Stellar Resources Ltd (ASX:SRZ) has modelled a large magnetic and conductive target at Severn South, within its flagship Heemskirk Tin Project on the west coast of Tasmania.
The company interprets that the large magnetic cupola (dome)-shaped body may represent a granite intrusion with an overlying magnetic cupola composed of massive or disseminated pyrrhotite, which is magnetic and conductive, that may host tin mineralisation.
Stellar plans to drill this target towards the end of the current Phase 1 drilling program.
Upside potential
Stellar Resources executive director Gary Fietz said: “Severn is already the largest of the four tin deposits comprising the Heemskirk Tin Project, the second-highest grade undeveloped tin resource in the world.
“The South Severn magnetic and conductive target recently modelled by Stellar’s geophysical consultants, Mira Geoscience and consulting geophysicist Jovan Silic, along with observations from the Phase 1 drilling program currently in progress highlights the significant upside potential of the Severn tin deposit, which remains open at depth and along strike.
“Stellar plans to drill the South Severn magnetic and conductive target towards the end of the drilling program currently underway.”
Modelling
A high resolution heliborne magnetic survey over the Heemskirk Tin Project and surrounding areas was flown by Stellar in 2012 and it identified a large magnetic high centred to the south of the largest of the deposits, Severn.
The company said that 3D magnetic inversion modelling of 2012 heliborne magnetic data had shown that the magnetic high at Severn could be explained by modelling a dome at a depth from surface of around 1,000 metres at the edges and about 600 metres at the centre of the dome.
Reprocessing of historical downhole EM data has modelled a large shallowly-dipping moderate conductor below historic drill hole ZS92.
The location of this off-hole conductor target is poorly defined but has been modelled sitting just above, and close to the centre of the South Severn magnetic target.
The interpretation that the dome may represent a granite intrusion with an overlying magnetic cupola composed of massive or disseminated pyrrhotite that may host tin mineralisation. is supported by:
➢ Continuation of mineralisation 240 metres down dip of the current Severn resource in the recently completed drill hole ZS140;
➢ The increased pyrrhotite, high magnetic susceptibility readings and visible cassiterite (tin) mineralisation observed in drill hole ZS143 currently in progress; and
➢ Generally higher magnetic susceptibility readings recorded in historic drill holes over the southern part of the Severn resource.
This provides encouraging support that pyrrhotite and cassiterite mineralisation may continue to the south towards the centre of the South Severn magnetic and conductive target.
Proposed deep hole to test
Stellar Resources is investigating the possibility of re-entering historic drill hole ZS92.
Re-entry of ZS92 could save the company the cost and time of drilling around 500 metres to test the South Severn magnetic and conductive target.
If re-entry of ZS92 is not possible, it plans to drill a new ~900 metres to 1,000 metres deep hole from a nearby location to test the South Severn target, towards the end of the Phase 1 program currently underway.