In September 2020, DevEx entered into an Earn-In Agreement with Thomson Resources Limited (ASX: TMZ, “Thomson”) on the highly prospective Wilga Downs Gold-Base Metal Project in the Cobar Basin region (Figure 1), with the right to earn 80% interest in the Project by spending up to $290,000 within 4 years from commencement of the Earn-In Agreement. DevEx will also free-carry Thomson in relation to a 10% interest through to a pre-feasibility study. In 2021, DevEx met its requirements to earn 80% in the Wilga Downs Project.
This acquisition followed after DevEx interpreted a strong coincident magnetic and gravity high beneath historical anomalous intercepts at the prospective faulted contact between outcropping Cobar Supergroup (Devonian) and the Girilambone Group (Ordovician).
This priority target is similar to those associated with other major gold-polymetallic deposits in the region, including Glencore’s CSA Copper Mine and other nearby mines such as the Peak and Great Cobar Copper-Gold Mines.
Encouraging assays have been received from the first diamond drill hole (20WD001). Drilling has encountered a 13-metre zone of veined to disseminated pyrrhotite mineralisation (a magnetic iron sulphide) with minor copper sulphides (chalcopyrite), close to the centre of the modelled magnetic high. Of particular interest was a narrow intercept of semi-massive pyrrhotite grading 1m @ 0.7% Cu and 0.7 g/t Au from 551.6m.
A follow-up down-hole electromagnetic (DHEM) survey has been conducted on hole 20WD001. Modelling of the DHEM results produced a large 150m long off-hole EM conductor at 250m depth, 40m east of the recently drilled hole (Conductor A).
An additional off-hole conductor (Conductor D) has been recognised in a DHEM survey of diamond drill hole 16WD02 (drilled in 2016). The conductor was located north of hole 16WD02 and modelled to dip to the north. An additional Moving Loop Electromagnetic (MLEM) Survey has also been completed, covering both the western (conductors A – C) and eastern magnetic anomalies. No additional conductors were identified.
Diamond drilling tested both Conductors A and D, intersecting massive pyrrhotite together with disseminate zinc and copper sulphides, including 7.8m @ 1.04% Zn from 404m. The company is currently carrying out a review of the alteration between holes, together with a study of the base metal variability, to understand where further potential might lie at Wilga Downs.
Figure 1: Generalised Geology Map of the central Cobar Mining District after David (2006), showing location of North Cobar Project and Wilga Downs Project.
DevEx holds a 100%-owned Exploration Licence within the highly prospective North Cobar Mineral Allocation Area.
The North Cobar Exploration License EL9051 overlies the interpreted northern extension to the Rookery and Endeavor Fault systems, a metalliferous fault network which hosts a number of significant Gold-Base Metal mines in the Cobar Region.
DevEx continues to progress land access in the North Cobar tenement, with plans to explore the extension and intersections of the Rookery Fault and Endeavor Fault.