April 2008 MONTHLY MEETING
DATE: Wednesday 16th April 2008
VENUE: Rugby Club, Level 3, Rugby Place (near Pitt &
Alfred St) Sydney
TIME: 5.30pm for 6:00pm
Technical Meeting
Plate tectonic and paleo-stress field evolution of Australia since the Eraly Cretaceous
Dr Dietmar Müller (University of Sydney)
Abstract:
In order to understand the effect of time-dependent geometries of mid-ocean ridges,
subduction zones and collisional plate boundaries on intracontinental basin evolution
and reactivation through time, now subducted ocean floor needs to be reconstructed,
with their plate boundary configurations restored. We reconstruct palaeo-oceans around Australasia
by creating “synthetic plates”, the locations and geometry of which is established on the basis
of magnetic lineations and fracture zones, geological data and the rules of plate tectonics.
We use a digital 2D finite element model of the (Indo-) Australian Plate that distinguishes cratons,
fold belts, basins, and ocean crust in terms of their relative differences in mechanical stiffness
for five time slices since the Early Cretaceous. Australian intraplate stress patterns
were relatively simple in the Cretaceous, but became progressively more complex
in the Tertiary reflecting the onset of several collisions, resulting in
major tectonic reactivation episodes in the Eocene and Miocene.
Between the Miocene and the present, the main change in Australian plate-driving forces was
represented by the onset of collision along Papua New Guinea and the enhanced collision
between India and Eurasia, paired with subduction plate segments between the Java Trench
and the Banda Arc that exert slab pull on Australia. We focus on the structural history of the
Northwest Shelf, the Bass Strait and the Adelaide Fold Belt to ground-truth our models,
which provide a framework for understanding tectonic reactivation through time.
[Home] [Meetings]
Please phone or email Gua Bin for
enquiries.
|