Sediment thickness of subsurface anomalous Sources Determined by 2D/3D modeling of Potential field Gravity data: Implications for Sokoto Inland Basin Structures, NW, Nigeria

AbstractDue to the promising potential for hydrocarbon exploration in Nigeria's inland basin, more and more emphasis is being paid to the structural setting associated with these basins, especially the current Sokoto basin. Lacoste and Romberg's CG-725 gravimeter collected a sizable amount of potential field gravity data for relative measurements in the region, which is used in this work. The depth of the Earth's subsurface was investigated in this study, which also provided information on the most likely process of emplacement for the bodies that gave rise to the anomalous structures in the Sokoto inland basin. The regional field, a plane with a gradient of 0.38 mG/km and an approximate 10° northeasterly dip, was used as a technique for regional-residual separation. The relative amplitudes of the negative Bouguer gravity anomaly in the region range from − 27.38 mGal to -74.88 mGal. In the southern part of the study area, a large positive anomaly with amplitude of 16.2 mGal can be detected on the residual anomaly map. The main techniques for applying enhancement filters include 2D forward modeling, analytical signal and tilt of angle derivative, directional filtering, power spectrum analysis, Werner deconvolution, and 3D inversion. The 2D spectral depth analysis of gravity data along the rift axis (NE-SW) indicates that source depths tend to deepen toward the south. The joint 2D forward modeling of gravity data provided more evidence for this, demonstrating that the top of the basement slopes both in the NW-SE and N-S directions. The 3D gravity model's findings concur with those derived from methods for estimating depth and surface geological properties. Two depth estimates—1.8 km and 2.93 km—that roughly match the locations of two density boundaries were obtained using the gravitational power spectrum analysis. In the up-dip parts of the Taloka and Gundumi-Illo Formations, intrusions were found at depths of 10–20 km and 5–10 km, respectively, according to gravity modeling of the upper crust. The quaternary faults and fractures in the Eocene sediment at Gwandu Continental Terminal are essential for the sediment cover of the regional hydrocarbon system.