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Spinifex Ridge, Coppin Gap |
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Western Australia, WA, Australia |
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Cu Mo
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Super Porphyry Cu and Au
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Coppin Gap, more recently enlarged and renamed Spinifex Ridge, is an Archaean age porphyry molybdenum-copper deposit in the Pilbara Craton, 50 km north-east of Marble Bar and 150 km ESE of the Indian Ocean port of Port Hedland in Western Australia (#Location: 20° 53' 22"S, 120° 6' 18"E).
The deposit lies within an east-west trending Archaean greenstone belt between two younger granitoid batholiths. Mineralisation is associated with a phase of 2978 ±102 Ma calc-alkaline quartz-feldspar (dacitic) porphyries and granodiorites intruding the Archaean greenstone belt volcanics and sediments.
The ore zone forms a cap around the apex of a south dipping apophysis of the granodiorite intrusion with an inner >0.09% Mo immediately sheathing the intrusive and an outer zone of >0.03% Mo. Grades within the apex of the granodiorite may reach levels in excess of 0.15% Mo.
The main molybdenum zone is largely hosted by a generally concordant dacite porphyry intrusion which is veined, altered and extensively mineralised. The dacite has intensely brecciated contacts and is bounded by strongly hornfelsed and silicified wall rocks.
In the immediate vicinity of the mineralisation the dacite and mineralising granodiorite intrude high magnesian basalts, basalts/dolerites and mixed felsic and basaltic volcanics and an adjacent komatiite flow.
Mineralisation comprises multiphase stockworks and veins with accompanying sulphides and strong silica, carbonate and sericite alteration.
Copper, mainly as chalcopyrite, occurs in basalts of the country rocks and in the granodiorite and quartz-carbonate stockworks. Molybdenum is principally in greasy grey quartz-carbonate stockwork veins, where it occurs as selvages and disseminations peripheral to the veins.
Reserves in 1990 were estimated at: 102 Mt @ 0.152% Cu, 0.105% Mo.
Following additional drilling, by late 2006, the resource had been enlarged to:
Measured - 187 Mt @ 0.07% Mo, 0.10% Cu, 1.8 g/t Ag
Indicated - 282 Mt @ 0.05% Mo, 0.08% Cu, 1.7 g/t Ag
Inferred - 31 Mt @ 0.05% Mo, 0.07% Cu, 1.6 g/t Ag
TOTAL 500 Mt @ 0.06 Mo, 0.09% Cu, 1.7 g/t Ag
The most recent source geological information used to prepare this decription was dated: 2006.
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.
Spinifex Ridge, Coppin Gap
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Selected References:
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Jones C B 1990 - Coppin Gap Copper-Molybdenum deposit: in Hughes F E (Ed.), 1990 Geology of the Mineral Deposits of Australia & Papua New Guinea The AusIMM, Melbourne Mono 14, v1 pp 141-144
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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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