Plastic Deformation and Deformation Fabric in Wadsleyite and Ringwoodite: Effects of Water and Grain-Size

Karato 0105493地幔对流与地幔过渡带（410至660公里深）的相互作用影响着地幔环流的模式，从而影响着地球的演化。这种相互作用强烈地依赖于在过渡区中发生的物理性质的变化，特别是流变性质。为了帮助理解过渡区材料的流变特性对这种相互作用的影响，PI建议在过渡区条件下对过渡区矿物（分别为wadsleyite和ringwoodite）的塑性流动进行实验研究，重点是水和粒度的影响。当对流通过过渡区时，颗粒大小和水都会发生显著变化。研究人员将把他们以前的研究扩展到两个新的方向：（1）研究水对流变学和变形组构的影响，（2）通过更好地定义（恒定应变率）变形实验和使用同步辐射设备和透射电子显微镜进行应力测量来提高数据质量。 这些结果将提供第一个定量数据集的水和粒度的影响流变学和变形组构的主要过渡带矿物和一个坚实的基础，解释地震各向异性的过渡带。

Karato 0105493 The interaction of convection currents in Earth's mantle with the mantle transition zone (410 to 660 km depth) affects the pattern of mantle circulation and hence evolution of this planet. This interaction depends strongly on the change in physical properties that occurs in the transition zone, particularly the rheological properties. To help understand the influence of rheological properties of transition zone materials on this interaction, the PI proposes to conduct experimental studies on plastic flow in transition zone minerals (wadsleyite and ringwoodite respectively) under the transition zone conditions with the emphasis on the effects of water and grain-size. Both grain-size and water can change significantly as convection currents go through the transition zone. The investigators will extend their previous studies into two new directions; (1) to investigate the effects of water on rheology and deformation fabric, and (2) to improve the quality of data by better-defined (constant strain-rate) deformation experiments and by stress measurements using the synchrotron radiation facility and transmission electron microscopy. These results will provide the first quantitative data set on the effects of water and grain-size on rheology and deformation fabric of major transition zone minerals and a firm basis for interpretation of seismic anisotropy in the transition zone.