Plate tectonic reconstructions

The importance of intraplate stresses for the subsidence of sedimentary basins has been recognized only recently. One of the main paradigms of plate tectonics was thought to be that there is a limited number of large tectonic plates that behave rigidly through long geological time intervals. Instead recent analyses of intra-plate earthquakes and well-breakouts have shown clearly that forces applied at plate boundaries, such as ridge push and slab pull, propagate into large plates, and produce significant intra-plate stresses. The relation between present day intra-plate stresses and plate driving forces for the Indo-Australian plate has been investigated by measuring in-situ stresses, and by calculating in-plane stresses based on models of plate-driving forces. However, the Indo-Australian plate exhibits a much more complicated stress pattern than most other major plates. Reconstructing past plate motions provides our only key to model the major forces that have driven plates in the past, resulted in differing intraplate stresses through time, and affected basin subsidence and uplift.

R. Dietmar Müller, Geology and Geophysics, University of Sydney
Steven Cande, Scripps Inst. of Oceanography, San Diego, CA, USA
Joan Stock, California Institute of Technology
Walter R. Roest, Geological Survey of Canada, Geophysics Division, Ottawa, Canada
Jean-Yves Royer, Lab. de Géodynamique, Villefranche sur Mar, France
Phil Symonds, Australian Geological Survey Organization

Ph.D. students:
Carmen Gaina, Geology and Geophysics, University of Sydney

Project aims
1) Create a self-consistent set of magnetic anomaly interpretations, in the Indian and central/North Atlantic oceans.
2) Compute of a set of plate reconstructions including uncertainty estimates for at least 15 time steps between chron 34 (83 Ma) and the present for Australia-India, and Australia-Antarctica, North America-Greenland-Eurasia, North America-Africa, and Antarctica-Africa-India, and Australia-Eurasia.
3) Determine of the timing of tectonic events within the resolution of our plate model as compared with tectonic events recorded in basins on Australia's passive margins.

The opening of the Tasman Sea:

A computer animation based on a new plate model used to rotate
present-day free-air gravity anomalies through time.