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Research Activities 2012

Earth Materials and Processes

 


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Introduction

The Earth Materials and Processes area comprises research groups in Rock Physics, Experimental Petrology, and Structure & Tectonics. A large part of our research centres around laboratory based measurements at high temperatures and pressures under carefully controlled conditions that simulate those occurring in nature; such experiments are characterized by a rich array of analytical equipment, which are also put to use studying natural samples. These activities are complimented 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 the Earth and planetary interiors in general, and the processes by which the Earth and other rocky 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 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.
  • Speciation 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. Laboratory studies of the seismic properties of the cracked and fluid-saturated rocks of the upper crust.
  • Building "The Map That Changes The Earth" 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. To provide critical data for the tectonic reconstructions "listening posts" are being established that provide samples that can be analysed and dated using 40Ar/39Ar and U-Pb geochronology.


Professor Hugh O'Neill
Associate Director, Earth Materials & Processes


Research Projects