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Croydon Goldfield - Federation, Glencoe, Jubilee, La Perouse |
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Queensland, Qld, Australia |
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Au
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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The Croydon Goldfield is located 20 km from the town of Croydon within the western most part of the Proterozoic Georgetown Inlier in northern Queensland, Australia. It includes the Federation, Glencoe, Jubilee and La Perouse deposits/pits.
The deposits are hosted by the up to 2500 m thick ~1550 Ma Croydon Volcanic Group which covers an area of 3100 sq. km in a 100 km long NNW trending belt intruded by a series of cogenetic granites, the largest of which is the 80 x 5 to 15 km, 1558±4 Esmeralda Granite. The contact between the granite and volcanic group is semi-concordant and dips shallowly to the NE. It is characterised by abundant graphite over a zone up to 3 km long and 500 m wide. Both the granite and Croydon Volcanic Group (which is composed of five rhyolite units) post date the Carpentarian metamorphism that affected the Georgetown Block.
Most of the mineralisation in the pits listed above is hosted by the Carron and Parrot Camp Rhyolite units of the Croydon Volcanic Group, comprising rhyolitic tuffs and massive rhyolitic quartz-feldspar porphyries with pyroclastics respectively.
At Federation mineralisation is present as 0.2 to 6 m wide vughy white quartz vein containing sulphides (pyrite, galena, arsenopyrite) within altered (quartz-sericite-kaolinite) and graphitic volcanics as a gently folded, 20 to 30° dipping 300 m long vein system.
At Glencoe, which is around 4 km east of Federation, gold is mainly within a 2 to 6 m wide iron oxide impregnated zone of alteration with generally low quartz that is 200 m long and dips at 40° E. Gold and silver occur as disseminated electrum associated with quartz in the alteration zone and as thin (up to 30 cm) veins rich in galena and pyrite.
At Jubilee, which is around 6 km south-east of Federation, gold is associated with a 1 to 8 m (averaging 2 m) thick, 200 m long vughy quartz vein zone dipping at 35° E within quartz-sericite altered volcanics. Gold is present free within the quartz and in association with sulphides.
At La Perouse, which is around 1 km south-east of Federation, gold is within a sheeted set of anastomosing, en echelon vughy quartz veins from 0.5 to 10 m (averaging 2 m) thick with sulphides (galena, pyrite, arsenopyrite) and free gold, which also occurs in the hangingwall and footwall of the veins.
The initial published reserve in 1987 was: 2.84 Mt @ 3.4 g/t Au.
The historic production plus know reserves in the Croydon Goldfield have been quoted at 35 t of Au.
For detail consult the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 1990.
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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Van Eck M, Child R 1990 - Croydon Gold deposits: in Hughes F E (Ed.), 1990 Geology of the Mineral Deposits of Australia & Papua New Guinea The AusIMM, Melbourne Mono 14, v1 pp 979-982
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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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