Geophysical Investigation of Solid Mineral Deposits in Ekiti State

This study integrates ground magnetic and induced polarisation methods to investigate solid mineral deposits in the basement complex of Ekiti State, South West Nigeria. Ekiti State's Precambrian basement rocks host diverse mineral occurrences including feldspar, quartz, marble, tourmaline, and gold, but geophysical investigation to support formal mineral development has been limited. This study targets a known gold-quartz vein occurrence in Ise-Orun local government area identified from NGSA stream sediment geochemical anomalies. Ground magnetic profiling is conducted along 14 east-west traverses at 10-metre station spacing covering 3.5 square kilometres. IP-resistivity data are acquired along four selected profiles using the dipole-dipole array at 20-metre electrode spacing. Magnetic data are processed for RTP and first vertical derivative. IP-resistivity sections are inverted using RES2DINV. Interpretation integrates geological field mapping conducted during the survey. Findings reveal a northeast-trending magnetic low corridor of 300 to 800 nanotesla amplitude coinciding with altered granite and quartz-feldspar veins mapped at surface. IP chargeability anomalies of 12 to 28 milliseconds at 20 to 60 metres depth along two of the profiles are interpreted as disseminated sulphides associated with gold mineralisation, consistent with arsenopyrite blebs observed in surface samples. The combined geophysical anomaly pattern delineates four exploration targets with different depth and geometry characteristics. Chip sampling of quartz veins confirms gold values of 0.4 to 2.8 grams per tonne, validating the mineral prospectivity of the identified targets. The study provides a detailed exploration dataset for Ekiti State's gold potential.

Keywords: magnetic survey, induced polarisation, gold mineralisation, Ekiti State, basement complex.