Article Volume 13, Number 5 25 May 2012 Q05W13, doi:10.1029/2011GC003919 ISSN: 1525-2027 Constraining the Jurassic extent of Greater India: Tectonic evolution of the West Australian margin Ana D. Gibbons EarthByte Group, School of Geosciences, University of Sydney, Sydney, New South Wales 2006, Australia (
[email protected]) Udo Barckhausen BGR, Federal Institute for Geosciences and Natural Resources, Stilleweg 2, D-30655 Hannover, Germany Paul van den Bogaard, Kaj Hoernle, and Reinhard Werner GEOMAR, Helmholtz-Zentrum für Ozeanforschung Kiel, Dienstgebäude Ostufer, Wischhofstr. 1-3, D-24148 Kiel, Germany )(( 855"#..%, andR. Dietmar Müller EarthByte Group, School of Geosciences, University of Sydney, Sydney, New South Wales 2006, Australia [1] Alternative reconstructions of the Jurassic northern extent of Greater India differ by up to several thousand kilometers. We present a new model that is constrained by revised seafloor spreading anomalies, fracture zones and crustal ages based on drillsites/dredges from all the abyssal plains along the West Australian margin and the Wharton Basin, where an unexpected sliver of Jurassic seafloor (153 Ma) has been found embedded in Cretaceous (95 My old) seafloor. Based on fracture zone trajectories, this NeoTethyan sliver must have originally formed along a western extension of the spreading center that formed the Argo Abyssal Plain, separating a western extension of West Argoland/West Burma from Greater India as a ribbon terrane. The NeoTethyan sliver, Zenith and Wallaby plateaus moved as part of Greater India until westward ridge jumps isolated them. Following another spreading reorganization, the Jurassic crust resumed migrating with Greater India until it was re-attached to the Australian plate 95 Ma.