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Gove, Nhulunbuy, Dhupuma Plateau |
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Northern Territory, NT, Australia |
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Al
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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 Gove and Dhupuma Plateau bauxite deposits are located on the Gove Peninsula. The Gove deposit is adjacent to the town of Nhulunbuy in the Northern Territory, Australia, some 650 km east of Darwin. The Dhupuma Plateau mine is 30 km south by road from the town of Nhulunbuy. The deposits lie near the coast, at a latitude of 12° 15'S of the equator and is in a region with a tropical, monsoonal climate (#Location: 12° 17' 14"S, 136° 50' 19"E).
Following the recognition of bauxite on the adjacent Wessel Islands group to the north of Gove in 1949, exploration commenced on the Gove Peninsular in 1952. This involved a reconnaissance by the Australian Bureau of Mineral Resources which recognised bauxite and its extent there also, and from 1955 follow-up exploration by a company owned 51% by the Australian Government and 49% by the British Aluminium Company. After 8 years of machinations and negotiations between the Australian Government and a number of major aluminium companies regarding establishment of a bauxite mining and processing industry in the Northern Territory, a special mineral lease, SML1, was granted to the North Australian Bauxite and Alumina Company Ltd (Nabalco). The principal shareholding in Nabalco was the Swiss company Alusuisse with an equal share of Australian interests. The land covered by SML1 and surrounding subsidiary leases was excised from the Arnhem Land Reserve, which had been proclaimed in 1931, but without prior reference to the inhabitants of the excision which led to legal action that was not successful. The conditions of the lease were that the company establish a mine and an alumina refinery with a capacity to produce no less than half a million tons of alumina per annum and that it should have 50% Australian ownership. These stipulations were the main cause of the long delay in the operation coming to fruition after discovery. The Gove mine operation began production in 1971, whilst refinery operations commenced in 1972. In 2001, Alcan purchased 100% of the Gove Project and the name of the mining operation was changed to Alcan Gove. In 2007, Rio Tinto Aluminium purchased Alcan and the name was changed to Rio Tinto Alcan, Gove Operations. Due to world prices, alumina production ceased at Gove in May 2014, with the operation reverting to direct export of bauxite only. In 2017, the Dhupuma Plateau mine opened immediately to the south of the Gobe leases. It is owned and operated by the Aboriginal owned Gulkula Mining Company. In 2020, dismantling of the refinery commenced and is expected to take 10 years to safely be completed, including rehabilitation. Annual production at Rio Tinto Alcan, Gove in 2021-22 was 10.9 Mt of bauxite, and at Dhupuma Plateau, 784 080 tonnes bauxite. Production at Gove is anticipated to be terminated before 2030 due to depletion of reserves. This history is largely drawn from Lee (2014) 'The Development of Bauxite at Gove, 1955-1975'.
The geology of the Gove Peninsular comprises a foliated, migmatitic, ~1870 Ma Palaeoproterozoic basement composed of metasedimentary rocks, mafic gneiss and intrusives of the Bradford Complex. This is unconformably overlain by flat lying Lower Cretaceous sedimentary rocks of the Yirrkala Formation - composed of quartzose and feldspathic sands, clays, siltstones and rare thin lenses of lignite - dominantly concealed by soil with few exposures, except on breakaways on the margin of the plateau they form. The Cretaceous sediments are 100 to 200 m thick, although the thickness varies with the basement relief. Lignites in the sediments were deposited in a lacustrine environment during the lower Cretaceous. The initial peneplanation, formation of a plateau and development of a laterite and bauxite profile is believed to have taken place soon after the sedimentation of the Mesozoic sequence, followed by later epeirogenic uplift, renewed erosion and dissection to form the present plateau remnants.
The main plateau which hosts the main Gove deposits is gently undulating and is typically 30 to 60 m above sea level (ASL), significantly lower than the surface of the Dhupuma Plateau which ranges between 85 and 115 m ASL. The thickness of the bauxite sheet in the Main Gove Plateau deposit averages ~3.7 m, and ranges from zero at the plateau edges to as much as 10 m thick on hill crests. At the Dhupuma Plateau, the thickness of the bauxite horizon is reported to range from 3 to 11m.
The bauxite profile at Gove comprises the following, from the base:
• Ferruginous-siliceous Laterite - more than 5 m of barren red-brown, massive, vesicular and conglomeratic rock without a well defined base into the Mesozoic protoliths.
• Tubular Ore - 1.0 m of red-brown massive rock with irregular, vesicular like, tubular shaped cavities that cut all original rock textures.
• Cemented Pisolitic Ore - 1.5 m of densely packed pisolites whose outer shells are fused with their neighbours, with only minor matrix and a porous nature. Pisolites have diameters of 1 to 15 mm. This band has a sharp undulose contact with the underlying Tubular ore.
• Loose Pisolitic Ore - 3.0 m of red to brown 1 to 10 mm pisolites loosely set within a subordinate matrix of sandy angular quartz, laterite fragments, bauxite grains and broken pisolites. The contact with the Cemented Pisolites is sharp and has a mild karstic appearance.
• Topsoil - 2.0 m of red-brown clayey loam with scattered pisolites and other fragments of the underlying profile.
The bauxite orebody is contained between the top of the laterite and the base of the topsoil. The principal minerals in the bauxite profile are gibbsite and hematite/goethite, with subordinate boehmite.
The mineable bauxite in the Gove mine leases covered an area of around 63 km2 with an average thickness of 3.5 m.
Total proven reserves in 1975 were: 250 Mt @ 51% Al2O3, 4% SiO2.
Production from 1972 to 2003 has totalled 150 Mt of bauxite for 40 Mt of Alumina, i.e., a recovered grade of 26.5% Al2O3.
Remaining Ore Reserves and Mineral Resources at 31 December 2008 were as follows (Rio Tinto Annual Report, 2008):
Proved + Probable Ore Reserves - 175 Mt @ 49.4% Al2O3;
Measured + Indicated + Inferred Mineral Resources - 46 Mt @ 49.7% Al2O3.
Remaining Ore Reserves and Mineral Resources at 31 December 2016 were as follows (Rio Tinto Annual Report, 2016):
Proved + Probable Ore Reserves - 147 Mt @ 49.2% Al2O3;
Measured + Indicated + Inferred Mineral Resources - 44 Mt @ 49.5% Al2O3.
Remaining Ore Reserves and Mineral Resources at 31 December 2022 were as follows (Rio Tinto Annual Report, 2016):
Proved + Probable Ore Reserves - 56 Mt @ 50.5% Al2O3, 5.8% SiO2;
Measured + Indicated + Inferred Mineral Resources - 13 Mt @ 48.3% Al2O3, 9% SiO2.
NOTE: Mineral Resources are Exclusive of Ore Reserves.
The Dhupuma Plateau bauxite mine is developed on Aboriginal freehold land immediately south of the Gove leases and is owned by the Aboriginal Gulkula Mining Company, which is not a publicly listed enterprise. As such it is not required to release Ore Reserve or Mineral Resources estimates, although in 2016, 'resources' were estimated at ~8-12 Million tonnes. The deposit is developed on a narrow, 'Y' shaped, 12 km long, incised plateau with a central broader core. A total estimated disturbance of 35 ha is planned in the first four years of mining, including mining areas and infrastructure. From project-year five onwards, an estimated 15 ha per year is planned to be disturbed by mining. The mining operation is expected to have a life of ~15 years, with production ramping up from 100 000 tonnes per annum to 500 000 tpa over the first four years and is anticipated to maintain that same level for the remaining life of the mine. The production of 784 080 tonnes of bauxite in 2021-22, the 5th year is exceeding plan. The bauxite mined is sold to Rio Tinto’s Gove operations where it is crushed, loaded onto ships and on-sold. Trucks loaded ore directly at the mine face and haul the bauxite ~14 km to the Rio Tinto hardstand stockpile.
The bauxite profile, is similar to that at Gove, comprising up to eight discrete layers in a complete bauxite laterite profile including from surface: topsoil; loose pisolite bauxite; cemented pisolitic tubular bauxite; lower nodular bauxite; nodular ironstone; mottled zone; and saprolite. The bauxite mineralogy, as at the Gove deposits, is composed of gibbsite and minor boehmite, particularly in the upper levels of the profile. Silica is present as free quartz and in
kaolinite and haematite and goethite are the main iron oxide constituents.
Details of the Dhupuma Plateau deposit are drawn from Vellacott, S., 2016 - Dhupuma Plateau Bauxite Mine, Mining Management Plan, Gove, NT; prepared by Landroc Pty Ltd, for the Gulkula Mining Company Pty Ltd. 71p.
For detail consult the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 2016.
Record last updated: 7/8/2023
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.
Gove
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Somm A F 1975 - Gove bauxite deposits, NT: in Knight C L, (Ed.), 1975 Economic Geology of Australia & Papua New Guinea The AusIMM, Melbourne Mono 5 pp 964-968
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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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