ABSTRACT

Aeromagnetic survey is la geophysical survey that is carried out using a magnetometer aboard or towed behind an aircraft. It measures and records using the sensor, the total I I ll]lagnetic intensity of the area under observation. The study area which lies within latitudes 6°00'N to 630'N and longitudes7'30'E to 800'E lying predominantly in the lower Benue Trough with geologic formations which includes the Asu river group, a poorly bedded, bluish-black shale with fine to medium grained sandstone and lies directly on top of the basement complex, the Nkporo shales formation with dark grey spate and soft mudstone and the Ezeaku formation containing alternating shale and s!ltstones. Structural and tectonic interpretation of Nkalagu area using high resolution aeromagnetic data was tarried out to determine the depth to basement, delineate the I • ' basement morphology and structural features associated with the basin thus widening an in depth knowledge of the geology of Nkalagu. The Aeromagnetic data obtained was subjected to various data preprocessing, enhancement and processing techniques. Results of the study from the contoured total magnetic intensity map, the reduction to pole map and the second vertical derivatives map of the study area revealed lineament with trend directions in! the N-S, NE-SW, NW-SE and E-W, with the NE-SW trend I ; being dominant., the enhanced data, when subjected to 2-D spectral analysis, revealed a two layer depth model, the shallower magnetic sources and the deeper magnetic sources with average depths of 1.041 km and 3.574km respectively. Similarly, the average sedimentary thickness of the study area was estimated as approximately 3.6km