Origin of hydrothermal CuZnPb mineralisation in the Olary Block, South Australia: evidence from fluid inclusions and sulphur isotopes

The Mt. Mulga barite–magnetite–copper–gold mineralisation, Olary Domain, South Australia

“…Distal to the vent, the hydrothermal fluid mixed up with basin water and the hydrothermal reduced sulphur oxidised to sulphate contributing to the formation of barite explaining the lower isotopic values and the general absence of sulphides outside the main ore body. For the cogenetic barite-iron-oxide-Cu-Au model, the δ 34 S composition of chalcopyrite around 0‰ fits well with a proposed crustal reservoir which was source of hydrothermal fluids during the Willyama Supergroup deposition as well as the Olarian Orogeny (Bierlein et al, 1994). Based on δ 34 S data of pyrite from many syn-and epigenetic mineralisations within the Olary Domain a δ 34 S signature of 0‰ to + 4‰ for this reservoir was suggested by Clark et al (2004).…”

Fertilizer Amendment of Mining-Impacted Soils from Broken Hill, Australia: Fixation or Release of Contaminants?

“…The δ34S measured in leachates from the unamended BH1 and BH2 soils correspond to previous δ34S data for Broken Hill sulfides (summarized in Bierlein et al 1996), ranging from approximately −4 to +7 per mil with a majority of samples in the range −2 to +2 per mil. Sulfur isotope analyses of the fertilizers demonstrate that the different amendments possess distinct δ 34 S isotopic signatures (Figs.…”

Lead isotope study on hydrothermal sulfide mineralisation in the Willyama Supergroup, Olary Block, South Australia

“…A distinction of these ore genesis models on the basis of lead isotope data alone is impossible. Nevertheless, although most samples plot within a broad mixing array (Figure 3), a mixing model for the lead development in the Olary Block is considered unlikely based on petrographic, structural and geochemical evidence (outlined below and in Bierlein 1995;Bierlein et al 1994Bierlein et al , 1995. These constraints dispute formation of 'ordinary' and 'radiogenic' lead sulfides during a single mineralisation event or subsequent partial remobilisation and contamination with 'radiogenic' lead.…”

“…Sulfur isotope and fluid-inclusion studies (Bierlein et al 1994) support intermittent mobilisation of fluid and metals from a relatively homogenised segment of crust to form the various styles of sulfide mineralisation present in the Olary Block. Hydrothermal fluids responsible for the formation of stratabound and epigenetic mineralisation are characterised by distinct, although relatively uniform sulfur isotopic compositions with 8 34 S ranging from +5 to +10%o for both types of mineralisation (Bierlein et al 1994).…”

“…Recent textural and geochemical investigations have revealed that epigenetic (i.e. post-dating peak metamorphism) emplacement of sulfides also occurred in the Olary Block, resulting in a wide range of structurally controlled vein-style Cu-Au and base metal deposits (Ashley et al 1994a,b;Bierlein 1995;Bierlein et al 1994Bierlein et al , 1995 Table 1). Many of these deposits were formed under epithermal to mesothermal conditions and are not associated with pre-existing mineralisation, zones of pervasive retrogression or intrusives.…”