AEROMAGNETIC SPECTRAL INVESTIGATION OF SUBSURFACE THERMAL STRUCTURE FOR GEOTHERMAL ENERGY EVALUATION IN YOLA ARM, UPPER BENUE TROUGH, NIGERIA

Abstract

Geothermal resources are increasingly recognized as a reliable and sustainable energy option for Nigeria. Despite previous investigations, a detailed characterization of subsurface thermal conditions, particularly within structurally complex basins such as the Upper Benue Trough, is required. This research investigates the potential for geothermal energy in Yola Arm by using spectral analysis of high-resolution aeromagnetic data. Six aeromagnetic sheets from the Nigerian Geological Survey Agency were processed with Oasis Montaj 8.4. The Magnetic data were corrected for low-latitude effects through Reduction to the Magnetic Equator, followed by separation of regional and residual components to isolate shallow anomalies. The residual data were partitioned into 28 overlapping segments for spectral analysis. Radially averaged power spectrum analysis was applied to evaluate Curie point depth (CPD), geothermal gradient, and heat flow. The results indicate that CPD varies between approximately 14 km and 26 km. Corresponding geothermal gradients range from about 22 to 39 °C/km, while heat flow values fall within 56 mW/m² and approximately 100 mW/m². Zones characterized by relatively shallow CPD exhibit higher thermal gradients and enhanced heat flow, suggesting favourable geothermal conditions. Conversely, deeper CPD zones are associated with lower thermal regimes. Spatial distribution patterns indicate that the southeastern portion of the area under study possesses a potential for geothermal energy