Zirconolite and xenotime U-Pb age constraints on the emplacement of the Golden Mile Dolerite sill and gold mineralization at the Mt Charlotte mine, Eastern Goldfields Province, Yilgarn Craton, Western Australia

In situ SHRIMP U-Pb dating of magmatic zirconolite (CaZrTi2O7) in the Golden Mile Dolerite from the Mt Charlotte gold deposit (Yilgarn Craton, Australia), yielded the first robust emplacement age (2680 ± 9 Ma) for the principle host-rock of gold mineralization in the Kalgoorlie district. In contrast, co-magmatic zircon gave ages from ca. 2680 Ma to ca. 2170 Ma, reflecting isotopic resetting of high-U and -Th crystals. In situ SHRIMP analysis of hydrothermal xenotime (YPO4), which co-exists with gold in alteration pyrite, provided a Pb/Pb isochron age of 2655 ± 13 Ma. This date indicates that the youngest deposit in the Kalgoorlie district (Mt Charlotte) predates circa2.65 Ga, and provides a new minimum age for the structurally older Golden Mile deposit. Our results indicate that gold mineralization at Mt Charlotte is ~50 million years older than indicated by recent 40Ar/39Ar ages and places new constraints on the timing of late-stage regional faulting (D4) in the province.