Investigation of High Pressure Faulting Associated with the Olivine Spinel Transition

深层聚焦的潜在失效机制 自70年代以来， 年前 高压断层被发现在 Mg 2GeO 4橄榄石在尖晶石稳定场中的变形 转化的动力学变得 在实验的时间范围内。 非常细粒度 尖晶石产于断裂带。 PI提出了四个主要的 问题：（i）微反裂纹是否不稳定？(ii)是什么 模式I抗裂连接导致贯通的过程 会发生故障吗？(iii)哪种转化机制在 反裂缝的尖端？(iv)抗裂机构是否工作 在x - B变换中？ 他们将回答问题（i）， 对高压装置进行仪表化， 定量地分析了丰度、震级、时间依赖性和波动性 故障前和故障期间的声发射形式。 问题 (ii)以及（iii）将通过电子沟道扫描来追踪 电子显微镜和透射电子显微镜 确定其大小、形状、方向和空间分布 微反裂缝的存在以及 尖晶石晶体的取向，在他们相对于 含有橄榄石晶体。 问题（iv）将由 对Mn_2GeO_4橄榄石进行了变形实验， B稳定场在HWG独特的5GPa变形装置。

The underlying failure mechanism responsible for deep-focus earthquakes has remained unknown since their discovery almost 70 years ago. High pressure faulting was discovered in specimens of Mg2GeO4 olivine deformed in the spinel stability field under conditions where the kinetics of the transformation become just possible on the time-scale of the experiment. Very fine-grained spinel is found in the fault zones. The PIs pose four major questions: (i) Are microanticracks unstable? (ii) What is the process by which mode -I anticrack link-up leading to through- going faults? (iii) Which transformation mechanism operates at the tips of anticracks? (iv) Does the anticrack mechanism operate in the x - B transformation? They will answer question (i) by instrumenting the high pressure apparatus and determining quantitatively the abundance, magnitude, time-dependence and wave form of acoustic emissions before and during failure. Questions (ii) and (iii) will be pursued by electron channeling scanning electron microscopy and transmission electron microscopy to determine the size, shape, orientation and spatial distribution of microanticracks and the grain-size and crystallographic orientation of spinel crystals within them with respect to the host olivine crystals. Question (iv) will be investigated by conducting deformation experiments on Mn2Geo4 olivine within the B stability field in HWG's unique 5GPa deformation apparatus.