Remote Sensing and Geophysical Targeting of Rare-Metal Pegmatites and Orogenic Gold in the Borgu Basement Terrain, Northwestern Nigeria

Abstract

The Nigerian Basement Complex is dominated by Precambrian migmatites, gneisses, schists, and granitoids that have undergone multiple phases of deformation, metamorphism, and magmatic intrusion. This study presents an integrated approach combining airborne geophysical data and satellite remote sensing imagery to evaluate the mineral prospectivity of the Borgu Local Government Area in Niger State, northwestern Nigeria, for rare-metal pegmatites (lithium, beryl, tourmaline) and orogenic gold. The outputs from geophysical interpretation, remote sensing analysis, and DEM evaluation were integrated within a Geographic Information System (GIS) framework. The study area lies within the Nigerian Basement Complex of the Pan-African mobile belt, predominantly underlain by granite gneiss. Aeromagnetic data interpretation revealed significant NE-SW trending structural features including faults, fractures, and lithological contacts that may control mineralisation. The Total Magnetic Intensity map indicates relatively low magnetic signatures, suggesting the presence of magnetite-poor felsic rocks typical of LCT (Lithium-Cesium-Tantalum) pegmatite host environments. Source Parameter Imaging indicates magnetic sources at depths of 120-180 m. Radiometric data analysis shows zones of potassium and thorium enrichment reflecting evolved granitic systems. Remote sensing analysis using Landsat imagery identified alteration indicators including iron oxide, clay, hydrothermal alteration, and quartz signatures. Integration of these datasets within a GIS environment enabled delineation of ten priority exploration targets. The results demonstrate that the Borgu basement terrain possesses favourable geological and structural conditions for pegmatite-related rare-metal mineralisation and structurally controlled gold deposits, warranting follow-up field investigations including detailed geological mapping, geochemical sampling, and ground geophysical surveys. Follow-up geophysical surveys—such as magnetic, electrical resistivity, and induced polarisation methods—are needed to better define subsurface structures and mineralisation.