Full-fit reconstructions of the southern Australian margin and Antarctica - implications for correlating geology between Australia and Antarctica

• Main Authors: Williams, SE, Whittaker, J, Muller, RD
• Format: Conference Object
• Language: English
• Published: Petroleum Exploration Society of Australia 2012
• Subjects: Earth Sciences; Geology; Marine Geoscience; Antarctic; Denman Glacier; The Antarctic; Wilkes Land; Antarc*; Antarctica
• Online Access: https://www.pesa.com.au/publications-overview; http://ecite.utas.edu.au/84449

The sedimentary basins along the southern Australian andconjugate Antarctic margins formed as a result of Mesozoicrifting. A number of alternative models have been proposed for thepre-rift configuration of Australia and Antarctica. They differ bothin how tight the fit between these continents is, and in the lateraljuxtaposition of the two continents, ie. some reconstructions placeAustralia further to the east, relative to a fixed Antarctica, thanothers. The continuity of comparable geological terranes, surfacemappedshear-zones, and geophysical signatures (e.g. magneticanomalies) between Australia and Antarctica within Gondwanahas implications for assessing these different reconstructionmodels.To investigate this issue, we tested a range of scenarios forthe full-fit configuration of Australia and Antarctica. In the lightof palinspastic reconstructions of the extended continental crustwithin each margin, we investigate how different reconstructionmodels reconcile geological and geophysical signatures from theconjugate plates. We find that a model that matches the LeeuwinFracture Zone (in the Australian margin) with the VincennesFracture Zone (in the Antarctic margin) reconciles Proterozoicstructures previously correlated between the continents based ontheir geological similarity. These include rocks from the Albany-Fraser orogeny, and the Kalinjala mylonite zone and Mertz shearzones. This model also reconciles the constraints from palinspasticreconstruction of Mesozoic extension better than modelsthat place Australia further east or west relative to Antarcticawithin Gondwana. This model does not produce a postulatedalignment between the Darling Fault in Western Australia andthe Denman Glacier in Western Wilkes Land. The preferred fullfitreconstruction model, together with other evidence from theearly breakup history between the Australian and Antarctic plates,suggests that the overall opening direction between the twocontinents was broadly NNW-SSE, but this includes phases of N-Sand NW-SEdirected extension.