Determination of heat flow and temperature variations for geothermal energy assessment over Sokoto Basin, Nigeria, using aero-magnetic and aero-radiometric data

Abstract

The Nigerian sector of Iullemmeden Basin (Sokoto Basin and its adjacent region) contains sediments between the ages of Cretaceous and Tertiary covering the entire Basin. The area is bounded by latitude 12° 5ˈ – 14°00''N and longitude 4°00'' – 7°00''E. The study investigates geothermal energy resource potential over the Sokoto Basin using aeromagnetic and radiometric data. Seventeen (17) blocks of aeromagnetic and aero-radiometric data were gridded and processed using dimension of 55 km x 55 km. Spectral centroid method was employed to approximate depths to top and centroid of the magnetic sources of the study area. The results divulge that values of CPD range from 5.0 km to 12.5 km having a mean value of 8.8 km, whereby, the values of geothermal gradient range from 46.4 ^oCkm^-1 to 116.9 ^oCkm^-1 having a mean value of 81.6 ^oCkm-1, while the values of heat flow range from 115.9 mWm^-2 to 292.1 mWm^-2 having a mean value of 204.1 mWm^-2. The study also reveals that, the values of radiogenic heat range between 0.81 and 2.87 μWm^-3. The zones having high concentration of thorium and uranium trending N-S and S-W extend to Niger Republic across mid-northern border. The result from this study also reveals that, Curie temperature could be attained at the depth of 6 km deep. Conclusively, those spots having shallow CPD and high heat flow may be potential for geothermal energy source.