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Gold mineralisation in the Yalgoo Singleton Greenstone Belt, Western Australia

alisation and allow protracted interaction of the mineralised system with the water table, resulting in considerable subsequent supergene enrichment (McInnes et al. 2005). The sub-economic Kassiteres porphyry – epithermal system is a key exemplar of post-collisional porphyry – epithermal mineralisation (Voudouris et al. 2006). Kassiteres is hosted by an Oligocene pluton within the Maronia Magmatic Corridor, and lies 10 km south of the Kechros Fault, a basal detachment of the Rhodope Metamorphic Core Complex. High-precision U–Pb zircon ages, in combination with detailed field observations and Al-in-hornblende geobarometry, suggest an exhumation rate for Kassiteres of >5 mm/yr; up to an order of magnitude higher than typically observed in porphyry – epithermal systems. Widespread argillic alteration and blank quartz-magnetite veining is observed over an area of at least 4 km with localised acid vents and Si-lithocaps suggesting considerable interaction between the wallrock, hydrothermal fluids, meteoric waters and the atmosphere. We propose that the extremely rapid exhumation of this system during porphyry emplacement led to a transition from intrusive to eruptive magmatism. As a result, the mineralising fluid was dispersed through the overlying highly permeable pyroclastic units leading to a breached porphyry system and the observed, sub-economic mineralisation.