Research School of Earth Sciences, ANU

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	Research School of Earth Sciences ANU COLLEGE OF SCIENCE

Research Areas in Geodynamics

Research of the Geodynamics Group is concerned with the processes that deform the Earth's crust and lithosphere as well as the planet as a whole. The broad objective is to seek an improved understanding of the physical processes acting on and within the planet through both numerical modelling and observational analysis. The Earth is a dynamic planet, constantly deforming in response to forces acting on and within it on time scales that range from seconds to millions of years. The emphasis in the group is on developing new physical models and numerical algorithms that facilitate the testing of the models against geomorphological, geological and geodetic data so as to permit improved estimates of the force and response functions.

The problems being addressed by the Geodynamics Group can be viewed as being at different ends of the time scale. At the longer end of the scale, research is focussed on paleotectonic problems of continental tectonics, of sedimentary basin structure and evolution, of mountain building and erosion, and of the manner of deformation of crustal blocks, faults and shear zones. These questions are addressed using observational evidence from seismic, gravity, magnetic and topographic measurements, and by numerical modelling which helps to place constraints on what is physically possible in the description of the history of the Earth's surface.

A second area of study involves the response of the Earth to the transfer of mass between the oceans and continental ice sheets during the major glacial cycles the Earth is currently experiencing. Evidence for detailed sea level histories is being obtained in a variety of ways for several parts of the Earth including the coasts of Australia, Antarctica and northwestern Europe. The combination of numerical modelling with this examination of the geological record makes it possible to infer the material properties of the Earth's mantle, including its effective viscosity on a timescale of tens of thousands of years, as well as placing constraints on the extent and distribution of the ice sheets themselves. Such quantitative information is crucial to the more speculative exercise of estimating the future sea-level variations which can be expected in response to climate change.

New developments in geodesy and geology have drawn our attention to very recent or "neotectonic" problems because it has become possible to directly measure rates of deformation. Thus some of the research activities of the group are being directed to neotectonic problems along the margins of the Australian Plate. A major new initiative in neotectonics is now directed at the study of recent deformation of the Earth's crust using a combination of geophysical, geological and geodetic methods including repeated precise position measurements using the satellite based Global Positioning System. A major study underway in Papua New Guinea and the Melanesian region is providing estimates of crustal deformation rates and distribution, and helping to establish the relative importance of the various proposed microplate boundaries.

Many of the research activities are carried out in cooperation with other areas of the School, most notably Seismology, Isotope Geochemistry, and Environmental Geochemistry. The research also involves cooperation with scientists from other Universities and Institutions both in Australia and overseas.

Some recent and current projects include:

Ice sheets and crustal rebound in northern Europe

Benchmark comparison of glacial isostatic adjustment

Holocene and Last Interglacial sea levels around Australia

Upper mantle lateral viscosity variations and postglacial rebound

Reconstructing Antarctic ice sheet history

Late Pleistocene glaciation of the Tibetan Plateau

Three-dimensional physical models of finite crustal deformation

Post-Cretaceous landscape evolution in southeast Australia

Teleseismic imaging of lithospheric structure in central Australia

Fluvial incision rates in the Finisterre Range, Papua New Guinea

Tectonic interpretation of geochronologically derived cooling events

A new model for asymmetric continental extension and its application to the Fitzroy Trough, northwestern Australia

Dynamics of a young compressional orogen - the Southern Alps of New Zealand

Radiocarbon time scale calibration

Geodetic monitoring of crustal movements in Papua New Guinea and the Solomon Islands

Estimation of atmospheric precipitable water