Plate Tectonic Reconstructions of Australia's Southern Margins

This report documents a study into the Late Jurassic to Recent breakup and drift history of southern Australia, Antarctica and New Zealand , and the relationship between these tectonic events and the stratigraphy and drainage history of these areas. The study was conducted between March 1999 and August 2000. Many of the goals have been achieved, but the plate reconstructions still need to be put into a proper geo-referenced kinematic framework. The purpose behind the study was to lay the framework for understanding the palaeogeography, lithofacies, tectonics and geomorphology of these areas in a reconstructed palinspastic setting; something that had not been accomplished before. 
The methodology has been to first of all compile structural elements maps for the southern Australian and conjugate Antarctic margins. An updated ocean age map was also prepared as a basis for a first-pass reconstruction. Then the stratigraphy was summarised for three representative cross sections in the Great Australian Bight, Otway and Gippsland Basins, and these were displayed as detailed chronostratigraphic sections in order to demonstrate the stratigraphic responses to the breakup history. One of the vital predictive conclusions was to try and understand the structure and stratigraphy under the lower continental margins; the prime tools for this part of the study were deep-penetration seismic lines shot by AGSO under the Law of the Sea and Continental Margins programs. Finally, a set of 18 plate reconstruction maps were compiled for the period from the Oxfordian to the Present Day, with elements of the tectonics and stratigraphy plotted on them.
Because of time constraints and the inability to work the appropriate plate kinematic software, the reconstructions presented here were prepared with scissors and tape from the ocean age map and hence must be regarded as indicative cartoons of the plate positions. This situation is obviously not ideal but is considered justified by the need to understand the geological relationships between the various terrains before going to a rigorous kinematic reconstruction.
AGSO supported this study as a Collaborative Research Project, providing both data and support with expenses. In addition, this work has been shown at various stages to a large number of people, all of whom helped by making comments and suggestions, and their contributions are gratefully acknowledged. Some of those involved were:-
Kevin Hill (La Trobe University)
Nick Hoffman (La Trobe University)
Mark Smith (Petroleum Consultant)
Alan Partridge (La Trobe University)
Heike Struckmeyer (AGSO)
Jennie Totterdell (AGSO)
Howard Stagg (AGSO)
Jacques Sayers (AGSO)
Russell Korsch (AGSO)
Colin Pain (AGSO)
Paul O'Sullivan (Syracuse University, NY)
Meredith Orr (Monash University)
Mike Hall (Monash University)
Steve Gallagher (Melbourne University)
Guy Holdgate (Melbourne University)
Barry Kohn (Melbourne University)
Dietmar Muller (U. Sydney)
Mike Gurnis (Caltech)
Chris Adams (NZIGNS)
Tom Bernecker (VDNRE)
Andrew Constantine (VDNRE)
David Moore (VDNRE)
Ross Cayley (Geol. Survey Victoria)
Cliff Ollier (ANU)
Graham Taylor (University of Canberra)

Tags: Earth Sciences, GA Publication, Published_External, Record, palaeogeography, plate tectonics, structural geology
Organization: Geoscience Australia Data