Plutonic has completed a campaign of five diamond drillholes at its Georgetown project in North Queensland on three cross sections along a 7.5km corridor containing anomalous gold in surface sampling.
The unlisted explorer has identified an epithermal gold target associated with this corridor, based on the style and intensity of alteration and geochemistry intersected in the drilling, and surface expressions of epithermal veins that have been previously identified, but now extended by recent Plutonic mapping.
Plutonic’s maiden drilling program at its 100% owned Georgetown Project has defined a very large magmatic-hydrothermal system with potential for discovery of epithermal gold mineralisation.
The company says the scale of the alteration detected by Plutonic drilling is large, providing a substantial search space. The inaugural program comprised five diamond drill holes (25GT001-25GT005) for a total of 2,630m across the 7.5km ‘falling in reverse’ corridor. This corridor hosts coincident geochemical and geophysical anomalies along the eastern margin of a major Permo-Carboniferous intrusive complex.
Plutonic’s drill program was designed to test for an intrusion-related gold system (IRGS), which is a style of gold system with characteristic sulphide associated mineralisation within intrusive bodies or associated breccias. While no economic concentrations of gold were intersected, the company says evidence was observed that was consistent with the IRGS system target having been overprinted by a younger oxidised magmatic-hydrothermal system.
Lion’s share
Lion Selection Group (ASX:LSX), which holds a 41% interest in Plutonic, sees “tremendous upside” with these results and the company broadly.
The firm says Plutonic has district-scale exploration projects at Georgetown (North Queensland) and Champion (Northern Territory). Both projects are defined by containing very large target areas, and if a discovery can be made Lion notes that there is a “huge” opportunity for potential upside.
Lion Managing Director Hedley Widdup explains that his firm’s philosophy around early stage exploration is to be extremely choosy – “it’s a risky field despite the tantalising prospect of huge value growth if a discovery is made”.
“So, we aim to invest only where we can satisfy two strict criteria: multiple shots at finding something, ideally hundreds rather than tens of targets,” Widdup says.
“Access to invest very cheaply, you can pay a lot for a listed explorer, but high levels of sentiment (that lead to high prices) don’t guarantee a discovery. What Lion has invested in Plutonic is covered by interest we have made on our cash over the years we have had this involvement.”
Lion solidifying Plutonic relationship
Lion works closely with the team, and Plutonic has two large ground positions that it is focused on, between North Queensland and the Northern Territory. Within these are large target areas that have seen little to no exploration, and Plutonic has targeted areas where there is a big footprint that discoveries could occur within.
Widdup says if Plutonic finds anything on these projects, it could discover a new district.
“Being unlisted, Plutonic is hard to invest in for more people so we are really pleased to have a holding like this in Lion – it offers tremendous upside, many chances of finding something, and the risk to Lion holders is far lower than investing in explorers directly,” he continues.
Recent drilling has hit a lot of alteration, Widdup notes, adding Plutonic was looking for confirmation of intrusion-related gold and there are indications that sort of system might be present, but the alteration hit is not related.
It is related to a different style of mineralisation, which Widdup says is characteristic of the minerals and the chemistry – porphyry / epithermal.
“So, what the drilling has shown us is we have an alteration system over 7km long that is related to a very characteristic (but not what we expected) style of gold mineralisation,” he adds.
“Plutonic has always known there were reported epithermal veins in the area – but poorly described, and because they are a small occurrence sticking out of an area otherwise under cover, really hard to explain especially against the concept of intrusion-related gold.
“These occurrences might even have been written off as incorrect observations in the reports.
“But the finding of this alteration beneath the cover that obscures a lot of the rocks we are interested in is aligned with the sort of intrusions that can drive epithermal gold deposits. These old observations now make a heap of sense.”
Plutonic has been able to re-map, and extend these old epithermal observations. They were drilled (1980s) – very shallowly – and returned anomalous gold.
Epithermal veins contain characteristic patterns and chemistry that can help locate where gold mineralisation might be. Widdup notes in this case, the textures and chemistry indicate what Plutonic is seeing is the top of an epithermal system.
“We wouldn’t expect to see gold at economic grades at this level of an epithermal system – if there is an economic concentration of gold, then Plutonic now has confidence to say its beneath what it sees at surface (that is – not removed by erosion). And, the low level anomalism suggests it’s a system that has gold in it,” Widdup adds.
“This is a big alteration zone, and big alteration zones can contain large, or a lot, of ore bodies. That is what excites us. You may want to ask – is this what we hoped for? No – we hoped that Plutonic might hit the edge of something that looked like an intrusion-related gold system.
“We didn’t have this outcome on our radar so it doesn’t line up with expectations at all – but it’s definitely as good an outcome because Plutonic wanted to demonstrate that a fertile mineral system was present, and it has done this. Given the footprint, scale of anomalism, alteration – this might be a larger target than we originally had in mind.”
Write to Adam Orlando at Mining.com.au
Images: Plutonic & iStock
