An integrated use of induced polarization and electrical resistivity imaging methods to delineate zones of potential gold mineralization in the Phitshane Molopo area, Southeast Botswana

Abstract

We used 2D and pseudo-3D induced polarization (IP) in conjunction with electrical resistivity imaging (ERI) data inversion to identify and characterize potential zones of gold mineralization in Phitshane Molopo area. Reports on historic exploration suggest that gold mineralization is associated with quartz and/or carbonate veins that cut across the banded iron formations. The 2D IP/ERI measurements were acquired along ten 300 m long profiles trending northeast southwest, with 15 m line separation and 7.5 m electrode spacing. Thereafter, we inverted the data using the standard Gauss-Newton optimization method to produce 2D and 3D models. Based on a combination of IP and resistivity results, we identified distinct lithological units comprising the mineralized and non-mineralized zones. High chargeability (≥6.86 mV/V) and high resistivity (≥641 Ωm) anomalies were attributed to the presence of disseminated sulfides or gold-bearing quartz and/or carbonate veins that obliquely crosscut (east west trend) the banded iron formation (BIF) units and the intensely silicified BIF units, respectively. Zones exhibiting a combination of low to intermediate chargeability (1.0–6.86 mV/V) and low to intermediate resistivity (1.4–641 Ωm) are likely non-sulfidized zones with little/no gold mineralization in the study area. The integrated use of IP and ERI methods was successful in delineating zones that are likely to be hosting disseminated sulphides and/or potentially gold-rich zones in the Phitshane Molopo area, Kraaipan Greenstone Belt.