Geothermal Prospect Evaluation of Northern Benue Tough, northeastern Nigeria, From High Resolution Airborne Magnetic Data

Geothermal prospect evaluation of the northern Benue Trough was carried out using high resolution airborne magnetic data, with a view to delineate zones of geothermal potential for possible geothermal development. The spectral analysis of 76 overlapping gridded blocks of filtered, transformed and enhanced residual magnetic data of the northern Benue Trough was carried out to generate geothermal gradient and heat flow across the area. Lineament mapping for delineation and extraction of regional linear structures known to aid permeability and ease conduction of the subsurface heat through conduits created for underground water by fractures were also undertaking from the horizontal component of tilt derivative. The analyses of the resultant spectral generated from the processed grids of overlapping blocks of airborne magnetic data indicate geothermal gradient that range in values from 5 ^o C/km to 42 ^o C/km and heat flow values range between 19 mW/m ² to 105 mW/m ² across the study area. The delineated linear structures range in length from 7 – 170 km and trend dominantly along NE-SW direction. Two prominent anomalous geothermal zones with geothermal gradients and heat flow magnitude of up to 20 ^o C/km to 42 ^o C/km and 50 mW/m ² to 105 mW/m ² , respectively, were delineated in the southwestern and southeastern part of the study area. The high geothermal zones coincide with zones of high lineament density and occurrence of warm springs and volcanic plugs.