Skyline produced 100,000t at between 3-12% copper, 7% zinc and 1-3oz/t silver at the turn of the 20th century but has seen little exploration since it was held by Noranda in the 1990s.
Firetail Resources (ASX:FTL) acquired the project in June 2024 and has been steadily carrying out work including an initial 5000m drilling campaign that returned a number of high-grade results.
It has now contracted Abitibi to carry out a 3D IP survey in April over the highly prospective Governor’s Target Zone, which extends for a strike length of ~1200m and is yet to be drill tested.
Abitibi will also carry out the first phase of an unmanned aerial vehicle-borne magnetic survey over the entire 8km by 2.5km ophiolite sequence at Skyline that is prospective for Cyprus-style VMS deposits.
Cyprus deposits are mafic-type VMS deposits which have produced from 5000BC until recently within Cyprus, while modern production totals 72Mt of massive sulphide ore with the largest deposit – Mavrovouni – producing 17Mt at 4.5% copper.
Magnetic surveying has the potential to identify these targets based on de-magnetised zones within the prospective upper and lower pillow basalt sequences.
Skyline’s stratigraphic sequence is identical to that of the Troodos Ophiolite sequence in Cyprus, host to Mavrovouni and >30 historical mines.
“We have conducted an in-depth evaluation of the mineralisation models across Cyprus, which hosts the globally significant Cyprus-type VMS deposits, and have refined our targeting methodology across the 8km by 2.5km ophiolite sequence at Skyline accordingly,” FTL managing director Glenn Poole said.
“High-resolution magnetics has been identified as a very cost and time effective method to identify the alteration envelope which surrounds the emplacement of Cyprus Style VMS deposits.
“By undertaking a high-resolution magnetics survey across the entire ophiolite sequence, we have the potential to directly identify and target mineralisation. Importantly, this survey will be the first of its kind to be completed across the Skyline Project.
“One of the challenges our predecessors faced was the ability to target blind mineralisation using geophysical methodologies – hence their focus on the York Mine Sequence.
“Stepping outside of the known host areas has highlighted the abundance of copper occurrences that have previously been overlooked, as their context was not properly understood.
“This significantly opens up the exploration search space for us to target mineralisation across the entire ophiolite sequence.”
While previous IP surveys at Skyline were limited both in terms of their extent and the fact they were conducted using a low-powered system, the 3D IP survey has the potential to directly target a combination of massive and disseminated sulphide mineralisation to a depth of 400m at Governor’s.
This will target zones of low resistivity and high chargeability and has the capacity to delineate the potential scale and geometry of buried mineralisation in high detail.
Sampling of mineral occurrences correlating to the Governor’s Target Zone anomaly has confirmed the presence of VMS mineralisation with grades of up to 1.37% copper, 1.7% zinc and 3.43g/t silver.
Meanwhile, evaluation of Cyprus-type deposits has concluded that the geological setting and stratigraphy of Skyline is identical to that of the Troodos Ophiolite sequence in Cyprus.
Magnetic surveys have been described as one of the most useful prospect identification techniques through their ability to identify magnetic low features associated with alteration and structure.
To date, very limited exploration has been undertaken in the upper basalts across the Skyline Project. Similar upper basalt sequences in the Troodos Ophiolite in Cyprus host multiple substantial deposits.
FTL has also identified significant copper grades from historical surface samples that lie about 750m apart as it moves to improve its understanding of the controls on deposition and hosting lithology around Cyprus-style deposits.
These samples lie along a topographical lineament and interpreted lithological contact between the upper basalt and plutonic mafics, directly analogous to the host horizons seen in the Troodos Ophiolite sequence in Cyprus.
This area will be covered in the upcoming prospecting program that will also include rock and soil sampling across the EM targets identified earlier this year.
