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

地幔对流与地幔过渡带（深度410 ~ 660 km）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。这种相互作用在很大程度上取决于发生在过渡区的物理性质的变化，特别是流变性质的变化。为了了解过渡带材料流变特性对这种相互作用的影响，PI提出在过渡带条件下对过渡带矿物（分别为wadsleyite和ringwoodite）的塑性流动进行实验研究，重点研究水和粒度的影响。对流通过过渡带时，颗粒大小和水分都发生显著变化。研究人员将把他们以前的研究扩展到两个新的方向；(1)研究水对织物流变和变形的影响；(2)通过定义更明确的（恒定应变率）变形实验和利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关于水和粒度对主要过渡带矿物流变学和变形结构影响的定量数据集，并为过渡带地震各向异性的解释奠定坚实的基础。

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.