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Teutonic Bore, Jaguar, Bentley |
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Western Australia, WA, Australia |
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Cu Zn Pb Ag
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Super Porphyry Cu and Au
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Teutonic Bore, Jaguar and Bentley Neoarchaean volcanic hosted massive sulphide Cu-Zn deposits are located some 60 km north of the town of Leonora on the northern Yilgarn Craton in Western Australia.
These deposits are located towards the western margin of the Kurnalpi Terrane of the Yilgarn Craton. For details of the regional setting, see Yilgarn Craton overview record.
The Teutonic Bore deposit is hosted by a sequence of mafic and felsic volcanic rocks in a regionally continuous linear belt of locally emergent volcanic centres separated by interbedded sub-aqueous tuffs and epiclastics. All of these rocks have been intruded by gabbroid and granitoid rocks. The deposit is also in a zone of regionally complex structure and lithology characterised by repeated periods of extensional tectonism. 2692.6±1.5 Ma
Mineralisation is hosted by a unit of pyritic black shale, chert and tuffaceous sedimentary rocks that are generally 3 m thick, but may locally thicken to >30 m as in the area of mineralisation. This unit immediately overlies a <30 to >170 m thick sequence of pillowed tholeiitic basalt that in turn, overlie a suite of rhyolitic volcanics and volcaniclastics. The rhyolitic suite is mainly massive or flow banded with minor breccia, and extends over a strike length of >20 km and ranges from 200 m to >1 km in thickness. Its upper section includes a 0 to 70 m thick unit of rhyolite contact sedimentary rocks, partially derived from the underlying rhyolites, locally very coarse grained, but grading to sandstone, siltstone and shale.
The mineralised volcano-sedimentary unit is overlain by the Upper Basalt and Andesite which is composed of massive and pillowed basalt and andesite lavas with minor volcanic breccias and sub-volcanic intrusive rocks. It varies from 700 m thick in the north to ~200 m in the south, made up of individual 5 to 50 m thick units of calc-alkaline to tholeiitic composition, separated by <30 m thick interflow units of carbonaceous shale with minor siltstone and sandstone. These are followed by the Upper Rhyolite which is <100 to >500 m thick.
A hanging wall rhyolite dyke at the related nearby Jaguar deposit has been dated at 2692.6±1.5 Ma, whilst the footwall rhyolite has yielded and age of 2694.2±0.6 Ma at the nearby Bentley deposit (TIMS U-Pb; Hayman, et al., 2014).
The Teutonic Bore orebody comprises a single, relatively steeply dipping lens of massive (i.e., >80%) sulphide that is ~ 320 m long, 2 to 35 m thick and extends down dip for 280 m. It is predominantly composed of banded massive pyrite, sphalerite, chalcopyrite and galena, with trace pyrrhotite, famatinite, cosalite, aikinite, bismuthinite and stannite, and a quartz and siderite gangue.
The massive sulphide mineralisation is banded on a 1 mm to 1 m basis, locally containing pyrite nodules, colloform textures, sulphide breccia and minor contortions/folds. The massive sulphide lens is Zn-rich in the core, with abundant Cu at the base and top. It is underlain by concordant and discordant stringer (40 to 80%) sulphide mineralisation composed of pyrite, chalcopyrite and sphalerite, occurring as disseminations in veins containing quartz, siderite, ankerite and chlorite. Alteration beneath the ore body is dominated by chlorite, siderite, ankerite and sericite, with chloritoid, andalusite and kyanite as metamorphic products of the alteration assemblage.
Weathering has penetrated to a depth of 75 m. An oxide assemblage of leached oxides and gossan occur in the upper sections of the profile, passing downward into a transition zone of supergene sulphides containing abundant secondary ore minerals befor passing into the hypogene ore assemblage.
In addition to the Teutonic Bore deposit, which was discovered in 1975, and mined from 1979 to 1984, subsequent exploration discovered the nearby, similar Jaguar deposit 4 km to the south in 2002, which was mined from 2007 to 2014. Although exploration had been undertaken in the area further to the south since 1977, the Bentley deposit was not discovered until 2008, with mining commencing in 2011. It is ~5 km south of Jaguar.
The Bentley deposit is the largest of the three and has a strike length of ~400 m. thickness of 2 to 30 m and down plunge extent of ~900 m. Jaguar has a 300 m strike, 2 to 10 m thickness and vertical extent of 375 m. Like at Teutonic Bore, both Bentley and Jaguar dip at 70 to 80°W. These latter two have, however, been split into discrete lenses by parallel post-mineralisation dolerite sills, while a rhyodacite intrusive has disrupted the southern margin of the main Bentley lens.
The stratigraphy and mineralisation at Jaguar and Bentley is similar to that described above for Teutonic Bore. Footwall alteration is well developed at all three deposits. At Bentley, which is th most representative, well developed footwall alteration comprises white-mica, quartz, pyrite, Fe-carbonate and lesser chlorite and minor chloritoid. The white-mica varies from a proximal paragonite-muscovite to a distal muscovite-phengite. Disseminated pyrite is ubiquitous, but minor in the footwall, and is less well developed in the hanging wall where the country rocks are bleached, silicified and contain less mica than in the footwall. Fe-rich chlorite occurs in the stringer zone, but is not a major alteration product.
Mining over a period of 5 years at Teutonic Bore removed 1.4 Mt @ 4.16% Cu, 16.14% Zn, 1.22% Pb, 203 g/t Ag from the massive sulphides and an additional 0.75 Mt @ 2.38% Cu, 1.92% Zn, 52 g/t Ag as stringer ore (Hallberg and Thompson, 1985).
Production and remaining resources as at 30 June 2016 were (Parker et al., 2017):
Production
Teutonic Bore - 1.684 Mt @ 10.8% Zn, 3.5% Cu, 140 g/t Ag;
Jaguar - 1.778 Mt @ 7.7% Zn, 2.7% Cu, 87 g/t Ag;
Bentley - 1.892 Mt @ 10.5% Zn, 1.7% Cu, 149 g/t Ag, 0.7 g/t Au;
Cumulative - 5.355 Mt @ 9.7% Zn, 2.6% Cu, 126 g/t Ag; 0.2 g/t Au.
Mineral Resource - Measured + Indicated + Inferred
Bentley - 2.107 Mt @ 8.6% Zn, 1.5% Cu, 138 g/t Ag, 1.0 g/t Au;
Teutonic Bore - 1.554 Mt @ 2.5% Zn, 1.6% Cu, 49 g/t Ag.
For more detail see the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 2017.
Record last updated: 25/8/2019
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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Barley M E 1995 - Archaean volcanic-hosted base metal sulphide mineralisation in Western Australia: in Australian Institute of Geoscientists Bull 16 pp 41-50
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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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Hallberg J A, Thompson J F H 1985 - Geologic setting of the Teutonic Bore massive sulfide deposit, Archean Yilgarn Block, Western Australia: in Econ. Geol. v80 pp 1953-1964
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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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Parker, P., Belford, S., Maier, R., Lynn, S. and Stewart, W., 2017 - Teutonic Bore-Jaguar-Bentley volcanogenic massive sulfide field: in Phillips, G.N., (Ed.), 2017 Australian Ore Deposits, The Australasian Institute of Mining and Metallurgy, Mono 32, pp. 167-172.
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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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