Qualitative, Lineation and Depth Evaluation of Potential Field Signatures in the Abeokuta Region, Southwestern Nigeria

Abstract

Abstract Ground gravity and magnetic geophysical surveys are proven veritable tool in the imagery of the subsurface through the analyses of their responses (potential field data). This research attempts to delineate subsurface linear structures that are possible conduits for mineral accumulation at a 2,500 square metres active exploration site of FUNAAB, Abeokuta region. Abeokuta is embayed in the Dahomey Basin comprising of magmatic older granites of Precambarian age to early Palaeozoic age. The qualitative interpretation technique employed by visualizing the grids reveals variations in density contrasts and susceptibilities which connote the lithological distribution of the basement. Areas of high gravity and magnetic values directly correspond to areas of high density bodies and magnetically susceptible mineral contents respectively. While the lows and steep discontinuities of both gravity and magnetic maps predict possible entrapments of mineral accumulation in the study area. The depth evaluation techniques employed are Peter’s Half Slope Method (PHSM) and 3D Euler deconvolution, showing the magnetic depths to basement range as 3.18 m to 5.88 m for PHSM and 1.00 m to 4.43 m for 3D Euler deconvolution. The gravity depth to basement reveals 7.03 m to 14.72 m for PHSM and 0.96 m to 4.13 m for 3D Euler deconvolution. The average depth results obtained clearly show that the study location is composed of shallow depth intrusive sources.