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Rosebery |
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Tasmania, Tas, Australia |
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Zn Pb Au Cu Ag
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Super Porphyry Cu and Au
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The Rosebery volcanic hosted massive sulphide ore copper, zinc, lead, silver, gold deposit is located ~195 km NW of Hobart and 90 km SSW of Burnie and 25 km NE of Zeehan on the west coast of Tasmania (#Location: 41° 46' 24"S, 145° 32' 35"E).
The deposit is hosted by the Central Volcanic Complex of the 250 km long, middle to late Cambrian Mt Read Volcanic Arc on the west coast of Tasmania, Australia. To the north-west of the Henty Fault this complex is composed of rhyolitic to dacitic acid lavas and pyroclastics with a higher andesites content than those to the south-east of this same structure and is the host to major Zn-Pb-Cu-Ag-Au mineralisation. The Central Volcanic Complex is unconformably overlain by the keratophyric tuffs, massive agglomerates, conglomerates, sandstones, shales and limestones of the Tyndall Group. During the Devonian shallow level post-tectonic granitoids intruded the mine area and resulting in metamorphism and recrystallisation of the ores.
In the immediate mine area the host sequence is composed of the following from bottom to top:
• Footwall Pyroclastics - >300 m of mainly pumiceous rhyolitic to dacitic, feldspar-phyric ash flow tuffs, commonly altered to schistose
quartz-sericite ± chlorite ± pyrite beneath the ore,
• Tuffaceous Shale (the ore host) - 35 to 200 m thick, a bedded volcaniclastic sandstone and siltstone, generally strongly altered to schistose sericite ± quartz ± carbonate ± chlorite ± pyrite near ore,
• Black Slate - the immediate hangingwall - 0 to 70 m thick,
• Hangingwall Pyroclastics (epiclastics) - 50 to >200 m thick, commonly rhyolitic to dacitic volcaniclastic breccia,
• Mount Black Volcanics (dacitic to andesitic lavas) - >1000 m thick.
This sequence is truncated immediately to the west of the ore zone by the high angle reverse Rosebery Fault.
The orebodies are tabular sheets up to 10 m or more thick, dipping at 45°E. They extend over a strike length of 4 km north-south and down plunge to a depth of more than 1.5 km. They form a gently north plunging cluster of overlapping lenses surrounding a siliceous core carrying stringer pyrite-chalcopyrite in the southern half.
There is a vertical zonation of mineralogy from bottom to top of:
• Disseminated pyrite-chlorite,
• Massive pyrite-chalcopyrite,
• Massive sphalerite-galena-pyrite with minor tetrahedrite, arsenopyrite and gold. This ore displays a strong mineralogical banding developed parallel to both lithological contacts and the well developed cleavage,
• Barite-carbonate zone,
• Hematite rich tuff.
Overall the ore minerals comprise 25% sphalerite, 5% galena, and 3% chalcopyrite with 30% pyrite with minor amounts of tetrahedrite, pyrrhotite and arsenopyrite.
Production and reserve figures in 1990 were:
Historic production - 15.3 Mt @ 0.7% Cu, 4.8% Pb, 15.7% Zn, 159 g/t Ag, 2.8 g/t Au,
Reserves - 8.0 Mt @ 0.5% Cu, 3.5% Pb, 10.4% Zn, 109 g/t Ag, 2.8 g/t Au.
According to Large, et al. (2001), production + resources were:
31.7 Mt @ 0.6% Cu, 4.4% Pb, 14.3% Zn, 146 g/t Ag, 2.3 g/t Au.
According to Seymour et al. (2007), the total production + resources were estimated at:
34.03 Mt @ 0.57% Cu, 4.1% Pb, 13.8% Zn, 143 g/t Ag, 2.2 g/t Au.
Remaining reserve in 2007 were (Zinifex, 2007):
11.7 Mt @ 0.42% Cu, 3.83% Pb, 13.0% Zn, 138 g/t Ag, 1.9 g/t Au.
Remaining measured + indicated + inferred mineral resources at 30 June, 2014 were (MMG, 2014):
17.2 Mt @ 0.4% Cu, 3.6% Pb, 11.3% Zn, 123 g/t Ag, 1.7 g/t Au,
Remaining proved + probable ore reserves at 30 June, 2014 were (MMG, 2014):
5.4 Mt @ 0.3% Cu, 3.4% Pb, 9.7% Zn, 115 g/t Ag, 1.4 g/t Au.
The total endowment (production + resources) as estimated in 2017 (Denwer, Garrick and Robertson, 2017) was:
52 Mt @ 0.5% Cu, 4% Pb, 132 g/t Ag, 13% Zn, 1.9 g/t Au; which included,
Measured + Indicated + Inferred Resources of:
22.3 Mt @ 0.26% Cu, 2.7% Pb, 7.9% Zn, 100 g/t Ag, 1.3 g/t Au, that in turn included,
Proved + Probable Reserves of:
5.4 Mt @ 0.24% Cu, 3.1% Pb, 8.3% Zn, 114 g/t Ag, 1.3 g/t Au.
For more detail see the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 2007.
Record last updated: 26/11/2015
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.
Rosebery
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Selected References:
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Berry M V, Edwards P W, Georgi H T, Graves C C, Carnie C W A, Fare R J, Hale C T, Helm S W, Hobby D J, Willis R D 1998 - Rosebery lead-zinc-gold-silver-copper deposit: in Berkman D A, Mackenzie D H (Ed.s), 1998 Geology of Australian & Papua New Guinean Mineral Deposits The AusIMM, Melbourne Mono 22 pp 481-486
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Bishop J R, Lewis R J G 1992 - Geophysical signatures of Australian volcanic-hosted massive sulfide deposits: in Econ. Geol. v87 pp 913-930
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Brathwaite R L, 1974 - The Geology and Origin of the Rosebery Ore Deposit, Tasmania : in Econ. Geol. v.69 pp. 1086-1101
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Burton C C J 1975 - Rosebery zinc-lead-copper orebody: in Knight C L, (Ed.), 1975 Economic Geology of Australia & Papua New Guinea The AusIMM, Melbourne Mono 5 pp 619-626
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Corbett K D 1981 - Stratigraphy and mineralization in the Mt Read volcanics, western Tasmania: in Econ. Geol. v76 pp 209-230
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Corbett K D 1992 - Stratigraphic-volcanic setting of massive sulphide deposits in the Cambrian Mount Read Volcanics, Tasmania: in Econ. Geol. v87 pp 564-586
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Denwer, K., Garrick, L. and Robertson, M., 2017 - Rosebery Cu-Pb-Zn-Ag-Au volcanogenic massive sulphide deposit: in Phillips, G.N., (Ed.), 2017 Australian Ore Deposits, The Australasian Institute of Mining and Metallurgy, Mono 32, pp. 817-822.
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Eastoe C J, Solomon M, Walshe J L 1987 - District-scale alteration associated with massive Sulfide deposits in the Mount Read Volcanics, western Tasmania: in Econ. Geol. v82 pp 1239-1258
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Gifkins C C, Allen R L 2001 - Textural and chemical characteristics of diagenetic and hydrothermal alteration in glassy volcanic rocks: examples from the Mount Read Volcanics, Tasmania: in Econ. Geol. v96 pp 973-1002
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Green G R, Solomon M, Walshe J L 1981 - The formation of the volcanic-hosted massive sulfide ore deposit at Rosebery, Tasmania: in Econ. Geol. v76 pp 304-338
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Large R R 1992 - Australian volcanic-hosted massive sulfide deposits: features, styles, and genetic models: in Econ. Geol. v87 pp 471-510
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Large R R, Allen R L, Blake M D, Herrmann W 2001 - Hydrothermal alteration and volatile element halos for the Rosebery K Lens volcanic-hosted massive Sulfide deposit, western Tasmania: in Econ. Geol. v96 pp 1055-1072
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Large R R, McPhie J, Gemmell J B, Herrmann W, Davidson G J 2001 - The spectrum of ore deposit types, volcanic environments, alteration halos, and related exploration vectors in submarine volcanic successions: some examples in Australia: in Econ. Geol. v96 pp 913-938
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Lees T, Zaw K, Large R R, Huston D L 1990 - Rosebery and Hercules Copper-Lead-Zinc deposits: in Hughes F E (Ed.), 1990 Geology of the Mineral Deposits of Australia & Papua New Guinea The AusIMM, Melbourne Mono 14, v2 pp 1241-1247
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Lees T. Khin Zaw, Large R R, Huston D L 1990 - Rosebery and Hercules Copper-Lead-Zinc Deposits: in Hughes Fe (Ed) 1990 Geology of the Mineral Deposits of Australia and Papua New Guinea The AusIMM, Melbourne v2 pp 1241-1247
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Smith R N, Huston D L 1992 - Distribution and association of selected trace elements at the Rosebery Deposit, Tasmania: in Econ. Geol. v87 pp 706-719
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Solomon M 1981 - An introduction to the geology and metallic ore deposits of Tasmania: in Econ. Geol. v76 pp 194-208
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Solomon M, Eastoe C J, Walshe J L, Green G R 1988 - Mineral deposits and Sulfur isotope abundances in the Mount Read volcanics between Que River and Mount Darwin, Tasmania: in Econ. Geol. v83 pp 1307-1328
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Solomon M, Vokes F M and Walshe J L, 1987 - Chemical remobilization of volcanic-hosted sulphide deposits at Rosebery and Mt. Lyell, Tasmania: in Ore Geology Reviews v2 pp 173-190
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Zaw K, Huston D L, Large R R 1999 - A chemical model for the Devonian remobilization process in the Cambrian volcanic-hosted massive Sulfide Rosebery deposit, western Tasmania: in Econ. Geol. v94 pp 529-546
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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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