EFFECT OF HIGH CONCENTRATION OF eTh AND eU WITHIN PART OF NORTH CENTRAL NIGERIA ON GEOTHERMAL PARAMETERS

Abstract

The study deployed aeromagnetic data to estimate geothermal potential and radiometric concentration data to evaluate the radiogenic heat in parts of Kaduna state, central Nigeria. The study area which has been noted for relative high concentration of Potassium (K), Uranium (eU) and Thorium (eU) within Nigeria is bounded by latitude 10°00' to 10°30' and longitude 7°30' to 8°30', an area of 6,050 km2. The modified Curie depth method was employed in evaluating the Curie depth, geothermal gradient and heat flow. The region is found to have its shallow Curie point depth of 8.43 km below Wugana. The heat flow of the study area has values ranging from 81.9 mW/m2 to 171.9 mW/m2 with an average value of 167.8 mW/m2. The geothermal gradients range from 32.76 to 68.8 degrees Celsius per kilometre, with an average of 67.16 degrees Celsius per kilometre. Results of radionuclide concentrations revealed that the northern central regions extending down to the central part of the study area recorded medium to high values of radiogenic heat flow in the range of 3.85 to 4.5 μW/m3. Correlating the result of geothermal potential with radiogenic heat production reveals that regions of low Curie point depth correspond to regions of medium to high radiogenic heat production. Hence, the regions of significant geothermal potential are the mid-northern and mid-western areas such as Wugana, New Kwasan, and down to Ron village.The geology consist of rocks such as Pophyritic Granite Biotite granite, medium-to-coarse grained Younger Basalt, and granite gneiss, these in-situ basement rocks has undergone structural deformation and weathering which account for high concentration of radionuclide which exhibit radioactivity and consequently generate heat at the subsurface.