ASX-listed junior explorer St George Mining is set to kick off a seismic survey next week across an under-explored western portion of the “Cathedrals Belt” at its flagship joint ventured Mt Alexander nickel-copper sulphide project in WA’s north-Eastern Goldfields region. The Perth-based company will be looking to map the host intrusive structures in the western area, where new electromagnetic conductors have been recently encountered.
St George says the eVibe geophysical survey may also lead to accumulations of sulphide mineralisation being detected within the structures.
Data from the high-definition mapping of the structures and potential mineralisation to depths of up to 2km from surface in the western part of the belt will help the company pinpoint further deeper drilling targets to test the multiple EM conductors identified by recent down-hole EM survey programs.
The DHEM survey investigating recently drilled hole MAD200 picked up three off-hole EM conductors with strike lengths of 250m, 60m and 40m.
One of the three new EM conductors is modelled as a large EM plate perched 75m to the north-west of MAD200 within an interpreted down-dip extension of the intrusive unit that houses massive nickel-copper sulphides in other parts of the Cathedrals Belt.
MAD200 intersected a 12.7m intrusive unit from 500.7m down-hole including about 1.4m of disseminated and blebby nickel-copper sulphides from 512m down-hole. Assays for the hole are pending.
St George says the nickel-copper sulphides occur on the basal contact, a geological setting it suggests may point to further nickel-copper sulphide deposits nearby.
An additional three “very strong” EM conductors – that are yet to be drill tested – have been identified in the area by a DHEM survey in hole MAD196 probing 50m up-dip from MAD200.
According to the company, the presence of multiple conductors proximal to MAD200 and MAD196 further supports the potential for significant nickel-copper sulphide mineralisation in this under-explored sector of the West End prospect.
The new EM anomalies uncovered in MAD200 are instead of weak to moderate conductance, St George says.
Significantly, several low-conductivity EM anomalies have been drilled on the Cathedrals Belt. They yielded encouraging nickel-copper sulphide intercepts including 2.74m at average grades of 3.77 per cent nickel, 1.48 per cent copper and 3.85 grams per tonne total PGEs from 25.4m from an earlier hole, MAD38.
In addition, one of the latest holes to be drilled, MAD201, returned a 2.4m-thick nickel-copper sulphide hit stemming from a low-conductivity EM anomaly. Assays are also pending for this hole.
St George notes the perforation of nickel-copper sulphides from drilling of previous targets indicates that weak conductors may represent a vector to high-grade sulphide mineralisation.
Mt Alexander sits about 100km west of Leonora and 120km south-south-west of the Agnew-Wiluna belt that takes in a bevy of world-class nickel deposits.
The company’s Stricklands, Cathedrals, Investigators and West End prospects straddle the project’s east-north-east-trending Cathedrals Belt – which contains mineralised ultramafics within granites – along a strike extent of more than 5.5km.
St George Mining Executive Chairman John Prineas said: “Our systematic step-out drilling at the Cathedrals Belt is continuing to extend the footprint of the intrusive unit that is already known to host massive nickel-copper sulphides. All deeper drill holes in the western part of the Cathedrals Belt have intersected intrusive-style rocks. These results indicate a very large mineral system at the Cathedrals Belt with potential for further discoveries of high-grade mineralisation in the under-explored western section of the belt.”
“The multiple EM conductors identified at West End are particularly exciting. These are favourably located within the interpreted intrusive unit and on the same plane as mineralisation intersected by recent drill holes. The results of the seismic survey … could be very important in better understanding the distribution of mineralisation in this area and planning the next drill program for these targets.”
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By Matt Birney
