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Cracow, Golden Plateau |
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Queensland, Qld, Australia |
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Au Ag
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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The Golden Plateau low sulphidation, epithermal gold deposits are located near the town of Cracow and are hosted by the Permian Camboon Andesites of the Camboon Volcanic Arc, 350 km north-west of Brisbane, in south-eastern Queensland, Australia.
The gold deposits of the Cracow district are localised within andesitic lavas, tuffs and coarse fragmentals of the NNW striking and roughly 25°W dipping early Permian (294 to 281 Ma) Camboon Andesite which forms the southern portion of the Camboon Volcanic Arc, which in turn is on the eastern margin of the Bowen Basin. The Camboon Andesites (which comprise a lower unit of felsic volcanics, overlain progressively by vesicular felsic volcanics and tuffs, andesitic volcanics and an upper felsic volcanic unit) unconformably overlie early Carboniferous acid lavas of the Torsdale Beds, and is in turn overlain to the west by early Permian fossiliferous limestone.
The ore shoots at Golden Plateau are developed to depths of 240 m in an east-west trending zone which is some 1000 m long and 30 m wide. They are part of an east-west trending, steeply south dipping quartz-lode system which has yielded 95% of the ore mined, with associated less important sub-horizontal lodes known as flatmakes. The main lode structure is offset by a series of NW trending cross faults.
High-grade gold mineralisation defined in resources from 2003 occurs within five deposits (the Royal, Crown, Sovereign, Klondyke North and Kilkenny shoots), each developed at the intersection of major structures. The Royal, Crown and Sovereign shoots have strike lengths of ~350, ~300 and 150 m respectively and average ~5 m in width.
Gold mineralisation is associated with quartz veining and zones of silicification, present as quartz lode-quartz lode breccia and as quartz vein breccia, both of which are the result of multi (up to 5) phase mineralisation. The lodes are 1 to 25 m wide and are constrained on their footwall and hanging wall by faults. Quartz vein breccia comprises swarms of brecciated veins up to several cms thick which bulk up to form medium grained mineable ore. In general the higher grade ore is associated with quzrtz lode breccia, fringed by a broader zone of vein stockworks up to 50 m across.
Alteration styles include:
1). propylitic (quartz-chlorite-carbonate ±adularia ±epidote ±albite ±laumontite ±illitic clay ±anhydrite ±pyrite), occuring in trachyandesites, peripheral to the quartz lodes,
2). argillic (quartz + illite-smectite ±illite ±chlorite ±carbonate ±adularia ±pyrite) which occurs within the lode system, and
3). intermediate argillic (kaolinite ±smectite ±hematite) which is found in the upper part of the lodes, above the main argillic zone.
Gold has been mined from 1932 to 1992 and 2002 to the present (2013). Annual production from 2010 to 2012 averages ~ 3.2 t of Au.
Production and reserve figures quoted are as follows:
Historic production from 1933 to 1976 - 18.528 tonnes of recovered Au and 20.902 t Ag
from 1.55 Mt @ 12 g/t Au, 13.5 g/t Ag.
Historic production from 1937 to 1992 - 7.910 tonnes of recovered Au
Total proved open pit reserves, 1987: 0.979 Mt @ 4.3 g/t Au at a 1.83 g/t Au cut-off.
Indicated resource: 2 Mt @ 0.5 to 2.0 g/t Au.
Measured + indicated + inferred underground resources, June 30 2012 (Evolution Mining, 2012): 4.09 Mt @ 5.8 g/t Au for 23.89 t Au.
Ore reserves, June 30 2012 (Evolution Mining, 2012): 1.28 Mt @ 5.9 g/t Au for 7.46 t Au.
For detail consult the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 2012.
Record last updated: 5/4/2013
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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Cracow Mining Staff, Worsley M R, Golding S D 1990 - Golden Plateau Gold deposits: in Hughes F E (Ed.), 1990 Geology of the Mineral Deposits of Australia & Papua New Guinea The AusIMM, Melbourne Mono 14, v2 pp 1509-1514
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Creenaune P, Braund K, McLeod R 2003 - The Cracow gold project, Cracow, Queensland, a discovery case history: in NewGenGold 2003, Conference Proceedings, Perth WA, Louthean Media, Perth pp 159-170
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Dong G Y, Zhou T 1996 - Zoning in the Carboniferous-Lower Permian Cracow epithermal vein system, central Queensland, Australia : in Mineralium Deposita v31 pp 210 - 224
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Ransom D M, Knight J A 1975 - Golden Plateau gold lodes: in Knight C L, (Ed.), 1975 Economic Geology of Australia & Papua New Guinea The AusIMM, Melbourne Mono 5 pp 773-779
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White, N.C., Leake, M.J., McCaughey, S.N. andd Parris, B.W., 1995 - Epithermal gold deposits of the southwest Pacific: in J. of Geochemical Exploration v.54, pp. 87-136.
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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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