Determination of sediments thickness in part of Lower Benue Trough, Nigeria, from the residualization of aeromagnetic data: Implication for diversification of the Nigerian economy

Abstract

Aeromagnetic data were used in the study to determine the sediment thickness in the Lower Benue Trough. To achieve the objectives of the study, geophysical techniques were employed to analyze four aeromagnetic maps on a scale of 1:100,000, covering parts of the Lower Benue Trough. These include map merging, polynomial fitting, directional derivatives and forward modeling. Nine (9) profiles were modeled to determine sediment thickness, presence of possible intrusives and the subtle structural features and their trend within the study area. Results from this study revealed the existence of many intrusives which were majorly granite and basalt rocks which suggests complex tectonic events which accompanied the evolution of the Benue Trough. Lineament orientation revealed is majorly NE-SW direction and other directions were NW-SE, E-W and N-S. A sedimentary thickness ranging from 7 to 10 km were suggested by a 3D forward modeling, and this estimated depth did not coincide with an average of 5 km suggested by earlier researchers. Huge variations within the basement complex are however induced by the presence of horst structures as well as graben and this is profound within the depocenters where sedimentary pile is thicker. Magnetic sources within the sediment in Abakiliki, Udi and Nkalagu areas have potentials for hydrocarbon accumulation due to the thickness of the sediments in these parts of the study area. However, Bansara area reveals the presence of lots of intrusives, indicating high geothermal regimes that may not be favourable for hydrocarbon accumulation but have high potentials for solid mineral resources. Therefore, the Bansara area is recommended for organised and formal solid mineral exploration, which can apparently diversified the economy of Nigeria.