Legacy product - no abstract available

Speculation is increasing that Proterozoic eastern Australia and western Laurentia represent conjugate rift margins formed during breakup of the NUNA supercontinent and thus share a common history of rift-related basin formation and magmatism. In Australia, this history is preserved within three stacked superbasins formed over 200 Myr in the Mount Isa region (1800-1750 Ma Leichhardt, 1730-1670 Ma Calvert and 1670-1575 Ma Isa), elements of which extend as far east as Georgetown. The Mount Isa basins developed on crystalline basement of comparable (~1840 Ma) age to that underlying the Paleoproterozoic Wernecke Supergroup and Hornby Bay Basin in NW Canada which share a similar tripartite sequence stratigraphy. Sedimentation in both regions was accompanied by magmatism at 1710 Ma, further supporting the notion of a common history. Basin formation in NW Canada and Mount Isa both concluded with contractional orogenesis at ~1600 Ma. Basins along the eastern edge of Proterozoic Australia are characterised by a major influx of sediment derived from juvenile volcanic rocks at ~1655 Ma and a significant Archean input, as indicated by Nd isotopic and detrital zircon data. A source for both these modes is currently not known in Australia although similar detrital zircon populations are documented in the Hornby Bay Basin, and in the Wernecke Supergroup, and juvenile 1660-1620 Ma volcanism occurs within Hornby Bay basin NW Canada. These new data are most consistent with a northern SWEAT-like tectonic reconstruction in a NUNA assembly thus giving an important constraint on continental reconstructions that predate Rodinia.

Legacy product - no abstract available

Legacy product - no abstract available

This work forms part of a major internation multi-disciplinary study of the Permian -Triassic boundary, end-Permian mass extinction and Middle Permian-Early Triassic timescale calibration. Studies undertaken in the overarching program include biostratigraphy, isotope geochronology, magnetostratigraphy, and chemostratigraphy.

Abstract for 34th IGC

The Rayner Complex of East Antarctica is exposed between 45??80?E in the Enderby Land through Princes Elizabeth Land sector of East Antarctica. It is known to correlate with parts of present day India and to have been deformed and metamorphosed at high grades in the earliest Neoproterozoic (990-900 Ma). The age and origin of the protolith rocks of the Rayner Complex however remains largely unknown, as does the tectonic setting in which these rocks formed. New age data collected from the northern Prince Charles Mountains (eastern Rayner Complex), demonstrate that the pre-orogenic rocks from this region consist of: (1) volcanogenic and terrigenous sediments deposited between 1400 Ma and 1020 Ma in a magmatically active basin characterised by limited input from cratonic sources and, (2) probable syn-sedimentary granitoids dated to 1150 Ma. Our data confirm the continuity of the Rayner Complex into Prydz Bay, a region that preserves a remarkably similar geologic history but which is often differentiated from the Rayner Complex on the basis of a higher grade early Cambrian (~520 Ma) overprint. On the basis of our data we further conclude that the Rayner Complex protoliths likely in formed in a back-arc system that existed along the margin of the pre-Gondwana Indian craton. Anticlockwise P-T paths and high-T, low-P metamorphism associated with the inversion of the Rayner back-arc (990-900 Ma) suggest this event resulted from the accretion of a number of independent microplates, rather than continent-continent collision.

Legacy product - no abstract available

Interpretation of deep seismic reflection profiling coupled with forward modelling of gravity and aeromagnetic data, new zircon U-Pb age dating and the interpretation of the basement geology beneath the southern margin of the Eromanga Basin has provided insights into the southern part of the underlying Thomson Orogen and its relationship with the Lachlan Orogen to the south. Our interpretations of these data suggest that the northern Lachlan and southern Thomson orogens possessed a similar history from the mid-Late Silurian through to the Carboniferous. Major older differences, however, are suggested by the presence in the southern Thomson Orogen of relics of a possible Neoproterozoic arc, of Late Ordovician turbidites, by the geophysical evidence for crustal thickening caused by elevation of reflective lower crustal metavolcanic rocks high into the crust on a low-angle, north-dipping detachment thrust, and by old K-Ar age dates in southwestern Queensland. The seismically-imaged, north-dipping, crustal-scale Olepoloko Fault corresponds to the surface expression of Thomson-Lachlan boundary, and reflects the dip-slip and strike-slip partial reactivation and short-cutting of an older fault, which occurred in the Carboniferous, and probably also in the latest Silurian and Early Devonian.

This Record contains zircon U-Pb geochronological data obtained between September 2000 and August 2001 on rocks from the Yilgarn Craton, Western Australia. The data were collected as part of the Norseman-Wiluna Synthesis project, a National Geoscience Accord project that operates in collaboration with the Geological Survey of Western Australia. They are helping to meet the objective of providing an improved geological and metallogenic framework for the Norseman-Wiluna region of the eastern Yilgarn Craton, and help provide geochronological constraints on geodynamic and tectonic models for the region. The data were acquired through a collaborative research agreement between Curtin University of Technology, Bentley, Western Australia and Geoscience Australia. This Record describes the samples analysed and the analytical results obtained, and provides a brief discussion of their geochronological interpretation. The broader geological implications of the data will be published elsewhere. The complete data files, including data for QGNG standards and thodoluminescence (CL) images showing SHRIMP spot locations, are stored in the Geoscience Australia database, OZCHRON.