INVESTIGATION OF THE GEOTHERMAL POTENTIAL WITHIN BENUE STATE, CENTRAL NIGERIA, FROM RADIOMETRIC AND HIGH-RESOLUTION AEROMAGNETIC DATA

Abstract

The study focuses on the analysis of high resolution Aeromagnetic data for the estimation of geothermal potential within the eastern part of Lower Benue Basin and correlating the results from the analysis of radiometric concentration data of the study area. The study area covers a total area of 18,150 km2, six aeromagnetic sheets cover the area, major towns are Markudi, Gboko,Otukpo, Agena, Akwana and Katsina-Ala, it is bounded by latitude 7.000 and 8.000 and longitude 8.000 and 9.500. The aeromagnetic data was subjected to Fourier analysis and then spectral analysis of 12 sub sections was carried out. From the spectral analysis, the depth to the top of magnetic sources varies from 0.28 Km to 0.36 Km while the depth to the bottom of magnetic sources varies from 5.52 Km to 9.63 Km. The modified Curie depth method was employed in evaluating the Curie point depth, heat flow and geothermal gradient were also obtained. The region found to have a shallow Curie depth of 9 km at the south-western and south-eastern part of the study area has an average geothermal heat flow 103.98 Wm-2. The geothermal gradient also has a value of 62℃/km and 30℃/km respectively with an average value of 41.59 oC/km, anomalous high heat flow of 153.35, and 135.62 Wm-2 was obtained within around Katsina- Ala and Oturkpo respectively. Correlating this result with the analysis of the radiometric values covering the study area, the ternary map shows that potassium and thorium radioactive content is noticeably high within these areas where relatively high heat flow values were obtained, The radioactive heat production within the two exothermally active areas was estimated to be1.47 μW/m3and 2.21 μW/m3 respectively this can be associated with the occurrence of these elements