Geological, geophysical and surface geochemical guides for gold exploration in the Falémé Volcanic Belt, West African Craton, Senegal

Abstract

The Paleoproterozoic sequences of the Kédougou-Kéniéba Inlier, West African Craton, contain major orogenic gold deposits mainly located in the vicinity of the Senegal-Mali Shear Zone in the Malian territory. Up to now few gold deposits has been discovered in the Senegalese side. Our new geological, geophysical and surface multi-element geochemistry data allow us to improve our understanding of the gold distribution within the Senegalese side (including the Boboti intrusion and its vicinity in the Falémé Volcanic Belt (FVB) and the Dialé-Daléma host rocks). On the one hand, the geological study shows variability of lithologies hosting gold mineralization in the FVB, including intermediate to felsic intrusions, andesite, quartz veins and sedimentary rocks. On the other hand, geophysical and surface multi-element geochemistry study, handled with regionalized Principal Component Analysis with kriging of gold factor unveil a change of the gold metal association from the Boboti intrusion (association of Au, Ni, Co, Cu and Pb) toward the FVB (association of Au and Zn), and the Dialé-Daléma sedimentary host rocks, where Au is only associated with As.

Such variability of metal association can be used as an exploration guide to characterize gold-rich zones, whether located in the Dialé-Daléma Series, within the Boboti metaluminous pluton, or in the FVB areas. Furthermore, a comparison between soil and termite sampling shows that the latter is a good and more effective and suitable exploration guide in areas of high weathering profile and with intense surface mining activities, such as the FVB area. The continuity of gold anomalies from surface to the subsurface levels is confirmed by drilling data. This study has allowed us to better constrain the gold geochemical anomalies in high weathering environment such as the southeastern part of Senegal and produce a practical guide for exploration companies.