Integrated Geophysical Characterisation of a Suspected Meteorite Impact Structure in Nasarawa State

A circular topographic depression in Nasarawa State, North Central Nigeria, exhibiting planar deformation features in quartz grains and shatter cone fragments documented in preliminary surveys, has been suggested as a potential meteorite impact structure, but systematic geophysical characterisation required to confirm impact origin has not been published. This study applies an integrated geophysical investigation programme to characterise the suspected impact structure in Nasarawa State using gravity, magnetic, and seismic refraction methods. Bouguer gravity anomaly data were acquired on a dense grid covering the depression and surrounding terrain, with results processed to derive residual gravity anomaly maps through regional trend removal using polynomial fitting. Aeromagnetic data from the Nigerian Geological Survey Agency were reprocessed and interpreted over the structure area. Seismic refraction profiles across the structure's inferred rim and interior provided P-wave velocity models of the upper five hundred metres. Subsurface velocity models are compared against typical impact melt and breccia velocity signatures documented from confirmed impact structures globally. Shock metamorphism indicators including planar deformation features and shatter cones in samples from the study area were characterised by scanning electron microscopy. The integrated data are interpreted against impact structure geophysical signatures established in the literature, providing a basis for either confirming or rejecting the impact hypothesis. Keywords: meteorite impact, geophysical investigation, Nasarawa State, shatter cones, impact structure.