Alluvial Gold Particles Microchemistry and Induced Polarization Geophysical Surveys in Makouré Area, Nyong Group, Cameroon: Constrain of Orogenic Gold Prospectivity

Makouré area belongs to the Nyong group and is located in the eastern vicinity of the Bidou polymetallic project. It is a green field terrain. To investigate the gold prospectivity of the area, 72 stream sediment samples were collected from which visible gold particles were picked and subjected to microchemical analysis; also, induced polarization geophysical surveys were done on eight (08) E-W lines, for a total distance of 26 km, using a pole-dipole array with 100 m long receiver dipoles and a station spacing of 50 m. Stream sediments in Makouré contain gold particles; the visible gold grains are subangular, subrounded, and dendritic with complex outlines. BSE images and microchemistry revealed two types of gold particles in Makouré area: the high-Ag gold particles showing Ag-depleted rim (Au: 77 to 98 wt%, Ag: 1.34 to 20.8 wt%) and the low-Ag gold particles having no zonation (Au: 98.14 to 99.85 wt%, Ag: 1.97 to 3.2 wt%). Cu contents of all the samples are less than 2.5 wt%, and other elements such as Pt, Ni, and Cr are almost undetectable in all the studied grains. Their fineness varies from 787.4 to 986.6. The overall composition of various studied particles infers mesothermal orogenic gold deposits in Makouré. The induced polarization geophysical surveys reveal two gold targets, namely, ME and MW, characterized by low resistivity (less than 700 Ohm-m) and high chargeability (more than 30 Mv/V). The almost perfect overlapping of low resistivity and high chargeability in the identified targets inferred a disseminated gold mineralization associated with sulfide and clay in Makouré area. The ubiquity of ME and MW in various surveyed IP lines suggests that the mineralization is controlled by structures trending N-S, subparallel to the regional shear zone affecting the Nyong group. To strengthen the reliability of ME and MW prospects defined from geophysical data in Makouré, geochemical surveys and diamond drilling are recommended.