Middle Island expands holding over NT copper-gold play

ASX-listed gold and base metals explorer, Middle Island Resources has expanded its ground position surrounding the surface copper oxide mineralisation discovered at its 100 per cent-owned Barkly copper-gold project in the NT’s East Tennant mineral district. 

The company has broadened its footprint around the recent Crosswinds copper discovery by 26 per cent to a colossal 4,411 square kilometres after an extensive surface composite sample chimed in at 0.76 per cent copper.

The two new tenements are in immediate proximity to the company’s package of ten exploration licenses which originally tallied to 3,253-square-kilometre across Middle Island’s greenfields Barkly project.

The Crosswinds copper discovery, announced just before Christmas 2020, gave punters a touch of excitement with the company’s share price surging 28 per cent on the news to 38.5¢ the day before Christmas eve, from a previous closing price of 30.5¢.

The flurry of activity on the Bourse stemmed from some impressive surface malachite exposures which produced a number of interesting spot portable XRF-gun readings from Crosswinds which graded from 24.8 per cent copper up to a stellar 76.2 per cent copper.

The Perth-based company said the XRF copper values were supported by composite chip sampling traverse assays for an aggregate interval of 130 metres going 0.76 per cent copper, including a continuous 20m sample grading an average of 0.93 per cent copper and a 65m sample that returned an average grade of 0.79 per cent copper.

The Crosswinds copper discovery is located a 150km east of Tennant Creek, along the sealed Barkly Highway, in an area where the near-surface rock layers of the Cambrian-aged Georgina sedimentary basin obscure the underlying, mineral-rich Proterozoic-aged basement rocks.

Middle Island said its technical team was awaiting the release of data from a Federal and NT Government-sponsored, 12-hole, 4,000m-plus stratigraphic basement diamond drilling program.  According to the company, the drilling data are due to hit the streets around March or April this year. 

The company says the IOCG mineralisation model it is chasing at Barkly has been based on collaborative research being undertaken by Geoscience Australia, the NT Geological Survey and MinEx CRC, thanks to around $100 million-plus coming from the Federal Government’s “Exploring for the Future”, or “EFTF”, program.

Middle Island’s geologists will churn through the pre-competitive drill results before embarking on some detailed geophysical surveys, slated for this year’s Top End dry season. The aim is to map up what they believe to be some serious basement-hosted, iron-oxide copper-gold, or “IOCG”, drill targets

The prize for Middle Island is the potential of duplicating the revered Olympic Dam discovery near Roxby Downs in South Australia - a Tier 1 IOCG deposit unearthed by Western Mining Corporation a generation or so ago in the uber-rich Proterozoic rocks of SA’s Gawler Craton.

The trick for WMC at Olympic Dam was that it too was buried beneath surface cover of younger, barren rock layers.  The prize of Olympic Dam was one of the reasons BHP took out Western Mining all those years ago.

According to Middle Island, other Tier 1 IOCG deposits in SA include Oak Dam, Prominent Hill and Carrapateena.  The company is using a similar model to track down IOCG prospects along the East Tennant Ridge which extends from Tennant Creek in the Northern Territory, east to Mt Isa in Queensland.

Middle Island’s initial interpretation of the Crosswinds mineralisation is one of secondary copper mineralisation that has migrated up faults extending from primary copper-gold mineralisation within the Proterozoic basement rocks through the otherwise barren Cambrian Georgina Basin sediments to precipitate at surface.

The company says the interpretation is thought to be broadly consistent with the setting that led to the discovery of the Osborne iron oxide copper-gold deposit south-east of Mt Isa in Queensland.

Interestingly, its Barkly exploration licences surround or immediately adjoin exploration applications made by or exploration licences owned by gold mining giant, Newcrest Mining.

With mining heavyweights like Rio Tinto and Newcrest sniffing around Middle Island’s Top End backyard, it seems that the company looks set to press its first-mover advantage and is already off to a flying start in the potentially company-making Barkly terrane.

Is your ASX-listed company doing something interesting? Contact: matt.birney@businessnews.com.au