Subsurface Structural Mapping Using Gravity and Magnetic Data Across the Oji River Area, Enugu State

The Oji River area in Enugu State lies within a geologically complex zone influenced by the Benue Trough tectonics, making it a significant target for subsurface structural investigation. This study presents an integrated analysis of Bouguer gravity anomaly and aeromagnetic data to map subsurface structural features, estimate sediment thickness, and identify potential hydrocarbon migration pathways in the Oji River area. The data, sourced from the Nigerian Geological Survey Agency, were processed using standard enhancement filters including upward continuation, total horizontal derivative, and Euler deconvolution. Second vertical derivative and analytic signal maps were generated to delineate structural lineaments and basement depth estimates. Gravity anomaly values range from negative 12 mGal to positive 8 mGal, indicating lateral density contrasts associated with fault-controlled sedimentary basins. Aeromagnetic anomalies reveal northeast-southwest trending lineaments consistent with regional tectonic fabrics of the Benue Trough. Basement depths estimated from Euler deconvolution range from 0.8 km to approximately 4.2 km, deepening toward the axis of the Anambra Basin. The integration of both datasets reveals three major fault zones that may serve as conduits for hydrocarbon migration or geothermal fluid movement. This study contributes to the regional understanding of basin architecture in Enugu State and provides actionable information for mineral and energy resource exploration. The methodology applied here is consistent with recent advances in potential field data integration in the West African context.

Keywords: gravity anomaly, aeromagnetics, Euler deconvolution, Benue Trough, structural lineaments