Middle Island Resources is widening its copper-gold chase at its Barkly project in the NT with its maiden drilling program throwing up all the trademarks of an iron oxide-copper-gold, or "IOCG”-style mineralisation.
The company plunged four diamond drill holes into its Crosswinds prospect last year seeking the deep-seated source of outcropping copper oxide mineralisation that yielded portable XRF readings of between 24.8 per cent and an astounding 76.2 per cent copper.
Middle Island has since notched its maiden drilling program up as a technical success after all four holes intersected broad zones of pyrite, hematite and silica alteration. Alteration mineral assemblage, along with the observed geology, is a key signature of the coveted IOCG deposits.
Additionally, all holes perforated the base of the overlying Georgina Basin sediments and hit the targeted prospective Helen Springs Volcanics and Alroy formation basement.
Whilst it intersected IOCG-style alteration, ultimately there was an absence of targeted sulphides. However, the company believes it may have intersected the outer edges of the mineral deposition.
With preliminary assays returned, Middle Island says it will await the final results to complete its analysis and correlate it with the extensive geophysical model that is developing.
The company has been on the hunt for all available sources of data to build into its geological model and complement the 40,000 line-kilometres of aerial geophysics it has flown over the past 12 months.
Of particular interest is a government-sourced SEEBASE survey which takes into account geological mapping, regional and local geophysical surveys along with State Government-funded drilling to pin down the depth of the Georgina Basin.
Middle Island says the survey has confirmed the depth to basement over the prospective area is within 500m of the surface.
Understanding the morphology of the Georgina Basin will help the company to remodel its aerial geophysical surveys and highlight magnetic and gravity anomalies within the more lucrative basement lithologies whilst steering the rig toward the source of IOCG mineralisation.
Additionally, data from a further 1,200 drill holes surrounding the Barkly tenure have been added to Middle Islands’ dataset to assist with constructing a regional alteration and geological model.
The company’s Crosswinds prospect sits a mere 5km south of Emmerson Resources’ high-grade Hermitage discovery that returned a stunning 116m hit going 3.38 per cent copper and 0.88 grams per tonne gold in 2021. More recently, the company coughed up an additional 94.4m grading at 2.74 per cent copper, 5.58 g/t gold, 17.88 g/t silver and 0.44 per cent bismuth from 85m.
In terms of the explorer’s target, IOCG deposits are highly sought after mineral systems due to their size, multi-commodities and potentially high metal content. Australia has two major IOCG regions of global significance, namely the Olympic IOCG province along the eastern margin of the Gawler Craton in South Australia and the Cloncurry district in the eastern Mount Isa Inlier of northwest Queensland.
Interestingly, geological body Geoscience Australia says several other provinces may contain small or medium sized IOCG deposits and the Tennant Creek district – where Middle Island is operating – is one of them.
With Emmerson’s Hermitage discovery is shaping up as a significant poly-metallic IOCG play only a stone’s throw away, Middle Island will been keen to replicate its neighbour’s success on its own patch of dirt in the emerging Northern Territory IOCG province.
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