The geology of uranium mineralization at Mika, N.E. Nigeria

The Uranium mineralization at Mike is located near Zing in Taraba State, N.E., Nigeria. The host rock consist of a sheared Pan-African medium-grained granite which is in places intruded by rhyolite and siliceous veins. Numerous joints, faults and fractures criss-cut the area. Some of the fractures are filled with secondary quartz. The ore occurs in two parallel N-S trending shear Zones with the western limb hosting a rhyolite body. Drill section reveals a subsurface extension of the mineralization. In the upper limb, mineralization consisting of metal autunite and coffinite occurs associated with the rhyolite body. In lower ore limb meta-autunite, coffinite and pitchblende occur along a set of two parallel shear surface. The pitchblende occurs massive and as vein lets in association with sulphides. The ore body is marked by distinct hydrothermal alteration zones which feature sericitization, silicification, hematization and kaolination. Reactivated regional structures of NE-SW and the N140oE and N170E played an important role in the formation of Mika mineralization. These acted as channel and as mechanical barrier for the mineralization fluid. The bimodal magmatism of the Burashika group is postulated to be related to the process of mineralization in view of the ubiquitous rhyolite in the mineralized bodies