WA Gold has outlined a compelling set of nine new geophysical targets stretching over a combined strike of four kilometres at its Bullabulling North project, 30km west of the historic gold mining town of Coolgardie in Western Australia.
The anomalies were defined by a high-resolution sub-audio magnetics (SAM) survey and are draped along two key locally sub-parallel structural shear corridors, with both considered highly prospective for gold. The westernmost structure, the major Bullabulling Shear Zone, is interpreted to be the northern extension of the same system that hosts Minerals 260's neighbouring 4.5-million-ounce Bullabulling gold mine, 3.5km south of the Great Eastern Highway.
The results of the 125-line kilometre survey have provided WA Gold with a substantial pipeline of well-defined targets for its next round of deeper reverse circulation (RC) drilling.
The SAM technology comprises an active-source survey method. Unlike passive methods, which sense naturally occurring fields, such as standard magnetometry, an active survey requires a controlled, human-generated signal beneath the surface. This involves sending an electrical current directly into the ground through a grounded dipole or transmitting a precisely controlled signal through an inductive loop.
As the electrical current travels underground, it flows more easily through conductive rocks and structures, creating signals that sensitive instruments can detect at the surface. By measuring both the ground’s natural magnetic properties and these artificially generated signals, SAM produces detailed maps that help geologists pinpoint promising mineral targets and hidden geological structures.
The method is a proven tool for identifying zones of sulphide alteration which can be associated with orogenic gold systems, particularly in areas like Bullabulling, where prospective structures are often hidden beneath surface cover.
Four of the anomalies defined by the SAM survey lie in a neat four-kilometre-long row along the interpreted Bullabulling Shear Zone. The biggest of the four anomalies is a 900-metre-long oval-shaped feature stretching along the shear zone and is now the company's priority for deeper drilling, despite earlier shallow scout drilling across it returning only low-level gold responses.
Tantalisingly, another of the western anomalies sits near previously acquired end-of-hole gold hits, including two metres at 0.16 grams per tonne (g/t) gold from 52m to the end of an earlier hole and a historical five-metre intercept grading 0.12g/t gold from 40m. The company considers the previous shallow drilling results may have only clipped the edges of a potentially larger mineralised system at depth.
The other five anomalies lie in the semi-parallel eastern survey area, between 1.7km and 2.3km east of the Bullabulling Shear Zone. The area covers part of a regional-scale ultramafic contact and a 2.6-kilometre-long trend going better than 20 parts per billion (ppb) gold, previously defined by WA Gold’s scout drilling.
At the northeastern end of the survey area, a strong SAM anomaly straddles the interpreted prospective shear zone near a mapped fold axis, where tectonic stresses can create favourable conditions for gold mineralisation. A smaller anomaly sits 500m further south along the same promising structure.
Yet another anomaly wraps around a previous end-of-hole intercept of 4m at 0.25g/t gold, offering a compelling coincident geophysical and geochemical target for follow-up.
WA Gold chief executive officer Ben Pollard said: “We now have nine compelling anomalies sitting on the same structures where our reconnaissance drilling returned encouraging gold anomalism. Having over 4km of strike to work with in our next round of drilling gives us multiple shots at discovery, and we believe it materially improves our chances of finding a new gold deposit at Bullabulling.”
All the new targets lie within the Coolgardie Domain of WA’s prolific Yilgarn Craton. In this gold-rich province, major geological structures cutting through altered mafic and ultramafic rocks have long proved fertile hunting grounds for the yellow metal. The sheer scale of the neighbouring 4.5-million-ounce Bullabulling gold mine reinforces the district’s strong gold endowment and with currently high gold prices, renewed regional exploration activity in the area continues to generate plenty of interest.
While Bullabulling presents a significant greenfields discovery opportunity, WA Gold is also advancing its more developed Abercromby gold project near Wiluna, where the company has already defined a 518,000-ounce gold resource. A subsequent scoping study has outlined a remarkably low-cost staged development, pointing to a pre-production capital requirement of just $8 million to kick off a mine targeting an initial 114,000 ounces of gold.
With a drill rig currently probing the earth at Abercromby, WA Gold plans to follow up its Bullabulling targets with a deeper RC drilling campaign, once its current program is complete. The company will first integrate its new SAM data into its existing geological and drilling datasets to rank the nine anomalies and prioritise the drilling.
With previous shallow drilling already picking up sniffs of the elusive yellow metal and its new conga-line of well-defined geophysical targets laid out along a world-class gold structure, WA Gold will be keen to see what a dedicated, deeper drilling campaign at Bullabulling can unearth.
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By Doug Bright
