Investigation of geothermal potential of the Dahomey basin, Nigeria, through analysis of geomagnetic and geo-resistivity dataset

ABSTRACT Geothermal resource has attracted industrial and environmental interest in the last decades. However, the thermal condition of the Dahomey basin, which is instrumental to harnessing such geothermal resource, has remained largely unknown. The geothermal characterisation of Dahomey Basin was therefore undertaken to determine its thermal potential. The methodology involved analysis of the power spectra density of aeromagnetic data and interpretation of geo-resistivity data. The aeromagnetic dataset was divided into twenty one blocks with each block overlapping the adjacent blocks by 50%. Spectra peak, Curie depth, geothermal gradient, heat flow and temperature at depth were computed. Two-dimensional geo-resistivity profiling method was implemented to locate the top of the thermal aquifer. The results showed varied Curie depth (11–27 km) and heat flow (53–130 mW/m2) while the geothermal gradient ranges from 21 to 52 °C/km. Results of resistivity profiling showed the thermal aquifer to be sand (1–20 Ωm) whose top is located at 155 − 210 m depth. From the estimated geothermal parameters, two new geothermal prospect areas were identified. This study established that Dahomey basin is a thermally unstable basin with a very high potential for geothermal resource that is attributable to crustal thinning and possibly mantle dynamics.