Legend Mining Ltd (ASX:LEG) has confirmed the prospectivity of two further nickel-copper targets during diamond drilling at the Rockford Project on Western Australia's Fraser Range.
During the exploration campaign, Legend hit a nickel-copper sulphide associated with a large electromagnetic plate at the Octagonal prospect.
Meanwhile, at the Magnus target, the first-ever diamond drill hole hinted at a large intrusive body and confirmed the target's prospective host rocks are akin to the famed Voisey’s Bay base metal asset in Labrador.
As it continues to explore its flagship asset in the prolific Fraser Range, Legend continues to search for three styles of mineralisation:
- Magmatic nickel-copper sulphide mineralisation;
- Volcanogenic massive sulphide (VMS/VHMS)style zinc-copper-silver; and
- Tropicana-style structurally controlled gold mineralisation.
Finding next Fraser Range nickel-copper mine
Speaking to the initial drill findings, Legend managing director Mark Wilson said: “The diamond hole at Octagonal essentially confirms that Octagonal is another large fertile intrusion, as is Mawson.
“Legend is in the enviable position of now having two locations to focus its exploration efforts to find the next nickel-copper mine in the Fraser Range.
“Magnus is very much a work in progress, with the first-ever deep hole into the intrusion confirming the right host rocks for the nickel-copper mineralisation we are looking for.”
Drilling down at Rockford
Regional exploration, using both an aircore and diamond drill rig, kicked off over two of Rockford’s tenements last month.
These areas host the advanced Octagonal and Magnus prospects, which are both characterised by 'eye' shaped aeromagnetic features and the presence of highly favourable mafic/ultramafic intrusive host rocks.
Both prospects lie within the same northeast-southwest trending structural corridor that hosts the Silver Knight and Nova-Bollinger nickel-copper deposits to the southwest.
Octagonal target
The Octagonal prospect, which sits within tenement E28/1717, has seen varied historical exploration, with soil sampling, aircore, reverse circulation and diamond drilling carried out over the target.
Past activity primarily targeted the prospect’s electromagnetic conductors as part of the hunt for nickel-copper mineralisation.
The mineralisation identified to date is discontinuous and subeconomic, however, it demonstrates all the characteristics of a fertile, magmatic nickel-copper sulphide system.
Legend’s first drill hole into the Octagonal prospect’s intrusion targeted fixed-loop transient and down-hole transient electromagnetic (FLTEM and DHTEM) plates, both of which are clearly associated with nickel-copper sulphide mineralisation.
Specifically, the DHTEM data indicates that the eastern contact of the Octagonal intrusion hosts a significant strike length of nickel-copper sulphide mineralised intercepts.
More broadly, the drill hole confirms that Octagonal is a large, fertile, orthomagmatic nickel-copper intrusive system, akin to known deposits like Nova-Bollinger and Silver Knight in the Albany-Fraser Belt.
Further work programs will interrogate the DHTEM from the first hole and target mineralisation across the Octagonal intrusion and at depth in a bid to define an economic nickel-copper sulphide accumulation.
Magnus target
In the past, tenement E28/1716’s Mangus prospect has seen only aircore drilling over its aeromagnetic features. As a result, Legend’s latest drilling campaign marks the first-ever diamond drill hole to test the prospect’s intrusion.
The company designed the maiden diamond hole to target a gravity feature and test below anomalous aircore geochemistry into what was believed to be a large mafic-ultramafic intrusion.
Although only minor nickel-copper sulphide disseminations were identified throughout the drill hole, the fractionated assemblages suggest the drill hole intersected the upper zone of a large intrusive body.
DHTEM completed on the maiden hole did not identify any off-hole conductors, but given the drill hole did not intersect a basal contact, the Magnus intrusion is interpreted to extend at depth, potentially below the levels of electromagnetic detectability.
Although not economic accumulations, the presence of nickel-copper sulphides in the first diamond drill hole confirms that Magnus contains prospective host rocks of an orthomagmatic system akin to Voisey’s bay, Nova-Bollinger, Silver Knight, Mawson and Octagonal.
Future work programs will focus on testing for economic accumulations of nickel-copper sulphide at depth and within marginal locations around the intrusion.
Next on the agenda
As part of the broader exploration campaign, detailed geological, structural and DHTEM analysis will take place on every diamond drill hole at Mangus and Octagonal.
Once the diamond drilling over these targets is complete, the drill rig will head south to test electromagnetic conductors at the Hurley and Crean prospects.
In the meantime, regional aircore drilling continues over the broader Rockford project.