Study of aeromagnetic anomalies of Idah and Angba areas, north central Nigeria, using high resolution aeromagnetic data

Abstract

Aeromagnetic data of Idah and Angba environs, north central Nigeria, has been interpreted by applying spectral analysis and forward and inverse modeling methods. Quantitatively, spectral analysis and forward and inverse modeling techniques were employed in interpretation with the aim of determining depth/thickness of the sedimentary Basin and magnetic susceptibilities that give clue on the type of mineralization prevalent in the area. The result from spectral analysis revealed two main magnetic anomaly source depths; deep magnetic anomaly source and the shallow magnetic anomaly source. The deep magnetic anomaly source varies between 2.194 and 6.764 km with an average depth value of 5.014 km which represents the depth to sedimentary thickness. The shallow anomaly source varies from 0.597 to 1.592 km with an average depth value of 1.093 km and these were observed within the basement region. Forward and inverse modeling estimated depths for profiles 1–5 were 526, 461, 4347, 1751, and 6847 m, respectively, with respective susceptibility values of 0.0003, 0.0879, 0.0800, 0.0004 and 0.0700 which indicate intermediate and basic igneous rocks (diorite, andesite and gabbro or basalts) and basic sedimentary rocks (sandstone and limestone). The maximum depths obtained from these two applied methods show sufficiently thick sediments suitable for hydrocarbon generation and accumulation.