Pétrologie et métallogénie (Au-EGP) des enclaves de granites et de péridotites dans les régions de Nyos et Kumba (ligne volcanique du Cameroun)

Abstract

The study area (Nyos and Kumba), belong to the southern part of the Cameroon Volcanic Line, comprised of a granite-gneissic basement rocks. This basement is overlaine by recent basaltic flows enclosing peridotite and granite xenoliths. These xenoliths have been studied here within the framework of the gold and platinum group elements exploration. The petrographic and mineralogical characteristics show that the peridotites have a porphyroclastic to protogranular texture. The granites which have a monzonitic tendency show a granular texture and have been submitted to hydrothermal alteration. Peridotite xenoliths are mainly composed of olivine, pyroxene and spinel whereas ganite xenoliths are made up of quartz, feldspars and biotite. The two rock types have been submitted to partial melting during their ascension and this influenced their chemical composition.