ASX-listed battery metal developer Ardea Resources has discovered a massive sulphide channel flow deposit at its Emu Lake project near Kalgoorlie in WA. Assay results from its third diamond drill hole hit high grade massive nickel sulphides driving the company’s share price up more than 50 per cent by the close of trade. Interestingly, drilling also cored through the basal channel contact into an underlying felsic footwall zone.
An intercept of 2.72 metres of sulphides running at a stunning 5.42 per cent nickel and 0.85 per cent copper from 391.04m included 1.23m at an astonishing 8.22 per cent nickel and 0.56 per cent copper from 391.04m.
This follows on from results tabled late last year from earlier diamond drill holes that gave up 4.8m at 1.44 per cent nickel and 0.16 per cent copper from 365.9m with 1.10m of this running at an impressive 4.78 per cent nickel and 0.16 per cent copper from 366.9m.
Notably, the massive sulphides appear to thicken at the footwall contact and have higher nickel and copper grades. The company says the interpreted 3D geometry of the discovery suggests the mineralisation is open in all directions allowing for further drill exploration.
Ardea has now delineated a new target horizon zone based on the intercepts from the first three drill holes at Emu Lake that it has dubbed the “western ultramafic-dacite contact zone.” Luckily, Ardea controls 20km of strike along this newly discovered contact zone.
The focus of historic Emu Lake exploration has been the Binti Gossan prospect area, 1km north of Ardea’s Western Ultramafic channel discovery. The Western Ultramafic is a separate and distinct high-magnesium ultramafic flow that was not prioritised by past explorers, presumably due to an absence of surface gossans as seen at the Binti Gossan. With the recently received assay results from core hole AELD0003 confirming high grade nickel sulphides located on an intact basal dacite contact with komatiite, we now have three adjoining drill holes with nickel sulphide mineralisation on the same contact which conclusively confirms that a discovery has been made.
The Emu Lake prospect is part of Ardea’s Kalpini project located 70 kilometres northeast of Kalgoorlie in WA. Kalpini covers over 121 square kilometres of ground that hosts 20km strike length of prospective ultramafic rocks within mostly granted mining leases.
Intriguingly, the project is only 35km east of the Poseidon-owned Black Swan nickel project that host’s the legendary Silver Swan underground mine. Silver Swan sits on a parallel komatiite volcanic belt to the Kalpini project and boasts grades running at a jaw-dropping 9.1 per cent nickel.
The first diamond drillhole in the Emu Lake campaign intercepted nickel mineralisation and was drilled to follow-up on a historic down hole electromagnetic conductor anomaly that had not previously been drill tested. This hole intersected a narrow zone of remobilised nickel sulphides and yielded a 4.8m hit grading 1.44 per cent nickel, 0.09 per cent copper, 0.2 grams per tonne platinum and 0.09 g/t palladium from 365.9m downhole.
A down hole electromagnetic conductor survey was completed at this first hole, that defined an “off-hole” conductor drill target and the second hole was then drilled to follow this up and also intersected nickel sulphides. This third hole seems to have confirmed the new nickel discovery.
Ardea says the new massive sulphide target confirms the prospectivity of the West Channel area within the Emu Lake prospect that has historically received little exploration attention. To date most of the historical drilling has targeted the Binti Gossan Main Zone located 1km to the north as it showed a surface gossan expression.
The Emu Lake massive nickel sulphide is hosted in overturned stratigraphy, however the stratigraphical footwall dacite is highly altered and contains iron and arsenic sulphides. Current CSIRO research supports the so-called thermal erosion model where concentrations of massive nickel sulphide accumulate at the base of an ultramafic lava flow. Key conditions believed to contribute to nickel sulphide accumulations include a very hot, very turbulent lava flow that scours and mixes high sulphide bearing basement rock into the flow. A preserved intact basal contact in the massive sulphides supports this depositional model that is believed to be the mechanism for mineralisation in both the Emu Lake and Silver Swan areas.
A recently completed reverse circulation drill hole up plunge recovered komatiite flows that are so intensely altered they can only be recognised as ultramafic rocks using geochemistry. This non-recognition of highly altered ultramafic lithologies has significantly contributed to the absence of historic drill exploration on what should have been a high priority target.
The channel style mineralisation is expected to generate a premium nickel sulphide concentrate with high copper and platinum group element credits. Significantly, the massive nickel sulphide mineralisation has no arsenic
penalty component and from a mining perspective, the absence of talc-chlorite schist in association with the mineralisation, suggests good ground conditions for any future mining.
A WA government co-funded Exploration Incentive Scheme diamond drill hole has been approved to test the down plunge extension of the hole and drilling will start as soon as a rig becomes available.
Additionally, Ardea have teamed with CSIRO researchers to study the nickel sulphide mineralisation at Emu Lake, with an aim of vectoring more precisely towards other economic massive sulphides within Ardea’s extensive Eastern Goldfields tenement holding.
With Ardea holding 20km of fertile komatiite strike at Emu Lake, there is significant scope to extend this nickel sulphide discovery and make additional discoveries. With the nickel price hitting ten year highs, Ardea’s discovery looks to be impeccably timed and it’s no surprise its share price has soared over 50 per cent on the day. Any results that continue on this trend and mirror the Silver Swan deposit will only further quicken the pulses.
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