Airborne Geophysical Data Interpretation of Nkalagu and Abakaliki Regions of the Lower Benue Trough, Nigeria: Implication for Mineral Potentiality

This study was carried out to delineate possible mineralized zones within Nkalagu and Abakaliki by mapping the structural and hydrothermal alteration zones deduced from the available aeromagnetic and aeroradiometric datasets. Magnetic enhancement techniques such as total magnetic intensity (TMI), reduction to the equator (RTE), analytical signal (AS) and center for exploration targeting (CET) were utilized. The Potassium, Thorium, Uranium, ternary image maps and the K/Th ratio map were produced to aid the interpretation process of alteration areas. The results obtained from the analysis of the airborne magnetic data identified and enhanced the magnetic signatures that reflect the structural features (lineament) of the study area, by revealing the structural trends at the ENE-WSW, NE-SW and WNW-ESE as major trends and NNE-SSW, NW-SE, NNW-SSE as minor trends. The analysis of radiometric data revealed the concentrations of Thorium (eTh), Uranium (eU), and Potassium (%K) concentrations, which were used for the classification of the rock types present in the area. These classifications identified intrusions of basically igneous rocks such as granite, gabbro, rhyolite, diabase, and metamorphic rocks such as quartzite and schist. The areas believed to be hydrothermally altered, aligned NW-SW, NNE-SSW, SE, central potions, and NE borders were identified based on the concentration of radioelements, using K/Th ratio and the ternary maps. Hence, the results obtained from the analysis of the two methods mapped geological structures, geological boundaries, and alteration areas that could be target areas of possible mineral deposits.