Heat flow and thermal structural mapping of part of Middle Benue Trough for Exploration of Geothermal Energy

This study focuses on delineating the potency of geothermal energy within part of the Middle Benue Trough (MBT) via analyses of airborne geophysical datasets. The integrated analyses of airborne magnetic and radiometric data is to foster collaborative imaging and enhance the localization of target resources. A spectral analysis was performed on the total magnetic field of the study area to reveal the essential parameters that could be indicators of a potential geothermal reservoir. The analysis evaluated Curie point depth (CPD), geothermal gradient (GG), and heat flow (HF). Estimated values of CPD, GG, and HF range from 10 to 22.65 km, 25 to 55 °C/km, and 60 to 140 mW/m2, respectively. Also, radiogenic heat production (RHP) range from 1.13 to 6.40 μW/m3 was evaluated via analysis of airborne radiometric data. The RHP was estimated with respect to the lithologies in the study area. Sampling of element concentration and heat generation revealed that granitic rocks, schist, and shale hosted more radioelements and consequently contributed more to RHP within the study area. Viable HF and RHP for geothermal resources were observed at the mid-portion of the northern region, corresponding to Mada, Nasarawa Egon, Akwanga, and at the western and south-eastern edges, covering Udeni and Keana. The delineated major structures in NE-SW direction might serve as migration conduits and channels for crustal HF within the study area. The regions of high HF coincide with those of anomalous RHP, which might be attributable to the geological stability of the study area. This agreement is of priority and interest for geothermal exploitation in the study area.