GOLD: Geophysical investigations of the Kalgoorlie Goldfield, Western Australia

Abstract

Leases held by Kalgoorlie Consolidated Gold Mines Pty Ltd over the Kalgoorlie Goldfield have an approximate area of 30 by 10 km, with the main production areas of Fimiston, Mount Charlotte and Mount Percy within the central portion of this tenement block. Due to the proximity of the leases to residential areas, significant portions of land are inaccessible for exploration. Near-surface contamination, as a result of historical mining and prospecting, also presents problems, as do the deep weathering profile and associated conductive overburden, which covers most of the Kalgoorlie Goldfield. Due to the relatively small size of the lease holdings and the constraints detailed above, the currently employed geophysical techniques mainly involve detailed ground surveys and include petrophysical studies of the three principal styles of mineralisation and the surrounding host rocks. The aims of the surveys are improved definition of geological features, and indirect detection of the three principal styles of mineralisation recognised at Fimiston (Golden Mile), Mount Charlotte and Mount Percy. The petrophysical data indicate that gravity, magnetics and induced polarisation can be used for the delineation of rock types whereas induced polarisation has potential to identify mineralisation. The combination of gravity and ground magnetic surveys at a prospect scale permits considerable refinement of the structural and lithological features in areas of poor outcrop. Studies are ongoing evaluating the potential use of downhole induced polarization for detection of Mount Charlotte-style stockwork mineralisation, and the use of ground penetrating radar to detect voids for underground mining.