Warburton Project
The Warburton Project comprises 2,000 km² of exploration licences within the western Musgrave Province. This largely unexplored terrain has the potential for stratabound sediment-hosted copper (e.g. Mt Isa and Michigan Copper belt), magmatic copper-nickel, uranium and gold as demonstrated by previous exploration and Rubicon's work to date. The Warburton Project is partly being explored in joint venture with a major Rubicon shareholder Vale Australia EA Pty Ltd, which is funding expenditure to earn an initial 51% interest in the project. Vale may earn up to 75% of the project by sole funding all work up to a decision to mine. The Bentley Tenement will be explored on grant by Dominion Mining Dominion which has the right to earn a 70% interest in the Bentley tenement through expenditure of $750,000 over a five year period.
The project is located on Aboriginal Reserve Land and access agreements with the Ngaanyatjarra have been negotiated on most tenements. Rubicon has been very pleased with its relationship with the Ngaanyatjarra People.
Joint Ventures
Five tenements (Jackie Junction, Caesar Hill and Mt Eveline sub-projects) are subject to the Warburton Joint Venture, an Evaluation and Farm-in Agreement with Vale Australia EA Pty Ltd, a wholly owned subsidiary of Companhia Vale do Rio Doce (Vale) which commenced in February 2008. Vale is spending $3 million over three years to earn a 51% interest in the tenements and may exercise an option to enter into an Exploration Joint Venture Agreement with Rubicon. Rubicon is managing the exploration on behalf of the joint venture.
Vale may proceed to a 70% interest in the project by sole funding exploration and development studies up to the commencement of a Bankable Feasibility Study (BFS) and an additional 5% interest by sole funding the BFS.
Quadrio Resources Pty Ltd (a wholly owned subsidiary of Dominion Mining Limited) has entered into an agreement to explore Exploration License 69/2578 (the Bentley tenement). The Bentley tenement is located approximately 60 kilometres northeast of the Warburton community in Western Australia.
Dominion has the right to earn a 70% interest in the Bentley tenement through expenditure of $750,000 over a five year period, commencing from the later date of signing of a formal joint venture agreement, granting of the Tenement or signing of a Land Access Agreement Dominion will spend a minimum of $140,000 (net of Land Access Agreement costs) within 12 months from the commencement date.
Dominion is a focused exploration and mining company and intends to principally explore for gold in the tenements as part of a larger project area, following the recent discovery of the Handpump gold mineralisation in the area by a third party. The Bentley tenement has a structural setting and similar rock types to those at Handpump.
The Bentley tenement was not previously subject to Rubicon's Warburton Joint Venture with Vale Ltd, which is principally focused on copper and nickel exploration. Rubicon also retains tenements in its own right in the area.
Project Areas
The Warburton Copper Area (100% Rubicon) is located on the partly outcropping southwest part of the Musgrave province, centred on the Warburton community and the Warburton Copper Prospects (Harry Simms Mine). The prospective area is dominantly basalt, sandstone and conglomerates. Copper mineralisation was discovered by prospectors in the early 1960s and the area was the subject of a significant exploration campaign in the late 1960s and early 1970s. Limited mining of narrow chalcocite-rich veins was also undertaken in the 1960s at the Harry Simms mine.
Around 200 copper mineral occurrences and geochemically anomalous soils over a 20 kilometre strike length have been identified. Previous exploration in the area included auger, vacuum drilling and percussion drilling and culminated in the drilling of 12 diamond core holes, of which four intersected significant copper mineralisation, up to 3.5m @ 8.2% copper and 16g/t silver.
Rubicon has completed a detailed aeromagnetic and gravity survey over the prospective stratigraphy, regional mapping and soil sampling, rock chip sampling of malachite-bearing mineralisation which averaged 5% copper ranging up to 15% copper and an 18-hole reverse circulation (RC) drill programme over targets in the Warburton Copper Area, with a best result of 49m @ 0.34%, including 6m @ 1.11% copper.
During 2010, Rubicon completed an aircore and diamond drilling program testing areas under cover and along strike of the historic copper prospects at Warburton. Drilling consisted of a 400 metre diamond hole at each of the Lilian and Keeweenaw (located to the WNW of Elder) prospects and aircore drilling (65 holes for 2,110 metres) at the Lilian, Keeweenaw, Jackie Junction and Elder prospects.
The diamond drilling and the previous year's RC drilling program were 50% funded by the Western Australian Co-funding Government-Industry Drilling Program. Drilling completed was essentially stratigraphic in nature to test for appropriate geological environments to host sedimentary copper mineralisation under recent cover. The drilling at Lilian, Keeweenaw and Elder intersected hematite altered conglomerates, sandstones, siltstones and mafic volcanics but there was no evidence of the interpreted reduced sediments favourable for copper mineralisation and no mineralisation was recorded.
Drilling at the Jackie Junction Prospect, located to the north of Warburton, was targeting a significant magnetic unit located under sand cover which is interpreted from magnetics and gravity as Giles Complex equivalent with potential for copper, nickel and PGE mineralisation. This mineralisation style is analogous to the Babel and Nebo copper-nickel deposits located approximately 80km to the southeast of Jackie Junction.
Aircore drilling (38 holes) tested across the magnetic feature to define lithology and geochemical indicators. Although the geology is complex, with drilling intersecting a range of lithologies, visual inspection shows that many of the holes intersected an intrusive mafic unit, often associated with significant pyrite.
Based on this encouraging result, the joint venture partners consider that the mafic units intersected at Jackie Junction warrant aggressive follow up for copper-nickel-PGM mineralisation. A VTEM (Versatile Time Domain Electromagnetic) survey was flown over the prospect area in late 2010. This survey covered an area of over 200km², where the recent drilling has verified mafic intrusive rocks and shallow cover conditions.
At the same time, the eastern part of the Caesar Hill tenement (E69/2253) was also tested with airborne VTEM. The Caesar Hill target area contains known basal Giles Complex rocks and has had no on-ground exploration by Rubicon to date. Processing of the data is currently underway.
