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Coronation Hill |
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Northern Territory, NT, Australia |
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Au Pd Pt PGE PGM U Ag
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Super Porphyry Cu and Au
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The Coronation Hill gold-platinum-palladium deposit, which is located in the South Alligator Valley, 80 km east of Pine Creek, lies within the Archaean to Palaeoproterozoic Pine Creek Inlier which covers an ENE elongated area of 400x150 km immediately to the south and east of Darwin in the Northern Territory, Australia.
The Pine Creek Inlier is composed of 2200-1870 Ma Palaeoproterozoic supracrustal meta-sediments and volcanics that are around 10-14 km thick, overlying Archaean crystalline basement exposed as three separate domal highs surrounded by the supracrustals. The sequence commences with the Namoona Group conglomerates, meta-arkose, gneiss, schist and dolomite, which were metamorphosed to amphibolite facies from 2100 to 2000 Ma, then overlain by further sediments, the Mount Partridge Group of principally fluviatile sandstone, dolomitic siltstone and mudstone. These were then unconformably followed by the South Alligator Group of carbonaceous mudstone, iron formation, greywacke and acid tuff which passed up into the greywackes and mudstone of the Finniss Group.
In the South Alligator Valley the oldest exposed unit is the Mundogie Sandstone (quartzite and conglomerate) of the Mount Partridge Group, followed by the East Alligator Group Koolpin Formation (represented locally by mainly siliceous and carbonaceous pelites and stromatolitic dolomite, disconformably overlain by a volcaniclastic unit). The Koolpin Formation is overlain by two distinct sedimentary breccias. These units are in turn unconformably overlain after a break by the post Finniss Group (which is localy absent) late Palaeoproterozoic Coronation sandstone (a basal coarse hematite altered pyroclastic and boulder conglomerate overlain by brown medium to coarse sandstone) and Pul Pul Rhyolite (a massive rhyolite ignimbrite) of the El Sherana Group and after a further break by the Kurrundie Sandstone (a medium to coarse lithic quartz sandstone with minor conglomerates) and Plum Tree Volcanics (intermediate to basic volcanics with volcaniclastics) of the Edith River group.
Two prominent intrusives, an altered quartz-feldspar porphyry and an altered quartz diorite to granodiorite occur as plugs in the deposit area.
All of these rocks are unconformbly overlain by the thick, Mesoproterozoic Kombolgie Formation composed of ferruginous conglomerate, quartz sandstones, basic volcanics and minor siltstone.
Gold and PGM/PGE mineralisation occurs as a NNW trending elongate zone with a strike of 250 m and width of 50 to 100 m. Within this are steeply east dipping, north to NNW trending, south plunging, from 2 to 35 m (averaging 10 m) thick tabular bodies, developed in zones of fracturing. In 1990 the known mineralisation was within 250 m of the surface, although some intersections were known to 400 m. Mineralisation was confined to rocks below the Coronation Sandstone but occurs within the two intrusives and the sedimentary breccias between the Koolpin Formation and the Coronation Sandstone. The previously mined uranium was focussed on one of the sedimentary breccias.
Two types of mineralisation have been recognised, namely: 1). a gold-PGM-selenide association with both pure and silver bearing gold, lead selenides, platinum-antimony minerals and other rare precious metal combinations without suphides, and 2). a gold-PGM-selenide-sulphide association, similar to the previous style, but with replacive pyrite within the altered intrusives.
The old Coronation Hill mine exploited a small uranium deposit and produced 26 000 tonnes of ore @ 2.6 kg/t U3O8 during the 1950's and 1960's. Gold at an average grade of 10.4 g/t Au accompanied the uranium.
The indicated resource in 1990 was 4.85 Mt @ 4.31 g/t Au, 0.19 g/t Pt, 0.65 g/t Pd at a 0.5 g/t Au cut-off. This resource has not been exploited as it is in a national park.
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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Carville D P, Leckie J F, Moorhead C F, Rayner J G, Durbin A A 1990 - Coronation Hill Gold-Platinum-Palladium deposit: in Hughes F E (Ed.), 1990 Geology of the Mineral Deposits of Australia & Papua New Guinea The AusIMM, Melbourne Mono 14, v1 pp 759-762
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Nicholson P M, Eupene G S 1990 - Gold deposits of the Pine Creek Inlier: in Hughes F E (Ed.), 1990 Geology of the Mineral Deposits of Australia & Papua New Guinea The AusIMM, Melbourne Mono 14, v1 pp 739-742
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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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