3D modeling of the Ashanti Belt,southwest Ghana: Evidence for a litho-stratigraphic control on gold occurrences within the Birimian Sefwi Group |
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| Affiliation: | 1. Université de Toulouse, UPS (SVT-OMP), GET, 14 Av. Edouard Belin, F-31400 Toulouse, France;2. Centre for Exploration Targeting, University of Western Australia, 35 Stirling Hwy, Crawley, 6009 WA, Australia;3. Monash University, School of Geosciences, Wellington Road, Clayton, VIC 3800, Australia;4. IRD, UR 234, GET, 14 Av. Edouard Belin, F-31400 Toulouse, France;5. CNRS, UMR 5563, GET, 14 Av. Edouard Belin, F-31400 Toulouse, France;6. Golden Star Resources Ltd., 150 King Street West, Sun Life Financial Tower, Suite 1200, Toronto, ON M5H 1J9, Canada;1. Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;2. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;3. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China;1. Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;1. Kenex Limited, PO Box 41136, Eastbourne, Wellington 5047, New Zealand;2. Dampier Gold Limited, PO Box 1981, West Perth, Western Australia, 6872, Australia |
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| Abstract: | A three-dimensional model of the gold-rich Paleoproterozoic Ashanti Greenstone Belt has been built with a “hybrid” geological modeling method using Geomodeller and Gocad, then inverted using VPmg software. The model helps to identify the main regional-scale controls leading to abundant gold mineralization in the southeast of the belt by highlighting the lithological distribution and geometry of geological structures. The three-dimensional geological model shows that 85% of gold occurrences in the Ashanti Greenstone Belt are proximal to a specific tholeiitic metabasaltic horizon “BV1”. This result is noteworthy given that the relatively thin, 300 m thick, BV1 layer represents only 10%, by volume, of the modeled Sefwi Group stratigraphy. A map of distance between the topography and the BV1 layer is produced and identifies areas showing a high probability to host gold deposits in the southeast of the Ashanti Belt. Possible structural controls performed by the BV1 tholeiitic metabasaltic rocks on the location of gold occurrences are discussed, and we hypothesize that the BV1 layer acted as a mineralization trap or source of gold. Both hypotheses agree with examples from the literature and explain the observed distribution of the mineralized sites. |
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