The Junee Project covers an area of 580km2 and lies within the highly endowed copper-gold province of the Macquarie Arc, a geological domain which hosts numerous major porphyry copper-gold deposits including the world-class Cadia-Ridgeway and Northparkes mines.
DevEx significantly upgraded the exploration potential of the Junee Project following the recent assessment by the Geological Survey of New South Wales1 (‘GSNSW’) which found that rocks within the Project are prospective for large-scale "type" porphyry copper-gold deposits.
In contrast to the intense exploration drilling activity within the main Junee-Narromine Volcanic Belt to the north, the Junee Project has had very little systematic exploration with previous cursory drilling within the Project dating back over 25 years ago (see ASX Announcement – 24th January 2018) for full details.
Exploration by DevEx has identified several new large-scale porphyry copper-gold targets at Junee, located 60km north-west of the Company’s Basin Creek Project.
Figure 1: The Junee Copper-Gold Project is strategically located within the Lachlan Fold Belt of New South Wales and in close proximity to the Company’s Bogong and Basin Creek Projects.
DevEx’s compilation of surface mapping, rock chip sampling and petrology at the Riversdale North and Billabong Creek Prospects identified several new areas of copper, gold and base metals mineralisation.
Anomalous rock-chip results ranging up to 2.81g/t gold and 1.26% copper are spatially associated with epidote and actinolite alteration/veins, including a gossanous base metals sub-crop (vein), and several breccias. This alteration style shows similarity to other large-scale porphyry copper-gold systems within the Macquarie Arc.
The collective fieldwork completed by DevEx and combined historical data have expanded the prospective strike to over ~20km
DevEx has defined several new large-scale targets, including (see Figure 2):
Figure 2: Several porphyry copper-gold targets have been identified based on mapping, historical exploration and interpretation of airborne magnetics (underlay) and gravity. White outline represents Figure 3 location.
A broad-spaced Induced Polarisation (IP) survey identified two large IP anomalies directly associated with existing porphyry copper-gold targets at the Riversdale North and Billabong Creek Prospects. The targets, which were originally identified through regional geophysical targeting, mapping and rock chip sampling, have been significantly enhanced by the presence of these IP anomalies at depth.
The identification of these anomalies combined with strong coincident rock chip results significantly upgraded these targets and reinforced the potential for a large-scale porphyry copper-gold system, similar to those seen at the world-class Northparkes and Cadia Ridgeway copper-gold porphyry deposits in the Lachlan Fold Belt.
Planning is now underway for Reverse Circulation and Diamond drilling to test these high priority targets in Q3 2020.
Figure 3: Copper assay results from rock chip sampling at Riversdale North and Billabong Creek underlain by airborne magnetics.
Drilling is also planned for a buried porphyry copper-gold target at the Nangus Road Prospect, for which DevEx has received collaborative funding towards drilling this target as part of the NSW State Government’s New Frontier Cooperative Drilling Grant.
The Junee Project area covers a sequence of Ordovician and Silurian volcanics, the Junawarra Volcanics, adjacent to a major crustal structure, the Gilmore Suture Zone, within a province with a high copper-gold endowment, the Macquarie Arc. The rocks of the Macquarie Arc host many large porphyry copper-gold deposits. This is the style of mineralisation targeted on the Company’s tenure.
The Project also contains the Billabong Creek gold prospect and the Riverdale monzonite porphyry associated copper-gold occurrences. The area has been subjected to previous exploration by other companies and a number of zones of altered rocks with anomalous geochemistry indicative of porphyry associated copper-gold mineralisation have been defined.
There is clear potential for discovery of a major porphyry-related copper-gold system.
1East Riverina Mapping Project - Some Highlights and Implications, Eastlake and Trigg