Structural Interpretation of Abakiliki – Ugep, using Airborne Magnetic and Landsat Thematic Mapper (TM) Data

Abstract

The study area is part of the Southern Benue Trough and lies within Latitudes 5º 30' - 6º 30' N and Longitudes 8º 00' - 8º 30' E. Structural interpretation of Abakaliki–Ugep area using aeromagnetic and Landsat data was carried out to determine the depth to the magnetic basement, delineate the basement morphology, relief, and the structural features associated with the basin uplift, (Abakaliki Uplift) as well as their trends/patterns. Aeromagnetic and Landsat data were subjected to various image and data enhancement and transformation routines. Results of the 2-D spectral analysis revealed a two  depth models: the shallower magnetic source bodies range in depth (D1) from 0.035km to 1.285km with an average of 0.656km while the deeper magnetic source bodies range in depth (D2) from 1.585km to 4.136km with an average depth of 3.096km.The shallower magnetic anomalies resulted due to basement rocks which intruded into the sedimentary rocks while the deeper magnetic anomalies are associated with intra-basement discontinuities associated with faults. The average sedimentary thickness of 3.096km estimated in the study area may favor hydrocarbon generation. The drainage pattern is dendritic which is indicative of lithological, structural and topographic differences and also indicative of alluvial rocks, which is typical of the geology of the area that consists mainly of sedimentary rocks. Also, results from the study revealed lineaments with trend directions in the N-S, NE-SW, NW-SE and E-W directions, with the NE-SW trends being dominant. The dominant trend of the magnetic data is the NE-SW which agrees with the fault orientation within the Benue Trough.

Keywords: Structural trends, Aeromagnetic anomalies, basement depths, Lineaments, Landsat