Aeromagnetic Investigation of the Subsurface Sturctures in Parts of Niger Delta, Nigeria

Abstract

The geophysical interpretation of Aeromagnetic data over the study area bounded by longitude 4°00′–5°00′ and latitude 5°30′–6°30′ provides crucial insights into the subsurface geological configuration, with significant implications for hydrocarbon exploration. Reduced-to-Equator (RTE) map reveals magnetic values ranging from 32,869.16 nT to 33,037 nT, reflecting the influence of subsurface lithology and tectonic structures. High magnetic intensities in the East–central and South Western part of the map, often correlate with the presence of ferromagnetic minerals, such as magnetite-rich mafic and ultramafic rocks, suggesting potential igneous intrusions or lithological boundaries, the lower magnetic zones, illustrated in blue west–central part of the map, indicate nonmagnetic sedimentary units, deep basement rocks, or zones of weathering and alteration. The high magnetic intensity closures observed within the basin are likely associated with the underlying basement rocks or with igneous intrusions that may have penetrated the sedimentary sequence. Depth estimation techniques such as Euler Deconvolution utilize a structural index (SI = 1) to delineate linear geological features like faults and dykes, with clustered solutions indicating complex basement architecture. Source Parameter Imaging (SPI) analysis estimates source depths exceeding 3.0 km, confirming the presence of thick sedimentary basins critical for hydrocarbon maturation. Spectral analysis indicates basement depths between 8.7 and 11.6 km, with deeper zones concentrated centrally and southeast part , aligning with potential depocenters. The First Vertical Derivative (FVD) map indicates the passage of the paleo-fracture zone through the area. This is also indicated in the discontinuity shown in the Total Magnetic Intensity (TMI) map. These datasets improve the geological interpretation of the region, reveal structurally controlled sedimentary basins, and help outline prospective zones for hydrocarbon exploration and development within the Niger Delta.