Application of scaling geology in magnetic basement mapping around the Middle Benue Trough in Northcentral Nigeria

Abstract

Using the scaling spectral method applied on high resolution aeromagnetic data, we mapped the magnetic basement and estimated the scaling exponents across various lithologies within the Middle Benue Trough of Northcentral Nigeria. We estimated a depth range of 1.8–6.3 km, with an average of 3.7 km to the basement beneath the Cretaceous sediments of the trough. Shallow basement depths of <3 km are mostly found on the trough's northern and southeastern margins. These are uplifted Precambrian Basement Complex regions made up of older granite, gneiss, and migmatite. Deeper basement depths of >4 km predominate in the southwestern, central, and northeastern portions of the study area, trending along the trough's axis. These deep zones are filled with Cretaceous sediments that must have accumulated after the Mesozoic development of the Benue Trough's subsided graben structure. Our study estimated scaling exponent ranging from 0 to 2. There were some correlations with the geology of the area, particularly around the crystalline basement complex in the northern portion. Within the central portion of the Middle Benue Trough, however, the source distributions are less correlated, uneven, and not always consistent with the geology of the area. This could be due to the region's dynamic and unstable tectonics, as numerous magmatic intrusions have been emplaced into the Cretaceous sediments at various depths, potentially influencing the scaling exponent values.