The transition zone of the Earth's mantle (~ 410 to 660 km deep) is the zone in which a series of phase transformations are considered to occur in mantle minerals and in which complicated interactions between convection currents and phase transformations are inferred from high resolution seismic tomography. The main aim of this project is to obtain experimental constraints on the rheological properties of transition zone minerals to better understand the details of these interactions. The team (PI, post doc and a graduate student) will conduct a detailed investigation of the rheological properties of germanate analogues of mantle minerals using their newly developed technique of large-strain shear deformation at high pressures and high temperatures. The relative strength of pairs of transition zone minerals as well as the sensitivity of deformation to grain-size will be determined. The results will provide the first quantitative data set to investigate the role of the transition zone in the global process of mantle convection.
