عنوان مقاله [English]
Geothermal energy potential investigation over Parts of Middle Benue Trough, Nigeria, has been evaluated using aeromagnetic and aeroradiometric dataset. The input data consists of nine aeromagnetic and aeroradiometric sheet respectively. Datasets from these aerogeophysical methods proved vital for identifying high geothermal areas. The application of aeromagnetic dataset in the study area helped in determining depth–to-top and depth-to-bottom of magnetic sources using spectral mathematically tool; and estimation of geothermal gradient, heat flow and Curie-point isotherm depths in the study area. The aeromagnetic data was assembled and digitized; this produces Total Magnetic Intensity anomalous map (TMI). Similarly, the radiometric data were contoured to produce maps for the three radiometric elements of K, Th and U. The rose diagram showed that the structural trend in the study area is trending NE-SW and the minor ones are trending E-W and NNE-SSW directions. The radiometric datasets revealed geochemical information on potassium (K), thorium (Th) and Uranium (U) concentrations within the study area used to delineate bedrock lithology, as well as alteration and contact zones. High K, Th and U concentrations were mapped in the study area. The high resolution airborne magnetic and radiometric data of the study area resulted in better definition of both geological structures and lithological boundaries. Radiometric heat model reveals area of high and low geothermal gradient. The results of quantitative interpretation reveals that the depth to acoustic magnetic sources (the sedimentary infilling) ranges between 0.76 and 4.46 km; while the depth to centroid ranges between 7.29 - 19.6 km. The Curie point depth (CPD) corresponds to the depth to the bottom of the acoustic magnetic source. The CPD varies from 12.70 - 37.22 km, the geothermal gradient varies between 15.58 - 45.670C/km, and the geothermal heat flow varies from 38.9 - 114.17mW/m2. The two dimensional structural models show uplifted crust and mantle in some areas due to magmatic intrusions which gave rise to low CPDs (12 to 28 km) which resulted to high geothermal heat flow values (60 to 115mW/m2). The geothermal heat flow values around Kwolla, Shendam, Lafia, Akiri, Ibi and Wukari South fall between 60 and 100mW/m2, which is the suitable standard for geothermal potentiality. This research work shows the usefulness of geophysical data in mapping possible geological structures that host geothermal resources within the study area. Lineament analysis using rose diagram showed the structural trend in the study area. The study also revealed the depth to magnetic bodies.