The eastern third of the Australian continent is a region known as the Tasmanides, and was built by a series of complex geological events that occured between ca. 550 and 200 Million years ago (Ma). It has long been recognized that episodic geological activity is key to the concentration of metals and minerals within Earth’s crust. Indeed, the successive tectonic and volcanic cycles of the Tasmanides exerted a first-order control on the development and preservation of known mineral systems running from Queensland to Tasmania. However, all easy-to-find mineral deposit discoveries have been made, and to meet net-zero targets we must look to buried or remote deposits.  A better understanding of the time-dependent geodynamic controls and their implications (e.g. pressure, deformation, temperature, vertical motions, fluid flow) is now needed in order to make more targeted discoveries of critical and strategic minerals.

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This project will cross present-day and deep time, and cover the surface to deep interior, to build geodynamic models of the Tasmanides and surrounding regions. Shown are selected datasets and key topics covered.

The Tasmanides can be subdivided into five recognized regions, or orogens (coloured polygons in first two panels above); the Delamarian (orange), Lachlan (blue), Thomson (purple), Mossman (pink), and New England (yellow), which overlap in time as well as space. The Tasmanide orogens relate to a series of deformation events, including mountain building, ocean subduction, arc accretion, rifting and extension, and volcanism, that occurred around 550-220 Ma, after which the eastern Australian margin became more “passive”. This past deformation was driven by horizontal and vertical changes in the solid Earth, which can be studied via the geological processes of plate tectonics and mantle convection.

The nature and timing of key Tasmanide events have recently come into focus via conceptual, typically 2-D geological models at specific points in space and time. Furthermore, there is now a wealth of publicly available geological, geophysical, geochemical and geochronological data covering the eastern margin. It is now timely for these observations, constraints and ideas about the Tasmanides to be placed into digital plate tectonic reconstructions, using the software GPlates. These tectonic reconstructions can then be used and tested as surface constraints for models of mantle convection, using the in-house G-ADOPT framework. One combined, these 4-dimensional geodynamic models will provide qualitative and quantitative insights into processes that affect mineral formation and preservation across the Tasmanides, for example, dynamic topography, heat flow, volcanism and melting, and mantle fertility. Anyone with an interest in any of the above is welcome to contact Grace.