Geochemical models of Sb(-As,Au,Ag) mineralization in the Archaean and modern hydrothermal settings : Examples from the Murchison Greenstone Belt and the Manus back-arc basin

Abstract

The topic of this PhD project was to deduce new geochemical models of Sb(-As,Au,Ag) mineralization in Archaean and modern hydrothermal settings by studying both the Murchison Greenstone Belt (MGB) and the Manus back-arc basin. To emphasise the parallels between these two settings, an in depth qualitative and quantitative research of Sb(-As,Au,Ag) behaviour in magmatic-hydrothermal hypogene and supergene deposits has been preformed. My results show that slight variations in temperature, oxygen fugacity and pH of the percolating fluid in combination with variations in buffering capacities of the host rock materials can cause great diversities in metal and metalloids speciations. Secondly, I have deduced that Sb enrichments occur at temperatures between 250-400 degrees Celsius, dominated by Sb(OH)3 (aq). Secondly, a striking strong correlation between the geochemical behaviour of As-Ag and Sb-Au has been observed. And finally, I would like to remark the importance of geochemical analyses of non-prominent metal concentrations within the field of ore petrology.