Proterozoic metamorphism in Tasmania: Implications for tectonic reconstructions

Tasmania forms an enigmatic province within the Neoproterozoic history of Australia. While now part of Australia, it was closer to East Antarctica in the Cambrian. It also lies at the boundary between Australia and North America in most Rodinia reconstructions. The Tasmanian Proterozoic stratigraphy has some common features with South Australia but there are major differences. New chemical U–Th–Pb monazite dating demonstrates that Tasmania was metamorphosed at 1290 Ma and again at 920 Ma, and intruded by granitoids at 1050 Ma. These results and a compilation of other data relevant to the Proterozoic evolution of Tasmania are used to test several aspects of Rodinia reconstructions. The Mesoproterozoic tectonic history of Tasmania is similar to the Musgrave Block in central Australia. However, the best correlation of Proterozoic history for Tasmania is with the Transantarctic Mountains. We conclude that the Western Tasmanian Terrane rifted from the East Antarctic margin at 580 Ma and was trapped outboard of the Cambrian Ross-Delamerian Orogen. The Victoria Land-Transantarctic Mountains-Western Tasmania block has many similarities to southwest Laurentia and provides additional support for the AUSWUS reconstruction of Rodinia.