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

Weidner 9909266 对深源地震过程仍然知之甚少。 俯冲板片材料的强度可能会限制这些事件的分布和规模。 此外，塑料不稳定性仍然是这些事件的可能原因。 本研究中获得的数据将定义断层材料的流变学对这些事件施加的限制。 首席研究员和同事将研究俯冲板片压力和温度域中橄榄石、瓦兹利石和尖角橄榄石相的流变特性。同步加速器 X 辐射源与多砧高压系统相结合，将用于在高达 20 GPa 的压力范围和从室温到 1200°C 的温度范围内对这些材料进行实验研究。该方法旨在表征俯冲板片在适当压力和温度条件下控制流动的流变学和基础过程。 研究人员将确定材料强度的温度依赖性以及这些条件下的应力-应变率关系。 该信息将产生流动过程的活化能的估计。 通过透射电子显微镜，他们将表征与不同变形状态相对应的材料的位错密度和结构。 总而言之，这些数据将有助于推断俯冲板片中存在的可能条件，并有助于限制地震过程以及描绘

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