Spectral analysis of aeromagnetic data for geothermal energy resources potential in Ikogosi, Southwestern Nigeria

Abstract

High-resolution aeromagnetic data (Sheet 244, Ikogosi, southwestern Nigeria) were subjected to spectral analysis to evaluate the lithospheric thermal regime and geothermal resource potential. The aeromagnetic grids were processed through standard corrections and transformations, including Reduction to the Equator (RTE), Upward Continuation (UC3000 m), and regional–residual separation. Spectral energy–wavenumber relationships from 25 overlapping residual blocks were analyzed to derive centroid depths (Z₀), top of magnetic sources (Z_t), Curie Point Depths (Z_b), geothermal gradients, and heat flow. The results delineate Z₀ values of 15–32 km, Z_t of 3–12 km, and Z_b between 21 and 54 km. Corresponding geothermal gradients range from 10.6 to 26.8 °C/km, with heat flow varying from 26.6 to 67 mW/m² (mean 37 mW/m²). Integration of TMI, REG, and RES maps reveals heterogeneous basement architecture with E – W and NE–SW structural lineaments, high-intensity central anomalies linked to shallow intrusive, and low-intensity corridors interpreted as hydrothermal alteration zones and fracture conduits. The southwestern and western margins exhibit shallow Curie depths (21–34 km) and elevated heat flow (50 mW/m²), highlighting structurally controlled geothermal “hotspots.” These findings underscore the coupling of intrusive-related thermal sources with fracture-enhanced permeability, positioning the southwestern–western corridor and central magnetic belt as the most prospective geothermal targets.