Rheology of Mantle Minerals In Subducted Slabs: Limits on Deep Seismicity

深震源地震过程仍然知之甚少。俯冲板块材料的强度可能限制这些事件的分布和大小。此外，塑性不稳定性仍然是这些事件的可能原因。在这项研究中获得的数据将定义断层材料流变对这些事件施加的限制。PI及其同事将研究俯冲板块压力和温度域中橄榄石、瓦德利岩和环伍德岩相的流变特性。将使用同步加速器x射线源和多砧高压系统对这些材料进行实验研究，实验压力范围为20gpa，温度范围为室温至1200℃。该方法是描述在俯冲板块的适当压力和温度条件下控制流动的流变学和潜在过程。研究人员将确定在这些条件下材料强度的温度依赖性和应力-应变率关系。这些信息将产生流动过程活化能的估计。通过透射电子显微镜，他们将表征与不同变形机制相对应的材料的位错密度和结构。综合起来，这些数据将有助于推断俯冲板块中可能存在的条件，并有助于限制地震过程和圈定地震

Weidner 9909266 The deep focus earthquake process remains poorly understood. The strength of the material of the subducting slab may limit the distribution and size of these events. Furthermore, plastic instabilities remain as a possible cause of these events. The data obtained in this study will define the limitations imposed by the rheology of the faulting material on these events. The PI and colleagues will investigate the rheological properties of the olivine, wadsleyite, and ringwoodite phases in the pressure and temperature domain of a subducting slab. A synchrotron x-radiation source coupled with a multi-anvil high-pressure system will be used to conduct an experimental study of these materials in the pressure range up to 20 GPa and temperatures from room temperature to 1200C. The approach is to characterize the rheology and underlying processes that govern flow in the appropriate pressure and temperature conditions of a subducting slab. The investigators will determine the temperature dependence of the strength of the materials and the stress - strain rate relation at these conditions. This information will yield estimates of activation energies for the flow process. With transmission electron microscopy, they will characterize the dislocation density and structure of the material corresponding to different regimes of the deformation. Taken together, these data will be useful to extrapolate to possible conditions that exist in the subducting slab and will be useful for constraining the earthquake process as well as delineating