The Whim Creek Project is located 115 km to the west of Port Hedland and includes:
- Resources at the Whim Creek, Mons Cupri and Salt Creek deposits where 67,000 tonnes of copper have already been produced from near surface oxide ores;
- the Evelyn Resource; and
- 18,100 ha of tenements over the highly prospective Whim Creek basin.
Following its capital raising in August 2016, Venturex has commenced an exploration program focussed on extending the existing high-grade zinc, copper and lead resources at the Whim Creek Project, where it has identified a range of targets adjacent to the Salt Creek and Mons Cupri deposits.
Specifically, drilling will initially focus on:
- extending the top portion of the very high grade zinc Resource at Salt Creek; and
- extending a high grade core at Mons Cupri.
With the existing infrastructure at Whim Creek, exploration success will provide an excellent near term production opportunity.
The Company’s aspirational target through this exploration strategy is > 4MT at > 2% Cu and > 4% Zn to Produce >20,000 tpa Zn and >10,000 tpa Cu per year by the end of 2018.
Little effective exploration work has been undertaken on the sulphide potential of the existing deposits in this region or exploration for additional deposits in nearly 3 decades. The Company sees a tremendous opportunity to expand the current resource and establish a viable sulphide mining operation.
Venturex has compiled all of the historical and disparate geological data sets from the series of owners of the tenements. A “back to basics” review of these data sets has highlighted the following opportunities to expand all of the Whim Creek Project Resources;
- The potential to use Induced Polarisation geophysical techniques to target stringer mineralisation that represents potential feeders to the VMS style of mineralisation at Mons Cupri;
- Data sets of down hole magnetometric resistivity (DHMMR) surveys carried out at Salt Creek in 2007 that have never been processed; and
- Airborne Versatile Time Domain Electro Magnetic (VTEM) and targeted ground Fixed Loop Transient Electro Magnetic (FLTEM) surveys carried out in 2007 on the Liberty Indee tenements that host Evelyn.
Zinc accounts for most of the metal endowment in the Whim Creek Project area and Venturex believes that progressing the potential of the Whim Creek Project offers leverage to the increasing Zinc price and positive outlook for the commodity. For further detail on the planned exploration programme at the Whim Creek Project refer to the Company’s ASX Announcement dated 26 August 2016 click here.
Current Mineral Resources at the Whim Creek Project are as follows:
A scoping study was conducted on the Whim Creek Project during 2010. This study identified a potential mining inventory supported by the existing Resources at Whim Creek sufficient to support a centrally located 600ktpa processing plant producing concentrates containing 7,800 tonnes of payable copper metal, 13,900 tonnes of payable zinc metal and 4,200 tonnes of payable lead for nine years. For more detail on the scoping study click here.
Set out below is a summary of:
- The history of the Whim Creek Project;
- Commentary on the geology around the Whim Creek Region; and
- Details of the existing deposits within the Whim Creek Project, namely – Whim Creek, Mons Cupri, Salt Creek and Evelyn.
Venturex acquired the Whim Creek Project in 2010. It previously operated from 2005 to 2010 as a heap leach and SX-EW copper oxide project producing 35,000 tonnes copper cathode.
Copper was discovered at Whim Creek in the early 1880s with small scale production from 1882. The Whim Creek deposit was mined underground from 1887 to 1912. Copper grades were 12.4% and about 60,000 tonnes of copper concentrate were produced. Some of this production was from the Mons Cupri deposit located 4km south of the Whim Creek deposit. A small oxide copper leaching operation was built in the 1960s ceasing operation in the early 1970s.
Modern systematic exploration began in the 1960s with Australian Inland Exploration and Texasgulf. They explored the area for 15 years compiling an extensive database of mapping, geochemical sampling, geophysics, diamond and open-hole percussion drilling. This work defined oxide and sulphide resources at the Whim Creek, Mons Cupri and Salt Creek deposits. During the 1980s and 1990s several companies explored the Project for both additional base metal deposits and gold.
In 1996 Straits took over the Whim Creek Project and completed extensive exploration for copper oxide mineralisation which led to production from 2005. Towards the end of the copper oxide production, Straits began evaluation of the sulphide copper- zinc deposits beneath the open pits. Straits defined substantial resources at the Whim Creek, Mons Cupri and Salt Creek deposits.
Subject to further exploration success, the existing infrastructure at the Whim Creek Project could facilitate an excellent near term production opportunity.
Infrastructure in place includes:
• Location – adjacent to a major sealed highway
• Offices, warehouse and basis workshop facilities
• Gas pipeline to site
This means that the time and cost to progress will be significantly lower than for an equivalent greenfields project.
The Whim Creek Project covers part of the Whim Creek Greenstone Belt which forms the north-western part of the Archaean Central Pilbara Tectonic Zone. The Whim Creek Greenstone Belt is an arcuate belt 85km long and 5 to 10km wide extending around the Caines Well Batholith. The northern side of the greenstone belt is truncated by the Sholl Shear and the south-eastern side is in faulted contact with sedimentary rocks of the Malina Basin (Huston 2006).
The basal unit of the Whim Creek Greenstone Belt is the Whim Creek Group consisting of the Warambie Basalt, rhyolite and volcaniclastic rocks of the Mons Cupri Volcanics overlain by conglomerate, sandstone, shale and felsic tuffs of the Bookingarra Group. The Bookingarra Group consists of the Cistern Formation, (conglomerate, tuffaceous sandstone and siltstone) overlain by the Rushall Shale and mafic rocks of the Louden and Mt Negri Volcanics (Huston 2006).
The base metal mineralisation style at Whim Creek, Mons Cupri and Salt Creek is volcanic massive sulphide (VMS) and all the known VMS mineralisation in the Whim Creek greenstone belt is hosted in the Bookingarra Group. The Whim Creek Deposit is hosted in the Rushall Slate and the Mons Cupri Deposit is hosted in the upper part of the Cistern Formation.
The Liberty Indee (Evelyn) Project covers the north plunging Croydon Anticline within the southern part of the Archaean Mallina Basin. The Mallina Basin is separated from the Whim Creek Basin to the West by the sub-vertical Loudens Fault. The Croydon anticline is cored by mafic to ultramafic sills assigned to the Millindinna Intrusion. These are flanked by the Constantine Sandstone which is the basal unit of the De Grey Group. VMS style mineralisation is located near the contact between the mafic–ultramafic sill and the Constantine Sandstone. Detailed mapping at the Evelyn deposit has also identified narrow zones of dacite to rhyolite volcanics along this contact. The current stratigraphic interpretation correlates the Constantine Sandstone with the Cistern Formation of the Whim Creek Basin (Smithies 1998). The inference from this is the Evelyn VMS mineralisation formed at a similar time to the Whim Creek, Mons Cupri & Salt Creek deposits.
Whim Creek Deposit
The Whim Creek deposit crops out on a low hill 1km south of the Whim Creek Hotel.
The oxide zone has been mined via open pit to 80m depth. Mineralisation occurs as a moderately north dipping single conformable zone, over 600m x 300m x 10 to15m thick hosted in the Rushall Slate about 150m above the contact with the underlying Cistern Formation. The eastern and western limits to the known mineralisation are defined by the post-mineralsation Martin and Jaffrey Faults.
Below the weathered zone the mineralisation consists of semi-massive and stringer sulphides comprising dominantly chalcopyrite with lesser sphalerite and galena.
The current resource detailed in the Resource & Reserves Section is:
0.97M tonnes @ 2.1% Cu, 1.1% Zn, 10.3g/t Ag, 0.2% Pb, 0.1g/t Au
Mons Cupri Deposit
The Mons Cupri deposit is hosted within conglomerate and breccia about 20m below the top of the Cistern Formation. The deposit originally consists of two gently dipping zinc-lead-silver rich massive sulphide lenses overlying a chalcopyrite rich stringer zone.
The Mons Cupri massive sulphide lens has been partially removed in the oxide pit and the remaining high grade zinc-lead-silver massive sulphide lens immediately west of the pit is 250m x140m x 5m thick, gently dipping and tapering to the west such that the zone is at less than 150m depth. It remains open down dip to the west. The underlying chalcopyrite rich stringer zone strikes east-west with a moderate to steep southerly dip and a gentle westerly plunge. It measures 500m x 150m tapering in a pipe shape to approximately 200m depth.
The Mons Cupri North West Pit contains three flat lying to gently dipping high grade zinc-lead-silver massive sulphide lenses located immediately west, south and east of the current oxide pit. They are underlain by copper rich stringer mineralisation. These three lenses are interpreted to have been one continuous zone of massive sulphides dismembered by faulting.
The western zone is approximately 150m x 100m x 2 to 5m thick. The eastern zone is 200m x 100m x 2 to 5m and the southern zone 100m x 100m x 2 to 5m thick. All the high grade zinc-lead massive sulphide zones extend up dip to the current pit. These zones are not currently included in the Mons Cupri Resource.
The total Mons Cupri Resource detailed in the Resource & Reserves Section is:
4.6Mt @ 0.9% Cu, 1.3% Zn, 24g/t Ag, 0.5% Pb, 0.1g/t Au
Salt Creek Deposit
The Salt Creek Deposit is located on the northern side of the Caines Well Batholith approximately 17km north of Whim Creek. It was discovered as a small outcropping gossan in the mid 1970s by Texasgulf. Massive sulphide mineralisation is hosted in a volcanoclastic siltstone between a hanging wall sequence of andesite to basalt lavas and a thick footwall rhyolite volcanic pile. Post mineralisation mafic dykes and sills are common. At Salt Creek the sequence is overturned and dips moderately to steeply southeast.
The deposit consists of three main separate high grade massive sulphide lenses. Two of the lenses are sphalerite (Zn) rich and one is chalcopyrite (Cu) rich. The two sphalerite lenses, Western and Eastern are 200m apart. The Western Lens starts at 40m depth and is 100m x 200m x 5m thick. It dips moderately southeast and is open down dip. The Eastern lens starts at about 40m depth and is 120m x 300m x 5m thick. The copper rich lens is adjacent to the Eastern zinc rich lens and has similar dimensions. These lenses are open at depth.
The total Salt Creek Resource detailed in the Resource & Reserves section is:
- 1 Mt @ 2.0% Cu, 7.1% Zn, 52g/t Ag, 2.1% Pb 0.3g/t Au
Contained in this resource is the zinc rich zone:
- 0.48 Mt @ 0.2% Cu, 14.1% Zn , 4.4% Pb, 107g/t Ag 0.5g/t Au
and the copper rich zone:
- 0.43 Mt @ 3.7% Cu 0.9% Zn, 2.7g/t Ag, 0.1g/t Au
Liberty-Indee Joint Venture (LIJV)
Venturex Resources Limited owns 70% of the LIJV which is located approximately 35km south of Whim Creek and 5km east of the Croydon Homestead. The LIJV comprises two exploration licences (EL) and one mining licence (ML) for 72km2. The ML is over the Evelyn Deposit. The Project is in the traditional lands of the Narguluma Aboriginal Community and covers part of the Mallina and Sherlock Pastoral Leases.
Copper was discovered in the 1890s and sporadic mining from 1898 to 1959 produced 118.4 tonnes of metal. The current joint venture began in 2006.
The Evelyn VMS copper-zinc-silver-gold deposit occurs on the contact between sediments and an intermediate volcanic. The mineralisation is semi massive to massive sulphides dipping steeply west and plunging moderately north parallel to the hinge zone of local drag folds. Drilling has been completed to 200m depth and mineralisation is open down plunge.
The Evelyn Deposit total current Resource detailed in the Resource & Reserves Section is:
- 657,000 Tonnes @ 1.8% Cu, 3.7% Zn, 35.9g/t Ag, 0.8g/t Au.