Evaluation of the mineralizing potential of the Mbengwi plutonics, Northwestern Cameroon, Central Africa

摘要

The Mbengwi area consists of Cenozoic alkaline rocks and Pan-African calc-alkaline plutonics. The alkaline magmatic series include volcanics (basanites, hawaiites, mugearite, and rhyolite) and syenites while the calc-alkaline plutonics comprise various granitoids (granites, granodiorites, quartz monzonites, and monzonites) associated with monzodiorites. These plutonics are calc-alkaline, metaluminous to weakly peraluminous, mostly I-type, displaying high potassic to shoshonitic affinities. Their magmas are relatively evolved and typically result from melting of the lower continental crust with variable involvement of the oceanic crust. According to the ranges of their Rb/Sr, Zr/Hf, and K/Rb ratios, these magmas have mostly not undergone post-magmatic hydrothermal activity which would lead to mineralization. With regard to their contents in certain elements such as Sr, Rb, and Ba in addition to their gradient in Sm/Eu and Rb/Ba ratios, the Mbengwi plutonics are typical of granitoids devoid of U and Ta deposits. They are also barren in Sn, W, and Mo but mostly productive regarding Cu, Zn, and Fe (Au) skarn.