DELINEATION OF HIGH-RESOLUTION AEROMAGNETIC SURVEY OF LOWER BENUE TROUGH FOR LINEAMENTS AND MINERALIZATION: CASE STUDY OF ABAKIKILI SHEET 303

Abstract

High resolution aeromagnetic dataset of Abakiliki (sheet 303 SW) was used for the characterization of the subsurface lithostructural features in part of the Lower Benue Trough, Nigeria. This study was necessitated for mapping and delineating hydrocarbon prospecting zones, in order to boost the Nation’s economy. The aeromagnetic data were subjected to several forms of filtering, reductions, and enhancement techniques for both qualitative and quantitative interpretations. The result of the reduction to equatortotal magnetic intensity (RTE-TMI) revealed the magnetic intensity of subsurface rocks ranging from 34.14nT to 61.40nT. These range of magnetic intensity values characterized the rocks in the area as shale and Limestone within the Asu River Group, Awgu shale, Eze-AKu shale and Nkporo shale. The upward continued RTE-TMI data to 500m, 1 km, 2 km, 3 km, 7 km and 10 km revealed regional trends of these rocks and structure thin –out with measure depth continuation. The second vertical derivative (SVD), Tilt-angle derivative (TDR) and Analytical signal (AS) revealed three (3) major faults; F1-F11, F2F12 and F3-F13 in NE-SW, ENE-WSW and NW-SE directions respectively. The depth to top of magnetic source were revealed by the radially averaged power spectrum (RAPS) and Euler deconvolution as 27m and 2.64km for shallower and deeper sources respectively. This study has demonstrated the efficiency of aeromagnetic methods, with their improved techniques as tools for regional mapping of lithologies and structures that may host important minerals and/or aid hydrocarbon accumulation and their probable depths.