Subsurface Structural Mapping over Koton Karifi and Adjoining Areas, Southern Bida Basin, Nigeria, using High-Resolution Aeromagnetic Data

Abstract

In this current work, we aim to delineate the subsurface structural trends, determine the depth to basement surface, and provide an illustrative 3D model for its subsurface structure. Four digitized aeromagnetic maps were acquired from the Nigerian Geological Survey Agency, Abuja. The total field aeromagnetic anomalies over Koton Karifi and adjoining areas have been evaluated. In order to map the subsurface structures and estimate the depth to basement surface the spectral analysis method was applied. To achieve such goals, a detailed analysis of the aeromagnetic data for the study area was performed. 2D interpretation was carried out for the aeromagnetic data. The processes used include contouring of the Total Magnetic Intensity (TMI) data, separation of regional and residual anomalies, structural detection methods such as analytic signal, vertical derivatives, and magnetic lineament mapping were used to map the contacts and faults within the study area. The first vertical derivative and the magnetic lineament maps show major geologic lineaments trending in East-West with minor ones trending Northeast-Southwest. In the south-eastern part of the study area, there is a dome-shaped linear feature. The result obtained using the spectral analysis method reveals two source depth models. The depths to deeper magnetic sources range from 2.81 km to 3.24 km with an average depth of 2.90 km. The deeper magnetic source bodies are identified with the magnetic basement. The shallower magnetic sources which range from 0.45 km to 1.81 km with an average depth of 1.13 km could be attributed to near surface magnetic sources which are magnetic rocks that intruded into the sedimentary formations or magnetised bodies within the sedimentary cover. Based on the sedimentary thickness range of 0.45 to 3.24 km, there is an indication that the possibility of hydrocarbon generation in the study area is feasible.

Analysis of High Resolution Aeromagnetic Data of Some Parts of Benue Trough, Nigeria

“…The graph of the natural logarithm of the amplitude against frequency plotted and the linear segment from the low frequency portion of the spectral drawn from the graph. The gradient of the linear segment is computed and the depth to the basement is determine using the equation 2 according (Negi, 1983;Chifu et al, 2019;Ikumbur et al, 2019;Anudu et al, 2020;Lucic, 2019) given as = − 2 2 Where Z is the depth to the basement M is the gradient of the linear segment L is the length of cross section of the anomaly.…”

“…The main purpose of the aeromagnetic survey is to detect minerals and rocks that have unusual magnetic properties which reveal them by causing anomalies in the earth magnetic field (USGS, 1997). Aeromagnetic survey is one of the most important tools used in modern geological mapping, determining depth and structure of crystalline basements rock underlying sedimentary basin (Onuba et al, 2012;Ikumbur et al, 2019). Previous studies were carried out in the study area in order to determine the basement depth.…”