Earth material science: from brittle fault zones of the upper crust to plastic flow of the upper mantle

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Knowledge of the deformation, rheology and physical properties of polyphase rocks, which are the Earth's constitutive materials, is critically important for understanding the tectonic activity (e.g., earthquakes) and dynamics of the crust and mantle. The long-term objectives of my research program are to improve our understanding of the deformation behavior, rheology and seismic properties of the crust and mantle rocks, and to apply the improved knowledge to problems in pure and applied Earth Sciences. The short-term objectives are two-fold: (1) Determination of physical and chemical processes controlling strain softening, shear localization, microstructural evolution and lattice-preferred orientation of olivine-orthopyroxene composites (peridotite), which is the dominant rock in the Earth's upper mantle, deformed at high temperature, high pressure and simple shear conditions using a gas-medium Paterson apparatus. We expect that the experimental results may explain why plate tectonic style of deformation occurs on the Earth, but not on Venus or Mars where stagnant lid style of convection occurs. (2) Intensive involvement, as the vice Chief-scientist, in the Wenchuan earthquake Fault Scientific Drilling (WFSD) project which offers a unique opportunity to drill, sample, observe and monitor the Longmen Shan fault zone (Sichuan China), the eastern margin of the growing Tibetan plateau, which failed in the M8.0 earthquake on 12 May 2008. The proposed investigations on key problems about earthquake physics and chemistry through in-situ observations (geological and geophysical probing), down-hole experiments, laboratory analyses of core materials recovered from the fault zone and its country rocks, and long-term monitoring, hopefully lead to a resolution of the mystery of how the major boundary of the Tibetan Plateau works. Thus, an extremely important impact of this proposed program is to involve the Canadian researchers in a novel international collaborative research project - WFSD, to improve our understanding of seismically active intracontinental fault zones at the eastern margin of the world's largest plateau.