A North American provenance for Neoproterozoic to Cambrian sandstones in Tasmania?

Abstract

Tasmania forms an enigmatic province within the Neoproterozoic to Cambrian history of Australia. It lies at the boundary between Australia and North America in most Rodinia reconstructions but no reliable lithostratigraphic correlations have been reported with either mainland Australia or North America. We used detrital zircon age spectra, measured by LAM-ICP-MS, of Neoproterozoic and Cambrian sandstones in Tasmania to search for evidence of correlations with these two continental blocks during the time slice critical to Rodinia breakup. The Tasmanian sandstones are dominated by 1600-1900 Ma and 1200-1500 Ma age zircons. There is little evidence for Grenville (~1100 Ma) and Ross (~550 Ma) Orogen sources in these sandstones, in contrast to detrital zircon age spectra of similar age rocks in South Australia. The detrital zircon age spectra of Tasmanian sandstones are different from age spectra reported from British Columbia. They are very similar to age spectra reported from Cambrian sandstones of Nevada, supporting Rodinia reconstructions that place southwestern USA near to Tasmania in the Neoproterozoic.