Earth Materials and Processes
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The Earth Materials and Processes area comprises research groups in Rock Physics, Experimental Petrology, and Structure & Tectonics. Our research centres around laboratory based measurements under controlled conditions, simulating those occurring in nature, but these activities are complemented by a rich array of analytical equipment and are supported by extensive field-based observations, often in collaboration with scientists from other institutions, nationally and internationally. Through such investigations we aim to develop understanding of the structure and chemical composition of planetary interiors, and the processes by which planets evolve. Our interests start at the very beginning of solar system history with how the Earth and other rocky planets accrete, and then cover the ongoing processes of mantle convection, volcanism, metamorphism, global tectonics and the formation of ore deposits.
Areas of current research activity include:
- The making of terrestrial planets. Chemical constraints on the accretion of the Earth and similar planets from the solar nebula, and the processes of core formation; mineralogical and chemical properties of the deep mantle and their influence on global tectonics.
- The nature of the Earth's upper mantle. Experimental studies and thermodynamic modelling of the phase equilibria relevant to upper mantle melting and ultra-high-pressure metamorphism associated with crustal thickening and subduction; experimental and microstructural studies of phenomena associated with lattice defects and grain boundaries including incorporation of water into nominally anhydrous minerals and microscopic mechanisms of seismic wave attenuation; experimental studies and modelling of grain-scale melt distribution and its implications for melt transport, rheology and seismic properties.
- Oxidation state and coordination of metal ions at high temperatures. Studies of crystals, melts and hydrothermal solutions by X-ray absorption spectroscopy, using synchrotron radiation. Studies of silicate glasses and melts to very high temperatures under controlled redox conditions. Analysis of hydrothermal solutions trapped in synthetic fluid inclusions is providing important basic information on metal complexes at high temperatures.
- Coupling between fluid flow and fault mechanics in the continental crust. Field-based studies of a normal fault system in Oman, along with complementary stable isotope and other geochemical studies of associated calcite vein systems, are being used to explore how fault-controlled fluid flow is localized among components of regionally extensive fault networks. Field-based and microstructural studies in two examples of intrusion-related ore systems (Porgera, PNG, and North Parkes, NSW) are providing insights about the dynamics of growth of fracture-controlled hydrothermal systems and localization of ore deposition in these settings. Laboratory studies of the seismic properties of the cracked and fluid-saturated rocks of the upper crust
- The mission to planet Earth in which we construct a virtual time machine (in collaboration with U. Sydney) to provide a spatio-temporal context that will allow a greater understanding of planetary tectonics from the point of view of plate-scale physical processes. This infrastructure development is supported by the NCRIS AuScope initiative. To provide critical data for the tectonic reconstructions, “listening posts” are being established that provide samples that can be analyzed and dated using 40Ar/39Ar and U-Pb geochronology in the Earth Chemistry.