Geophysical Mapping of Fault Systems in the Benue Trough Using Gravity and Magnetic Methods

This study maps fault systems and structural architecture in a section of the Benue Trough using combined gravity and magnetic geophysical methods. Fault systems in the Benue Trough play a critical role in controlling mineralisation pathways for barite, lead, zinc, and fluorite, as well as influencing groundwater flow and compartmentalisation within the trough sediments. This study reprocesses aeromagnetic data from the NGSA archive for the middle Benue Trough area in Kogi and Nasarawa States and supplements it with 58 ground gravity stations acquired along four profiles crossing interpreted aeromagnetic lineaments. Standard processing including IGRF removal, RTP transformation, first vertical derivative, and upward continuation is applied to the aeromagnetic data. Ground gravity data are corrected to Bouguer anomaly level and filtered. Linear features in the derivative maps are manually traced and classified by orientation. Cross-correlation with known geological faults in NGSA maps validates the geophysical lineament interpretations. Findings reveal a conjugate fault pattern with NE-SW and NW-SE trending fault sets consistent with the regional tectonic framework for the Benue Trough rift system. Gravity gradients across mapped faults confirm offsets of 100 to 600 metres in the basement surface. Coincidence of NW-SE faults with known barite vein zones in Benue State confirms the structural control on mineralisation. The study provides a detailed structural map for the central Benue Trough that can guide mineral exploration, groundwater management, and geological research.

Keywords: fault mapping, Benue Trough, gravity, magnetic, structural geology.