Abstract
Structural interpretation of aeromagnetic data over Nkalagu-Igumale area of the Lower Benue Trough of Nigeria was carried out to determine the depth to magnetic basement and delineate the basement morphology and the structural features associated with the basin and their trends. The aeromagnetic data were subjected to series of computer based image and data enhancement techniques before spectral analysis. Results of the 2-D spectral analysis revealed two depths source models with the depth model (D1) for deep magnetic source bodies which are associated with intra-basement discontinuities and faults ranging from 2.15 to 5.25 km while the depth model (D2) of the shallow magnetic source bodies range from 0.35 to 0.99 km. From an economic viewpoint, the results indicate possible mineralization and existence of a reasonable Cretaceous sedimentary thickness in the area which is deep enough for hydrocarbon accumulation. The average sedimentary thickness obtained in the area is 3.75 km. Key words: Benue Trough, depth to magnetic basement, aeromagnetic data, spectral analysis, intrusive bodies.
Highlights
Magnetic method is a measurement of the earth’s magnetic field intensity, typically involving the total magnetic field and/or vertical magnetic gradient, horizontal or vertical component or horizontal gradient of the magnetic field (Biswas et al, 2017)
Structural interpretation of aeromagnetic data over Nkalagu-Igumale area of the Lower Benue Trough of Nigeria was carried out to determine the depth to magnetic basement and delineate the basement morphology and the structural features associated with the basin and their trends
To contribute to a better understanding of the depth and nature of mineralization, geology and development of the tectonic history in the Lower Benue Trough, we have considered the use of spectral analysis of the aeromagnetic data over Nkalagu and Igumale areas to compute for depths to magnetic sources
Summary
Magnetic method is a measurement of the earth’s magnetic field intensity, typically involving the total magnetic field and/or vertical magnetic gradient, horizontal or vertical component or horizontal gradient of the magnetic field (Biswas et al, 2017). The shape, dimensions and amplitude of an induced magnetic anomaly is a function of the orientation, geometry, size, depth and magnetic susceptibility of the body, as well as the intensity and inclination of the earth’s magnetic field in the survey area (Biswas, 2016; Biswas and Acharya, 2016) For exploration purposes, both ground and aeromagnetic data have been used to investigate the presence of. To contribute to a better understanding of the depth and nature of mineralization, geology and development of the tectonic history in the Lower Benue Trough, we have considered the use of spectral analysis of the aeromagnetic data over Nkalagu and Igumale areas to compute for depths to magnetic sources. The problems of aliasing effect and Gibb’s phenomenon which are normally encountered in the course of performing spectral analysis were taken care of by the use of small sampling intervals to reduce frequencies greater than Nyquist frequency
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