Estimating sedimentary pile thickness, structural lineaments and heat flow in parts of North Central Nigeria from aeromagnetic data

Abstract

Evaluation, analysis and interpretation of aeromagnetic data acquired over parts of North Central Nigeria were carried out in order to characterise structural features and lineaments, sedimentary pile thickness, geothermal gradient and heat flow in the study area. Fourier domain digital filtering and reduction to pole (RTP) operations were done to enhance the data, while spectral analysis and source parameter imaging (SPI) were used to analyse the data. Results from the 2-D spectral analysis of the enhanced magnetic data suggest that the depth range to the top of magnetic sources Zt is 0.33–0.73 km (average depth of 0.55 km); depth range to magnetic centroid Zo is 2.51–5.83 km (average depth of 3.94 km); Curie point depth range is 4.41–10.96 km (average depth of 7.32 km); and average sedimentary rock cover thickness is 3.94 km. This compares with the results from SPI which gave depth ranges to various magnetic sources as 0.27–3.01 km. Structural lineament analysis indicates the major trend of the structural lineament is in the NE–SW, NW–SE and NNE-SSW. Average geothermal gradient of 82.87°Ckm−1 and heat flow of 207.19 mWm−2 were estimated, with a general increase in heat flow from the southern parts towards the northern parts of the study area. These relatively high geothermal gradient and heat flow may be associated with the mineralogical, thermal and tectonic history of the area, suggesting the study area has the potential of geothermal energy.