Source of metals related to gold occurrences in Cameroon, Central African Belt

Suites of granitic and metamorphic rocks form a perfect geological environment in which to investigate the source of metals related to gold deposits. In the East Province of Cameroon, the source of metals-related gold (grade ~ 4.6 g/t) that occurs within metamorphic and granitic rocks remains ambiguous. The host rocks were subjected to XRF and ICP-MS whole-rock geochemistry and BSE/EDS mineral analyses to investigate the source(s) of metals related to gold in the Province. Petrographically, chalcopyrite-pyrite and magnetite-ilmenite are the main sulfides and oxides of granites, respectively. The low-grade metamorphic rocks are sulfide-rich consisting of arsenopyrite, chalcopyrite, pyrite, and sphalerite, and oxides include magnetite, ilmenite, hematite, and rutile. Cu, Ni, Co, Sb, Sc, and Zn concentrations depleted in high-grade metamorphic rocks and granites compared to low-grade metamorphic rocks. As well, Bi, Cd, Co, Cu, Ni, Sb, V, W, and Zn concentrations decrease with increasing temperatures from low-grade rocks to high-grade rocks and granites. The suite of depleted elements in high-grade rocks and granites is almost identical to those enriched in gold occurrences. We conclude that metals (Bi, Cd, Co, Cu, Ni, Sb, and Zn) related to gold mineralization in the East Province of Cameroon likely originated from metal-rich low-grade metamorphic rocks during prograde metamorphic processes prior to partial melting.