Delineation of structural lineaments of Southeast Nigeria using high resolution aeromagnetic data

Abstract

Structural lineaments of Southeast Nigeria were delineated using high-resolution aeromagnetic data. Advanced methods such as enhanced horizontal gradient amplitude (EHGA) involving a 3D model and tilt depth method (TDM) were used in this study. The simulated magnetic model involving the EHGA detector positioned peaks over source borders and created sharp and clear edges for magnetic sources. The TDM is a cutting-edge depth determination method revealing the depth of the contacts and thickness of sedimentary bodies that vary from ∼500 to ∼2,500 m and ∼3,000 to ∼5,000 m, respectively. Lineaments of the study area were extracted from the EHGA map. The structural map showed the dominance of short-ranged (∼0.29 to ∼1.48 km) linear magnetic anomalies. In addition, regional geologic structures (∼2.8 to ∼24.5 km) occur at the western flank of the study area. In general, these structures trend in the NE-SW, NNE-SSW, N-S, E-W, and NW-SE directions. They are indicators of subsurface faults, contacts, and tectonic structures of the thermo-tectonic events associated with Santonian Abakaliki Anticlinorium, Tertiary-Recent Ikom-Mamfe Rift, and structural deformations of the basement rocks associated with the Oban Massif.