CURIE DEPTH AND GEOTHERMAL GRADIENT FROM SPECTRAL ANALYSIS OF AEROMAGNETIC DATA OVER UPPER ANAMBRA AND LOWER BENUE BASIN, NIGERIA.

Abstract

A high amount of heat flow from a shallow curie depth is essentially related to a promising geothermal resource. This work explores the depth of demagnetisation due to high radiogenic heat content of the basement rocks. The Total Magnetic Intensity and the radiometric data, consisting of the Potassium count, the Uranium and Thorium equivalents, were employed for the research work. Sheet 145 (Kajuru) and 146 (Geshere) both on latitude 10°00'N to 10°30'N and longitude 7°30'E to 8°30'E covering 6,050 km2 within Kaduna State of Central Nigeria is an area with notedly high concentrations of these radionuclide by previous researchers. A shallow Curie point depth of 8.43 km was observed below Wugana while heat flow values ranging from 81.9 mW/m2 to 171.9 mW/m2 was estimated with an average of 167.8 mW/m2. Also, the geothermal gradients varied from 32.76 to 68.8 0CKm-1, with an average value of 67.16 0CKm-1. The effect of heat generated from the Potassium count, equivalent concentrations of Uranium and Thorium indicated the Northern end down to the Mid-western end displays medium to high radiogenic heat production. In conclusion, areas with low Currie depth that coincide with relatively high radiogenic heat production are located within Wugana, New Kwasan, and down to Ron villages, which are generally located at the Mid-North and Mid-Western areas with intrusive granitic rocks