Warburton Project
The Warburton Project is located at the Warburton Community in the far western Musgrave province, approximately 750 kilometres northeast of Kalgoorlie in Western Australia. The Project comprises 11 exploration licence applications totalling approximately 2,900km². The Project is sub-divided into the Warburton Copper area, the Gunbarrel area and the Caesar Hill area.
The project area was initially identified as being prospective for Iron Oxide Copper-Gold (IOCG) mineralisation (e.g. Olympic Dam, Ernest Henry, and Prominent Hill). It is also considered to be prospective for other styles of mineralisation such as Mount Isa-style sediment-hosted copper mineralisation and the Caesar Hill tenement is also prospective for magmatic nickel-copper-PGM mineralisation (e.g. BHP Billiton's Babel-Nebo deposits).
The West Musgrave area is considered by the Company as highly prospective based on the following:
- The host rocks are mid-Proterozoic, continental rift-related sequences, which typically host many of the world's large base metal deposits, with volcano-sedimentary sequences prospective for base metals and gold.
- The Giles mafic-ultramafic intrusive complex hosts nickel-copper-platinum group elements (PGEs) mineralisation at Babel and Nebo and copper mineralisation is known at Warburton and the Tollu prospect to the east, with small scale mining undertaken at Warburton in the 1960s.
- Previous exploration has displayed positive indications of alteration and copper mineralisation styles consistent with IOCG deposits.
- The area is genuinely under-explored due to its remoteness, large tracts of covered terrain and access restrictions in the past.
The Musgrave province is an arcuate belt of Proterozoic metamorphic and intrusive rocks covering approximately 140,000km² in Central Australia. It is located at a craton margin and is, importantly for mineralisation, sited at the triple junction between the West, Northern and South Australian Blocks, as well as at the junction of major suture zones and lineaments/faults. It is also sited along the major G10 lineament that encompasses the Olympic Dam and Broken Hll deposits.
The project lies within the Bentley Supergroup, which includes sedimentary and volcanic rocks of low metamorphic grade in the project area overlying the metamorphic and granitoid core rocks of the Musgrave province. Three large cauldron subsidence complexes of felsic volcanic rocks and granite are also known. Of these, the Scamp and Palgrave Cauldrons are adjacent to Rubicon tenements. The Giles Complex is a series of concordant to locally discordant sills and lopoliths of mafic magma intruded at several crustal levels between 10 and 20 kilometre depth.
The Warburton Copper Area is located on the partly outcropping southwest part of the Musgrave province, centred on the Warburton community and the Warburton Copper Prospect (Harry Simms Mine). Copper mineralisation was discovered by prospectors in the early 1960s and was subjected to a major 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. Exploration in the area included geological mapping, costeaning, extensive stream sediment and soil geochemistry programs, auger and vacuum drilling and percussion drilling. The program culminated in the drilling of 12 diamond core holes, of which four intersected significant copper mineralisation, of up to 3.5m @ 8.2% copper and 16g/t silver. A pervasive red hematite alteration occurs in most rock types in the drilling, often associated with magnetite. The presence of this widespread hematite alteration associated with copper mineralisation is a feature common to many IOCG systems.
Previous exploration identified the Gunbarrel Area as being prospective for IOCG mineralisation based on discrete magnetic and gravity anomalies on a broad magnetic/gravity high. Structural interpretations generated 15 IOCG targets and two deep diamond holes tested one of the coincident magnetic and gravity high targets. The drilling penetrated approximately 250 metres of largely Permian cover before intersecting various mafic igneous and metasedimentary rocks with weak to moderate levels of alteration (albite-hematite-magnetite-feldspar) and some areas of hematite-carbonate veining. While this alteration is consistent with IOCG systems, there were no significant copper or gold assays.
The Caesar Hill tenement is located to the east of the Palgrave cauldron where the volcanic rocks of the cauldron are in faulted contact with Giles Complex, immediately northwest of the Babel-Nebo mineralisation and north of a chrysoprase pit (chrysoprase is a green chalcedony where the colour is related to nickel-rich silicates). The tenement was explored in conjunction with the discovery of the Babel and Nebo deposits, although there was little work completed on it.
Proposed Exploration
The Company has re-processed publicly available aeromagnetic and gravity data, undertaken review of previous exploration and conducted a targeting exercise based on that information. Based on this work, a number of targets have been defined. The main target selection criteria, consistent with the IOCG exploration model, are as follows:
- Magnetic and gravity anomalies (highs and/or contacts to lows);
- Interpreted structural intersections and possible "extensional" structural zones;
- Magnetic anomalies on major faults and structural intersections;
- Magnetic anomalies coincident with copper mineral occurrences; and
- Areas along strike of known copper mineralisation (e.g. Warburton).
IOCG alteration systems around known deposits are very large and contain some barren satellite mineralised systems (e.g. Ernest Henry terrane). The application of modern detailed geophysical surveys (e.g. gravity, magnetics, electrical or electromagnetic methods) will be used to help define high-quality targets within the Warburton alteration systems. Gravity data will identify direct drill targets, representing potential areas of higher density alteration (e.g. Prominent Hill is a significant gravity anomaly that is only well defined from local-scale surveys). Electromagnetic or electrical surveys may help to identify conductors representing sulphide-rich mineralisation (e.g. the Ernest Henry deposit has a significant induced polarisation (IP) anomaly). The main host rocks at Warburton are largely resistive sediments, so subtle conductors representing sulphides should be identified as electromagnetic anomalies. Target generation by geophysical methods will be particularly required in the covered Gunbarrel Area.
The main targets within the Caesar Hill tenement are the Giles Complex rocks which occur in close proximity to the Babel and Nebo deposits and the major structures that form the Palgrave Cauldron margin. A single point gravity anomaly occurs along these structures and is a prime IOCG target. It is proposed to undertake a detailed gravity survey across the western part of the tenement to refine the regional gravity anomaly and to establish the presence of other anomalies within the cauldron volcanic rocks.
Given that a significant copper-nickel soil anomaly has been defined in the southeast corner of the Caesar Hill tenement, appropriate geochemical sampling is proposed. Landsat images indicate the presence of outcrop and geological and regolith mapping will establish the optimal sampling method. Ground EM surveys will also be considered across the Giles Complex rocks.
Any geophysical, geochemical and/or geological targets will be tested by initially RAB, followed by RC and diamond drilling as appropriate.
