Integrated Aeromagnetic and Radiometric Mapping of Lithological Units in the Nasarawa Basement Complex, North-Central Nigeria

Abstract

This study presents lithological mapping of Nasarawa State, North-Central Nigeria, and using integrated high-resolution aeromagnetic and airborne radiometric data covering about 27,000 km². Aeromagnetic data were processed using Reduction to Equator (RTE), Analytic Signal (AS), First Vertical Derivative (FVD) and Tilt Derivative (TDR), while airborne radiometric data were used to generate potassium (K), thorium (Th), uranium (U), radioelement-ratio and ternary maps. The integrated interpretation delineated the major lithological domains, including migmatite-gneiss complexes, schist belts, granitoids, Younger Granite intrusions, pegmatites, mafic to intermediate intrusive rocks and sedimentary formations of the Middle Benue Trough. The migmatite-gneiss complex generally exhibits moderate to high magnetic responses and low to moderate radioelement concentrations, whereas granitic and Younger Granite bodies show comparatively low to moderate magnetic responses and elevated K, Th and U. Schist belts display variable radiometric responses, reflecting compositional and metamorphic differences, while mafic intrusive rocks are characterised by stronger magnetic responses and generally low radioelement concentrations. Sedimentary formations show low K with moderate Th and U responses. The integrated magnetic-radiometric interpretation provides improved discrimination of lithological boundaries and identifies areas that may warrant further investigation for mineral exploration. The resulting lithological interpretation provides a regional framework for geological mapping and mineral exploration in Nasarawa State, particularly within granitoid, schist, pegmatite and sedimentary terrains.