http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:7940 Research Doctorate - Doctor of Philosophy (PhD) 2011-12-09T04:50:18.586Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:3193 Felsic volcanic units of the Early Devonian Bindook Volcanic Complex host the Yerranderie epithermal silver–gold–lead district 94 km west–southwest of Sydney. Mineralization in the district forms part of a fault-controlled, intermediate sulfidation, epithermal silver–gold–base metal vein system that has significant mineral and alteration zonation. Stage 1 of the mineral paragenesis in the veins developed quartz and carbonate with early pyrite, whereas stage 2 is a crustiform banded quartz–pyrite–arsenopyrite assemblage. Stage 3, the main stage of sulfide deposition, comprises early sphalerite, followed by a tetrahedrite–tennantite–gold assemblage, then a galena–chalcopyrite–native silver–pyrite assemblage, and finally a pyrargyrite–polybasite–pearceite assemblage. Stage 4 involves the deposition of quartz veins with minor (late) pyrite and stage 5 is characterized by siderite that infilled remaining voids. Mineral zonation occurs along the Yerranderie Fault, with bornite being restricted to the Colon Peaks–Silver Peak mine area, whereas arsenopyrite, which is present in both the Colon Peaks–Silver Peak and Wollondilly mine areas, is absent in other lodes along the Yerranderie Fault. The Yerranderie Fault, which hosts the major lodes, is surrounded by a zoned alteration system. With increasing proximity to the fault the intensity of alteration increases and the alteration assemblage changes from an outer quartz–muscovite–illite–(ankerite) assemblage to a quartz–illite–(pyrite–carbonate) assemblage within meters of the fault. ⁴⁰Ar/³⁹Ar dating of muscovite from the alteration zone gave a 372.1 ± 1.9 Ma (Late Devonian) age, which is interpreted to be the timing of the quartz–sulfide vein formation. Sulfur isotope values for sulfides range from 0.1 to 6.2‰ with one outlier of −5.6 δ³⁴S‰. The results indicate that the initial ore-forming fluids were reduced, and that sulfur was probably sourced from a magmatic reservoir, either as a direct magmatic contribution or indirectly through dissolution and recycling of sulfur from the host volcanic sequence. The sulfur isotope data suggest the system is isotopically zoned. 2010-04-27T05:24:56.357Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:5643 The Hill End Trough (HET) is a deformed middle Silurian to Early Devonian sediment-dominated rift within the northeastern Lachlan Orogen. The HET hosts the Hill End, Hargraves, Napoleon Reefs, Stuart Town and Windeyer low-sulfide orogenic gold deposits. Adjacent to the HET are the Bodangora and Gulgong gold deposits. In this study we present 91 new sulfur- and 18 new lead-isotope analyses and collate a further 25 sulfur- and 32 lead-isotopes analyses from unpublished sources for these deposits. Larger gold deposits in the HET have near 0 δ³⁴S‰ values indicating that sulfur in these systems was sourced from a magmatic reservoir. The dominant lead isotope signature for HET-hosted deposits reflects a crustal source however some mantle-derived lead has been introduced into the HET. Sulfur- and lead-isotopic results suggest that gold was sourced from mantle-derived magmatic units beneath the HET. The study supports earlier studies at Hill End by concluding that the majority of orogenic gold mineralisation in and adjacent to the HET formed during the Early Carboniferous period. 2010-04-27T04:38:47.900Z ]]>