A Geodynamic Model for the Tectonic Evolution of the Benue Trough from Potential Field and Seismic Evidence

This study develops an original geodynamic model for the tectonic evolution of the Benue Trough, North Central Nigeria, based on integration of new and reprocessed potential field and seismic evidence. The origin and geodynamic evolution of the Benue Trough remains one of West Africa's most debated geological problems, with competing rift, wrench, and hot spot hypotheses inadequately constrained by existing data. This study produces the most comprehensive geophysical database for the trough to date by combining new high-resolution ground gravity (485 stations), new aeromagnetic data from DPR archives at 200-metre flight height, and newly acquired 2D seismic reflection profiles (280 kilometres). Advanced processing creates enhanced anomaly maps. Two-dimensional and 3D gravity-magnetic modelling constrained by all available deep borehole control produces quantitative basement models. Seismic interpretation provides stratigraphic and structural constraints. Receiver function analysis from 18 broadband seismometers deployed for 12 months along the trough axis quantifies crustal thickness variation. Findings reveal an asymmetric crustal thinning pattern with Moho shallowing from 36 to 24 kilometres from the basement flanks to the trough centre, consistent with a simple shear rift model with detachment toward the northeast. Magnetic modelling identifies two distinct basement terranes juxtaposed along a northeast-trending suture that reactivated as the master rift fault. Seismic reflection data image a series of half-graben structures controlled by the reactivated Pan-African suture. The combined evidence supports a model of oblique rifting along a reactivated Pan-African terrane boundary without mantle plume influence, representing an original contribution to the geological understanding of the Benue Trough.

Keywords: Benue Trough, geodynamics, tectonic evolution, potential field, seismic evidence.