A Pseudogravimetric Study of Part of the Upper Benue Trough, Nigeria

Pseudogravimetric transform is a linear filtering procedure for converting the magnetic anomaly over a magnetization distribution into the corresponding gravity anomaly. The transformation typically eliminates the characteristic asymmetrical nature of magnetic anomalies relative to their sources and enhances the long wavelength anomalies while attenuating those with short wavelengths. This method was employed in a study of part of the Upper Benue Trough in northeastern Nigeria carried in which case a grid of the total magnetic field intensity (TMI) of the studied area was transformed into a grid of pseudogravimetric (PSG) anomaly. The Total Magnetic Intensity ranged between -172.9 nT and 195.1 nT, while the Pseudogravimetric (PSG) anomaly of the TMI ranged from -42.4 milliGal to 19.7 milliGal. Qualitative interpretation, computation of the derivatives of the pseudogravimetric (PSG) anomaly and comparisons of the grid satellite gravity data with the grid of the pseudogravimetric (PSG) data have been carried out to facilitate the understanding of the origin of the magnetic anomalies in the trough. The result of the analysis shows a correlation between the PSG anomaly and the satellite gravity data in the southern part indicating a common source probably basement igneous intrusions and a negative correlation between them in the northern part probably indicating a sedimentary section with high magnetic susceptibility within it (intra-sedimentary magnetic anomaly). The derivatives of the Pseudogravimetric (PSG) anomaly identified igneous basement intrusions, basement topography, and variable magnetic susceptibility as probable causes of the magnetic anomalies. Spectral analysis was used for quantitative interpretation, determining depths ranging from 443 m to 7.74 k