Collaborative Research: Dehydration Embrittlement of Serpentine at High Pressures: Implications for Intermediate and Deep Earthquakes

9725575绿色 30年来，人们已经知道，在低压脱水过程中，含水相受到应力，会产生机械不稳定性，导致断层。 这种现象被认为是解释地球30至300公里深处地震的主要候选者，也是地震存在的所有深度的可能机制。 对这种现象的公认的解释基于这样的假设，即在这种脱水反应中产生的流体的体积大于脱水相的体积。 现在我们知道，在非常高的压力下，这种反应产生的总体积实际上小于母相的体积，这就提出了一个问题，即这种现象是否可以作为一种地震机制在深部运作。 该项目将利用独特的高压仪器对叶蛇纹石进行压力大于2.2 GPa的变形实验，物理条件是产品组合的总体积小于脱水阶段的体积，以测试在这些条件下是否存在机械不稳定性。 据推测，在这些条件下，主要的故障单元将从流体生成的拉伸微裂纹的形成切换到流体生成的压缩微反裂纹的形成，并且不稳定性将被保留。 ***

9725575 Green It has been known for 30 years that hydrous phases subjected to stress during dehydration at low pressures can develop a mechanical instability leading to faulting. This phenomenon is considered to be the leading candidate to explain earthquakes at depths between 30 and 300km in Earth and a possible mechanism at all depths at which earthquakes exist. The accepted explanation of this phenomenon rests on the assumption that the volume of fluid produced in such dehydration reactions is greater than the volume of the dehydrating phase. It is now known that at very high pressure, the total volume produced by such reactions is actually smaller than that of the parent phase, raising the question as to whether this phenomenon can operate as an earthquake mechanism at depth. This project will utilize unique high pressure instrumentation to conduct deformation experiments on antigorite serpentine under pressures greater than 2.2 GPa, physical conditions such that the total volume of the product assemblage is smaller than that of the dehydrating phase, in order to test whether a mechanical instability can exist under these conditions. It is hypothesized that under these conditions, the primary failure unit will switch from formation of fluid-generated tensile microcracks to formation of fluid- generated compressive microanticracks and that the instability will be preserved. ***