School of Earth Sciences - Theses
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ItemDetrital zircon geochronology of Neoproterozoic glacials, flinders ranges, South Australia( 2009)A geochronological survey of Neoproterozoic glacial sediments in the Flinders Ranges, South Australia has traced possible source rocks and potential transport directions. A distinct change in the dominant detrital zircon populations present in the earlier Sturtian glacials and the later Marinoan glacials is clearly evident. The major zircon populations present in each of the Sturtian-age samples lie within 1500 -1800Ma, while the majority of Marinoan samples lie between 1100-1400Ma. Potential source rocks for the 1500-1800Ma population include the Gawler and Cumamona Cratons, which are local to the study area. The 1100-1400Ma. population can be traced further north to the Musgrave Inlier in addition to the Albany-Fraser belt and Pinjarra Orogen , north west of the sample localities. The change in zircon population could therefore be accounted for by a change in glacial transport direction during the respective epochs. This may indicate a difference in the severity of the glaciations. An alternative explanation for the difference in detrital zircon signatures could be a change in source rock erosion during each glacial period. Uplift of the Musgrave Inlier or similar basement terrains between the glaciations would provide younger zircons for deposition within the Marinoan sediments. The large unconformity known as `The South Ranges Movement' that is evident in much of the former Centralian Superbasin may testify to such an orogenic event having occurred. Previous studies of detrital zircons in the region provide support for this conclusion.