Victorian orogenic gold deposits, Australia

Lithogeochemistry of central Victorian orogenic gold deposits, Australia Dennis Arne Emily House, Vladimir Lisitsin  

Keywords lithogeochemistry, orogenic gold, central Victoria 

Nearly 900 fresh diamond drill core samples were collected from multiple drill holes along two or more cross sections through each of the deposits under investigation. Field determinations for ferroan carbonate were made on all fresh 

Analytical and quality control details are summarised in Arne et al (2008). Gold was determined by fire assay, and major elements by ICP-OES following a four-acid digestion, with the exception of fresh drill core samples from Wildwood, which were analysed by lithium borate fusion and XRF. Trace elements were determined by ICP-MS. Refractory elements (W, Zr, Ba and Ti) were analysed by pressed powder XRF. 

The interpretation of lithogeochemical data from basaltic structural domes is complicated by lithological changes associated with the transition from basalt to overlying siliciclastic rocks, as well as by the polydeformed nature of the host sequence. Ferroan carbonate alteration is well developed, and low-level Au enrichment extends for a considerable distance away from zones of economic interest. Arsenic and Sb/AI anomalies are restricted to within approximately 10 m of mineralized zones. Sericite alteration is indicated by Na depletion and K enrichment in basalt within 20 to 40 m of mineralized zones. A number of other elements, including Mn, P, S, Zn, Mo, Cu, Se and Ba, are variably enriched within the rocks hosting Au mineralization, but it is not clear whether elevated concentrations of these elements are a product of syn-sedimentary exhalative activity or result from later hydrothermal alteration. 

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