Basic Petrological and Structural Analysis in the Zimbi Gold Area (East Cameroon)

Abstract

The plutono-metamorphic series of the locality of Zimbi, extends over a narrow strip of 135 km2 on the eastern edge of the gold district of Baden-Colomine in East Cameroon. The work carried out in this locality is based on a cartographic approach (processing of maps and Landsat-7 ETM + images), combined with a geological and mining survey on the ground using conventional tools. On the morphostructural level, we observe NE-SW oriented penetrative lineaments. The trajectories of these are deviated or not in contact with other less dense lineaments, organized in networks of directions N-S, NE-SW, ENE-WSW, E-W, NW-SE. Parallel to the main Cameroon Center Shear (N070E), the ENE-WSW network which induces a significant reversal of foliation on contact, defines a structuring dexter shear zone accompanied by NE-SW and EW satellite shear zones with dexter kinematics and NW-SE and NS of senestrial kinematics. The lithological diversity allows the facies of calc-alkaline granite to predominate. Zimbi's range of structural elements highlights a magmatic fluidity substituted in foliation. The foliation directed NE-SW, of dip (40-90 °) either towards the NW, or towards the SE; carries a linearization of stretch submeridienne. The folding that affects it is induced by two directions of compression perpendicular N-S to NE-SW and E-W to NW-SE, which define the voltage slots favorable to mineral concentrations by circulation of mineralizing fluids. The shear zones and the quartz-feldspathic veins, structures favorable to mineralization such as gold, secondarily affect this complex. These geomorphological, lithological and structural geology data make the plutono-metamorphic procession of Zimbi a privileged area for mining research, in the gold district of Baden-Colomine.