Basement and structure near the southwestern margin of the lower Benue Trough between, and including, the Anambra basin and Afikpo syncline, as derived from aeromagnetic and gravity data

Abstract

We present depth estimates and structural information, using aeromagnetic and gravity data, relating to the basement near the southwestern margin of the lower Benue trough between, and including, the Anambra basin and Afikpo syncline. The basement depth is calculated on the basis of the scaling spectral method, Euler deconvolution, and source parameter imaging (SPI) applied to gridded aeromagnetic data and 2D gravity modeling across the three main tectonic features (i.e., Anambra basin, Abakaliki anticlinorium, and Afikpo basin/syncline). We interpreted basement depths between 8.4 and 9.1 km within the Anambra basin, 3.1 and 9.8 km within the Abakaliki anticlinorium, and 3.8–8.5 km within the Afikpo basin/syncline. The magnetic basement depths estimated from the three methods applied on the aeromagnetic data are in good agreement with each other and that provided by the 2D gravity model which produced a reliable picture of the basement relief in the region. We also mapped and interpreted magnetic lineaments/faults in the region. Three well-defined magnetic lineaments/ faults (NE–SW, ENE–WSW, and WNW–ESE) correlate very closely with the trends of geological structures of the Pan-African plate which predated the compressional folds and faults within the Cretaceous sediments and strike-slip movements during the separation of Africa and South America.