Geophysical mapping and mineralisation characterisation of the mesothermal auriferous basement complex in southern Kebbi, NW Nigeria

The Precambrian basement complex in southern Kebbi hosts various sulphuric and iron-oxide deposits which contain ore minerals associated with hydrothermal processes that occur within geologic structures. This study applied integrated geophysical approach to map and classify the structures and lithotypes of the basement complex so as to delineate geologic features that may support mineral prospecting. Airborne magnetic and radiometric datasets were enhanced through data reduction to display characteristics of surface and subsurface geology of the area. The derivative and analytic signal maps processed from the magnetic data highlighted major geologic structures such as the Zuru-Bini Yauri lineament and Anka lineament. The ternary map of the area displayed several metasedimentary and metavolcanic lithotypes bearing characteristics of potassium, thorium and uranium dominance. The Anka shear zone showed an elongated stretch of lineament trending NE-SW among other NNE-SSW, N-S, E-W trending shallow and deep-seated faults. Several shallow structures connected to the regional hydrothermal conduits within the alteration zone were delineated as potential auriferous-rich veins. The results of this study showed that the delineated Anka shear zone borders a plutonic region of brittle-ductile deformation inferring tectonic fracturing for fluid movement and related hydrothermal alteration deposits towards mineralisation in the area.