Geology of Basement Complex rocks in Kabo area, Kano, Northwestern Nigeria: Insights into the Trends of Mineralization in the Region

Abstract

Nigeria is situated in a mobile zone separating older cratons of West Africa and Gabon, and underlain by nearly equal proportions of sedimentary and crystalline rocks. The crystalline basement rocks comprises three lithological groups (the Basement Complex, the Younger Granites and the Tertiary-Recent Volcanics) that were affected by Pan African (~550 Ma) thermo-tectonic events. The Basement Complex (Precambrian) encompasses gneisses- and migmatite-complex with schist belts, granites and minor charnokites and syenites with complex history and geochronology. In Kano (Kabo NE, Sheet 80 of Nigerian Geological Survey Agency maps) NW Nigeria, outcrops of these late Precambrian – lower Paleozeoic crystalline rocks are being mined of economic minerals. However, only a few studies exist on the geology of Kabo region. Therefore, this study describes the geology (lithology, composition, associated structures and field relationship) of rocks that characterize Kabo region, Kano and discuss trends of associated mineralization using field mapping and thin section petrography. Our data also includes high-resolution photographs of evidential geology of the area, parts of which are now defaced due to intense mining activities. Results showed that Kabo area is underlain by three rock groups: a migmatite-gneiss complex, an infolded schist belt (Younger Metasediments) and the Older Granites (porphyritic biotite granites, porphyroblastic biotite-rich gneiss and fine-medium grained granites). The porphyroblastic biotite-rich gneisses of the Older Granite division trend mainly in NE-SW and cut through the migmatite-gneiss complex; they exhibit preferred mineral alignment, suggesting that they are probably granitization products of the migmatite-gneisses, later metamorphosed and deformed. The granitized bodies are enriched in tourmaline that occur both in the NE-SW porphyroblastic rocks and the schist belt. The study thus serves as guide for investment decisions on solid mineral exploration in the area, and as a handbook for students of geology and tourists who now find Kano as a relatively safe geoheritage site.