Cambrian U-Pb age for the Mewstone Granite

A report on the age of the Mewstone Granite has been published by MRT. The main purpose of the report is to document a U-Pb age obtained from zircon from the Mewstone. Petrographic and geochemical data are also presented and compared with those from other southwest Tasmanian granites.

The Mewstone Granite is one of three small bodies of outcropping granite in far southwest Tasmania. It forms the Mewstone, a small (~13 ha) island which rises steeply to about 150 m asl, located 22 km south of the nearest point on the Tasmanian mainland and 12 km SE of Maatsuyker Island (43°44’18’’S, 146°22’22’’E). Earlier work has shown that the other bodies, the South West Cape Granite and Cox Bight Granite, are Cambrian and Devonian in age respectively, but the granite composing the Mewstone has not previously been dated. The main purpose of this report is to document a U-Pb age obtained from zircon from the Mewstone. Petrographic and geochemical data are also presented and compared with those from other southwest Tasmanian granites.