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Savage River |
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Tasmania, Tas, Australia |
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Fe
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
Available as Full Text for direct download or on request. |
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The Savage River iron deposit is situated 43 km west of the Murchison Highway and 98 km southwest of the city of Burnie in northwest Tasman, Australia. The ore, which is predominantly composed of magnetite, is crushed, magnetically concentrated, slurried and piped 83 km to the north coast where it is magnetically separated and pelletised for export from Port Latta (#Location: 41° 28' 5"S, 145° 12' 35"E).
Ironstone outcrops around Savage River were first discovered by State Government surveyor C.P. Sprent in early 1887. In 1965, Savage River Mines Ltd, a joint venture of Australian, Japanese and American interests was formed to develop the deposit. The operator, Pickands Mather International (PMI), developed an open pit mine, concentrator plant and township at Savage River to exploit the magnetite reserve. A pipeline from the concentrator plant to the pelletising plant and dedicated port facilities at Port Latta located on the northwest coast were also constructed. Mining commenced in 1967. At the end of the 30 year mine lease, on March 26 1997, PMI ceased mining and transferred ownership of the Savage River Project to the Tasmanian Government. At the end of March 1997, Australian Bulk Minerals (ABM) purchased the assets of the Savage River Project from the State Government and continued mining the existing pits through a series of cut-back operations, mined the previously undeveloped South Deposit, and began exploration around the Long Plains area. ABM was initially wholly owned by Ivanhoe Mines, who exited and sold the operation to Stemcor in 2005, who, in turn, sold a 90% interest to Jiangsu Shagang Group in 2007. In January 2009 Grange Resources merged with ABM, to form a new entity that took the Grange Resources name.
The ore deposits lie within and towards the eastern margin of the Proterozoic Arthur Metamorphic Complex in northwestern Tasmania. This complex is a 10 km wide, NE-SW trending zone of increased schistosity and metamorphism exposed along a northeast-southwest trending structural corridor, the Arthur Lineament, which separates Neoproterozoic sedimentary rocks to the northwest from a variety of Palaeozoic (Cambrian to Ordovician) rocks to the southeast. The dominant unit of the Arthur Metamorphic Complex in the vicinity of Savage River is the Whyte Schist, which has been subdivided into an eastern and western sequence. The eastern sequence is mainly composed of quartz-mica rocks including thin micaceous quartzite beds, schist and phyllite, while the western sequence comprises amphibolite, chlorite and albite schist or quartz-muscovite schist. The degree of metamorphism ranges from upper greenschist to amphibolite facies.
The magnetite deposits of the Savage River mine site are the largest of a series of lenses that extend in a narrow belt over a strike length of 25 kilometres. The deposit is subdivided into the main mining areas of the South Deposit, Centre Pit, South Lens and North Pit. The magnetite orebodies are hosted within a strongly sheared and strike-faulted belt of mafic and ultramafic schist (amphibolite) and mylonite. This belt is around 500 metres in width, strikes NNE-SSW and is enclosed within the Whyte Schist. The magnetite ore, which ranges from 40 to 150 metres in width, is almost entirely enclosed within ultramafic rocks, mainly serpentinite and talc-carbonate schist, in what is known as the Main 36 Ore Zone. The Main Ore Zone has a known strike length of 4 kilometres and can occur as two or more thinner lenses. Down dip continuity is indicated to depths of up to 600 metres.
The individual deposits are all relatively similar, comprising subvertical NNE-SSW striking magnetite lenses, separated by structural breaks, within a schist-serpentinite sequence. The ore may be massive, layered with varying interlayers (metamorphic foliation parallel segragations) of gangue minerals, or disseminated, and ranges from being fine-grained to coarsely crystalline. The magnetite ores comprise three volumetrically important groups: pyritic ores, serpentinitic ores and talc-carbonate ores. Pyrite and serpentinite are ubiquitous. Talc, tremolite, actinolite, antigorite, chlorite, epidote, dolomite, quartz and apatite occur in varying amounts. Pyrite is an important gangue, minor chalcopyrite and trace sphalerite, rutile and ilmenite. Massive magnetite is generally defined as having a Davis Tube Recovery ('DTR' which essentially indicates the percentage of recoverable magnetite) of greater than 40%. A lower cut off of 15% DTR is used to define ore.
In 1990, production + reserves in the first stage mine was 140 Mt @ 46.5% Fe.
At December 31, 2001, proved + probable reserves were 88.5 Mt @ 48.4% Fe while measured + indicated + inferred resources totalled 206.2 Mt @ 52.4% Fe, including reserves (Ivanhoe MInes, 2002).
Resources at June 30, 2007 totalled 323.8 Mt @ 50.9% recoverable magnetite (Tas Gov. website, 2009).
Mineral resources at 30 June 2011 (Grange Resources, 2012) were:
Measured - 81.4 Mt @ 54.2% Fe;
Indicated - 131.5 Mt @ 53.5% Fe;
Inferred - 86.9 Mt @ 48.8% Fe;
Total resources - 299.8 Mt @ 52.3% Fe, which include: Proved + probable reserves of - 113.9 Mt @ 51.5% Fe.
Remaining JORC compliant mineral resources at 30 December 2014 above a cut-off of 15% DTR (Grange Resources, 2015), were:
Measured - 71.8 Mt @ 52.7% DTR, 68.1% Fe, 0.04% Ni, 0.64% TiO2, 1.57% MgO, 0.009% P, 0.39% V, 0.12% S;
Indicated - 156.3 Mt @ 49.9% DTR, 68.0% Fe, 0.05% Ni, 0.69% TiO2, 1.58% MgO, 0.009% P, 0.35% V, 0.10% S;
Inferred - 155.1 Mt @ 42.6% DTR, 68.5% Fe, 0.04% Ni, 0.64% TiO2, 1.30% MgO, 0.008% P, 0.36% V, 0.09% S;
Total resources - 383.2 Mt @ 47.7% DTR, 68.2% Fe, 0.04% Ni, 0.66% TiO2, 1.46% MgO, 0.009% P, 0.36% V, 0.10% S;
which include:
Proved + probable reserves of - 90.7 Mt @ 51.3% DTR, 67.7% Fe, 0.04% Ni, 0.90% TiO2, 1.62% MgO, 0.008% P, 0.37% V, 0.06% S.
Note: Elemental compositions in the 2014 resources/reserves are measured from Davis Tube Concentrates (DTR), while in the earlier estimates are as a percentage of the total ore.
Between 1967 and 1997, annual pellet production peaked at 2.4 million tonnes. Sales in the 2006-07 financial year were 1.787 Mt of pellets, 14 800 tonnes of concentrate and 60 000 tonnes of iron ore chips (Tas Gov. website, 2009). During 2011-12, 1.97 Mt of premium quality blast furnace pellets were produced and exported (Grange Resources, 2012). Pellet production in 2014 totalled 2.34 million tonnes (Grange Resources, 2015).
The most recent source geological information used to prepare this decription was dated: 2007.
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.
Savage River - North Pit
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Coleman R J 1975 - Savage River magnetite deposits: in Knight C L, (Ed.), 1975 Economic Geology of Australia & Papua New Guinea The AusIMM, Melbourne Mono 5 pp 598-604
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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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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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