Deformation and Microstructural Evolution of Harzburgite

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。板块构造是地球科学中的一个统一理论，它描述了地球在此过程中发生的变化。S面沿着狭窄的边界移动。这些板块边界对社会具有巨大的重要性，因为它们代表了许多自然灾害的焦点，包括地震和火山。为了理解板块边界的行为，我们必须了解这些边界内材料的物理性质。该奖项资助了在这些条件下模拟材料行为的努力。为了模拟这种行为，需要许多专门的设备，包括大型气动或液压机来产生高压条件。在高分辨率扫描电子显微镜中使用一种特殊类型的相机对实验进行分析。在这项研究中收集的数据将帮助我们了解沿板块边缘发生的物理过程，这将为广泛的地球物理研究提供信息。从自然变形橄榄岩的研究中可以明显看出，变形微观结构，如晶格优选取向（LPO），晶粒尺寸和形状，以及相偏析（或混合），继续演变，超出了几乎所有变形实验中获得的应变。由于变形微观结构既影响流变学，也影响地质和地球物理资料的解释，因此研究变形微观结构的形成和演化具有重要意义。正在进行两个系列的实验。(1)第一组实验研究了在大应变变形过程中白云岩和辉锌矿的微观结构和流变演化（γ10）。(2)第二系列实验将引入额外的复杂性，通过改变实验过程中的剪切意义来分析变形运动学与微观结构和流变演化动力学之间的反馈。这些实验是在具有扭转能力的帕特森型气体介质装置中进行的；另外的实验将在目前正在建造的旋转Drickamer装置中进行。显微结构分析将使用电子背散射衍射（EBSD）以及其他基于光学和电子显微镜的技术进行。本研究收集的数据将提高我们对(1)地幔次级相对变形的影响，(2)地幔剪切带的物理过程，(3)俯冲带和洋中脊等角流环境的地震各向异性的认识。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)Plate tectonics is a unifying theory in the Earth sciences that describes the processes by which Earth?s surface shifts along narrow boundaries. These plate boundaries are of tremendous importance to society, as they represent the foci of many natural hazards, including earthquakes and volcanoes. To understand the behavior of plate boundaries it is essential that we understand the physical properties of material within these boundaries. This award is funding an effort to simulate the behavior of materials at these conditions. To simulate this behavior, a number of specialized apparatuses are needed, including large pneumatic or hydraulic presses to generate high pressure conditions. Analysis of the experiments takes place using a particular type of camera in a high-resolution scanning electron microscope. The data that are collected in this study will help us understand the physical processes that occur along plate margins, which will inform a broad spectrum of geophysical research.It is evident from studies of naturally deformed peridotites that deformation microstructures such as lattice-preferred orientation (LPO), grain-size and shape, and phase segregation (or mixing), continue to evolve beyond the strains achieved in almost all deformation experiments. As deformation microstructures affect both rheology and the interpretation of geological and geophysical data, it is important for us to study their formation and evolution. Two series of experiments are being conducted. (1) The first set of experiments investigates microstructural and rheological evolution of dunite and harzburgite during deformation to very large strains (γ10). (2) The second series of experiments will introduce additional complexity by changing the sense of shear during experiments to analyze the feedback between the kinematics of deformation and the kinetics of microstructural and rheological evolution. These experiments are being conducted in a Paterson-type gas medium apparatus with torsion capability; additional experiments will be conducted in a rotational Drickamer apparatus currently under construction. Microstructural analysis will be conducting using electron backscatter diffraction (EBSD), as well as other optical and electron microscope-based techniques. The data collected in this study will improve our understanding of (1) the effects of secondary phases on deformation in the mantle, (2) physical processes in mantle shear zones, and (3) seismic anisotropy in corner flow environments such as subduction zones and mid-ocean ridges.