Shooting Fish in a Barrel? Using VTEM for Gold Exploration in Sierra Leone

The Baomahun deposit in Sierra Leone is likely to become one of the country’s first modern gold mines, and there has been significant interest in exploring adjacent areas for similar deposits.

After commissioning a magnetic/radiometric survey to understand regional geology, Cluff Gold accepted a recommendation from Reid Geophysics to use VTEM for direct targeting of sulphide-hosted gold mineralization within its Baomahun and Victoria project areas.

The geological model of mineralization was pyrrhotite-hosted gold closely associated with BIF and preferentially concentrated in steeply-plunging fold noses.

The following indicators were applied for defining and prioritizing target zones: High magnetic susceptibility to indicate BIFs, and specifically zones associated with folding or discontinuities; High conductivity values to indicate presence of massive pyrrhotite, although medium to lower conductivities (due to more disseminated sulphides) should not be completely disregarded; Elevated arsenic and/or gold soil geochemistry values; Artisanal mining activities in close proximity.

Using the above indicators, eight target zones were selected for follow up drilling and/or ground survey programmes. In 2010, Cluff Gold announced a 6,000m diamond drilling programme to test seven of these target zones.