Structural trends and spectral depth analysis of the residual field of Pategi Area, Nigeria, using aeromagnetic data

Abstract

Pategi area is located between longitude 530´E and 600´E and latitude 830´N and 900´N and lies at the southwestern part of the Bida basin in west central Nigeria and is filled with Campanian-Maestrichtian sediments comprising mainly sandstones that are underlain by basement rocks comprising of granite-gneiss and migmatites. The area is covered by one half-degree aeromagnetic map, which was digitized at 1.5 km grid and re-contoured. The compiled magnetic map shows that an approximately NE-SW trending fabric characterizes the upper part of the area down to latitude 8.84N. This trend changes to largely E-W in the central portion between latitudes 8.63N and 8.84N. Below latitude 8.63N the trend changes again to approximately NE-SW particularly at the southwest fringe of the map. A major lineament depicting the Romanche paleofracture zone was found in the area. The Pategi area has complex magnetic signature. Short to moderately long discontinuities were found in the magnetic map. Several magnetic closures of various sizes were also noticed. While the discontinuities indicate the presence of minor to moderately long fault zones in the area, the closures depict the sizes of the anomalies that lie beneath the basin. Spectral depth determination indicates that the area contains average sediments up to a thickness of 3.27km. A sedimentary thickness of this size may be recommended for further investigation for petroleum exploration. The intra-basin fault zones may have hydrocarbon implication.

Keywords: Magnetic, Bida basin, fault zones, Pategi area.

Nigerian Journal of Physics Vol. 18 (2) 2006: pp. 271-276