Evaluation of Aeromagnetic Anomalies Over Okigwe Area, Southeastern Nigeria

Abstract

Total field aeromagnetic anomalies over Okigwe area have been evaluated in order to map lineaments and estimate the depths to basement (sedimentary thicknesses). Aeromagnetic contour map of Okigwe (Sheet 312) was acquired, digitized and analyzed. Regional-residual separation and Slope methods were applied. The magnetic lineament map shows major geologic lineaments trending in NE-SW direction with minor ones trending in NW-SE direction. The major trend is in conformity with the trend of the Benue Tough. Visual study of the map shows presence of igneous intrusives in the northeastern part of the area. The results obtained using Slope methods indicate two depth sources in the area. On the average the deeper magnetic sources range from 2.0 to 4.99km, while the shallower magnetic sources range from 0.4 to 1.99km. Deeper magnetic sources probably depict depths to Precambrian Basement, whereas shallower sources probably depict depths to igneous intrusives and/or magnetized bodies within the sedimentary covers. Hydrocarbon exploration is not recommended since the area has low thickness of sediments on the average All these deductions were reached at after due consideration to both qualitative and quantitative interpretations supported by geological information of the area.