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Yeelirrie |
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Western Australia, WA, Australia |
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U
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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The Yeelirrie uranium deposit is hosted by Recent surficial carbonate rocks (valley calcrete), spatially and genetically related to Cretaceous to Tertiary palaeodrainage channels, now reflected by broad, dry creeks and strings of playa lakes. It is located over and towards the northern magin of the Archaean Yilgarn Craton 20 km WNW of Yeelirrie Homestead and 650 km north-east of Perth in Western Australia..
The basement in the catchment of the host palaeochannel is mainly deeply weathered Archaean granitic rocks, mainly biotite adamellite, belonging to the Montague Range and Wiluna greenstone belts. The present day channel is regarded to be the remains of an extensive early Cretaceous river system, rejuvinated during the Tertiary when it etched up to 100 m into the then lateratised plateau surface. With increasing aridity from the late Tertiary onwards the topography has been buried by alluvium and become a plain. The calcrete is developed at the top of the alluvial sediments filling the palaeochannels.and has been dated at around 20 900 to 36 500 years.
The channel fill is a monotonous iron stained kaolin and coarse detrital quartz, with some narrow, local, thin, kaolinised sand overlying granite basement, narrow grit bands and a 1 to 2 m tick overburden of loam, sand, powdery carbonated loam and saline clay.
The current water table is at depths of 4 to 5 m. The carbonate horizon maintains a fairly constant thickness of 4 to 5 m (up to 7 m) below surface, being developed by an early replacive process (replacing kaolinite and quartz) to produce friable 'earthy' calcrete which was then displaced by the subsequent formation of hard, nodular, porcellanous calcrete, commencing as small nodules which grew and coalesced to form permeable bulbous masses with a high proportion of voids. These nodular masses grew up and out to displace the channel sediments and somtimes breached the surface to form mounds and ridges shedding an oolitic gravel layer when eroded.
The orebody is approximately 90% below the water table, and the lower grade mineralisation near the base being in carbonated clay-quartz below the main calcrete. Grade is highly irregular in detail. The only ore mineral is carnotite, which was one of the last species to form and is deposited independantly of host lithology, occuring disseminated through seams of 'earthy' calcrete, coating quartz grains in the clay-quartz, coating fracture planes in indurated alluvium and on slickensides on the margins of growth mounds. In the nodular porcellanous calcrete it lines cavities and coats spheres. The most important host is the clay rich carbonated rocks of the transition zone at the base of the calcrete profile.
The deposit contains a total resource of approximately - 52 500 t of U3O8, comprising:
Prime ore - 13 Mt @ 0.24% U3O8 for 32 000 tonnes of U3O8,
Intermediate ore - 22 Mt @ 0.09% U3O8 for 20 500 tonnes of U3O8.
The main channel at Yeelirrie contains a number of elongate flat lenses of mineralisation, the largest of which encompasses the orebody. This lens is 20 km long, 2.5 km wide and averages 7 m in thickness, with the orebody it contains being 9 x 1.5 km, with ore in general being in the interval from 4 to 8 m below the surface.
For detail consult the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 1990.
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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Cameron E 1990 - Yeelirrie Uranium Deposit: in Hughes F E (Ed.), 1990 Geology of the Mineral Deposits of Australia & Papua New Guinea The AusIMM, Melbourne Mono 14, v2 pp 1625-1629
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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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