GEOPHYSICAL INVESTIGATION FOR POTENTIAL GOLD MINERALISATION IN SHAKWATU AREA OF NIGER STATE, NIGERIA USING VERY LOW FREQUENCY AND ELECTRICAL RESISTIVITY METHODS

Abstract

Minerals serve a very important economic commodity to the growth and development of any nation, state or community. In an attempt to delineate potential zones for gold mineralisation, a geophysical investigation was carried out around Shakwatu area of Niger State, Nigeria. Mineral potential (especially gold) is evident by the extensive artisanal mining activities in the area. The Very Low Frequency Electromagnetic-VLF EM and electrical resistivity method was employed in the study. A total of six (6) profile lines (500 m in length), and 100 m inter-profile spacing were established on the study area at a sampling rate of 20 m each. The VLF-EM and the geoelectric data were qualitatively interpreted using the Karous Hjelt Fraser Filtering (KHFF) and RES2DINV Software respectively. VLF-EM data revealed a number of subsurface zones with high real component current density which define the potential subsurface structural features (fractures/ faults zones) with possible gold mineralisation. These zones were interpreted as the potential or inferred structurally controlled fracture zones with possible gold mineralisation, with profiles 1 – 6 showing significantly conductive mineralised zones at a depth of 20-80m. Results from 2D resistivity imaging show an elevated (high) resistivity zones and a variation in shape due to heterogeneous nature of mineralisation within the study area at different depths. The two results when compared show a degree of correlation. The high resistivity zones which could infer a quartz veining structure.