Integration of Magnetic, Gravity and Geologic Data in Mapping Geologic Structures: A Case Study of Part of Lafiagi [Sheet 203], Central Nigeria

Abstract

The geophysical study of part of Lafiagi (Sheet 203) in the Nigerian topographical map, which is a transition environment between the Basement complex rocks of the south-western Nigeria and the Sedimentary rocks of the Nupe Basin was carried out. It was aimed at mapping the subsurface morphology so as to identify the tectonic features responsible for the structural setting and improve on the geological map of the area. This work involved the qualitative and quantitative analysis of aeromagnetic and pseudo-gravity data using geological and geophysical softwares like Oasis MontajTM. Gravity and magnetic (GM) data have been widely used to interpret features in the Earth's lithosphere. These data can be used to identify natural hazards, to explore for natural resources, and to study crustal-scale structures for understanding the tectonic development of a region. The need to continue with and to step up efforts on the hydrocarbon exploration programmes in Nigeria's other sedimentary basins outside the Niger Delta as mitigating measure against agitation for resources control, dwindling national and global reserves etc has made gravity and magnetic surveys to become powerful tools for informing geoscientists about subsurface structures under thick sediments and in basement complex terrain. The approaches of Spectral Frequency Analysis and 3-D Euler inversion of the acquired aero-magnetic and pseudo-gravity data augmented with geological information obtained from reliable sources were employed in the interpretation works. The results have shown that: The drainage system in the study area is structurally controlled. The details of the depth to anomaly sources obtained from the 2-D power spectral interpretations and standard 3-D Euler Deconvolution on the Reduced- to- Equator filtered map of the study area have shown that the depths to basement and location of structures and intra-sedimentary structures are both near surface and deep seated. The near surface structures (SI= 0.5) which were mostly faults/fractures, linearment features, dykes and sills were confirmed by both the magnetic and pseudo-gravity methods had some plotted on the modified geologic map of the study area. The deep seated structures gave additional information on the geological/tectonic nature of the study area.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015