High-resolution aeromagnetic mapping and 2d magnetic modelling for detailed depth profiling of subsurface magnetic sources in parts of the Nupe Basin, North-Central Nigeria

Abstract

The Nupe Basin, located in North-Central Nigeria, forms part of Nigeria’s inland sedimentary basins and has attracted increasing interest due to its potential for hydrocarbon exploration. This study therefore utilizes high-resolution aeromagnetic data to investigate the depth to magnetic sources of selected portions of the basin for the purpose of investigating the hydrocarbon potential of the study area. Data covering sheets 162 (Akerre), 163 (Zungeru), 183 (Egbako), and 184 (Bida) were employed to determine the depth to magnetic sources and to conduct two-dimensional (2D) modelling of the area. The analysis was performed using Oasis Montaj software while incorporating depth estimation techniques which include Euler Deconvolution (ED), Source Parameter Imaging (SPI), and 2D forward and inverse magnetic modelling, with the aim of assessing the hydrocarbon potential of the region. Depth estimates from ED have values between 0.38 km and 1.44 km, while SPI results indicate depths from 0.63 km to 1.48 km. These values suggest the presence of shallow depth to magnetic sources in the northern, eastern, and north-eastern parts, and comparatively deeper sources in the northwestern, western, and southern parts of the study area. The 2D modelling results revealed magnetic intensities ranging from –100 nT to 60 nT, with corresponding depths between 0.5 km and 3.0 km. Structural discontinuities interpreted as faults were identified along several profiles. The predominance of short-wavelength anomalies and shallow magnetic sources likely reflects regions of reduced overburden thickness, potentially attributable to near-surface granitic intrusions. Although portions of the study area, particularly the southern, western, and northwestern zones exhibit greater magnetic source depths; the maximum sedimentary thickness, estimated at less than 2.3 km, is insufficient to support significant hydrocarbon generation. Consequently, the basin is considered to have limited potential for conventional hydrocarbon exploration.