Spectral analysis and source parameter imaging of aeromagnetic anomaly over Ogoja and Bansara areas of lower Benue trough, Nigeria

Abstract

Qualitative and quantitative interpretations of aeromagnetic anomalies over Ogoja and Bansara areas of Anambra Basin, Lower Benue Trough of Nigeria were carried out using spectral analysis and source parameter imaging methods. The study area which covers an area of approximately 6050 km 2 lies within latitude 60° 0' to 7° 0' North and longitude 8° 30' to 9° 0' East. The regional anomaly was separated from the total magnetic intensity map to obtain the residual anomaly using first order polynomial fitting technique. The residual data was analyzed spectrally to obtain 18 spectral blocks for sedimentary depth estimates (deep and shallow depths). The edges and causative bodies of the residual anomaly were also sharpened to reduce anomaly complexity as well as fault trend amplification using first, second and horizontal derivatives. The 3-D basement topography map of the study area shows linear depression with deepest sedimentary thickness at the southeastern region of the study area, which implies that the feasibility of hydrocarbon potential will be higher in Bansara area than in Ogoja. The deepest depths obtained from spectral analysis and source parameter imaging are 5437.0 and 5059.9 m, respectively.

2-dimensional modeling of high-resolution aeromagnetic data over Yola arm of the upper Benue trough, Northeastern Nigeria

“…According to Ugwu et al, (2018), "the discrete Fourier transform numerical instrument utilized for spectral analysis and applied to regularly spaced data such as the aeromagnetic data to calculate and decipher the spectrum of the potential field". To perform this investigation, "graphs of the natural logarithms of the amplitude against frequency were plotted and the gradient of the linear segments computed in order to acquire the depths to the basement by utilizing the equations" of Ugwu et al,…”

“…Geophysical survey using airborne approach is an important aspect of modern geophysics which enables faster, cheaper and wider coverage of the exploration area (Ugwu et al, 2018). The high-resolution aeromagnetic data utilized for this work was acquired over the Yola Trough and surroundings of the basement blocks (Figure 1), in which a 2-dimensional modeling of the subsurface structures (horst and graben) was carried out.…”

Estimation of sedimentary thickness using spectral analysis of aeromagnetic data over Otukpo and Ejekwe areas of the lower Benue Trough, Nigeria

“…The use of spectral analysis in interpretation of aeromagnetic data has been successfully carried out and reported by so many authors (Spector, 1968;Mishra and Naidu, 1974;Ofoegbu and Onuoha, 1991;Onwuemesi, 1997;Abudullahi et al, 2014;Alasi et al, 2017;Ikeh et al, 2017;Ugwu et al, 2018). This research is therefore considered useful, especially on reconnaissance basis, for oil and mineral prospecting in the area.…”

Interpretation of High-Resolution Airborne Radiometric Data Over Part of Lower Benue Trough, Nigeria

“…Most of the geophysical works carried out in the basin employed airborne magnetic investigations for spectral depth or sedimentary thickness determinations (Igwesi & Umego, 2013;Ike et al, 2017;Alasi et al, 2017;Ugwu et al, 2018;Asielue et al, 2019;Okoro et al, 2021). Hence, an aeroradiometric investigation of the area is important in order to evaluate the mineralization in the area from the relative abundance of these three radionuclides of Uranium, Thorium and Potassium.…”