Rio Tinto confirms major copper discovery at Paterson Province, juniors scramble to peg ground

Mining giant Rio Tinto (ASX: RIO) has put to rest industry speculation surrounding a potential new discovery, with confirmation this morning of a significant copper-gold find at the Winu project in the highly-prospective Paterson Province in Western Australia’s Pilbara region.

Since late 2017, rumours have circulated on details of the discovery in light of revelations by satellite images and aerial photos that Rio had set up a mine camp, core farm and drill rigs in the Yeneena Basin.

But the minerals giant had remained tight-lipped until today’s announcement, which confirmed that assay results from exploration drilling in the 12 months to December 2018 indicated “relatively wide intersections of copper mineralisation associated with gold and silver”.

The statement, which coincided with the release of Rio’s annual report, said vein-style copper, gold and silver mineralisation was discovered beneath relatively-shallow cover of up to 100m.

The 1.4 kilometres of strike length remains open at depth and to the east, north and south.

The greenfields discovery was made by a team from Rio’s subsidiary Rio Tinto Exploration during a program targeted at finding copper mineralisation in the province.

Rio Tinto’s exploration team in WA’s Paterson Province.The team drilled 28 holes on exploration licence E45/4833 between December 2017 and the end of 2018 for a total 13,286m, with assays already received for 22 holes.

Another four holes for 1,409m were completed in January with assays pending.

Early stages

The Winu project is 130km north of Newcrest Mining’s (ASX: NCM) world-class Telfer deposit and has been the subject of target generation since 2016 including regional interpretation, area selection, tenement application and geophysical surveys.

Ground target testing began in late 2017 with the completion of two reverse circulation drill holes.

An 80-person temporary exploration camp was built in stages throughout 2018 specifically for Winu activities. However, Rio has been reluctant to get too excited about the discovery.

“We have had some early success in copper exploration at the Winu project where phase two drilling is now underway,” the company said.

“While results are encouraging, the exploration project is still at an early stage and drilling to date does not allow sufficient understanding of the mineralised body to assess the potential size or quality of the mineralisation nor to enable estimation of a mineral resource.”

The company said a program of extensive drilling will continue into 2019 focused on high-quality exploration targets.

Riding the prospectivity wave

The Paterson Province is a globally-recognised, strongly-endowed and highly-prospective mineral belt which has long been considered hot property by majors such as Rio and Newcrest.

In recent times, though, smaller operators have also been clamouring to peg ground there in the hope of riding the same prospectivity wave.

This week, Metalicity (ASX: MCT) announced it would “significantly expand its footprint” with three new project applications covering 3,000 square kilometres of highly-prospective nickel-copper-gold ground in the region.

The Warburton, Paterson South and Pandora projects were identified following the company’s full review of geophysical data sets over the province.

They join other high-priority copper targets across the company’s Mandora and Desert Queen projects, which are along strike and associated with the same structures as Winu.

“The exceptional, high quality public data on offer provided [us] with an opportunity to interrogate the entire strike length of the [region],” said Metalicity general manager (exploration and development) Jason Livingstone.

“We believe these three projects represent highly-prospective ground for nickel-copper-gold and possible platinum group metals mineralisation and we are excited to be able to present these acquisitions to our shareholders.”

Junior explorer Antipa Minerals (ASX: AZY) is a step ahead of Metalicity, with plans well underway to commence a 20,000m drilling program in April over its wholly-owned Paterson Province tenements in proximity to Winu and Telfer.

In October, the company intersected a new band of thick high-grade copper-silver-gold mineralisation during a reverse circulation drilling program at the Minyari Dome prospect, located within its wholly-owned North Telfer project.

The new program will assess greenfields targets which may deliver large-scale discoveries based on analogues at Winu, Telfer and Greatland Gold’s (AIM: GPP) successful Havieron deposit, and “aggressively advance” multiple exploration and development opportunities across the tenements.

Managing director Roger Mason said the landholding would be “systematically evaluated” with the aim of “making a world-class discovery in the underexplored Paterson Province”.

Alloy Resources (ASX: AYR) maintains its foothold in the Paterson Province via a farm-in and joint venture agreement established in June with Rio Tinto Exploration to advance exploration at Alloy’s tenements.

Under the terms of the agreement, Rio can earn up to 70% interest in Exploration Licence EL 45/4807 by spending a $500,000 on exploration and completing at least 500m of drilling within three years.

Alloy executive chairman Andy Viner said the company would benefit from Rio’s modern exploration techniques and geological models.

“We are pleased to have Rio’s interest in exploring our large exploration area north-west of Telfer,” he said.

“[The company] has been actively exploring in the region since 2015 and we are hopeful this intellectual knowledge can accelerate definition of the potential for gold-copper mineralisation within our tenement”.

During 2018, Red Metal (ASX: RDM) secured a significant land position across the Paterson Province in the search for giant sedimentary-hosted copper-cobalt styles similar to the Nifty and Maroochydore deposits owned by Metals X (ASX: MLX).

The Yarrie and Oakover projects were pegged in light of data from the Geological Survey of Western Australia and Geoscience Australia which the company said is “forcing a paradigm shift in base metal and gold targeting across the province”.

Yarrie comprises five exploration licences over 2,000sqkm and lies close to a number of new licence applications by Rio.

The project is included in the recently-executed Greenfields Discovery Alliance between Red Metal and OZ Minerals (ASX: OZL) where a minimum $2.5 million has been committed towards proof of concept exploration programs over the next two years.

Oakover targets a regional gravity feature just 60km northeast of Winu and seeks copper and gold mineralised hematite breccia akin to the giant Olympic Dam deposit in South Australia.

Red Metal is proposing to use infill gravity surveying to define potential drill targets.

“Our experienced copper exploration team is very excited about [these] new Paterson Province plays and is proposing to utilise modern, deep penetrating, electro-magnetic surveying methods to map prospective stratigraphy and rank the dome-shaped structures for drill testing,” the company said.

For Sipa Resources (ASX: SRI), the end of the quarter brought only good news, with assays from a deep diamond hole at its Obelisk prospect, within its Paterson North copper-gold project, intersecting a style of oxidised alteration and mineralisation “not previously observed”.

Managing director Lynda Burnett was understandably excited about the results.

“[It] is quite different to anything we’ve seen in the area before and shows that the mineral system at Obelisk has strong zonation and is potentially even more complex and prospective than we thought previously,” she said.

“Given its proximity to the Rio discovery just 10km from our tenement boundary and the potential scale of discovery opportunities in this area, we are very much looking forward to the next phase of exploration.”