The Goornong South gold deposit and its implications for exploration beneath cover in Central Victoria, Australia

The Au mineralisation at Goornong South occurs under at least 5 m of transp orted cover and thus provides a good initial case study for exploration in areas of transported overburden in Central Victoria. The Au mineralisation is associated with As, Sb and W, with the abundances of the Au and As in sa prolitic samples (>10 ppb and >100 ppm, respectively) sufficient to define the mineralisation. Dispersion of these elements occurs into the overlying alluvium but their mode of occurrence varies, Cold is concentrated into the clay-rich fine faction (-63 mu m) of the surficial soil, whereas As is enr iched in the coarse (+2 mm) ferruginous fraction. These elements in these f ractions of the soil produce anomalies which may be up to twice the size of those in the weathered bedrock. Because the fine fraction of the soils is subject to possible contamination by aeolian material and it is time-consum ing to prepare, use of the coarse fraction is probably the most cost-effect ive sampling medium for these areas of shallow cover. in this area of Centr al Victoria, mechanical dispersion is probably more important than hydromor phic dispersion processes. Thus areas with deeper cover, where hydromorphic dispersion is likely to dominate dispersion processes, need to be tested. (C) 1999 Published by Elsevier Science B.V. All rights reserved.