ASX-listed gold and base metals explorer, Middle Island Resources has discovered what it says is “significant” copper oxide mineralisation at surface at the Crosswinds prospect within its 3,253-square-kilometre greenfields Barkly copper-gold project in the Northern Territory’s East Tennant mineral district.
The discovery gave punters a pre-Christmas touch of excitement, with the company’s share price climbing to as high as 38.5¢ today from its closing price of 30.5¢ yesterday, after it revealed some cracking spot portable XRF-gun readings of between 24.8 per cent and 76.2 per cent copper at Crosswinds.
Perth-based Middle Island says the copper values have been validated by composite chip sampling traverse assays for an aggregate interval of 130m 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 discovery, situated next to the sealed Barkly Highway, comes after the company’s recent reconnaissance site visit to gain a better feel for the lie of the land.
Middle Island Managing Director, Rick Yeates said: “Even disregarding the high-grade copper results, the Crosswinds discovery is particularly significant in that it’s interpreted to provide ‘proof of concept’ for the Barkly mineralised model.”
“Crosswinds is an extremely exciting discovery. While there is little doubt that more such surface occurrences will be identified by ongoing exploration, the focus is the potential for significant primary copper deposits within the basement.”
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.
Geoscience Australia says the East Tennant region is characterised by a range of geological features that are favourable for mineralised systems even though it is almost completely covered by sedimentary rocks of the Georgina Basin that obscure potential host mineralised systems.
Despite the lack of exposed basement rocks in the East Tennant area, East Tennant has been selected for ongoing detailed geoscientific investigation and stratigraphic drilling.
Middle Island says the Barkly iron oxide copper-gold mineralised model has been predicated on collaborative research being undertaken by Geoscience Australia, the NT Geological Survey and MinEx CRC, courtesy of the Federal Government’s $100 million-plus Exploring for the Future, or “EFTF” program.
Although gold has been mined from the Proterozoic rocks around Tennant Creek since the early 1930s, there has been almost no mineral exploration in the covered rocks to the east of Tennant Creek in the past 90 years.
MinEx CRC Chief Executive Officer, Andrew Bailey said: “The East Tennant drilling campaign was designed to test stratigraphic and structural interpretations and assess the mineral potential of basement rocks to the east of the Tennant Creek mineral field. These basement rocks are under-explored and concealed by hundreds of metres of younger sedimentary rocks.”
The mineralised model has been developed based on the identified potential for Tier 1 iron oxide copper-gold deposits occurring within the Proterozoic basement rocks extending along the East Tennant Ridge beneath the Georgina Basin between Tennant Creek in the NT and Mt Isa in Queensland.
Middle Island will be aided in its exploration planning for Crosswinds by the EFTF’s drilling and research work that is assessing the minerals potential of basement rocks in the region.
It anticipates the soon to be released results from the Federal and NT Governments’ current 12-hole, 4,000m-plus stratigraphic basement diamond drilling program will shed more light on the iron oxide copper-gold potential of basement rocks at the Barkly project.
According to the NT Geological Survey, the East Tennant drilling program carried out under the collaboration presents an exciting opportunity to understand the potential of the under-explored Barkly area.
NT Geological Survey Executive Director, Ian Scrimgeour said: “The range of ancillary datasets that have been acquired during the drilling campaign, coupled with the ongoing research activities on the drill core, will transform the understanding of minerals systems in the region.”
Middle Island says it intends launching an exploration campaign at Crosswinds next year during the NT dry season – from April to October.
Interestingly, its Barkly exploration licences surround or immediately adjoin exploration applications made by or exploration licences owned by gold mining giant, Newcrest Mining.
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