Shear Deformation of Upper Mantle Minerals: The Role of Water, Dynamic Recrystallization and Deformation

PI提出为上地幔矿物地震各向异性的地球动力学解释提供新的实验约束。重点是水和动态再结晶的作用。PI实验室开发的简单剪切变形技术将用于实验，电子背散射模式分析（EBSP）将用于研究晶格的优选方向。制备上地幔矿物合成多晶试样，在富水和贫水条件下，高温高压进行简单剪切，变形成大应变（~100 ~ 300%）。EBSP技术将研究包括晶格优先取向在内的微观结构发展，并预测与特定变形机制和变形几何相对应的地震各向异性。这些结果将与地震学观测结果进行比较，以对上地幔的流动模式提出新的限制。＊＊＊

9706329 Karato The PI proposes to provide new experimental constraints on the geodynamical interpretation of seismic anisotropy in upper mantle minerals. The focus will be on the role of water and of dynamic recrystallization. Simple shear deformation techniques developed in the PI's laboratory will be used in the experiments and electron backscatter pattern analysis (EBSP) will be utilized to investigate lattice preferred orientation. Synthetic polycrystalline specimens of upper mantle minerals will be prepared and deformed to large strains (~100-300 %) at high temperature and pressure in simple shear under water-rich and water-poor conditions. The microstructural development including the lattice preferred orientation will be investigated by the EBSP technique and seismic anisotropy corresponding to specific deformation mechanisms and deformation geometry will be predicted. The results will be compared with seismological observations to place new constraints on the flow pattern in the upper mantle. ***