Magnetic lineaments and basements interpreted from high-resolution aeromagnetic data underneath lower part of Benue Trough, Nigeria

Abstract

The high-resolution aeromagnetic data of part of Benue trough has been used for the interpretation of magnetic lineaments and basements for exploration of economic minerals in the region. We used the vertical derivative filters as the techniques for the interpretation of magnetic lineaments. Lineament analysis of the aeromagnetic data demonstrated four tectonic trends in the area. The lineaments are in the northeast to southwest (NE–SW), east, northeast to west, southwest (ENE – WSW), north to south (N – S), and east to west (E–W) directions. The NE – SW and ENE–WSW are the most dominant whereas the N–S and E–W are the minor trends. By implication, we see that the interpreted lineaments has link with the orientation of the trough and directions of major thermo-tectonic activity in the region. The total grid map of the TMI of the area was made into 25 blocks of 50 x 50 km with 50 % overlap where 25 power spectrum were generated for the depth estimations using spectral analysis. We have estimated different values of magnetic basement between 2 km and 5 km and the shallow magnetic sources (depth to top of intrusions) vary between 0.24 km and 1.20 km. In many blocks, the estimate of the shallow depth to magnetic sources were rejected on the basis that in those blocks, either there are insufficient observation data points (at least three) or no local maxima were obtained for the estimation of depth to top of magnetic sources. This could suggest the complex tectonic nature of the region.