Great Southern Mining and its joint venture partner Gold Fields have drilled two deep diamond holes totalling 1535 metres at the Mt Dillon target within the Edinburgh Park project, located about 100 kilometres south of Townsville. The program was designed to test an induced polarisation chargeability anomaly beneath a preserved lithocap, a geological feature often associated with large mineral deposits.
Both holes were extended beyond their planned depths to 762.1 metres and 772.8 metres after encountering visual signs of a significant mineral-rich structure. Core logging revealed a 60- to 80-metre-wide fault zone near the surface, followed by volcanic and intrusive rocks showing pervasive alteration and disseminated pyrite (iron sulphide), which is commonly linked to epithermal gold mineralisation. Lower sections of the core contained several hydrothermal breccia zones with stronger alteration and pyrite content of up to 5 per cent.
Great Southern managing director Matthew Keane described the finding as promising. "This is a big target with multiple geological facets that make it attractive for a large-scale IRGS discovery," he said. The company noted that the alteration, widespread sulphides and breccias are all consistent with an intermediate-sulphuration epithermal system.
The drilling is being carried out under an earn-in agreement that allows Gold Fields to spend up to A$15 million on exploration in return for a 75 per cent stake in the project. Assay results are expected in the coming weeks and will determine whether the joint venture advances to further drilling.