Geophysical investigation of subsurface features influencing mineralization in Minna area of Nigeria using aeromagnetic and airborne radiometric data

Abstract

The growing demands for critical raw materials like copper, lithium, lead–zinc and iron ore which are essential commodities that will drive the global sustainable energy development has reignited the interest of the Nigerian government to reinvigorate the mining sector of the economy. Sparse availability of detailed structural and mineral data that will guide future exploration programs in most parts of the country emphasizes the need for a regional geophysical study to identify new mining sites in potential prospective areas within the mineralization-prone basement setting of northcentral Nigeria, like the Minna area and environs. Hence, the main goal of this study was to map subsurface features controlling hydrothermal mineralization occurrences in the Minna area of Nigeria, based on integrated interpretation of aeromagnetic and airborne radiometric data. The aeromagnetic data were subjected to various processing techniques using filtering algorithms including reduction to the equator, regional–residual separation (employing the polynomial fitting method), first vertical derivative, analytical signal, source parameter imaging, and spectral analysis, to detect the boundaries and depths of occurrences of linear geologic features. The airborne radiometric data were gridded to generate color composite, ternary, and ratio maps of potassium (K), thorium (eTh), uranium (eU), and K/eTh, in order to identify the various lithological components, as well as potential hydrothermally altered zones in the area. The results revealed potential prospective hydrothermal alteration zones that are characterized by long lineaments length and high lineaments density. The lineaments showed major orientations in the ENE–WSW, NE–SW, WNW–ESE, and E–W directions, synonymous to the Pan-African and earlier tectonic cycles that impacted the Precambrian Basement rocks of Nigeria. These geological features may have enhanced the formation of hydrothermal mineralization in the area by acting as pathways for the migration of hot mineralized fluids from depths, thereby creating room for the chemical activities responsible for wall rock alteration. The integrated approach adopted in this study can serve as guide for mineral exploration campaign in Nigeria, and other parts of the world with similar geological disposition.