (cal. age).Two other trenches have been excavated across the Orsara fault whose analysis indicated that the most recent displacement event occurred between 20630-19795 BP and 765-675 BP (cal. age). The upper chronological limits of the displacements give some indications about the minimum elapsed time since the last fault activation (about 5,300 years for the Naole fault and 5-8 centuries for the Orsara fault). Both 1) the maximum expected magnitude of the earthquakes which may originate along the Mt. Baldo thrust and 2) the identification of a main fault responsible for the displacements along the complex net of minor faults affecting the Lessini Mts. are still open questions. As for point 1 although historical earthquakes with magnitude 4.5-5 may be associated with the Mt. Baldo thrust, the investigations carried out in this area did not clarifu whether larger magnitude earthquakes may be expected. As for point 2, the cause of the displacements along the Orsara (Lessini Mts.) fault may be related to the activity of a major blind fault (which, however, has never been identified), responsible for the uplift of the Lessini Mts. More generally, the obtained results demonstrate the limits of traditional paleoseismological analyses in Alpine areas whose erosional/depositional activity has been strongly conditioned by the Late Pleistocene glacial history. The lack of units younger than loess and colluvial sediments related to the Last Glacial Maximum makes it impossible to define narrower chronological constraints for the displacements and to estimate the number and size of the displacement events. Moreover, the rebound following the retreat of the thick glacial cover affecting the Alpine area may have induced stresses responsible for higher deformation rates after the Last Glacial Maximum. Higher surficial deformation rates could imply shorter recurrence intervals for faulting episodes and/or larger magnitude earthquakes. Therefore, paleoseismologically inferred data in Alpine areas may not correctly define the fault behaviour related to the present tectonic regime. |
| Application of paleoseismological techniques to the study of Late Pleistocene-Holocene deep-seated gravitational movements at the Montirolo Pass (central Alps, Italy) | 2001 | Onida, M.; Galadini, F.; Forcella, F. | 80(3-4) | Paleoseismological techniques have been used to investigate gravitational deformations at the Mortirolo Pass (Valtellina region, central Alps), in order to improve the knowledge on the activation mechanisms and the evolution of deep-seated gravitational slope movements. The deformation has been responsible for mass sliding towards the Valtellina depression through the activation of several-hundred-metre-long shear planes. Minor shear planes dipping towards the mountain played the role of antithetic structures. Four trenches were excavated across scarps representing the surficial expression of shear planes affecting the bedrock and Late Pleistocene-Holocene deposits. The excavations enabled to investigate the stratigraphy of Quaternary deposits and the geometry and kinematics of the shear planes affecting them. Radiocarbon analyses on organic material contained in sediments and paleosols enabled to define a succession of displacement events which occurred during the Late Pleistocene-Holocene. Collected data indicate the persistence of the activity until recent times (last movement related to 1810-1540 cal. BP). A sudden movement has been detected along one of the main shear surfaces (dipping towards the valley) with a vertical displacement of several metres. In contrast, numerous displacements (with lower vertical offset) have been detected along the antithetic shear planes. Different hypotheses have been proposed in the past to define the origin of huge gravitational movements (glacial retreat, uplift of the Alpine chain, fault activity). However, the Late Pleistocene cycles of glacial loading and unloading on the mountain slopes seem to be the most probable factors causing deep-seated gravitational movements in the investigated region. A recent dramatic landslide in an area adjacent to the investigated one (Mt. Zandila-Valpola) testifies to the paroxistic evolution of the large scale gravitational deformations. The densely inhabited Valtellina region is affected by a large number of gravitational structures similar to those of the Mortirolo area. In consideration of the possible effects of the paroxistic activation of these structures, detailed studies on the chronology and kinematics of the deformations through the application of paleoseismological techniques should therefore be encouraged. |
| Seismogenic faulting in an area of low | 2001 | Masana, E.; Villamarin, J.A.; Sánchez Cabañero, J.; Plaza, J.; Santanach, P. | 80(3-4) | Given that earthquakes do not occur only along high slip-rate faults, slow moving seismogenic faults should be characterized in order to minimize seismic hazard uncertainties. Although no historical earthquakes related to the El Camp fault have been documented, earlier regional geological analysis and the presence of a fault scarp provide evidence of its activity. A paleoseismological study on the southern part of the fault was performed in accordance with the following steps: l) geological and geomorphologic analysis focussing on the detection of evidence for the seismogenic behavior of the fault, 2) near fault analysis to select the best trenching sites, and 3) trenching to establish and characterize the paleoseismic events. Different dating procedures were used in regional and trenching analyses (Thermoluminiscence, U/Th, Radiocarbon, Pollen analysis). The seismogenic nature of the fault was established by the presence of liquefaction features related to the fault, and by the presence of colluvial wedges composed of large angular blocks. We identified a segment boundary to the north of the Porquerola creek and we focussed our attention on the southern segment, which was active after 125000 yr. The slip rate in this southern segment is 0.02 mm/yr. A minimum of three seismic events were detected, from young to old: the last event Z took place some time prior to 1195 yr AD, the penultimate event Y between event X and the Holocene, and, finally, event X occurred after 125000 yr and prior to 60000 yr. The recurrence period is between 25000 and 35000 yr, the elapsed time is estimated to be no longer than 3000 yr; and the maximum estimated earthquake considering both the onshore and the offshore part of the fault is Mw 6.7 +/- 0,5. |
| Preliminary geologic, geomorphologic and geophysical studies for the paleoseismological analysis of the Amer fault (NE Spain) | 2001 | Fleta, J.; Santanach, P.; Goula, X.; Martínez, P.; Grellet, B.; Masana, E. | 80(3-4) | The Amer fault is a 30 km long normal fault, which generated the damaging earthquakes of March and May 1427. Triangular facets, wine glass drainage basins, alluvial fans and scarps along the Amer fault mountain front provide evidence of its recent activity. Topographic profiling, electrical logging, tomographic and high-resolution seismic profiling along the northern segment of the Amer fault showed the following: i) no evidence of surface deformation in recent deposits; ii) fault scarps produced by the Amer fault located only on old alluvial fans, probably Pleistocene in age, and iii) Amer fault related deformation reaching upper Quaternary levels, but not the uppermost horizons. The high sedimentation rate (nearly one order of magnitude greater than the fault slip rate) due to the filling of the lake, which resulted from the damming of the Fluvià river by the Bosc de Tosca lava flow (17,000 yr BP), can account for the absence of surface deformation on Holocene sediments. |
| Active and recent deformation at the Southern Alps-Ligurian basin junction | 2001 | Larroque, C.; Béthoux, N.; Calais, E.; Courboulex, F.; Deschamps, A.; Déverchère, J.; Stéphan, J.F.; Ritz, J.F.; Gilli, E. | 80(3-4) | The SouthernAlps -Ligurian basin junction is one of the most active seismic areas in$ Western Europe countries. The topographic and the structural setting of this region is complex because of (i) its position between the high topography of the Southern Alps and the deep, narrow Ligurian oceanic basin, and (ü) the large number of structures inherited from the Alpine orogeny. Historical seismicity reveals about twenty moderate-size earthquakes (up to M=6.0), mostly distributed along the Ligurian coast and the Vésubie valley. A recent geodetic experiment shows a significant strain rare during the last 50 years in the area between the Argentera massif and the Mediterranean coastline. Results of this experiment suggest a N-S shortening of about 2-4 mm/yr over the network, this shortening direction is consistent with the seismological (P-axes of earthquakes) and the microtectonic data. The Pennic front (E-NE of the Argentera massif) and the northern Ligurian margin are the most seismically active areas. In the Nice arc and in the Argentera massif, some seismic lineaments correspond to faults identified in the field (such as the Täggia-Saorge fault or the Monaco-Sospel fault). In the western part of the Alpes Maritimes, no seismic activity is recorded in the Castellane arc. In the field, geological evidence, such as offsets of recent alluvial sediments, recent fault breccia, speleothem deformations, radon anomalies and others indicates recent deformation along these faults. Nevertheless, to this date active fault scarps have not been identified: this probably results from a relatively high erosion rate versus deformation rate and from the lack of Quaternary markers. We also suspect the presence of two hidden active faults, one in the lower Var valley (Nice city area) and the other one at the base of the Argentera crustal thrust-sheet. Offshore, along the northern Ligurian margin, the seismic reflection data shows traces of Quaternary extensional deformation, but the accuracy of the data does not yet allow the construction of a structural map nor does it allow the determination of the continuity between the offshore and onshore structures. From these data set we propose a preliminary map of 11 active faults and we discuss the questions which remain unsolved in the perspective of seismic hazard evaluations. |
| Major active faults ln Italy: available surficial data | 2001 | Galadini, F.; Meletti, C.; Vittori, E. | 80(3-4) | An inventory of the available surficial data on active faults in Italy has been compiled by gathering all the available information on peninsular Italy (project by CNR, National Group for the Defense against Earthquakes), the central-eastern Alps and the Po Plain (EC 'PALEOSIS' project). Such information has been summarised in maps (reporting surficial expressions of faults with length I>11 km) and in a table where fault parameters relevant for seismic hazard assessment (e.g. slip rates, recurrence intervals for surface faulting events, etc.) have been reported. Based on the geological characteristics of the Italian territory, a fault has been considered as active if it shows evidence of Late Pleistocene-Holocene displacements. Active faults in Italy are distributed throughout the entire Apennine chain, in the Sicilian and Calabrian regions and in some Alpine sectors, but knowledge is not homogeneously distributed through the territory. The largest amount of data is related to the central Apennines. In contrast, fault geometries and parameters are less well defined in the southern Apennines, Sicily and Calabria, where investigations have started more recently. knowledge is sparse in the northern Apeninnes, where data necessary to define fault parameters are lacking and also the chronology of the activity has to be considered cautiously. Abundant blind faulting in the Po Plain hinders the detection of active faults by means of the classical surficial investigations and therefore the present knowledge is limited to the Mantova fault. Blind faults and the peculiar recent geological history of the Alpine areas, which is strongly conditioned by the erosional and depositional activity during and after the last glacial maximum, also hinder the identification of active faults in the central-eastern Alps. Some faults in this Alpine sector are believed to be active, but data on their segmentation are still missing. Available information indicates that Italian active faults are usually characterised by slip rates lower than 1 mm/yr. Recurrence intervals for surface faulting events are longer than 1,000 years in the central and southern Apennines. This review on the Italian active faults represents the first step to produce a map of the major seismic sources in ltaly, which in turn will result from the merge of surficial data with seismological and geological subsurficial data. The available knowledge gathered in this paper indicates those areas where data are presently sparse. It should be, therefore, possible to better plan future geomorphological and paleoseismological investigations. |
| Recent active faults in Belgian Ardenne revealed in Rochefort Karstic network (Namur Province, Belgium) | 2001 | Vandycke, S.; Quinif, Y. | 80(3-4) | This paper presents observations of recent faulting activity in the karstic network of the Rochefort Cave (Namur Province, Belgium, Europe). The principal recent tectonic features are bedding planes reactivated as normal faults, neo-formatted normal faults in calcite flowstone, fresh scaling, extensional features, fallen blocks and displacement of karstic tube. The seismotectonic aspect is expanded by the presence of fallen blocks where normally the cavity must be very stable and in equilibrium. Three main N 070° fault planes and a minor one affect, at a decimetre scale, the karst features and morphology. The faults are still active because recent fresh scaling and fallen blocks are observable. The breaking of Holocene soda straw stalactites and displacements of artificial features observed since the beginning of the tourist activity, in the last century, also suggest very recent reactivation of these faults. This recent faulting can be correlated to present-day tectonic activity, already evidenced by earthquakes in the neighbouring area. Therefore, karstic caves are favourable sites for the observation and the quantification of recent tectonic activity because they constitute a 3-D framework, protected from erosion. Fault planes with this recent faulting present slickensides. Thus a quantitative analysis in term of stress inversion, with the help of striated faults, has permitted to reconstruct the stress tensor responsible for the brittle deformation. The principal NW-SE extension (σ3 horizontal) is nearly perpendicular to that of the present regional stress as illustrated by the analysis of the last strong regional earthquake (Roermond, The Netherlands) in 1992. During the Meso-Cenozoic, the main stress tectonics recorded in this part of the European platform is similar to the present one with a NE-SW direction of extension. The discrepancy between the regional stress field and the local stress in the Rochefort cave can be the result of the inversion of the σ2 and σ3 axes of the stress ellipsoid due to its symmetry or of a local modification at the ground surface of the crustal stress field as it has been already observed in active zones. |
| Seismic hazard analysis results for the Lower Rhine Graben and the importance of paleoseismic data | 2001 | Atakan, K.; Ojeda, A.; Camelbeeck, T.; Meghraoui, M. | 80(3-4) | Seismic hazard in low seismicity areas of Europe has traditionally been considered insignificant. However, in the light of the recently conducted paleoseismic studies along the Rhine Graben, a revision is required. Previously applied standard probabilistic seismic hazard assessment (PSHA) methods, using Poissonian approach for the earthquake occurrence, can now be substituted by renewal models where fault parameters such as the maximum magnitude, recurrence interval and the elapsed time since the last occurrence of a large earthquake, can be utilized. In this study, the application and the influence of the available paleoseismic data in the Lower Rhine Graben to seismic hazard analysis is demonstrated. The resulting hazard, maps, when compared to the standard PSHA using Poissonian approach, indicate a more precise geographical distribution of the estimated seismic hazard levels. The influence of the paleoseismic data seem to be less important for return periods less than a 1000 years. Among the different input models, the highest values reach to 170 cm/sec2 for a 1000 year return period using a combination of Poissonian and renewal models. |
| Modelling of speleothems failure in the Hotton cave (Belgium). Is the failure earthquake induced? | 2001 | Cadorin, J.F.; Jongmans, D.; Plumier, A.; Camelbeeck, T.; Delaby, S.; Quinif, Y. | 80(3-4) | To provide quantitative information on the ground acceleration necessary to break speleothems, laboratory measurements on samples of stalagmite have been performed to study their failure in bending. Due to their high natural frequencies, speleothems can be considered as rigid bodies to seismic strong ground motion. Using this simple hypothesis and the determined mechanical properties (a minimum value of 0.4 MPa for the tensile failure stress has been considered), modelling indicates that horizontal acceleration ranging from 0.3 m/s2 to 100 m/s2 (0.03 to 10g) are necessary to break 35 broken speleothems of the Hotton cave for which the geometrical parameters have been determined. Thus, at the present time, a strong discrepancy exists between the peak accelerations observed during earthquakes and most of the calculated values necessary to break speleothems. One of the future research efforts will be to understand the reasons of the defined behaviour. It appears fundamental to perform measurements on in situ speleothems. |
| Palaeoseismic investigations in Belgian caves | 2001 | Delaby, S. | 80(3-4) | In some karstic caves, the observation of numerous broken stalagmites may provide potential secondary evidence for intense palaeoearthquakes during recent past times. We have named these morpho-sedimentologic features seismothems. A methodology has been developed to discriminate broken speleothems due to earthquake-induced effects or caused by other mechanisms. A study has been carried out in the Belgian karst areas. In the Vesdre Valley, it seems difficult to find evidence of the well-known Verviers earthquake, probably the most destructive historical earthquake known in Belgium which occurred in 1692 AD. The most important concentration of broken stalagmites was discovered in the caves between Hotton and Han-sur-Lesse. The observations in the cave of Hotton suggest a seismic origin, the other origins can not be the cause of the speleothem break. This result implies a strong earthquake situated close to the cave. A preliminary AMS 14C age suggests a minimum age of 10100 ± 1200 cal 14C yr BP. for one stalagmite rupture in the Hotton cave. |
| A large new mosasaur from the Upper Cretaceous of The Netherlands | 2002 | Dortangs, R.W.; Schulp, A.S.; Mulder, E.W.A.; Jagt, J.W.M.; Peeters, H.H.G.; Graaf, D.T. de | 81(1) | We report the discovery of a new species of marine reptile, a mosasaur, from the Upper Cretaceous (Maastrichtian) of The Netherlands. Prognathodon saturator sp. nov. is represented by an almost complete skull and much of the postcranial skeleton, and is one of the largest mosasaurs discovered to date. The stout skull and extremely massive jaws are more powerfully built than in any other known mosasaur. Bite marks, the partial disarticulation and scattering of the skeleton, and the presence of associated teeth of Squalicorax and Plicatoscyllium suggest extensive scavenging by sharks. |
| The Pleistocene College Farm Silty Clay at Great Blakenharn, Suffolk, England - additional information on the course of the early River Thames | 2002 | Moorlock, B.S.P.; Riding, J.B.; Hamblin, R.J.O.; Allen, P.; Rose, J. | 81(1) | The Pleistocene College Farm Silty Clay Member of the Creeting Formation at Great Blakenham, Suffolk, south-east England is shown to contain indigenous and recycled dinoflagellate cysts and other derived palynomorphs. The indigenous dinoflagellate cysts indicate a marine influence during deposition of the clay, whilst the other palynomorphs demonstrate derivation of sediment from a wide catchment of Carboniferous, Jurassic and Cretaceous bedrocks. It is argued, by comparison with palynological data from the Chillesford Clay Member of the Norwich Crag Formation some 25km to the east, that these sediments were eroded from western, south-central and south-eastern Britain, and transported by the early River Thames to its estuary, where they were redeposited at the western margin of the Crag Basin, during the Early Pleistocene Tiglian TC3 Substage. This interpretation refines earlier research which concluded the College Farm Silty Clay was deposited in a predominantly freshwater environment, such as a lagoon, without any direct access to the sea or major river. |
| Deep subsurface temperatures in the Roer Valley Graben and the Peelblock, the Netherlands - new results | 2002 | Balen, R.T. van; Verweij, J.M.; Wees, J.D. van; Simmelink, H.; Bergen, F. van; Pagnier, H. | 81(1) | The deep subsurface temperature data of the Roer Valley Graben have been re-analysed and combined with new temperature data from hydrocarbon exploration wells. The results show that the deep subsurface temperature distribution in the Roer Valley Graben is essentially the same as in the relatively stable high bordering the Roer Valley Graben to the southwest. Thus, the Cenozoic tectonic evolution of the Roer Valley Graben, which is characterized by uplift and denudation during the Late Eocene and subsidence due to rifting starting from Late Oligocene, has hardly affected the temperatures in the graben, which is probably due to the slow subsidence and sedimentation rates. In contrast to what is suggested on previously published temperature maps, the Roer Valley Graben is probably not a relatively cold area in the Netherlands. |
| Internal structure and development of an aeolian river dune in The Netherlands, using 3-D interpretation of ground-penetrating radar data | 2002 | Dam, R.L. van | 81(1) | Ground-penetrating radar data from a regular grid are used to study the internal structure and development of a 9-m high aeolian river dune in the Dutch Rhine-Meuse delta. The purpose of this investigation was to image the internal sedimentary structures to better understand the development of these aeolian river dunes. Three radar facies can be recognised in the GPR sections. Radar facies 1 has a maximum thickness of 5 to 6 m and is characterised by dipping, parallel reflections with a maximum length of at least 20 m. The reflections from perpendicular sections, analysed using closed-loop correlation in 3-D-interpretation software, form eastward dipping (14° maximum) surfaces. Radar facies 2 is one continuous, sub-horizontal reflection. This high amplitude reflection is most probably caused by a thin organic horizon. Radar facies 3 has a thickness of 3 to 4 m and is made up of sets of short, predominantly eastward to north-eastward dipping reflections separated by rather continuous, sub-horizontal reflections. The eastward dipping surfaces in radar facies I are foresets of a dune that was deposited by prevailing westerly winds in the Younger Dryas, the last cold period in the Pleistocene. During the Early Holocene, an increasing vegetation cover stabilised the dune and formed a thin organic horizon. Subsequent resumption of dune forming processes led to the formation of radar facies 3 on top of the vegetated Pleistocene dune. Sedimentation by small dunes, partly eroding each other, led to sets of cross-stratification separated by bounding surfaces. The results suggest a small change in palaeo wind direction. |
| Paleoseismic investigations along the Peel Boundary Fault: geological setting, site selection and trenching results | 2002 | Berg, M. van den; Vanneste, K.; Dost, B.; Lokhorst, A.; Eijk, M. van; Verbeeck, K. | 81(1) | On the basis of a multidisciplinary approach we have unraveled the palaeo-earthquake history of a trenched section across the Peel Boundary Fault. The area shows at present one of the largest contrasts in relative motion on both sides of the fault on the basis of repeated levelling. The geological record for the last 25 thousand years, recovered in the trench, shows evidence of two heavy earthquakes (moment magnitude between 6.0 and 6.6), that occurred in a relatively short timespan around 15 thousands years ago. A third less severe event occurred somewhere in the mid Holocene. The time interval between the two large events is in the order of 1500 years, an interval comparable to that between the last volcanic explosions in the nearby Eifel area. Both records together seem to suggest a relation between large-scale faulting and volcanic activity in the nearby Eifel area, but this interpretation is based on one trench only and should be tested by opening more trenches in the zone that is assumed to be affected by these large events. |
| The coversands and timing of Late Quaternary earthquake events along the Peel Boundary Fault in the Netherlands | 2002 | Frechen, M.; Berg, M.W. van den | 81(1) | The coversands along the Peel Boundary Fault in the Netherlands were investigated by a luminescence dating approach combining Infrared Optically Stimulated Luminescence (IRSL) and Thermoluminescence (TL) methods. At the Neer trench, ten samples were collected and investigated in order to set up an independent chronological framework for the deposition history of the fluvio-aeolian and aeolian sediments and hence the timing of Late Weichselian and Holocene earthquake events. Five sedimentary units could be distinguished by this chronological approach. The oldest fluvio-aeolian unit yielded a mean deposition age of 35.9±0.4 ka and is designated to correlate with the Middle Weichselian. An IRSL age estimare of 20.1±2.9 ka was determined for the sediment that most likely represents the Older Coversands I, and a mean luminescence age of 15.1±1.2 ka for deposits iust below the Beuningen gravel bed. The aeolian sediment from above the Beuningen horizon yielded an IRSL age estimate of 9.4±1.0 ka. The youngest deposits from the colluvial wedge yielded <6.9±0.7 ka BP, and so an earthquake event was likely to occur during the Middle or Late Holocene, as evidenced by the luminescence age estimates. |
| Soil formation in Late Glacial Meuse sediments related to the Peel Boundary Fault activity | 2002 | Miedema, R.; Jongmans, T. | 81(1) | Micromorphological studies relating the soil formation history (processes and timing) to activity events of the Peel Boundary Fault (PBF) showed rotation features (circular distribution pattern of sand grains) in mechanically displaced rounded fragments of Bt bands. These features are interpreted as being caused by 'mudflow' during active faulting event (PBF event F2). The micromorphological interpretation of Late Weichselian soil formation (clay illuviation, degradation features and offsetting of Bt bands) agrees with the hypothesized 3 PBF periods of fault activity events (F1, F2 andF3). |
| Introduction to Pages Symposium, Amsterdam, 3 November 2000 | 2002 | Hooghiemstra, H. | 81(1) | |
| Calibration of the 14C time scale: towards the complete dating range | 2002 | Plicht, J. van der | 81(1) | Radiocarbon calibration based on dendro-chronology and U-series dated corals yield a calibration curve (INTCAL98) well into the Late Glacial, back to ca. 15,600 calendar years ago. Beyond this limit, various calibration curves are produced, mainly based on laminated sediments and various carbonates dated by U-series isotopes. Such calibration curves now cover the complete 14C dating range of about 45,000 years, but are not consistent with each other. Each calibration method (other than dendro-chronology) has its own assumptions and pitfalls. Thus far, the calibration curve obtained from Lake Suigetsu laminated sediments is the only terrestrial (atmospheric) one. |
| Paleogeographic evolution and avulsion history of the Holocene Rhine-Meuse delta, The Netherlands | 2002 | Berendsen, H.J.A.; Stouthamer, E. | 81(1) | Approximately 200,000 lithological borehole descriptions, 1200 14C dates, 36,000 dated archaeological artifacts, and gradients of palaeochannels were used to reconstruct the Holocene evolution of the fluvial part of the Rhine-Meuse delta. Ages of all Holocene channel belts were stored in a Geographical Information System database that enables generation of palaeogeographic maps for any time during the Holocene. The time resolution of the palaeogeographic reconstruction is about 200 years. During the Holocene, avulsion was an important process, resulting in frequent shifts of areas of clastic sedimentation. Palaeogeographic evolution and avulsion history of the Rhine-Meuse delta are governed by complex interactions among several factors. These are: (1) Location and shape of the Late Weichselian palaeovalley. In the Early Holocene, rivers were confined to the Late Weichselian valley. When aggradation shifted upstream) the margins of the valley were crossed by newly formed channel belts. (2) Sealevel rise, which resulted in back-filling of the palaeovalley. (3) River channel pattern. In the central-western part of the delta, a straight anastomosed channel pattern with large-scale crevassing developed as a result of sealevel rise and the associated decrease of stream power. (4) Neotectonics. Differential tectonic movements of the Peel Horst and Roer Valley Graben seem to have influenced river behaviour (formation of an asymmetrical meander belt, location of avulsion nodes in fault zones), especially from 4500-2800 14C yr BP when the rate of sealevel rise had decreased. After 2800 14C yr BP sealevel rise further decreased, and tectonic influence still may have influenced avulsions, but from then on other factors became dominant. (5) Increased discharge, sediment load and/or within-channel sedimentation After 2800 14C yr BP, meander wavelengths increased, which is interpreted as a result of increased bankfull discharge and/or within channel sedimentation. After 2000 14C yr BP both discharge and sediment load increased as a result of human influence. (6) Coastal configuration. The limited number of tidal inlets and extensive peat formation restricted the number of avulsions in the western part of the delta, and enhanced channel reoccupation. (7) Composition of the substrate and river banks. Meandering river channels tended to adhere to the sandy margins of the Late Weichselian palaeovalley, and high channel sinuosity is found in areas where river banks consisted of sand. Peat formation, which was most extensive in the western part of the back-barrier area especially between 4000 and 3000 14C yr BP, more or less fixed the river pattern at that time, hampering avulsions. (8) Marine ingressions, e.g. the 1421 AD St. Elizabeth's flood caused large-scale erosion in the southwestern part of the fluvial deltaic plain, resulting in a shift of the main drainage to the SW. (9) Human influence. Since about 1100 AD human influence dominated the palaeogeographic evolution. Rivers were embanked and natural avulsions did no longer occur. |
| Thermal gradients in Europe during the last glacial-interglacial transition | 2002 | Renssen, H.; Isarin, R.F.B.; Vandenberghe, J. | 81(1) | Temperature profiles along east-west and north-south transects in Europe are presented for four time-slices covering the two most prominent warming phases of the last glacial-interglacial transition: Late Pleniglacial (LP), early Bølling (BL),Younger Dryas (YD), and Preboreal (PB).These temperature profiles are based on two methods: 1) simulation experiments with an atmospheric general circulation model, 2) reconstructions based on terrestrial geological and palaeoecological data. The profiles have The Netherlands as intersection point (52°N, 5°E). During the cold phases (LP and YD), the simulated and reconstructed temperature gradients are very steep in a north-south direction, ranging in January from -25°C in northern Europe (56-60°N) to at least 5°C near the Mediterranean, and in July from 0°C to 20°C. The east-west profiles along 52°N for LP and YD show that temperatures in Eastern Europe were similar to the Atlantic coast (i.e. between -15°C and -25°C). During the warm phases (BL and PB), the temperature regimes resembled present-day thermal conditions, although steeper northsouth and east-west temperature gradients were present during BL and PB. The model simulations suggest that continental Europe was a few degrees warmer during PB and BL than today in July under influence of the relatively high summer insolation. Considering the change of climate through time, the profiles show that in The Netherlands the warming during the two transitions (LP-BL,YD-PB) was relatively small compared to regions to the West and North, whereas in Eastern and Southern Europe the temperature increase is even smaller. This reflects the dominant influence of latitudinal movements of the North Atlantic polar front and associated sea-ice margin. |
| Climatic and environmental events over the Last Termination, as recorded in The Netherlands: a review | 2002 | Hoek, W.Z.; Bohncke, S.J.P. | 81(1) | The Last Termination, or Weichselian Lateglacial (ca 15-10 ka cal. BP), is a time period with rapid changes in climate and environment. The oxygen-isotope records of the Greenland ice-cores are regarded as the most complete climate proxy for the North Atlantic region. In The Netherlands several other proxies have been investigated and dated in great detail over the last few decades. However, changes registered in the different records are not by definition causally related to climate changes. Comparison of the different records on a common time-scale permits evaluation of the interrelationships arid correlations to the Greenland ice-cores. Some events are the result of the complex interplay of different environmental variables and have no causal relationship with climate changes at all. By comparing the different records on a common time-scale and examining spatial patterns, the links between the proxies become evident |
| Preface: Rift tectonics and syngenetic sedimentation - the Cenozoic Lower Rhine Basin and related structures | 2002 | Schäfer, A.; Siehl, A. | 81(2) | |
| Rifting processes in NW-Germany and the German North Sea Sector | 2002 | Kockel, F. | 81(2) | Since the beginning of the development of the North German Basin in Stephanian to Early Rotliegend times, rifting played a major role. Nearly all structures in NW-Germany and the German North Sea - (more than 800) - salt diapirs, grabens, inverted grabens and inversion structures - are genetically related to rifting. Today, the rifting periods are well dated. We find signs of dilatation at all times except from the Late Aptian to the end of the Türonian. To the contrary, the period of the Coniacian and Santonian, lasting only five million years was a time of compression, transpression, crustal shortening and inversion. Rifting activities decreased notably after inversion in Late Cretaceous times. Tertiary movements concentrated on a limited number of major, long existing lineaments. Seismically today NW-Germany and the German North Sea sector is one of the quietest regions in Central Europe. |
| Characterisation and correlation of Tertiary seismostratigraphic units in the Roer Valley Graben | 2002 | Verbeek, J.W.; Leeuw, C.S. de; Parker, N.; Wong, T.E. | 81(2) | Within the Cenozoic sedimentary section of the RoerValley Graben ten seismostratigraphic units have been identified. They are closely related to the lithological framework which makes it possible to recognize them also on well logs in this region. The Lower Tertiary seismic units, representing mainly marine sediments, have a uniform development that can be correlated over large distances into the German part of the Roer Valley Graben. The marine to continental Upper Tertiary and Quaternary seismic units display a more complex development due to lateral facies changes (including prograding delta systems) and rift tectonics |
| Facies interpretation from well logs applied to the Tertiary Lower Rhine Basin fill | 2002 | Klett, M.; Eichhorst, F.; Schäfer, A. | 81(2) | The Cenozoic fill of the Lower Rhine Basin is investigated with data from industry wells and open-cast mines on lignite coal. The geophysical logs of digitised well data are used to calculate lithofacies logs with a newly developed technique. The lithofacies logs allow the interpretation of shallow marine and continental environments in a sequence stratigraphic approach. In addition, base level analysis with both the lithofacies logs and the geophysical logs provide a stratigraphical frame for environment interpretation, modelling, and simulation. |
| Biostratigraphy and paleoecology of continental Tertiary vertebrate faunas in the Lower Rhine Embayment (NW-Germany) | 2002 | Mörs, T. | 81(2) | This paper discusses the faunal content, the mammal biostratigraphy, and the environmental ecology of three important continental Tertiary vertebrate faunas from the Lower Rhine Embayment. The sites investigated are Rott (MP 30, Late Oligocene), Hambach 6C (MN 5, Middle Miocene), Frechen and Hambach 11 (both MN 16, Late Pliocene). Comparative analysis of the entire faunas shows the assemblages to exhibit many conformities in their general composition, presumably resulting from their preference for wet lowlands. It appears that very similar environmental conditions for vertebrates reoccurred during at least 20 Ma although the sites are located in a tectonically active region with high subsidence rates. Differences in the faunal composition are partly due to local differences in the depositional environment of the sites: lake deposits at the margin of the embayment (Rott), coal swamp and estuarine conditions in the centre of the embayment (Hambach 6C), and flood plain environments with small rivulets (Frechen and Hambach 11).The composition of the faunal assemblages (diversity and taxonomy) also documents faunal turnovers with extinctions and immigrations (Oligocene/Miocene and post-Middle Miocene), as a result of changing climate conditions. Additional vertebrate faunal data were retrieved from two new assemblages collected from younger strata at the Hambach mine (Hambach 11C and 14).They are important for the understanding of the Plio-Pleistocene transition in the southern part of the Lower Rhine Embayment and for correlating depositional sequences in the Dutch/German borderland. |
| Facies and paleogeography of the Tertiary of the Lower Rhine Basin - sedimentary versus climatic control | 2002 | Utescher, T.; Mosbrugger, V.; Ashraf, A.R. | 81(2) | Based on recent studies, the impact of global sea-level and climate change on the paleogeographic and sedimentary evolution of the Tertiary of the Lower Rhine Basin is analysed. It is shown that major changes in global climate and sea-level, such as the high-stand during the Middle Miocene climate optimum, the extreme low-stands near the base of the Tortonian and within the Messinian, are clearly reflected in the sedimentary succession. Continental climate curves, as reconstructed from Tertiary macrofloras of the Lower Rhine Basin, can be correlated with the marine, long-term isotope record. As shown by the analyses, a warm and humid climate with mean annual temperatures above 13°C and mean annual precipitation not below 1000 mm, persisted throughout the Late Miocene to Early Pliocene. Continental, high-resolution, climate data show that Late Miocene alternations of lignites and clastics are rather caused by tectonic and sedimentary processes (such as the repeated migration of the river system) than by major climate changes. |
| Stratigraphy and paleoecology of the Late Pliocene and Early Pleistocene in the open-cast mine Hambach (Lower Rhine Basin) | 2002 | Heumann, G.; Litt, T. | 81(2) | More than 400 samples for paleobotanical and sedimentological investigations were collected from Late Pliocene and earliest Pleistocene beds in the open-cast lignite mine Hambach. They were analysed to obtain information about the paleoecology and paleoclimate of this time interval. The sedimentation type changed from a high-energy meandering fluvial system to floodplain, swamp and oxbow lake sedimentation. The typical Tertiary floral elements decreased with the onset of increasingly cooler climatic conditions and disappeared at the beginning of the Pleistocene to be substituted by a impoverished and cold-adapted flora. These combined litho- and biostratigraphic investigations led to an improved and reproducible separation of Late Pliocene from Early Pleistocene deposits. |
| The Pleistocene drainage pattern in the Lower Rhine Basin | 2002 | Boenigk, W. | 81(2) | During the Pleistocene the drainage pattern in the Lower Rhine Basin changed twice, from a flooding of the whole basin by the river Rhine from SW to NE to an influence restricted to the NE only. The first dominance of the river Rhine is documented from the Reuverian to the Tiglian, the second one in the Cromerian. In between this time, the Meuse River drained the central Lower Rhine Basin in NE direction. For the sediments of that river, the term 'Holzweiler Formation' is introduced. Since the Late Cromerian, the influence of the Rhine is again restricted to the NE of the Lower Rhine Basin. The central part of the basin is drained by small local rivers. |
| Neotectonic evolution and sediment budget of the Meuse catchment in the Ardennes and the Roer Valley Rift System | 2002 | Balen, R.T. van; Houtgast, R.F.; Wateren, F.M. van der; Vandenberghe, J. | 81(2) | Using marine planation surfaces, fluvial terraces and a digital terrain model, the amount of eroded rock volume versus time for the Meuse catchment has been computed. A comparison of the amount of eroded volume with the volume of sediment preserved in the Roer Valley Rift System shows that 12% of the eroded volume is trapped in this rift. The neotectonic uplift evolution of the Ardennes is inferred from the incision history of the Meuse River system and compared to the subsidence characteristics of the Roer Valley Rift System. Both areas are characterized by an early Middle Pleistocene uplift event. |
| Pleistocene to Recent tectonics in the Rhenish Massif (Germany) | 2002 | Meyer, W.; Stets, J. | 81(2) | Uplift of the Rhenish Massif can be demonstrated by means of the stream-made river terrace system that accompanies the Rhine river and its tributaries along their way through or within this part of the Variscan fold and thrust belt. The height difference between a former valley floor, especially that of the Younger 'Hauptterrasse' (Main Terrace), and the recent one allows to quantify the uplift by the amount of downcutting erosion. The uplift velocity increased just after the BRUNHES / MATUYAMA boundary, i.e. about 0.8 Ma B.P. Since that time, a domal uplift of more than 250 m is documented in the eastern Hunsrück and in the south-eastern Eifel. The area of this maximum height anomaly is situated just between the East and West-Eifel Quaternary volcanic districts. Thus, causal connections are supposed. The domal uplift is affected by normal faulting partly inherited since Tertiary rifting. |
| Recent movement pattern of the Lower Rhine Embayment from tilt, gravity and GPS data | 2002 | Campbell, J.; Kümpel, H.J.; Fabian, M.; Fischer, D.; Görres, B.; Keysers, C.J.; Lehmann, K. | 81(2) | As part of the activities of the Collaborative Research Centre 'SFB 350', measurements of geodetic and geodynamic changes in the area of the Lower Rhine Embayment and the Rhenish Shield are being performed at different scales in space and time. Continuous borehole tilt measurements and repeated microgravimetric surveys yield information on the local stability of the ground and changes in horizontal gravity gradients that are both dominated by seasonal fluctuations. Results of more than seven years of regular GPS campaigns are discussed in terms of vertical and horizontal point motions. The most prominent motions are man-induced effects occurring in or near the browncoal mining areas, where groundwater withdrawal produces subsidence of up to 2.2 cm/y in the area under investigation. Horizontal and vertical motions at other GPS points are smaller by one order of magnitude and in most cases are only marginally detectable. The eastward motion of two points in the Bergisches Land and the westward motion of two points in the Eifel near the Belgian border may be interpreted as a result of the ongoing extension of the Cenozoic rift system in the western part of the Eurasian plate. |
| Kinernatic subsidence modelling of the Lower Rhine Basin | 2002 | Jentzsch, T.; Siehl, A. | 81(2) | Kinematic geological models can greatly enhance our understanding of the interaction and timing of processes involved in the formation of sedimentary basins. The prototype tool for the calculation and visualisation of such models presented here is aimed at studying subsidence rates and patterns at basin scale: A backstripping algorithm is applied to a geometrical 3Dmodel consisting of prismatic volumes, constructed from an initial set of stacked triangulated surfaces. As a result, we obtain a collection of palinspastically restored volumes for each timestep of basin evolution. The backstripped volumes of each layer are then arranged within a timescene, and the set of timescenes collected as a hierarchical timetree. By interpolating between succeeding key-frames, the subsidence history of the basin can be viewed as an interactive, continuous animation. The approach is illustrated using a high-resolution dataset from the German part of the Cenozoic Lower Rhine Basin. |
| Towards a balanced 3D kinematic model of a faulted domain - the Bergheim open pit mine, Lower Rhine Basin | 2002 | Thomsen, A.; Siehl, A. | 81(2) | In the context of the investigation of the sedimentary and structural evolution of the Cenozoic Lower Rhine Basin, the construction of a volume-balanced kinematic model of a small faulted domain with detailed spatial information on strata and fault geometry from a set of parallel geological sections is under development. A 3D geometry model is built that allows for relative movements of blocks at fault surfaces. Rouby's method of restoration in the map plane is used to determine horizontal displacement fields. The 3D and 3D(t) geometry models are supported by the object-oriented geometry database tool Geo-ToolKit for storage and retrieval of selected parts of the model using queries referring to spatial and temporal criteria, while visualization is based on key frame technique |
| Spatial and Temporal Database Support for Geologists - An Example from the Lower Rhine Basin | 2002 | Breunig, M.; Balovnev, O.; Cremers, A.B.; Shumilov, S. | 81(2) | Within the collaborative research centre SFB350 at the University of Bonn a component software called GeoToolKit has been developed, which is intended to facilitate the design and implementation of 3D/4D geological applications. It provides a range of geo-oriented software building blocks for application developers involving database management system based spatial and temporal data maintenance, support for efficient spatial and temporal retrieval, communication, visualization and graphical interfaces which the user could assemble in a ready-to-use application. As such, GeoTooKit is not a GlS-in-a-box package - rather it is a library of C++ classes that allows the incorporation of spatial functionality within an application under development. It is primarily oriented towards software engineers with the C++ experience involved in the development of special-purpose geological applications, which can hardly be modelled within standard GISs. We present applications using GeoToolKit, which have been developed to support the geological reconstruction of the Lower Rhine Basin. |
| Preface: Special Issue arising from the meeting in Mainz, Germany, of the Fluvial Archive Group | 2002 | Bridgland, D.R.; Sirocko, F. | 81(3-4) | |
| Global correlation of long Quaternary fluvial sequences: a review of baseline knowledge and possible methods and criteria for establishing a database | 2002 | Bridgland, D.R.; Maddy, D. | 81(3-4) | Fluvial sequences, particularly major terrace staircases, represent potential archives of palaeoclimatic fluctuation during the Quaternary. Such sequences can span much if not all of the Quaternary and, provided that dating is possible, can serve as stratigraphical frameworks for correlation with evidence from other depositional environments. In particular, they can provide a terrestrial lithostratigraphical framework that can be correlated with the global marine oxygen isotope record. Fluvial lithostratigraphical frameworks also provide important contexts for records of faunal evolution and human occupation, the latter largely determined from the occurrence of artefacts in fluviatile sediments. This paper announces a new project within the International Geological Correlation Programme, devoted to fluvial sequences (IGCP 449 'Global Correlation of Late Cenozoic fluvial deposits'). It attempts to summarize existing baseline knowledge at the outset of the project and outlines the proposed methods and criteria for establishing a database of fluvial sequences. |
| Geomorphological consequences of weak lower continental crust, and its significance for studies of uplift, landscape evolution, and the interpretation of river terrace sequences | 2002 | Westaway, R. | 81(3-4) | Effects of flow in the lower continental crust have often been ignored in the geomorphological literature on the growth of topography during the Quaternary. However, the ability of the lower crust to flow in response to horizontal pressure gradients, caused by lateral variations in the depth of the base of the brittle upper crust, results in two mechanisms for the growth of topography, which can occur either separately or in combination. First, an increase in the rate of erosion in a region will result in a progressive reduction in the depth of the base of the brittle layer, which will drive inflow of lower crust to beneath the region, which will increase the crustal thickness and thus the altitude of the Earth's surface. It is important to note that this mechanism can increase the mean altitude of the Earth's surface, not just the altitude of summits formed of erosion-resistant rock or other features that are not eroding, which will rise faster than the surrounding eroding landscape. Second, repeated cyclic surface loading by ice sheets or fluctuations in global sea-level will cause net flow from areas of relatively cool lower crust to beneath areas of warmer crust. This process will thus usually result in net flow of lower crust from beneath offshore areas to beneath land areas, thinning the crust and increasing the bathymetry offshore but adding to the crustal thickness and so uplifting the land surface onshore. Although these two processes have different mechanisms, the time scale over which both operate is governed by the time required for heat diffusion, resulting from lower-crustal flow (which is concentrated near the Moho), to affect the position of the base of the brittle layer. As a result, the uplift responses for both processes can be very similar. This means that to resolve the physical cause of uplift at any locality requires knowledge of the regional conditions before uplift began, not just evidence (such as river terrace sequences) from during the course of uplift. This study illustrates the complexities and practical difficulties that can result from these issues, using case studies of localities that have been modeled in detail. It also points out that, although the ability to carry out quantitative calculations involving lower-crustal flow is new, the idea that such flow provides a general mechanism for the growth of topography was first suggested in the early 19th century, but was later abandoned - apparently mistakenly. An early Middle Pleistocene increase in uplift rates is widely-recognised from river terrace records, and typically marks a transition from broad valleys in areas of low relief to narrower, more deeply incised gorges. It is suggested that the isostatic response to cyclic surface loading, caused by the growth and decay of continental ice sheets and the associated sea-level fluctuations, is the main cause of this change, following the increase in scale of ice sheet development from oxygen isotope stage 22 (~0.9 Ma) onwards. The less well resolved earlier increase in uplift rates, evident in some river terrace records at ~3 Ma, is more likely to result from the isostatic response to increased rates of erosion linked to the contemporaneous deterioration in climate. |
| Long-term river terrace sequences: Evidence for global increases in surface uplift rates in the Late Pliocene and early Middle Pleistocene caused by flow in the lower continental crust induced by surface processes | 2002 | Westaway, R. | 81(3-4) | Long-term river terrace sequences reveal that many regions have uplifted by several hundred metres since the Middle Pliocene. They indeed provide evidence of a global increase in uplift rates in the Late Pliocene, followed by a calm period then a renewed increase around the Early-Middle Pleistocene boundary. It is suggested that this uplift pattern has resulted from thickening of the continental crust caused by flow in the lower crust which has been induced by cyclic surface loading caused by growth and decay of ice sheets and the associated global sealevel fluctuations. Observed uplift histories are modelled using a technique which incorporates increases in the strength of forcing of this process caused by step changes in the intensity of glaciations starting at ~3.1, ~2.5, ~1.2, and ~0.9 Ma. |
| An evaluation of climate, crustal movement and base level controls on the Middle-Late Pleistocene development of the River Severn, UK. | 2002 | Maddy, D. | 81(3-4) | The Pleistocene development of the lower Severn valley is recorded in the fluvial sediments of the Mathon and Severn Valley Formations and their relationship to the glacigenic Wolston (Oxygen Isotope Stage 12), Ridgacre (OIS 6) and Stockport (OIS 2) Formations. The most complete stratigraphical record is that of the Severn Valley Formation, which post-dates the Anglian Wolston Formation and comprises a flight of river terraces, the highest of which is c.50 m above the present river. The terrace staircase indicates that the Severn has progressively incised its valley during the post-Anglian period. The terrace sediments are predominantly composed of fluvially deposited sands and gravels, largely the result of deposition in high-energy rivers under cold-climate conditions. Occasionally towards the base of these terrace deposits low-energy fluvial facies are preserved which contain faunal remains and yield geochronology which support their correlation with interglacial conditions. This simple stratigraphy supports a climate-driven model for the timing of terrace aggradation and incision, with the incision mode at its most effective during the cold-warm transitions and the aggradational mode at its most effective during warm-cold climate transitions. The chronology of terrace aggradation in the lower Severn seems to correspond with the Milankovitch 100ka climate cycles. The timing of incision events suggests that base level (eustatic sea-level) changes do not play a significant role i.e. incision occurs as sea-level is rising. Although climate change is significant in governing the timing of incision, the long-term incision of the River Severn appears to be driven by crustal uplift. A long-term incision rate of 0.15 m ka-1, calculated using the base of the terrace deposits, is believed to closely equate with the long-term uplift rate. Superimposed on this long-term uplift are periods of complex terrace sequence development resulting from rapid incision during periods of glacio-isostatic rebound, with large incision events reflecting the rebound adjustment to late glacial stage isostatic depression. However, in no case in the Severn valley has glacial encroachment led to enhanced incision, suggesting that there has been no additional uplift resulting from isostatic compensation for glacial erosion. |
| The fluvial archive of the Middle and Lower Dnieper (a review) | 2002 | Matoshko, A.V.; Gozhik, P.F.; Ivchenko, A.S. | 81(3-4) | Information about the morphology and alluvial sediments of the Dnieper Valley is reviewed. The Dnieper Valley originated in the Late Miocene. The Middle Dnieper Valley is an intercontinental alluvial basin and the Lower Dnieper Valley is a shallow canyon that ends with a delta. Identification of the alluvial dynamic facies (channel, overbank, abandoned channel) is crucial for stratigraphical analysis. The dynamic facies form regular sequences - alluvial suites that combine into series. Individual suites and series are characterized by their mode of occurrence, facies composition, lithological features and expression in the modern landscape. Their stratigraphic position is established with reference to index beds and palaeontological, geochronological and archaeological research, allowing them to be correlated along the valley. Correlation between different parts of the Dnieper system uses a combination of facies and geomorphological analyses, whereas correlation with other river systems makes use of mammalian and molluscan biostratigraphy. Global events (marine regressions and glaciations) that brought about similar reactions in different fluvial systems can be also used for correlation. |
| Correlation of English and German Middle Pleistocene fluvial sequences based on mammalian biostratigraphy | 2002 | Schreve, D.C.; Bridgland. D.R. | 81(3-4) | In this paper interglacial mammalian assemblages from key Middle Pleistocene fluvial sites in Germany are compared to Mammal Assemblage-Zones (MAZs) recently established in the post-Anglian/Elsterian sequence of the Lower Thames, UK. It is believed that four separate interglacials are represented by the Lower Thames MAZs, correlated with oxygen isotope stages (OIS) 11, 9, 7 and substage 5e (although the last of these is Late Pleistocene). Nowhere in Germany can a full sequence of these interglacials be identified from mammalian evidence in a single terrace staircase, as is the case in the Lower Thames, although further research on the Wipper terraces at Bilzingsleben may identify such a sequence. It is also possible that the sequence of overlapping fluvial channels in the lignite mine at Schöningen will eventually produce a comparable mammalian story. Excellent correspondence has been recognized between the mammalian assemblages at Steinheim an der Murr and Bilzingsleben II and the Swanscombe MAZ from the Thames. These three sites are attributed to the Hoxnian/Holsteinian interglacial and are thought to correlate with OIS 11. Close comparison can also be made between the mammalian sequence from the celebrated travertine locality at Weimar-Ehringsdorf and two separate MAZs from Aveley, in the Thames, attributed to separare substages of OIS 7. An equivalent to the Purfleet MAZ of the Thames, which is believed to correlate with OIS 9, has yet to be identified in Germany. |
| Reconstructing Late Quaternary fluvial process controls in the upper Aller Valley (North Germany) by means of numerical modeling. | 2002 | Veldkamp, A.; Berg, M.W. van den; Dijke, J.J. van; Berg van Saparoea, R.M. van den | 81(3-4) | The morpho-genetic evolution of the upper Aller valley (\7eser basin, North Germany) was reconstructed using geological and geomorphologic data integrated within a numerical process model framework (FLUVER-2). The current relief was shaped by Pre-Elsterian fluvial processes, Elsterian and Saalian ice sheets, followed by Weichselian fluvial processes. Structural analysis based on subsurface data and morphological interpretations were used to reconstruct uplift/subsidence rates. A detailed analysis led to the hypothesis that we are dealing with either a NNW-SSE or a WSW-ENE oriented compression leading to uplift in the upper Aller valley. It is also hypothesised that the NNW-SSE compression might have caused strike-slip deformation leading to differential block movement and tilt. Two different uplift rate scenarios were reconstructed and used as a variable parameter in numerical modelling scenarios simulating the Late Quaternary longitudinal dynamics of the Aller. Each different scenario was run for 150.000 years and calibrated to the actual setting. The resulting model settings were consequently evaluated for their plausibility and validity. Subsequently, regional semi-3D simulations of valley development were made to test the two tectonic stress hypotheses. Differential tectonic uplift and regional tilt seems to have played an important role in shaping the current valley morphology in the upper Aller. Unfortunately, due to the uncertainties involved, we were unable to discriminate between the two postulated tectonic stress scenarios. |
| Fluvial deposits as a record for Late Quaternary neotectonic activity in the Rhine-Meuse delta, The Netherlands | 2002 | Cohen, K.M.; Stouthamer, E.; Berendsen, H.J.A. | 81(3-4) | Neotectonic movements have caused differential subsidence in the Lower Rhine Embayment during the Quaternary. The Late Weichselian and Holocene Rhine-Meuse fluvial archive in the central Netherlands was used to quantify neotectonic movements in a setting that was primarily controlled by sealevel rise and climate change. Evidence for neotectonic activity in the central Netherlands is reviewed. Sedimentary evidence shows that fluvial deposits of Late Weichselian and Holocene Rhine and Meuse (Maas) distributaries are vertically displaced along the northern shoulder of the Roer Valley Graben system. Elevation differences in the longitudinal profiles of Late Weichselian terrace deposits were used to quantify tectonic displacements. New results for the southeastern Rhine-Meuse delta (Maaskant area) show that displacements in the top of the Pleniglacial terrace along the Peel Boundary Fault are up to 1.4 m. The maximum displacement between the Peel Horst and the Roer Valley Graben is 2.3 m. This is equivalent to relative tectonic movement rates of 0.09-0.15 mm/yr, averaged over the last 15,000 years. |
| The evolution of river valleys in Lithuania from deglaciation to recent changes and data from the sediment infill of oxbow lakes | 2002 | Gaigalas, A.; Dvareckas, V. | 81(3-4) | Generalized analysis of geological geomorphological structures of river valleys in Lithuania has been carried-out. Lithuania's fluvial topography results from the retreat of the Scandinavian Nemunas (=Vistulian and/or Valdaian) Glaciation, as is shown by the study of geomorphological structures in the recent river valleys (representing the last 15,000 years), which were formed as the ice sheets progressively retreated and ice-barrier lakes were drained. Oxbows in the river valleys are most often located on the floodplain itself and on the first terrace above the floodplain. The oxbow lakes are subdivided into two groups: (1) formed in the near-river stage and (2) formed in the lake-bog stage. Separate development phases can be recognized within both groups of oxbow lakes. The more organic components of oxbow deposits provide specific information for palaeoecological reconstructions. Anthropogenic changes to the natural landscapes of Lithuania have resulted in considerable geological transformation of rivers. Increased sediment volume, shallowing, silting and overgrowing of channels, lateral erosion of floodplains and the spread of ravine erosion on valley-side slopes are all phenomena characteristic of all the valleys in Lithuania. At present the natural components of river valleys and their ecosystems are being changed, mainly with negative consequences for humans. |
| Holocene fluvial response to climate change and human activities; Burgundy, France. | 2002 | Straffin, E.C.; Blum, M.D. | 81(3-4) | Alluvial deposits of the Loire/Arroux trunk/tributary system record distinct, synchronous episodes of regional fluvial adjustment. Changes in facies and depositional style through time can be interpreted with a modern analogue model that relates vegetative cover/human influence with sediment supply and modes of atmospheric circulation with the paths and styles of storms that drive variable discharge regimes across western Europe. Zonal atmospheric circulation results in a Mediterranean style climate over southern Burgundy producing dry conditions punctuated by infrequent, large floods. Episodic overbank sedimentation and the burial of thin paleosols in sandy overbank facies is indicative of this style of fluvial activity, ca 1300 years BP. Humans may have increased the available volume of fine grained sediment at this times through increased agricultural activity along valley axes, however facies match that expected from a 'flashy' discharge regime. In contrast, meridional circulation patterns result in a maritime style climate over southern Burgundy with the intrusion of storms, moist conditions and frequent, moderate magnitude discharges. Wide, deep channels, thick channel facies and thin overbank facies are indicative of this style of fluvial activity, recorded in deposits dating to ca 4050 to 3200 years BP. Stong meridional conditions and extreme climatic variability during the Little Ice Age resulted in very large discharges that straightened and widened channels, while scouring and obscuring older terraces (ca 500 years BP). Deposition over the last two centuries is related to increasingly zonal circulation and infrequent, large (over-bank floods. Changes in fluvial dynamics over the last 300 years can be attributed primarily to climatic control, as there has been very little change in land-use over that period. |
| Young tectonic and halokinetic movements in the North-German-Basin: its effect on formation of modern rivers and surface morphology | 2002 | Sirocko, F.; Szeder, T.; Seelos, C.; Lehne, R.; Rein, B.; Schneider, W.M.; Dimke, M. | 81(3-4) | Field mapping of fluvial terraces, aerial photographs, ground penetrating radar and seismic data from gas and oil exploration were used at four different locations to detect young tectonic and halokinetic movements in the North-German-Basin. i) The course of the Rivers Weser and Aller follow precisely a shallow Tertiary graben on the northwestern flank of the Verden salt diapir. Recent local depressions and vegetation anomalies on the alluvial plain have the same orientation as the strike direction of the faults at subsurface depth. Apparently, the river follows tectonic lines, and thus the river sediments can be used for the interpretation of recent crustal movements. ii) The Wedehof diapir, in contrast, is topped by a local topographic high which follows exactly the shape of the underlying salt. Either the diapir formed an obstacle for the advance of the continental glaciers or one has to assume halokinetic uplift of more than 50 m during the post-Saalian Pleistocene. Either way, the Wedehof diapir shows control of the modern surface morphology by halokinesis. iii) The course of the river Hunte, in contrast, outside the area of salt diapirism, shows anomalies of incision and terrace width over a local updoming caused by tectonic inversion of distinct blocks in the basin. The confluence of several tributaries of the Hunte lies exactly over the updoming of Barnstorf. Thus, the rivers do not avoid the local high, but focus in this area, which is characterised by a graben on top of the domestructure, as visible in seismic profiles. Again, tectonism controls river development. iv) The last case study is from Lake Plön, where seismic profiles reveal that linear shorelines of the lake parallel the flanks of two local graben structures of Tertiary age. It is apparent that the Weichselian glaciers that formed the lake and the surrounding moraines interacted with the existing grabens. The Tertiary morphology in the North German basin was apparently draped by Quaternary glacial deposits, but rivers and lakes that dominate the topography of the modern landscape still reflect the geodynamic centers of Tertiary tectonism and halokinesis. Faults from the depth of the Tertiary penetrate the Quaternary strata and allow upward fluid migration, which becomes visible on aerial photographs as linear vegetation anomalies. |
| Geofluids in the Netherlands: introduction | 2003 | Verweij, J.M. | 82(1) | |
| Reactive-Transport modeling as a technique for understanding coupled biochemical processes in surface and subsurface environments | 2003 | Regnier, P.; Jourabchi, P.; Slomp, C.P. | 82(1) | Reactive-transport models contribute significantly to the field of modern geosciences. A general mathematical approach to solving models of complex biogeochemical systems is introduced. It is argued that even though mathematical models for reactive-transport simulations can be developed at various levels of approximation, the approach for their construction and application to the various compartments of the hydrosphere is fundamentally the same. The workings of coupled transport-reaction systems are described in more detail by means of examples, which demonstrate the similarities in the approach. Three models of the carbon dynamics in redox-stratified environments are compared: porous media flow problems in a coastal sediment and in a contaminated groundwater system; and a surface flow problem in a eutrophic estuary. Considering the interdisciplinary nature of such models, a Knowledge Base System for biogeochemical processes is proposed. Incorporation of the proposed knowledge base in an appropriate modeling framework, such as the Biogeochemical Reaction Network Simulator, proves an effective approach to the modeling of complex natural systems. This methodology allows for construction of multicomponent reactive-transport models applicable to a wide range of problems of interest to the geoscientist. |
| Radionuclide transport in clay during climate change | 2003 | Wildenborg, A.F.B.; Orlic, B.; Thimus, J.F.; Lange, G. de; Cock, S. de; Leeuw, C.S. de; Veling, E.J.M. | 82(1) | The Dutch national research programme into the feasibility of retrievable storage of radioactive waste (CORA Programme Phase I; CORA: Comité Opslag Radioactief Afval = Committee on Radioactive Waste Disposal) examined the suitability of Tertiary clay deposits for such storage. Long-term isolation - up to 1 million years - of high Level radioactive waste under varying conditions is essential. A key concern is the hydro-mechanical response of the clay deposits in which radioactive waste might possibly be stored, in particular during glacial climate conditions as has happened repeatedly in the Netherlands during the Pleistocene. To evaluate this possibility hydro-mechanical computer simulations and mechanical laboratory experiments have been performed to analyse the effects of glacial loading by a thousand-metre-thick ice sheet on the permeability characteristics, fluid flow rates and the associated migration of radio-nuclides both within and out of Tertiary clays. Glacial loading causes the expulsion of pore water from deeply buried clay deposits into adjoining aquifers. The rates and duration of the consolidation-driven outflow of water from the clay deposit, are very sensitive to the permeability of the clay and the dynamics of the advancing ice sheet. The maximum outflow rate of pore water is I mm per year. This rate is approximately three times faster than the flow rate of water in clay prior to ice loading. These preliminary simulation studies also indicate that cyclic loading can result in more rapid migration of radio-nuclides in clays. In clay deposits that are covered by a thick ice sheet, the contribution of dispersed transport relative to the total transport by diffusion amounts to 14%, assuming that there is no absorption of radio-nuclides by the clays and a longitudinal dispersivity of 50 m. |
| Geological processes and the management of groundwater resources in coastal areas | 2003 | Kooi, H.; Groen, J. | 82(1) | In this contribution, a case is made for the significance of sedimentation and sea-level change for groundwater management of coastal areas. In groundwater practice these geological processes are rarely considered. The role of sediment loading in causing anomalous fluid pressures and flow fields in relatively shallow aquifer systems is discussed and illustrated via both case studies and generic modelling studies. The role of sea-level changes in controlling current salinity distributions is discussed likewise. Central in the discussion is the concept of memory of groundwater systems, which provides the basic reason why processes that were operative in the geological past are still of relevance today. It is argued and shown that awareness and knowledge of the influence of sediment loading and sea level change on current hydrological conditions can lead to improved characterization of the distribution of hydraulic parameters and of the distribution of water quality in coastal areas. This improved characterization, in turn, serves to enhance the validity of impact assessment studies for the long-term development and management of those areas. |
| The impact of faults on the hydrogeological conditions in the Roer Valley Rift System: an overview | 2003 | Bense, V.F.; Balen, R.T. van; Vries, J.J. de | 82(1) | The hydrogeology of the Roer Valley Rift System is strongly influenced by the hydraulic properties of faults. The hydrogeological impact of faults is illustrated by examples from the SE Netherlands and the adjacent lignite mining areas within the Roer Valley Rift System, near Bonn in Germany. Hydraulic head discontinuities over the main faults in the latter area can be up to tens of meters as a result of extremely large groundwater extractions in combination with the relatively low conductivity of the main faults. Within the Netherlands, outside the mining areas, such large groundwater extractions do not take place, and groundwater fluxes are smaller. In this situation natural hydraulic head differences over the main faults are limited to several meters. Hydraulic head profiles over faults provide a first estimate of fault hydraulic properties that can be quantified using simple analytical solutions. The impact of faults on near surface processes is reflected in vegetation patterns and the structure of drainage networks, aquifer structure and hydraulic head patterns. Faults can thus be of great influence on transport processes in the subsurface as well as on water-related phenomena at the surface, and should accordingly be taken into consideration in studies related to water-management) contamination and environmental impact. Faults that have an enhanced vertical permeability are difficult to detect when horizontal groundwater flow is studied, which is probably the main reason why they are rarely described. Though, these faults may form important preferential paths to vertical groundwater flow. |
| Fluid flow in the northern Broad Fourteens Basin during Late Cretaceous inversion | 2003 | Bouw, L.; Oude Essink, G.H.P. | 82(1) | A basin-scale hydrogeological study of the inverted northern Broad Fourteens Basin, Netherlands offshore, has resulted in a reconstruction of geological evolution, an estimate of Late Cretaceous topography and model scenarios of syn-inversion meteoric water infiltration. This study was performed in the scope of a basin-scale analysis of the hydrogeological setting and hydrodynamic evolution of the Broad Fourteens Basin. This analysis is aimed at obtaining quantitative knowledge of depositional history and hydrogeological parameters, and qualitative knowledge of hydrodynamic evolution of the Broad Fourteens Basin from Carboniferous to present-day. We present an overview of the tectonic and depositional history the most likely hydrogeological setting and model scenarios of Late Cretaceous meteoric water infiltration in the northern Broad Fourteens area. We constructed a detailed south-west north-east geological cross-section of the present-day northern Broad Fourteens Basin, and reconstructed Late Cretaceous basin geometry and topography. Using this geometry in a numerical model of density-dependent topography-driven fluid flow, we modelled several scenarios of meteoric water infiltration with estimated ranges of basin-scale permeabilities and water table head. Results indicate that a deep freshwater lens was developed during Late Cretaceous inversion, if the basin-scale hydraulic conductivity of the Rijnland and Altena Groups was at least 1•10-9 to 1•10-10 m/s, which is in general the highest value for claystones. |
| History of petroleum systems in the southern part of the Broad Fourteens Basin | 2003 | Verweij, J.M.; Simmelink, H.J.; Balen, R.T. van; David, P. | 82(1) | 2D Basin modelling was used to evaluate the response of source rock maturation, and of petroleum expulsion, migration, accumulation and preservation to the evolution of the southern part of the inverted Broad Fourteens Basin. Modelling results show that the temperature, maturation and petroleum generation history as well as migration characteristics of both the Jurassic oil systems and the Carboniferous gas systems vary over short distances relative to the differences in burial history of the basin. Model results indicate that no major gas accumulations are preserved in the Slochteren Formation along the cross-section at present-day. Gas accumulations are predicted in sandstone-dominated Triassic units in the southern part of the section. Present-day oil accumulations predicted in the Vlieland Sandstone Formation sealed by the Vlieland Claystone Formation (in P9 and Q1 crestal structures) are in accordance with known oil accumulations. Additional oil accumulations are predicted in the sandstone-dominated Middle Werkendam Member, and in sandstones of the Delfland Subgroup. The modelling offers an explanation for the different geochemical compositions of the accumulated oils in the P9 and Q1 areas. Modelling implies, that the oils in the Q1 oil field were sourced by remigrated oils expelled over time, from early mature to mature source rocks of the Posidonia Shale Formation. The biodegraded and water-washed nature of the Q1 oil is explained by the concentrated topography-induced groundwater flow through the Vlieland Sandstone Formation during the Late Cretaceous inversion of the basin. The oils accumulated in the P9 area were sourced from an early mature part of the Posidonia Shale Formation and were probably not affected by water washing and biodegradation because of post-inversion charging of the reservoir. |
| Expressions of shallow gas in the Netherlands North Sea | 2003 | Schroot, B.M.; Schüttenhelm, R.T.E. | 82(1) | Surface and sub-surface expressions of shallow gas in the Netherlands part of the southern North Sea are described, using standard E&P 2D and 3D seismic surveys, as well as higher frequency acoustic surveys. Surface expressions observed are pockmarks, which are geomorphologic features at the seabed indicative for venting of gas, and cemented sandstones. The subsurface expressions found comprise both phenomena indicating efficient trapping of gas in reservoir sands, such as shallow bright spots and flat spots, and phenomena, which are indications of migration or leakage to the seabed. We refer to the latter as 'seismic anomalies indicating leakage'. These anomalies include gas chimneys or seismic chimneys. All chimneys found in the area have in common, that they belong to a seepage style, which is called 'small and localised'. Much of this seepage is situated over salt domes, with the accompanying normal fault above the domes acting as pathways for the gas or fluids. Although there is admixture of biogenic gas, it is believed that many of the features observed relate to thermo-genic gas. |
| Editorial Netherlands Journal of Geosciences | 2003 | 82(2) | ||
| Relative water-level rise in the Flevo lagoon (The Netherlands), 5300-2000 cal. yr BC: an evaluation of new and existing basal peat time-depth data | 2003 | Makaske, B.; Smeerdijk, D.G. van; Peeters, H.; Mulder, J.R.; Spek, T. | 82(2) | The rise of Holocene (ground)water level as a function of relative sea-level rise has been extensively investigated in the western Netherlands, whereas few studies focused on the Flevo lagoon in the central Netherlands. In this study, all available 14C dates from the base of basal peat overlying the top of compaction-free Pleistocene sand in the former Flevo lagoon were evaluated in order to reconstruct water-level rise for the period 5300-2000 cal. yr BC. The present basal peat 14C data set from Flevoland consists of two subsets: (1) the largely new Almere data (41 dates) representing the southern part of the former Flevo lagoon, with 26 dates especially carried out for this study and (2) the existing Schokland data (21 dates) representing the eastern part of the lagoon. The Schokland area is located about 50 km from the Almere area. The quality of all basal peat time-depth data was palaeo-ecologically and geologically evaluated, all 14C dates were calibrated to the same standards, and error margins of age and altitude determination were estimated. After plotting the data as error boxes in time-depth graphs, lower limit curves for water-level rise were constructed for both data sets. Comparison with the mean sea-level curve for The Netherlands (Van de Plassche, 1982) suggests that water-level rise in the Almere area between 5300 and 2000 cal. yr BC corresponded closely to the rise in mean sea level. The same holds for the Schokland area for the period 5000-4200 cal. yr BC. For the period 4200-2000 cal. yr BC, however, the Schokland data suggest water-level rise to have been slower than mean sea-level rise, leading to local water levels apparently below mean sea level, which is virtually impossible. Hypothetical explanations for this discrepancy include: errors and uncertainties in mean sea level and local water-level reconstruction, basin subsidence and temporal differences in intra-coastal tidal damping. The presently available data are inconclusive at this point and Holocene water-level rise in the Flevo lagoon awaits further investigations. |
| The origin of brackish and saline groundwater in the coastal area of the Netherlands | 2003 | Post, V.E.A.; Plicht, H. van der; Meijer, H.A.J. | 82(2) | An explanation is presented for the origin of brackish to saline groundwater in the coastal area of the Netherlands based on geological, chemical (chlorinity), isotopic and geophysical data. A critical review of all possible salinization mechanisms shows that the origin of the brackish water is related to former transgressions. Both the vertical salinity distribution and the carbon-14 activity of the groundwater indicate that connate sea water from the Pliocene to Early Pleistocene is not the source of the brackish to saline waters in the overlying Pleistocene fluvial aquifers. Instead, it derives from Holocene transgressions. The salinization mechanism is discussed in relation to the paleogeographical development during the Holocene and the occurrence of low-permeability strata. Finally, freshening of the aquifers following retreat of the sea is briefly considered. |
| The paleosol in the Kerkom Sands near Pellenberg (Belgium) revisited | 2003 | Herreweghe, S. van; Deckers, S.; DeConick, F.; Merckx, R.; Gullentops, F. | 82(2) | In an area east of Leuven (central Belgium), a buried sandy estuarine deposit of Oligocene age contains a dark colored organic layer of about 4 m thick. Our results suggests that the organic matter is an illuvial horizon, therefore warranting the hypothesis that the layer may qualify for a giant buried spodic horizon rather than a remainder of a Tertiary oil seepage as suggested by Van Riessen and Vandenberghe (1996). Of particular importance is the micro-morphological evidence, which reveals that the mainly monomorphous organic matter is present as ubiquitous coatings and concentrations around the quartz grains. These coatings show the for Podzols very typical polygonal cracked patterns. The geochemical signature (stable carbon isotope analysis) also gives strong indications for â continental origin of the organic carbon and therefore support the pedogenetic origin of the horizon. The paleopedological scene into which this soil has developed is inferred from the data. |
| Turtle remains (Testudines, Chelonioidea) from the Middle Turonian of northwest Germany | 2003 | Diedrich, C.; Hirayama, R. | 82(2) | Turtle remains ascribed to the family Cheloniidae (Testudines, Cryptodira, Chelonioidea), collected from the lamarcki zone (Middle Turonian) at Wüllen (NW Germany) are described. The material consists of a right humerus, a scapula, a complete costalia, and costalia fragments of a single individual with the humerus indicating a primitive cheloniid of the 'toxochelyid grade'. The present material, as well as previously recorded chelonioid humeri from the Cenomanian and Turonian of Germany illustrate a progressive diversification of chelonioids during the early Late Cretaceous |
| Deformation of the Carboniferous of the Oldenburg High and the Location of the Variscan Front in Northwest Germany | 2003 | Hartmann H. von | 82(2) | The article tries to answer the question of the origin and structural development of the deformation of the pre-Permian units southwest of Bremen. An interpretation of a 3D-seismic survey was made to resolve the structural style of the Upper Carboniferous with the aim to get some clues for the Variscan deformation of the Variscan foreland. The area is suitable for the evaluation because of the existence of a 3D-seismic survey. Moreover, the depth of the Zechstein at. 4500 m is not to deep for imaging deeper reflections and there is not a severe distortion of the reflection pattern by later tectonic developments. Because of the 3D insight into the complex and deep seated structures, other 2D-seismic investigations which image similar parts can be better understood and interpretation errors can be avoided. It is concluded that only 3D-seismic measurements can resolve the complex structural development at this site. |
| Late Quaternary tectonic evolution and postseismic near surface fault displacements along the Geleen Fault (Feldbiss Fault Zone – Roer Valley Rift System, the Netherlands), based on trenching | 2003 | Houtgast, R.F.; Balen, R.T. van; Kasse, C.; Vandenberghe, J. | 82(2) | In northwest Europe the pattern of earthquake distribution is correlated with known Quaternary faults. Excavation of fault scarps revealed that these fault zones have been active during the Late Pleistocene. In this paper we present the results, of an exploratory trenching study across the Geleen Fault, part of the Feldbiss Fault Zone, the Netherlands. Middle Saalian fluvial deposits of the Meuse, overlain by local slope deposits, were excavated.The Geleen Fault has displaced the fluvial deposits by at least 5 meters. The upper layers of local slope deposits could be correlated across the fault and were all dated at approximately 15 ka B.P. This gives the opportunity to reconstruct the sequence of events that occurred about 15 ka ago. Liquefactions provide evidence for an earthquake event. However, the main offset along the Geleen Fault is not stratigraphically related to the liquefactions. The liquefactions and the fault offset are stratigraphically separated by a period of erosion. We therefore propose a sequence of events starting with an earthquake accompanied by liquefaction, followed by a period of postseismic displacement with high rates compared to the long-term average. After this period normal displacement rates occurred, comparable to the long-term average. The duration of the period of high displacement rates could not be determined. |
| Boron metasomatism in the Brabant Massif (Belgium): Geochemical and petrographical evidence of Devonian tourmalinite pebbles | 2003 | Corteel, C.; Paepe, P. de | 82(2) | New petrographical and geochemical evidence of tourmalinite pebbles from two Lower and three Middle Devonian formations from Belgium is presented. Petrography, REE, transition metal and microprobe data of the studied rocks suggest it are (meta)sediment-derived tourmalinites formed by boron metasomatism (and hydrothermal brecciation) in an intrusive setting. Tourmaline mineralizations within eastern Avalonia are known in south-east Ireland, the English Iake District and East Anglia. Based on previously suggested relations between Early Palaeozoic igneous activity in last two mentioned regions and the Brabant Massif, it is presumed that the Brabant Massif also underwent granite-related tourmalinization and that this was the source of the studied pebbles. Petrologic differences between pebbles found in Middle Devonian formations and pebbles from Lower Devonian formations, suggest that fluid circulation occurred on a regional scale, possibly extending into the Stavelot massif. |
| Identification by RAMAN Microscopy of rnagnesian vivianite formed from Fe2+, Mg, Mn2+ and PO43- in a Roman camp near fort Vechten, Utrecht, The Netherlands | 2003 | Kloprogge, J.T.; Visser, D.; Martens, W.N.; Duong, L.V.; Frost, R.L. | 82(2) | The presence of a magnesian vivianite (Fe2+)2.5(Mg,Mn,Ca)0.5(PO4)2.8H2O, has been identified in a soil sample from a Roman camp near Fort Vechten, The Netherlands, using a combination of Raman microscopy and scanning electron microscopy. An unsubstituted vivianite and baricite were characterised for comparative reasons. The split phosphate-stretching mode is recognised around 1115,1062 and 1015 cm-1, while the corresponding bending modes are found around 591,519, 471 and 422 cm-1. The substitution of Mg and Mn for Fe2+ in the crystal structure causes a shift towards higher wavenumbers compared to pure vivianite. As shown by the baričite sample substitution causes a broadening of the bands. The observed broadening however is larger than can be explained by substitution alone. The low intensity of the water bands, especially in the OH-stretching region between 2700 and 3700 cm-1 indicates that the magnesian vivianite is partially dehydrated, which explains the much larger broadening than the observed broadening caused by substitution of Mg and Mn in vivianite and baričite. |
| The first record of siegenite (Ni,Co)3S4 from the Netherlands | 2003 | Bongaerts, H. | 82(2) | Epigenetic mineralisations occurring in the former coal-mining district of Limburg predominantly consist of sphalerite, galena, chalcopyrite, quartz, Fe-dolomite/ankerite and calcite. The present note describes siegenite which was collected for the first time from this paragenesis some years ago. |
| The 150th anniversary of the Maastrichtian Stage - a celebratory conference: Introduction | 2003 | Jagt, J.W.M.; Schulp, A.S.; Graaf, D.T. de | 82(3) | |
| Oligotrophic oceans and minimalist organisms: collapse of the Maastrichtian marine ecosystem and Paleocene recovery in the Cretaceous-Tertiary sequence of New Jersey | 2003 | Gallagher, W.B. | 82(3) | The inner Atlantic Coastal Plain of New Jersey reveals exposures of fossiliferous Maastrichtian and Danian deposits. Recent fossil discoveries in this interval are here reported, and placed in the context of Cretaceous/Tertiary (K/T) faunal changes. The exposure at the Inversand Pit at Sewell (New Jersey) is the last active marl mine in the region, and stands as an important reference section for the many significant discoveries of vertebrate fossils produced by the marl mining industry at its zenith. Changes in planktonic populations across the I(JT boundary are related to Maastrichtian/Danian marine ecosystem community reorganisation, by demonstrating changes in abundance of dominant marine invertebrates in successive fossil assemblages. Marine invertebrates with non-planktotrophic larval stages were briefly the commonest fossils preserved in the Danian sediments of this region. Late surviving examples of Cretaceous fauna now restricted to the Indo-Pacific region may imply biogeographic changes linked to the K/T mass extinction event. |
| Stratigraphy of Maastrichtian Forarniniferida from the United Kingdom; the Maastrichtian of Norfolk | 2003 | Hart, M.; Swiecicki, T. | 82(3) | Onshore Maastrichtian strata in the United Kingdom are limited to a few small, isolated blocks of chalk floating within glacial sediments on the Norfolk coast. Isolated outcrops of Campanian and Maastrichtian chalks used to be available around Norwich but the majority of these exposures are now badly degraded. Offshore, in the North Sea Basin, there are complete chalk successions that range throughout the Upper Cretaceous and Lower Cenozoic. There is a limited succession of Maastrichtian chalks exposed on the north coast of Northern Ireland below the Cenozoic flood basalts. In the Western Approaches Basin, Maastrichtian and Danian chalks are known from exploration wells and core samples. West of the United Kingdom a number of DSDP/ODP boreholes have penetrated the Upper Cretaceous succession. Beginning in the Cenomanian, in southeast England, the whole of the Upper Cretaceous is within the chalk facies, possibly one of the longest intervals of relatively stable environment in the geological record. The Foraminiferida of the chalk have been studied for more than a hundred years and therefore the fauna is exceptionally well known and fully documented. Fifty years ago, the benthonic Foraminiferida were identified as having the potential to provide a viable zonation of the chalk facies and we now have precise, cross-basinal correlation using these taxa. The planktonic fauna is restricted by both palaeolatitude and water depth. The latter appears to be the most influential as the faunas from onshore are more limited than those recorded from the deeper waters of the North Sea Basin and the Atlantic Margin. Even with this restricted fauna, however, it is still possible to develop a general correlation with the standard Tethyan zonation based on planktonic taxa. |
| The echinoid genus Echinogalerus in the Maastrichtian type arrea | 2003 | Ham, R. van der; Birgelen, M. van | 82(3) | The Late Cretaceous echinoid genus Echinogalerus König, 1825 is remarkably diverse in the Maastrichtian type area (SE Netherlands and adjacent parts of NE Belgium and western Germany). So far, five species have been recognised, namely. E belgicus (Lambert, 1898), E. minutus (Smiser, 1935), E. muelleri (Schlüter, 1902), E. pusillus Lambert, 1911 and E. vetschauensis (Schlüter, 1902), which occur from the base of the Lower Maastrichtian (E. belgicus, E. pusillus, E. muelleri up to the K/T boundary (E. minutus). Echinogalerus muelleri, which has the longest stratigraphical range, is the most diverse, while E. pusillus is the smallest echinoid in the area, reaching maximum lengths of 4.5 mm. Comparisons with other species of Echinogalerus described in the literature have now led to the recognition of three tentative infrageneric alliances. It is argued that the ordinal position of Echinogalerus (Holectypoida or Cassiduloida) cannot be evaluated as long as many species are still insufficiently known and two genera, from the Maastrichtian of northern Germany and Denmark, intermediate between the two orders, remain undescribed. |
| The stratigraphic range of the index ammonite Pachydiscus neubergicus (von Hauer, 1858) in the type area of the Maastrichtian Stage1 | 2003 | Jagt, J.W.M.; Felder, W.M. | 82(3) | In the extended type area of the Maastrichtian Stage (southern Limburg, the Netherlands; provinces of Limburg and Liège, Belgium; Aachen area, Germany), the pachydiscid Pachydiscus (P.) neubergicus (von Hauer, 1858) ranks amongst the rarer species of Campanian-Maastrichtian ammonites. To date, just four specimens are known, which show P. (P) neubergicus in this area to have been confined to the Vijlen Member (Intervals 0-6, Gulpen Formation). This would correspond to the basal sumensis Zone to the lower cimbrica Zone, or tegulatus/junior Zone, depending on placement of the Lower/Upper Maastrichtian boundary. Material available has been collected in recent years at the CBR-Lixhe (Liège, Belgium) and ENCl-Maastricht by (Maastricht) quarries as well as from outcrop 62D-26 at Vijlenerbosch (Vijlen, the Netherlands). Records of P. (P.) neubergicus, the proposed index for the base of the Maastrichtian Stage, from elsewhere in Europe (northern Spain, SW France, Austria, Denmark, Bulgaria), suggest it to have been fairly long-ranging and show local first occurrences to have been diachronous. |
| On the alleged presence of Halisaurus (Squarnata, Mosasauridae) in the latest Cretaceous of the Maastrichtian type area, | 2003 | Mulder, E.W.A. | 82(3) | The presence of Halisaurus (Squamata, Mosasauridae) in the uppermost Cretaceous of the Maastrichtian type area, suggested by Lingham-Soliar (1996) on the strength of two partial vertebrae, is questioned. The anatomy of these elements suggests that they pertain not to Halisaurus, but more probably to Plioplatecarþus marshi Dollo, 1882. |
| Faunal/floral and isotopic responses to Milankovitch precession cycles and environmental changes in the upper Gulpen Formation (Upper Maastrichtian) at the CBR-Lixhe and ENCl-Maastricht by quarries | 2003 | Felder, P.J.; Keppens, E.; Declercq, B.; Normand, S.; Streel, M. | 82(3) | Two sections, just below the Nivelle Horizon in the upper Gulpen Formation (Upper Maastrichtian), and seven kilometres apart (CBR-Lixhe and ENCl-Maasticht by quarries) have been analysed (samples every 5 cm) for dinocyst, pollen grains and bioclast contents as well as for carbon and oxygen isotopic composition, to obtain better insight into the influence of weathering on these sediments. The CBR section lies above groundwater level, while that at the ENCI quarry is some metres below. At the former quarry we recognised the influences of weathering (karst) nearby. At ENCI, palynological, bioclast and stable isotope results of the carbonate phase (mainly consisting of coccoliths) co-vary remarkably displaying two cycles which may be interpreted tentatively as climatic fluctuations. The δ18O curve varies roughly between -1.6‰ and -1,.1‰ (on PDB scale), corresponding to a temperature change of about 2°C. Less negative values (i.e. cooler seawater) coincide with larger amounts of pollen of Normapolles and Triporates type assumed to represent temperate forest elements of a vegetation also containing tropical elements such as palms. Assuming the 5 cm sample intervals at ENCI to correspond to 1 ka, climatic maxima (and minima) may be 20-25 ka apart, obviously recalling Milankovitch precession cycles. These are independent of a sharp sedimentological change noted in the upper part of the lowest cycle (samples 42 to 24). Upwards of sample 2,bioclast contents increase and dinocysts, Spiniferites in particular, decrease significantly, corresponding to a marked shallowing. This turning point is also recorded in the ât3C curve at ENCI. Bioclast percentages appear to follow composite trends that are influenced by both climatic and sedimentological conditions. |
| Correlation of calcareous nannofossil zones to the local first occurrence of Pachydiscus neubergicus (von Flauer, 1858) (Ammonoidea) in European Upper Cretaceous sections | 2003 | Wagreich, M.; Küchler, T.; Summesberger, H. | 82(3) | The first occurrence (FO) of the ammonite Pachydiscus neubergicus (von Hauer, 1858) has been correlated to calcareous nannofossil zonations in several European sections along the northern margin of the Tethyan palaeobiogeographic realm. Both the proposed stratotype section of Tercis (SW France) and complete, ammonite-bearing sections in northern Spain document the FO of P. neubergicus within standard nannofossil zone CC23a (UC16), below the LO of Broinsonia parca constricta. Other sections such as the type locality Neuberg (Austria), Nagoriani (the Ukraine) and Bjala (Bulgaria) indicate considerable diachroneity of local FOs and show P neubergicus to range up to nannofossil zone CC25b/c (UC20; Late Maastrichtian). |
| Diagenesis, regular growth and records of seasonality in inocerarmid bivalve shells from mid-Maastrichtian hemipelagic beds of the Bay of Biscay | 2003 | Gómez-Alday, J.J.; Elzora, J. | 82(3) | Inoceramid bivalve shells from outcrops of mid-Maastrichtian deep-water carbonate, hemipelagic beds in the Bay of Biscay exhibit post-depositional diagenetic alteration. New data from isotopic analysis (carbon and oxygen), together with observations of the inoceramid shells and carbonate host-rock using cathodoluminescence (CL) and scanning electron microscopy (SEM), confirm a lateral, westerly increase in the degree of diagenesis, without any substantial textural changes in the alternating dark and clear growth lines of the shell microstructure. Under CL, a bright yellowish to red colour is observed in the most diagenetically altered inoceramid samples. Non-luminescent areas are restricted to the central parts of the less altered shells. A detailed geochemical analysis by electron microprobe, along intrashell profiles of the non-luminescent and luminescent zones has revealed that Mg/Ca, Sr/Ca, Na/Ca, Fe/Ca and Mn/Ca ratios show oscillatory curves but behave differently. Fe/Ca, Mn/Ca and Na/Ca ratios are well correlated but usually show an opposite relationship when compared with the Mg/Ca and Sr/Ca ratios of both luminescent and non-luminescent shell areas. Our findings have palaeoenvironmental implications in that the geochemistry of the regular, alternating dark and clear growth lines seems to be related to the input of seasonally controlled phytodetritus to the basin floor. |
| First record of Pachydiscus noetlingi Kennedy, 1999 (Ammonoidea) from the Maastrichtian type area (the Netherlands) | 2003 | Jagt, J.W.M.; Kennedy, W.J. | 82(3) | Two specimens of a pachydiscid ammonite, a fragmentary silicified phragmocone from the Kunrade Limestone facies at Kunrade (Schunck), and a partial external mould preserved in flint from the Nekum Member (both Maastricht Formation, Belemnitella junior Zone of authors) at the former Blom quarry (Berg en Terblijt), are identified as Pachydiscus (P) noetlingi Kennedy, 1999, a species previously known only from the Upper Maastrichtian of Baluchistan (Pakistan). This new record underscores the proposal of incursions of Tethyan biota into the type area of the Maastrichtian Stage, previously documented for other groups, including echinoderms and bivalves, as well. |
| Maastrichtian or Maestrichtian? A proposal to the Subcommission on Cretaceous Stratigraphy (IUGS, International Commission on Stratigraphy) | 2003 | Herngreen, G.F.W. | 82(3) | This contribution deals with the dual spelling of the terminal Cretaceous Stage, the Maastrichtian or Maestrichtian. From a historical point of view and in agreement with the recommendations of the International Stratigraphic Guide (1st and 2nd editions) only Maestrichtian is justified. Nevertheless, the spelling Maastrichtian is proposed, or equivalents in other languages, because stratigraphic names should employ the spelling of place names in the country of their origin and, to be realistic, because Maastrichtian has been well established by its use in an overwhelming majority of the publications which have appeared during the last decades. |
| Reservoir characterisation using process-response simulations: the Lower Cretaceous Rijn Field, West Netherlands Basin | 2003 | Alberts, L.J.H.; Geel, C.R.; Klasen, J.J. | 82(4) | Petroleum geologists always need to deal with large gaps in data resolution and coverage during reservoir characterisation. Seismic data show only large geological structures, whereas small-scale structures and reservoir properties can be observed only at well locations. In the area between wells, these properties are often estimated by means of geostatistics. Numerical simulation of sedimentary processes offers an alternative method to predict these properties and can improve the understanding of the controls on reservoir heterogeneity. Although this kind of modelling is widely used on basin scale in exploration geology, its application on field scale in production geology is virtually non-existent. \7e have assessed whether the recent developments in numerical modelling can also aid petroleum geologists in the interpretation of the reservoir geology. Seismic data, well data and a process-response model for coastal environments were used to characterise the Lower Cretaceous oil-bearing Rijn Field. Interpretation of seismic and well data led to a definition of the structural setting and the depositional model of the Rijn Member in the area. From the sedimentological interpretation the sea-level history could be estimared, which is the one of the most important input parameters for the process-response model. Application of the process-response simulator to the Rijn Field resulted in approval of the depositional model. The output was presented in a 2-dimensional north-south profile, which corresponds very well to the well logs along this section. The results demonstrate that numerical simulations of geological processes can be very useful as a tool to explore many likely geological scenarios. While it cannot be used to supply a unique solution in many cases, it forms a helpful guide during reservoir characterization to find an optimal scenario of the controls on deposition of the Rijn Member, which contributes to the understanding of the inter-well reservoir heterogeneity. |
| Restoration of former wetlands in the Netherlands; effect on the balance between CO2 sink and CH4 source | 2003 | Bos, R. van den | 82(4) | Drained coastal peatlands are a source of greenhouse gas (GHG) through abundant CO2 release caused by aerobic peat degradation. Published rates of CO2 fixation and CH4 release for natural peatlands suggest that areas of peat formation are a (small) net source of GHG emission because the radiative effect of emitted CH4 exceeds the CO2 uptake by the vegetation. It is shown here that wetland restoration of reclaimed peat areas in the western Netherlands leads to a reduction of GHG emission because the expected increase in anaerobically generated CH4 release is much smaller than the decrease in aerobically produced CO2. |
| Redeposited chalk hydrocarbon reservoirs of the North Sea caused by the Chicxulub K-T bolide impact | 2003 | Rider, M.; Kroon, D. | 82(4) | A widespread, slumped, redeposited, uppermost Cretaceous chalk interval, up to 60m thick, immediately below the Cretaceous-Tertiary (K-T) boundary recognised in oil company boreholes across the central North Sea and a major hydrocarbon reservoir, were-interpret as the result of a single, catastrophic event caused by secondary effects related to the bolide impact at Chicxulub. A thin, dark clay bed immediately above the redeposited chalks, we suggest correlates to the outcropping, Iridium rich, Danish 'Fish Clay', rapidly deposited after the impact. Physical effects on sea-floor sediments, caused by the K-T bolide impact, have not previously been interpreted in the North Sea. |
| Inverted basins in the Netherlands, similarities and differences | 2003 | Jager, J. de | 82(4) | All Dutch rift basins that formed during Jurassic and Early Cretaceous extension have been inverted during the Late Cretaceous and Early Tertiary. Several inversion pulses occurred more or less simultaneously in all basins. Analysis of vitrinite reflectance data, in combination with fission track and fluid inclusion data show that the magnitude of uplift and erosion generally did not exceed 2 km. Inversion was strongest in the Broad Fourteens, Central Netherlands and West Netherlands basins. The direction of maximum compressive stress was generally not at right angles to the pre-existing fault trends, and resulted in transpressional movements. Within the NW-SE striking basins, dextral strike-slip movements can often be interpreted, which is consistent with a general N-S to NNW-SSE direction of maximum compression related to Alpine structural events. Where no Zechstein salt is present, trends of flower structures formed through reverse reactivation of pre-existing faults. Where the Zechstein salt is thick, re-activated faults could not breach the salt, and a broad uplift of the post-salt succession resulted, while faulting below the salt caused acceleration of halokinesis. In areas where the Zechstein salt was thin, and where the offsets of reverse faults exceeded the thickness of the salt, impressive thrusts with the Zechstein salt as detachment horizon developed. The later Tertiary inversion pulses did not affect all basins, and caused broad basin uplift in the West and Central Netherlands basins while individual faults were no longer reactivated. It appears that due to crustal thickening during the first inversion pulses the crust could become stabilised such that further compression could only be accommodated by broad basin uplift. |
| Inversion structures in Central Europe - Expressions and reasons, an open discussion | 2003 | Kockel, F. | 82(4) | The diversity of morphological features of Mesozoic inversion structures in NW Germany as representatives of inversion structures in northern Europe is presented and their origin analysed and geologically dated. The particular role of salt in inverted basins and the re-shaping of pre-existing salt structures during the inversion act is demonstrated and the term 'salt wedge', a Zechstein salt intrusion into salt layers within the Triassic sedimentary pile, introduced. The leading theories on inversion (continent-continent collision, re-activation Variscan features) are discussed and discarded, but no new comprehensive theory was developed. The impact of inversion on HC prospectivity of sedimentary basins is debated and proposals for future interdisciplinary research are made. |
| Reservoir characteristics of intracontinental carbonate ramp deposits- Upper Muschelkalk, Middle Triassic, NE Netherlands | 2004 | Pöppelreiter, M.C.; Simone, A.; Hoetz, G. | 83(1) | The Upper Muschelkalk is an unusual reservoir in NW Europe, producing only in the Coevorden Muschelkalk field, onshore the Netherlands. Origin and nature of the gas producing intervals were poorly known. The objective of the paper is to provide a comprehensive description of facies, cyclicity and petrophysical characteristics. From this description a depositional and sequence stratigraphic model is proposed, which explains why there is gas production only from certain intervals of the sequence. Our investigation is based on seismic, core and open hole log data. It indicates that the reservoir consists of dolomites, which are either muddy lagoonal to sabkha, or grainy backshoal deposits. The best reservoir quality is encountered in peloidal-oolitic packstones to grainstones. These represent storm-dominated backshoal deposits and constitute the inner part of a homoclinal carbonate ramp. The succession shows a conspicuous hierarchical cyclicity. Porous backshoal deposits form during maximum transgression and early regression. However permeable, gas producing backshoal deposits only occur in the upper 15 to 20 m, which forms the large-scale regressive hemi-cycle of the Upper Muschelkalk. Better reservoir quality in the upper hemi-cycle is due to changes in grain type and early diagenesis. The investigation might serve as calibration point for further exploring the Upper Muschelkalk reservoir and its facies pattern in the N'W European basin. |
| A sporomorph ecogroup model for the Northwest European Jurassic - Lower Cretaceousi: concepts and framework | 2004 | Abbink, O.A.; Konijnenburg-Van Cittert, J.H.A. van; Visscher, H. | 83(1) | Based on recent vegetation distribution and an integration of macropalaeobotanical and palynological information, a palaeocommunity model is explored that may permit detailed interpretations of quantitative sporomorph distribution patterns in the Jurassic and Early Cretaceous of NW-Europe in terms of changes in palaeoenvironment (sea-level, climate). The conceptual model is based on the recognition of Sporomorph Ecogroups (SEGs) that reflect broad co-existing plant communities, viz. upland, lowland, river, pioneer, coastal, and tidally-influenced SEGs. In successive palynological assemblages, shifts in the relative abundance of SEGs are thought to be indicators of sea-level changes. Climatic changes may be recognised through significant shifts within the quantitative composition of individual SEGs. |
| Marine Miocene deposits in the Maaseik well 49W/220 in eastern Belgium: biostratigraphy by means of various microfossil groups | 2004 | Hooyberghs, H.; Wouters, K.; Spiegler, D. | 83(1) | A micropalaeontological analysis (foraminifera, ostracoda and bolboforma) has been undertaken for the interval between 299.7 and 201.5m of the Maaseik borehole. This interval includes marine glauconitic sands, which are generally not or nor strongly decalcified. Independent from each other, the observed taxa of the different microfossil groups indicate a Late (range down to Middle) Miocene age for the interval. On the base of the biozonations of the various microfossil groups, some correlations can be presented with Late Miocene deposits of other areas in Belgium (Antwerp and Campine area), and of other places in NW Europe |
| Strontium (87Sr/86Sr) dating of marine shells from Pliocene and Pleistocene shallow marine deposits in The Netherlands | 2004 | Jansen, H.S.M.; Huizer, J.; Dijkmans, J.W.A.; Hinte, J.E. van | 83(1) | 87Sr/86Sr (Strontium) ratio analyses of shell material (mainly Arctica islandica) from 24 levels in the Maassluis Formation of boreholes Noordwijk, Zegveld and Terschelling suggest that the age of the formation ranges from 0.82 to 2.34 Ma (± 0.5 Ma), and that the Oosterhout Formation at Noordwijk could be as much as 2.5 Ma older than hitherto assumed. |
| Faults in the Asquempont area, southern Brabant Massif, Belgium | 2004 | Debacker, T.N.; Herbosch, A.; Verbiers, J.; Sintubin, M. | 83(1) | The literature suggests that the Asquempont fault, a supposedly important reverse fault forming the limit between the Lower to lower Middle Cambrian and the Ordovician in the Sennette valley is poorly understood. Nevertheless, this fault is commonly equated with a pronounced NW-SE-trending aeromagnetic lineament, the Asquempont lineament, and both the geometry of the Asquempont lineament and the supposed reverse movement of the Asquempont fault are used to develop large-scale tectonic models of the Brabant Massif. New outcrop observations in the Asquempont area, the "the locality" of the Asquempont fault, in combination with outcrop and borehole data from surrounding areas, show that the Asquempont fault is not an important reverse fault, but instead represents a pre-cleavage, low-angle extensional detachment. This detachment formed between the Caradoc and the timing of folding and cleavage development and is not related to the aeromagnetic Asquempont lineament. The Asquempont area also contains several relatively important, steep, post-cleavage normal faults. Apparently, these occur in WNW-ESE-trending zone between Asquempont and Fauquez, extending westward over Quenast towards Bierghes. This zone coincides with the eastern part of the WNW-ESE-trending Nieuwpoort-Asquempont fault zone, for which, on the basis of indirect observations, previously a strike-slip movement has been proposed. Our outcrop observations question this presumed strike-slip movement. The Asquempont fault may be related to the progressive unroofing of the core of the Brabant Massif from the Silurian onwards. Possibly, other low-angle extensional detachments similar to the Asquempont fault occur in other parts of the massif. Possible candidates are the paraconformity-like contacts depicted on the most recent geological map of the Brabant Massif. |
| A new record of Clidastes (Squamata, Mosasauridae) from the Upper Campanian of the Münster Basin (NW Germany) | 2004 | Diedrich, C.; Mulder, E.W.A. | 83(1) | From Upper Campanian turbiditic marls at Beckum in the Münster Basin (NW Germany) the anterior portion of a mosasaurid premaxilla with abutting fragments of the left and right maxilla is described and referred to the genus Clidastes .It shows the process of tooth replacement very well. This taxon is recorded for the first time from Germany. Clidastes co-existed in central Europe with other mosasaurids such as representatives of the genus Leiodon and Mosasauridae indet. |
| Faults in the Asquempont area, southern Brabant Massif, Belgium | 2004 | Debacker, T.N.; Herbosch, A.; Verbiers, J.; Sintubin, M. | 83(1) | The literature suggests that the Asquempont fault, a supposedly important reverse fault forming the limit between the Lower to lower Middle Cambrian and the Ordovician in the Sennette valley, is poorly understood. Nevertheless, this fault is commonly equated with a pronounced NW-SE-trending aeromagnetic lineament, the Asquempont lineament, and both the geometry of the Asquempont lineament and the supposed reverse movement of the Asquempont fault are used to develop large-scale tectonic models of the Brabant Massif. New outcrop observations in the Asquempont area, the "type locality" of the Asquempont fault, in combination with outcrop and borehole data from surrounding areas, show that the Asquempont fault is not an important reverse fault, but instead represents a pre-cleavage, low-angle extensional detachment. This detachment formed between the Caradoc and the timing of folding and cleavage development and is not related to the aeromagnetic Asquempont lineament. The Asquempont area also contains several relatively important, steep, post-cleavage normal faults. Apparently, these occur in a WNW-ESE-trending zone between Asquempont and Fauquez, extending westward over Quenast towards Bierghes. This zone coincides with the eastern part of the WNW-ESE-trending Nieuwpoort-Asquempont fault zone, for which, on the basis of indirect observations, previously a strike-slip movement has been proposed. Our outcrop observations question this presumed strike-slip movement. The Asquempont fault may be related to the progressive unroofing of the core of the Brabant Massif from the Silurian onwards. Possibly, other low-angle extensional detachments similar to the Asquempont fault occur in other parts of the massif. Possible candidates are the paraconformity-like contacts depicted on the most recent geological map of the Brabant Massif. |
| Editorial Netherlands Journal of Geosciences | 2004 | Wong, T.E. | 83(2) | |
| A sporomorph ecogroup model for the Northwest European Jurassic - Lower Cretaceous II : Application to an exploration well from the Dutch North Sea | 2004 | Abbink, O.A.; Konijnenburg-Van Cittert, J.H.A. van; Zwan, C.J. van der; Visscher, H. | 83(2) | Jurassic shallow marine to non-marine depositional sequences are among the most important economic targets in the North Sea. Detailed, 'high resolution' stratigraphy of these sequences has become a necessity in both predictive geological exploration models as well as in production reservoir models. In these paralic sequences, palynomorphs are the most abundant (micro) fossil group. Palynology is increasingly challenged to improve the biostratigraphic control, and to support the sequence stratigraphical framework. Based on a recently developed, conceptual Sporomorph EcoGroup model, the quantitative distribution patterns of terrestrial palynomorphs are grouped in six Sporomorph EcoGroups (SEGs), viz. Upland, Lowland, River, Pioneer, Coastal, and Tidally-influenced SEG. Application of the SEG model to data from a marginal marine, uppermost Callovian - Middle Oxfordian section of NAM well F17-4 from the southern part of the Central North Sea Graben allows the recognition of sea-level fluctuations and climate changes. A marked palaeoclimatic shift occurred in the earliest Middle Oxfordian. The relatively cool-subtropical, humid climate changed into a warmer, subtropical-tropical, drier climate. The sea-level reconstructions based on the SEG model are validated against a latest Callovian - Earliest Oxfordian depositional sequence. |
| The geometry and stratigraphic position of the Maassluis Formation (western Netherlands and southeastern North Sea) | 2004 | Jansen, H.S.M.; Huizer, J.; Dijkmans, J.W.A.; Mesdag, C.; Hinte, J.E. | 83(2) | The geometry and depositional history of the Maassluis Formation is described from an East-West oriented transect located in the west-central Netherlands and P- and Q-blocks in the Dutch offshore area. The Late Pliocene to Early Pleistocene Maassluis Formation was deposited under near coastal marine conditions. Two distinct facies are distinguished: (1) medium grained sands with a blocky GR/SP-log pattern that were deposited under intertidal and aeolian conditions and (2) medium to coarse grained sands deposited in a subtidal environment showing a clear coarsening upward trend. The lower part of the Maassluis Formation is laterally equivalent to the shallow marine Oosterhout Formation and gets progressively younger towards the West. The upper part is lateral equivalent to estuarine and mudflat deposits (Balk Member, c.q. Peize Formation) in the central part of The Netherlands and to river deposits (Peize Formation) further to the East. |
| Assessing the contamination risk of five pesticides in a phreatic aquifer based on microcosm experiments and transport modelling at Sint-Jansteen (Zeeland,, the Netherlands) | 2004 | Gaus, I.; Vande Casteele, K. | 83(2) | The risk of five pesticides (atrazine, simazine, bentazone, mecoprop and MCPA) contaminating a Quaternary phreatic aquifer (the water supply area of Sint-Jansteen, the Netherlands) is assessed based on laboratory experiments and solute transport modelling (MODFLOW-MT3D). Batch experiments either show long half-lives (at least 1500 days) or no degradation at all for bentazone, atrazine and simazine while mecoprop and especially MCPA degrade much faster (half-lives down to 4.1 days). Column experiments show significant sorption to the aquifer sediment only for atrazine and simazine under certain circumstances. A series of experiments were conducted during which the type of the sediment, the grain size, the content of the organic matter and the acidity of the groundwater were varied. These experimental results were subsequently incorporated in a solute transport model for the aquifer resulting in the following ranking of the contamination risk for the selected pesticides (from low to high): MCPA, mecoprop, simazine, atrazine, bentazone. This ranking was confirmed by observed pesticide concentrations in samples taken from piezometers and extraction wells from the aquifer. |
| Palaeozoic and Mesozoic igneous activity in the Netherlands: a tectonomagmatic review | 2004 | Sissingh, W. | 83(2) | To date, igneous rocks, either intrusive or extrusive, have been encountered in the Palaeozoic-Mesozoic sedimentary series of the Netherlands in some 65 exploration and production wells. Following 17 new isotopic K/Ar age determinations of the recovered rock material (amounting to a total of 28 isotopic ages from 21 different wells), analysis of the stratigraphic distribution of the penetrated igneous rock bodies showed that the timing of their emplacement was importantly controlled by orogenic phases involving intra-plate wrench and rift tectonics. Magmatism coincided with the Acadian (Late Devonian), Sudetian (early Late Carboniferous), Saalian (Early Permian), Early Kimmerian (late Late Triassic), Mid-Kimmerian (Late Jurassic), Late Kimmerian (earliest Cretaceous) and Austrian (latest Early Cretaceous) tectonic phases. This synchroneity presumably reflects (broadly) coeval structural reorganizations of respectively the Baltica/Fennoscandinavia-Laurentia/Greenland, Laurussia-Gondwana, African-Eurasia and Greenland/Rockall-Eurasia plate assemblies. Through their concomitant changes of the intra-plate tectonic stress regime, inter-plate motions induced intra-plate tectonism and magmatism. These plate-tectonics related events determined the tectonomagmatic history of the Dutch realm by inducing the formation of localized centres, as well as isolated spot occurrences, of igneous activity. Some of these centres were active at (about) the same time. At a number of centres igneous activity re-occurred after a long period of time. |
| New subsurface temperature maps for the Tertiary Lower Rhine Basin and the adjacent Variscan Basement – Germany, The Netherlands, Belgium | 2004 | Karg, H.; Bücker, C.; Schellschmidt, R. | 83(2) | The regional subsurface temperature field at the transition between the Palaeozoic Variscan Basement and the Cenozoic Lower Rhine Basin in Dutch, German and Belgium territories was mapped up to a depth of 1000 m. Temperature data from 66 wells and 11 coal mine subcrops were available. In 46 wells, temperature logs, covering a cumulative depth interval of 6600m, were measured for this study. |
| The sand extraction potential of embedded land surface lowering in the Netherlands | 2004 | Meulen, M.J. van der; Kleine, M.P.E. de; Veldkamp, J.G.; Dubelaar, C.W.; Pietersen, H.S. | 83(2) | In the Netherlands, mineral extraction by means of dredging or quarrying meets with considerable societal resistance. Land surface lowering prior to large land reconstruction projects may raise fewer objections. We have calculated the potential yields of sand and gravel from land surface lowering embedded in planned building and construction projects, and in nature, farmland and recreation area development. Our primary data sets were a compilation of spatial plans for the period 1995 – 2005 and about 95,000 borehole descriptions. Even if embedded consistently, land surface lowering would contribute modestly (up to 5.4 Mio m3/a) to the filling sand provision (annual demand 45 - 50 Mio m3/a). |
| Introduction Symposium On the Paleogene Preparing for Modern Life and Climate', held in Leuven, Belgium, August 2003 | 2004 | Vandenberghe, N. | 83(3) | |
| Stratigraphic architecture of the Upper Cretaceous and Cenozoic along the southern border of the North Sea Basin in Belgium | 2004 | Vandenberghe, N.; Simaeys, S. van; Steurbaut, E.; Jagt, J.W.M.; Felder, P.J. | 83(3) | The Late Cretaceous and Cenozoic sedimentary record in the Campine Basin along the southern border of the North Sea Basin is analysed in terms of sequence stratigraphy. All available biostratigraphic, and in some cases, magnetostratigraphic data are used to constrain the sequence chronostratigraphy. The relative geographic extent of the strata is used as an indication of the relative sea level. Tectonic and eustatic components could be distinguished in several cases using regional geological information. Generally, sequences consist of transgressive and highstand systems tracts only and have flat, abrasion type lower boundaries. Lowstand deposits are only identified as infill of erosional space, which generally implies marked tectonic uplift. Several eustatic and tectonic events can be correlated with similar events known elsewhere in the North Sea Basin. The time intervals spanned by the different sequences vary considerably, pointing out different control mechanisms. |
| Pyritized diatoms: a good fossil marker in the Upper Paleocene-Lower Eocene sediments from the Belgian and Dieppe-Hampshire Basins | 2004 | Eetvelde, Y. van; Dupuis, C.; Cornet, C. | 83(3) | Assemblages of brackish and marine diatoms have been examined from Upper Paleocene-Lower Eocene strata of the Belgian Basin (Knokke well) and the Dieppe-Hampshire Basin (Saint-Josse borehole and Ailly sections). The diatoms observed are invariably preserved in pyrite as internal moulds and their siliceous skeletons are completely replaced by pyrite by epigenesis. Three major diatom assemblages have been observed which can be used to approximate the position of the recently defined Paleocene-Eocene boundary (defined by the Carbon Isotope Excursion).This isotope excursion occurs just below the strong increase in the abundance of Fenestrella antiqua and in the vicinity of the abundance peak of Coscinodiscus morsianus var. moelleri. They also allow correlations of the lithostratigraphic units of the Belgian Basin with the formations of the Dieppe-Hampshire and central North Sea Basins. For instance, investigations of diatoms recorded in the Knokke Clay Member of the Knokke well indicate that this unit corresponds to the lower units of the 'Sparnacian facies' of the Dieppe-Hampshire Basin and to the Sele Formation of the North Sea Basin. |
| A rapid clay-mineral change in the earliest Priabonian of the North Sea Basin? | 2004 | Saeys, R.; Verheyen, A.; Vandenberghe, N. | 83(3) | In the Eocene to Oligocene transitional strata in Belgium, clay mineral associations vary in response to the climatic evolution and to tectonic pulses. Decreasing smectite to illite ratios and the systematic occurrence of illite-smectite irregular interlayers are consequences of a cooling climate. A marked increase in kaolinite content occurs lust after a major unconformity formed at the Bartonian/Priabonian boundary and consequently is interpreted as resulting from the breakdown of uplifted saprolites. |
| Insectivores (Mammalia) from the earliest Oligocene (MP 21) of Belgium | 2004 | Smith, R. | 83(3) | Insectivore remains are not common in the Lower Oligocene of Europe. For this reason, the study of the earliest Oligocene insectivore fauna (MP 21) from Boutersem and Hoogbutsel, all together yielding nine species, representing five families, constitutes an important progress in the knowledge of the I-ate Eocene and Early Oligocene insectivore evolution. Some of the genera discovered in Belgium are known from upper Eocene sites (Saturninia, Amphidozotherium, Euronyctia, Eotalpa), whereas others are not known before the Oligocene (Butselia, Tetracus, Heterosoricinae ind.).The co-occurrence of primitive species of Nyctitheriidae with modern forms belonging to the Plesiosoricidae, Talpidae and Erinaceidae at the Eocene-Oligocene boundary suggests a transition fauna. Between the Priabonian (Late Eocene) and the Rupelian (Early Oligocene), the endemic European insectivores were in competition with the new immigrants. This faunal turnover is generally accepted as the 'Grande Coupure' event (the MP 21 event). |
| Stable oxygen isotope record of the Eocene-Oligocene transition in the southern North Sea Basin: positioning the Oi-1 event | 2004 | De Man, E.; Ivany, L.; Vandenberghe, N. | 83(3) | Preliminary stable oxygen isotope data are presented from the southern North Sea Basin successions, ranging from the Lutetian to Rupelian. Analyses were performed on fish otoliths, nuculid bivalves and benthic foraminifera and are presented as bulk δ18O values relative to a well established regional sequence stratigraphic framework. The most significant positive shift in δ18O values clearly falls at the top of the regionally recognized Bassevelde 3 sequence, which base corresponds to the Eocene-Oligocene GSSP boundary. The here documented δ18O shift is closely associated with the base of the traditional Rupelian unit-stratotype and is tentatively correlated to the globally recognised Oi-1 event. |
| Sea-level related molluscan plankton events (Gastropoda, Euthecosomata) during the Rupelian (Early Oligocene) of the North Sea Basin | 2004 | Gürs, K.; Janssen, A.W. | 83(3) | Spacio-temporal distribution patterns of North Sea Basin Early Oligocene (Rupelian) pteropoda (holoplanktonic gastropods: Mollusca, Gastropoda, Euthecosomata) are studied. These patterns indicate three short term invasions of a single pteropod species during the Rupelian. These invasions are indicated here as Clio blinkae Event, Praehyalocylis laxeannulata Event and Clio jacobae Event. The conspicuously short occurrences of the species, their abundances and some lithological features of the pteropod bearing strata lead to the conclusion that these plankton events are linked to sea level high-stands allowing currents from the worlds oceans to enter into the North Sea Basin |
| Magnetostratigraphy and rock magnetism of the Boom Clay (Rupelian stratotype) in Belgium | 2004 | Lagrou, D.; Vandenberghe, N.; Van Simaeys, S.; Hus, J. | 83(3) | This paper presents the results of a detailed rock magnetic and magnetostratigraphic study of the Lower Oligocene Rupelian unit-stratotype. Notwithstanding the relatively low intensity of the natural remanent magnetisation and the diverse and often unstable behaviour during demagnetisation, close-spaced sampling and accurate polarity determinations allowed us to determine the magnetic polarity zonation. The recognition of the characteristic magnetic polarity and the correlation with the standard magnetobiochronologic time scale yields an accurate chronostratigraphic dating of the Boom Clay Formation. The boundary between the geomagnetic chrons C12n and C12r nearly coincides with the lithostratigraphic boundary between the Terhagen and Putte Members. Rock magnetic techniques point to magnetite and probably also iron sulphides as the main magnetic remanence carriers. These magnetic minerals could, however, not be identified with classical mineralogical techniques performed on magnetic extractions. The failure to detect them may be due to the low concentration of these minerals, the small grain size, and the close physical relation with pyrite. |
| Late Oligocene Warming Event in the southern North Sea Basin: benthic foraminifera as paleotemperature proxies | 2004 | De Man, E.; Van Simaeys, S. | 83(3) | The investigation of foraminiferal assemblages from a series of Oligocene borehole sections allowed paleoenvironment and paleoclimate reconstructions for the Rupelian and Chattian (Lower and Upper Oligocene) Stages in their type region, the southern North Sea Basin. A striking feature coinciding with the Rupelian-Chattian (R-C) unconformity is the major change in paleotemperature and paleobathymetry. The shallow marine to restricted marine subtropical fauna at the base of the Chattian is in strong contrast with the deeper marine and cooler upper Rupelian assemblages. This study suggests that the early Chattian transgression is genetically related to a widespread major warming pulse, known as the Late Oligocene Warming Event. |
| The Rupelian-Chattian boundary in the North Sea Basin and its calibration to the international time-scale | 2004 | Van Simaeys, S. | 83(3) | The classical problem of the nature and age of the Rupelian-Chattian (Early-Late Oligocene) unconformity in its type region is here approached using organic walled dinoflagellate cyst (dinocyst) correlations between the North Sea Basin and well calibrated central Italian (Tethyan Ocean) sections. Useful Oligocene dinocyst events are the last occurrence of Enneadocysta pectiniformis (~29.3 Ma), and the first occurrences of Saturnodinium pansum (~29.4 Ma), Distatodinium biffii (~27.9 Ma) and Artemisiocysta cladodichotoma (~26.7 Ma).The latter event marks the earliest Chattian. The improved correlations indicate that the Rupelian-Chattian (R-C) boundary is associated with the so-called 'Oligocene Glacial Maximum'. This phase of important global cooling and glacio-eustatic sea level fall is genetically related to the unconformity between the classic Oligocene stages. Subsequent global warming (so-called 'Late Oligocene Warming Event'), induced a major sea level rise, leading e.g. to the time-transgressive deposition of the typical basal Chattian glauconitic sands. The oldest of the Chattian units have a GPTS age of ~26.7 Ma. It further appears that a hiatus of ~500 kyrs spans the classic Rupelian-Chattian unconformity. |
| Rib fracture in Prognathodon saturator (Mosasauridae, Late Cretaceous) | 2004 | Schulp, A.S.; Walenkamp, G.H.I.M.; Hofman, P.A.M.; Rothschild, B.M.; Jagt, J.W.M. | 83(4) | Two unusual bumps occur on the internal surface of a rib of the marine reptile Prognathodon saturator from the Upper Cretaceous (Maastrichtian) of Maastricht, The Netherlands. These bumps are interpreted as stress fractures, possibly related to agonistic behaviour. |
| A new Ordovician astylospongiid sponge (Porifera) as an erratic from Baltica | 2004 | Rhebergen, F. | 83(4) | Until now hemispherical astylospongiid sponges were invariably referred to as Caryospongia juglans var. basiplana Rauff. Renewed investigations have now shown that part of the material should be assigned to â new genus and species, Tympanospongia vankempeni, which is characterised by a system of very irregular canals. These flat-based sponges originate from the Baltic region and occur in two assemblages of silicified Late Ordovician sponges known exclusively as erratics from The Netherlands and northern Germany. These fossils were transported by the River Eridanos, a former drainage system from the Baltic region that filled the North European Basin during the Miocene to Early Pleistocene. Specimens of Tympanospongia vankempeni gen. et sp. nov. also occur in the Upper Pleistocene of Gotland, Sweden. The new sponge described herein principally differs from other genera of the Astylospongiidae found frequently in the erratic sponge assemblages by its irregular system of apochetes which ramify and anastomose commonly. |
| A southern North Sea Miocene dinoflagellate cyst zonation | 2004 | Munsterman, D.K.; Brinkhuis, H. | 83(4) | An integrated stratigraphical analysis emphasizing organic-walled dinoflagellate cyst (dinocyst) distribution has been carried out on multiple boreholes penetrating the Miocene in the subsurface of the Netherlands (southern North Sea Basin).The bulk of the investigated successions is attributed to the Breda Formation, a regional lithostatigraphical unit most complete in the south-eastern part of the Netherlands. In concert with a first regional integrated bio (chrono) sequence-stratigraphical framework, fourteen informal dinocyst zones for the southern North Sea Miocene (SNSM), and three subzones are proposed for the Breda Formation. By also integrating (chrono)stratigraphic information from Mediterranean and North Atlantic dinocyst studies a first ever detailed age-model is here proposed for the Miocene in the subsurface of the Netherlands. |
| A geophysical profile at the foot of the Dutch coastal dunes near the former outlet of the 'Old Rhine' | 2004 | Seijmonsbergen, A.C.; Biewinga, D.T.; Pruissers, A.P. | 83(4) | The apparent electrical conductivity of the subsurface along the Dutch coast between 'Wassenaarse Slag' (beach post 92.250) and north of Noordwijk aan Zee (beach post 77.750) reflects the spatial distribution of Holocene coastal deposits. Using a Geonics EM-34 a threefold division based on the mean electrical conductivity could be made in the outlet area of the River Old Rhine. 1) A section showing a sequence of sandy deposits that resembles the Schoorl Member of the Naaldwijk Formation on top of the Zandvoort Member of the Naaldwijk Formation. 2) A section underlain by a shallow clay/peat layer of varying thickness belonging to the Naaldwijk Formation (Walcheren Member) / Nieuwkoop Formation (Hollandveen Member), intercalated within the Schoorl Member and Zandvoort Member of the Naaldwijk Formation. South of the Old Rhine locally Wormer Member deposits of the Naaldwijk Formation underlie these clay/peat layers. 3) A section characterized by channel fill deposits of the former Rhine reaching to -20 m below Normaal Amsterdam Peil (N.A.P.), and belonging to deposits of the Wormer Member of the Naaldwijk Formation, and to two facies of the Naaldwijk Formation (Walcheren Member). The geophysical transect was calibrated using existing nearby drill hole data, so that a continuous snapshot of the subsurface was gained. Therefore this research also contributes to the recent genesis of this part of the Dutch coast. |
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