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Wiluna Uranium - Centipede, Lake Way, Dawson-Hinkler, Millipede, Nowthanna

Western Australia, WA, Australia

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The Wiluna Uranium Project includes the Centipede, Lake Way, Dawson-Hinkler, Millipede and Nowthanna deposits. The centres of the largest of these, Lake Way and Centipede are ~15 km SE and ~30 km SSE of the town of Wiluna in Central Western Australia, and 65 km NE of the Yeeliree deposit (#Location: 26° 42' 30"N, 120° 20'E and 26° 51'N, 120° 21'E respectively).

The regional geology of the Wiluna area comprises Archaean crystalline bedrock, dominated by granite, cut by the eastern margin of the Archaean Norseman-Wiluna greenstone belt, which is characterised by sedimentary and basic volcanic rocks. Granite and gneiss are found to the east. Mineralisation occurs as a series of shallow calcrete-hosted uranium deposits, the largest of which are Centipede and Lake Way. These are associated with the broad palaeochannel deltas that empty into the Lake Way hyper-saline playa, which itself represents the remnants of a major primary palaeo-drainage system of predominantly Tertiary age. Centipede is on the southwestern margin of the NW-SE elongated, 30 x 10 km, Lake Way, while the Lake Way deposit is on the Lake's northern margin (Toro Energy, 2010).

The carnotite mineralisation sits within a wide, shallow, flat lying and relatively continuous horizon that is 2 to 4 m (maximum ~6.5 m) thick, located below alluvial overburden at a depth between 1 and 12 m below the surface, associated with, but not limited to, a thicker zone of calcareous concretions. Uranium mineralisation is associated with calcrete/dolomite, carbonated silty clay and carbonated sand. These occur within a typical fluviatile/deltaic sequence composed of shallow surficial sediments ranging from narrow clay layers to areas of coarse sand and grit with minimal clay that may be up to 40 m thick. These sediments were laid down within the palaeochannel drainage system and follow the ancient channel structures. The present day drainage has eroded the existing channels resulting in a complex, discontinuous ore body. The mineralisation generally occurs at, or in close proximity to the current water table, typically 1 to 2 m below ground level. Mineralisation formed through hydro-geological processes, associated with groundwater interaction in drainage channels and deltas that flow into present day salt lakes (Toro Energy, 2010).

The mineralisation at both Centipede and Lake Way is dominated by carnotite (K2(UO)2(VO4)2.3H2O), a potassium-uranium vanadate mineral, which has been precipitated out of solution and preserved within the lower reaches of tributary palaeochannels following subtle changes in groundwater chemistry and evaporation. It occurs as micro- to crypto-crystalline coatings on bedding and slippage planes, small concentrations within silty clay and clay sequences, and within interstices between sand and silt grains, in fissures and voids within calcrete, dolomitic calcrete, siliceous calcrete and silcrete, and appears to have been precipitated onto any available surface (Toro Energy, 2010).

The Lake Way deposit has irregular outlines within a 4 km diameter area, while Centipede has a horseshoe shape over a similar area.

Published resource estimates (Toro Energy, 2013) at a 200 ppm U
3O8 cut-off are:
    Centipede and Lake Way:
        Measured + indicated resource - 13.21 Mt @ 0.542 kg/t U
3O8 = 7165 tonnes of U3O8;
        Inferred resource - 9.68 Mt @ 0.480 kg/t U
3O8 = 4642 tonnes of U3O8;
    Millipede, Dawson-Hinkler and Nowthanna:
        Indicated resource - 1.77 Mt @ 0.412 kg/t U
3O8 = 728 tonnes of U3O8;
        Inferred resource - 30.51 Mt @ 0.386 kg/t U
3O8 = 11762 tonnes of U3O8;
    Total Wiluna District Resource:
        Measured + indicated + inferred resource - 55.17 Mt @ 0.441 kg/t U
3O8 = 24 297 tonnes of U3O8.

The most recent source geological information used to prepare this summary was dated: 2012.    
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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