Stream Sediment Geochemistry and Placer Gold Microchemical Signatures

Stream sediment survey and the microchemical signatures of alluvial gold particles have been widely used in reconnaissance exploration for gold to determine their primary sources in areas with poor outcrops and thick overburden such as the Eastern and Southern Cameroon goldfields. Stream sediment samples were collected from the Lom river drainage system, draining over a metasedimentary Pan African unit and from Ebap and Mbal tributaries of the Nyong river system draining over a Paleoproterozoic complex comprising of metamorphosed ultramafic rocks, amphibolites and granulites gneisses.The geochemistry of the two contrasting terrains have been presented in this study wherein grains from both locality are Au-Ag alloys with the Nyong grains significantly low in Ag compared to the Lom gold grains. Also the Nyong grains contains Pt, Pd, and Cr suggesting a link with ultramafics while the Lom grains have substantial Sb and Zn level pointing to a hydrothermal quartz veining as possible primary mineralization system. The grains from both localities have Ag-depleted rims.