Full‐fit, palinspastic reconstruction of the conjugate Australian‐Antarctic margins

• Published in: Tectonics
• Main Authors: Williams, SE, Whittaker, J, Muller, RD
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley-Blackwell Publishing, Inc. 2011
• Subjects: Earth Sciences; Geology; Marine Geoscience; Antarctic; Antarc*; Antarctica
• Online Access: https://doi.org/10.1029/2011TC002912; http://ecite.utas.edu.au/84436

Despite decades of study the prerift configuration and early rifting history betweenAustralia and Antarctica is not well established. The plate boundary system during theCretaceous includes the evolving KerguelenBroken Ridge Large Igneous Province in thewest as well as the conjugate passive and transform margin segments of the Australianand Antarctic continents. Previous rigid plate reconstruction models have highlightedthe difficulty in satisfying all the available observations within a single coherentreconstruction history. We investigate a range of scenarios for the early rifting historyof these plates by developing a deforming plate model for this conjugate margin pair.Potential field data are used to define the boundaries of stretched continental crust on aregional scale. Integrating crustal thickness along tectonic flow lines provides an estimateof the prerift location of the continental plate boundary. We then use the prerift plateboundary positions, along with additional constraints from geological structures and largeigneous provinces within the same Australian and Antarctic plate system, to computefull‐fit poles of rotation for Australia relative to Antarctica. Our preferred modelimplies that the Leeuwin and Vincennes Fracture Zones are conjugate features withinGondwana, but that the direction of initial opening between Australia and Antarcticadoes not follow the orientation of these features; rather, the geometry of these featuresis likely related to the earlier rifting of India away from Australia‐Antarctica. Previousfull‐fit reconstructions, based on qualitative estimates of continental margin overlaps,generally yield a tighter fit than our preferred reconstruction based on palinspasticmargin restoration.