|The West Musgraves|
West Musgraves Prospectivity
The West Musgraves Region is highly prospective for intrusion-hosted Ni-Cu-PGE deposits and IOCG deposits for the following reasons:
- It is of Proterozoic age which is a peak time for the development of Ni-Cu-PGE and IOCG deposits worldwide and has a favourable structural setting and source rocks, which include the massive mafic-ultramafic Giles Complex and A-type Tollu Granite.
- The Giles Complex is one of the largest layered mafic-ultramafic intrusive complexes in the world and is related to the continental-scale Warakurna Igneous Province. Large intrusive complexes elsewhere host magmatic Ni-Cu-PGE deposits (i.e. Voisey's Bay, Canada and Duluth, USA).
- The district has had very little modern exploration. The virtual exclusion from exploration for the 25 year period to the late 1990s (due to the Ngaanyatjarra Land Council restrictions), means that the bulk of the West Musgraves Region has never been subjected to modern exploration techniques. This is true for the Redstone ground holdings.
- The West Musgraves Region is predominately blanketed by thin cover, which hindered explorers in the 1950s and 60s due to the lack of appropriate exploration tools at the time. This terrain is amenable to modern geochemical sampling (such as soil/lag geochemistry and Rotary Air Blast (RAB) drilling), which allows exploration for multiple commodities quickly, effectively and inexpensively.
- Supergene processes are demonstrated to have created broad halos of supergene mineralisation, which not only aid exploration targeting but may yield supergene enriched minable deposits.
- The distribution and diversity of known mineral occurrences, including Ni-Cu-(Co)-PGE, Ti, V, Cu-Au (with fluorine, uranium and rare earth elements: ie. potential IOCG), support the applied exploration models and strategies.
Mineral Deposits and Occurrences
There are numerous mineral occurrences in the Musgraves Block. Potential exists for Ni-Cu-PGE-Co deposits, base metals (sediment and volcanic hosted Cu-Pb-Zn-Ag) and various types of gold mineralisation. Major deposits and known mineral occurrences in the district include:
- Wingellina is a large nickel laterite deposit containing 186Mt @ 0.86%Ni with average widths of 40m, located in the Western Musgraves Block in WA n ear the border with South Australia and the Northern Territory. This deposit was discovered in the late 1950s by Southwestern Mining Co (Inco) and is currently in feasibility studies. The deposit is associated with limonitic ocherous laterite with gem quality chrysoprase and sits atop an ultramafic intrusive of the Giles Complex.
- Claude Hills nickel laterite lies 30km east of Wingellina in South Australia and contains approximately 4.5Mt @ 1.5% Ni. Mt Davies lies to the south of Claude Hills and is relatively enriched in cobalt.
- Babel-Nebo is a major nickel sulphide deposit discovered by WMC in 2000. Drill intersections include 106.5m @ 2.4% Ni, 2.7% Cu and 0.2g/t PGE, and a resource of about 1 million tonnes contained Ni and 1 million tonnes contained Cu+Co has been released, with an in-ground value of AU$25 billion. Nebo-Babel was discovered using lag sampling and outcropped as scattered gossan, and is therefore principally a geochemical discovery. However, strong magnetic, EM and gravity anomalies highlight the massive and disseminated mineralisation which is hosted within a shallowly WSW-plunging, pipe of gabbronorite intrusive (1078Ma), offset by a fault. The style of deposit is almost identical to the giant Voisey's Bay Ni deposit in Canada.
- The Halleys Cu-PGE mineralisation is situated on a magmatic flow through zone on the SE flank of the Saturn intrusive complex. Intercepts from Redstone Resources drilling of up to 74m @ 0.33% Cu and 0.24g/t PGE + Au include 20m @ 0.56% Cu, 0.32g/t PGE + Au and 0.14% Ni require deep follow-up drilling.