Great Southern Mining to Resume Drilling at Mt Dillon Gold Target in Queensland

Targeting a Large-Scale Gold System at Mt Dillon

Great Southern Mining (ASX:GSN) is gearing up to recommence diamond drilling at the Edinburgh Park joint venture in northern Queensland, with a clear focus on the Mt Dillon prospect. Scheduled for May 2026 after the northern wet season, this drilling campaign will test a compelling induced polarization (IP) anomaly that could signal a significant intrusion-related gold system.

Mt Dillon stands out as the highest-ranked target identified so far, characterised by advanced argillic alteration within a preserved lithocap and a >20mV chargeability anomaly detected some 200 to 300 metres below surface. The anomaly aligns with a resistivity low suggestive of pervasive hydrothermal alteration typical of porphyry systems. This geological setting mirrors globally significant copper-gold deposits found beneath lithocaps, such as Quebradona in Colombia and Valeriano in Chile, underscoring the prospect’s potential scale.

Early Drilling at Other Targets Falls Short of High-Grade Source

Earlier drilling in 2025 at the Molongle and Megan Veins targets, located in the northern part of the project area, has now been fully assayed. Despite historic surface samples showing high-grade gold anomalies; up to 5.27 g/t Au at Molongle and 10 g/t Au at Megan Veins; the six holes drilled did not intersect the source of this mineralisation. The shallow zones encountered at Molongle appear to represent distal expressions of epithermal systems rather than the core mineralised zones.

These initial results highlight the early-stage nature of exploration at Edinburgh Park, a province-scale project spanning 1,565 km2 within a region renowned for large epithermal and intrusion-related gold systems. The project lies near major deposits such as Ravenswood (~10Moz), Mt Leyshon (+3Moz), and Mt Carlton (~2Moz), reinforcing the geological prospectivity of the area.

JV with Gold Fields and Planned Geophysical Surveys

The Edinburgh Park JV, struck in late 2023, allows Gold Fields to earn up to a 75% interest by investing A$15 million in exploration. Gold Fields has taken the lead on drilling and geophysical programs, including the gradient array and pole-dipole IP surveys that delineated the Mt Dillon anomaly.

Further geophysical and geochemical surveys are planned for 2026, including an IP survey over the Rhyolite Hill target approximately 20 km southwest of Molongle. This target features a circular aeromagnetic high and anomalous base metal pathfinder elements from historic surface geochemistry, potentially adding new drill targets to the pipeline.

Great Southern Mining’s Managing Director Matthew Keane emphasised the scale and early stage of the project: "Multiple targets within Edinburgh Park display the attributes required for large-scale gold systems, including deep-seated structures with pervasive hydrothermal alteration from surface and coincident geochemical anomalies." The company’s approach mirrors its broader exploration push, as seen in recent deep diamond drilling campaigns at its Western Australian projects, including Golden Boulder, where government co-funding has accelerated testing of structural controls on gold mineralisation.

Technical Rigor and Next Steps

The exploration program benefits from detailed technical work, including high-quality diamond drilling with core oriented using IMDEX ACT III™ tools, and rigorous sampling and assay protocols conducted by ALS Townsville. IP surveys have been performed with industry-standard equipment and comprehensive QAQC measures, lending confidence to the geophysical interpretations guiding drill targeting.

Looking ahead, the market will keenly await results from the Mt Dillon drilling campaign, which could materially shift the project’s valuation if it confirms a significant intrusive-related gold system. Meanwhile, the company’s ability to generate and test additional targets like Rhyolite Hill will be critical to sustaining exploration momentum across this vast tenure.