New constraints on Phanerozoic magmatic and hydrothermal events in the Mt Painter Province, South Australia

Zircon and monazite U–Pb dating show a punctuated history of tectonic, magmatic and hydrothermal activity in the Mt Painter Province (South Australia) that spans most of the Palaeozoic. The Cambro-Ordovician Delamerian Orogeny was characterised by very limited intrusions of sodic pegmatitic leucogranites, for which the Hf isotopic data show influence of an isotopically more primitive source than the local Mesoproterozoic granitoids and metasediments. Another phase of magmatic activity occurred in an intraplate setting around 460–440Ma, with more extensive met- and peraluminous granitoids and another phase of sodic leucogranites. Both intracrustal reworking and potential mantle input are seen at this stage. Iron-rich uranium ores yielded a monazite U–Pb age of 355±5Ma, and whole rock Sm–Nd isotope systematics indicate that the ores were sourced from the local Mesoproterozoic granitoids. The Palaeozoic events in the Mt Painter Province span a period of 200My, and occurred during more than 10km of exhumation of the Mesoproterozoic basement rocks. This study shows that central South Australia was more strongly affected by large-scale regional tectonics (Alice Springs Orogeny and Lachlan Orogeny) than hitherto known.