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Great Australia |
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Queensland, Qld, Australia |
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Cu Au Co
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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The small, high grade hypogene and supergene Great Australia Cu-Au-Co deposit is located ~1 km south of Cloncurry in the northern part of the 1900 to 1600 Ma Eastern Succession of the Mt Isa Block in Northwest Queensland, Australia.
For geological background on the setting, see the Cloncurry IOCG Province record.
Mineralisation occurs within a dilational jog in a major splay of the regional north-south trending Cloncurry Fault and is hosted by the Proterozoic Toole Creek Volcanics (greenschist facies basalt, andesite and interbedded meta sediments) of the Cover Sequence 3 Soldiers Cap Group and metasediments of the Cover Sequence 2 Corella Formation (dominated by bedded meta-carbonates and meta-siliciclastics altered to calc-silicate lithologies).
Both host units have been subjected to brittle deformation with breccia zones associated with NE-SW trending faults. The hypogene mineralisation consists solely of chalcopyrite within brecciated fault veins grading up to 8% Cu, 1g/t Au, 0.35% Co in the two largest zones, the Main Lode and B Tangye Lode. Fluid inclusion data from euhedral intergrowths of dolomite and quartz suggest a formation temperature of 400 to 500°C, although secondary inclusions with low salinities indicate a later <200°C event (Cannell and Davidson, 1998).
The hypogene mineralisation consists solely of chalcopyrite within brecciated fault veins grading up to 8% Cu, 1g/t Au, 0.35% Co (Cannell and Davidson, 1998).
Supergene ores comprise surficial iron and copper cemented breccias, locally highly silicified, with deeper layers of malachite, azurite, chrysocolla, cuprite, native copper, atacamite, connellite and abundant copper phosphate. Below and near the current water table, near the intersection of the two main hypogene sulphide lodes, a coarsely crystalline assemblage of chalcocite, djurleite occurs as a sulphide enriched zone. Djurleite crystals up to 7 cm long with smaller, but well-crystallised chalcocite crystals, were cemented by multiple crystallisation calcite phases. The deposit has been subjected to a long complex period of weathering and enrichment. All of the supergene events took place at <93°C.
The supergene leachable orebody contained 1.7 Mt @ 1.2% Cu in 1998.
For more detail consult the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 2001.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Selected References:
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Melchiorre, E.B., Williams, P.A., 2001 - Stable isotope characterization of the thermal profile and subsurface biological activity during oxidation of the Great Australia deposit, Cloncurry, Queensland, Australia: in Econ. Geol. v.96, pp. 1685-1693.
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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