High pressure, down under: the first Australian high-pressure synchrotron facility for geoscience research

Because the deep Earth is not directly accessible, geoscientists rely on laboratory experiments and computer models in order to understand the properties of minerals at the extreme pressure and temperature conditions of deep crust, the mantle and the core. In the field of high-pressure mineral physics and chemistry, we use our understanding of mineral properties, stress–strain relationships in multiphase rocks, and processes such as partial melting at high pressures and temperatures, to interpret geophysical observations of the deep Earth. Studies have constrained the pressure sensitivity of deformation of minerals such as olivine under subduction zone conditions, and the effect of pressure on slip systems in high-pressure minerals such as wadsleyite and perovskite. These results have important implications for the variation of mantle viscosity with depth, the geodynamic interpretation of seismic anisotropy, and changes in mantle rheology as a function of composition. However, the rheology and dynamics of the deep Earth are still poorly understood. Fortunately, technical development has been undertaken over the past 10 years in the USA, and scientific advances have been helped by the development of high-P–T deformation apparatus, such as the large volume multi-anvil deformation apparatus known as the D-DIA. This has opened up the possibility of determining physical and chemical processes in the upper mantle, and into the mantle transition zone. To participate in this exciting new area of research, we are now developing a high-pressure facility at the Australian Synchrotron. In this overview paper, we describe the background and current research that is being conducted in other synchrotron high-pressure facilities and what will now be possible for the Australian Synchrotron.