Author: A. Lambert
Phi (Φ) structures are geological entities that combine ring shaped fault segments with crossing shear zones. Their closeness to mineral occurrences is recognised but many geologists do not consider them useful for prediction of deposits and challenge their detection. This paper reviews the geology, genesis and economic worth of the structures, focusing on gold mining in Europe. In addition, 203 large mines or mining districts worldwide are investigated for the presence of phi structures. Methods used to identify them include Computer Vision and Machine Learning algorithms, Hough and Radon transforms, and global gravity gradient maps. Results show phi patterns in the vicinity of mining in 61% of the cases. A companion web archive provides learning images, routines and detailed examples.
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