Early Career: Development of a New Rock Deformation Apparatus for Investigating Earth's Upper Mantle

这项建议概述了继续发展大体积扭转仪(LVT)的计划，这是一种新的岩石变形仪器，旨在研究地壳和地幔顶部压力和温度下的微结构现象。开发一种新的岩石变形仪器将在许多方面使社区受益。该设备将针对关键的和未被调查的变形条件进行优化，这将为探索地球上地幔和其他类地行星的内部开辟新的途径。这项支持将有助于培养一名早期职业科学家，并将加强岩石力学研究工程师的培训和发展。学生和博士后研究人员的教育机会将是巨大的，因为他们将参与新仪器的设计、校准和实施的所有阶段。新仪器的设计将公之于众，其构造细节将通过互联网发布。获得这些设计将使其他早期职业科学家和成熟的研究人员受益，因为他们正在计划他们的第一个实验室或扩大现有的实验室。岩石变形仪器无法商业化，努力设计具有独特能力的设备对于推进岩石力学以及构造地质学和地球物理学的许多活跃研究领域至关重要。LVT的一个关键特征是它在扭转时使材料变形。这种几何形状的好处是，样品可以变形成极大的应变。在较低压力和温度下的研究强调了大应变对形成稳态变形微观组织的重要性。产生粘性各向异性的微结构和重现地幔剪切带中观察到的微结构需要大应变；粘性各向异性和局部变形是控制板块动力学的关键因素。还需要大应变来研究晶体组构的产生；这些组构与地震各向异性之间的关系对于解释地幔中的流动模式是必不可少的，特别是在板块边界附近。通过抑制意外的相变、熔化和脆性变形，这种仪器设计可以提高压力，从而扩大了可以研究的材料和行星条件的范围。

This proposal outlines a plan for the continued development of the Large Volume Torsion apparatus (LVT), a new rock deformation apparatus designed to investigate microstructural phenomena at the pressures and temperatures of Earth's crust and uppermost mantle. The development of a new rock deformation apparatus will benefit the community in a number of ways. The apparatus will be optimized for a critical and under-investigated range of deformation conditions, which will open new avenues for exploration of Earth's upper mantle and the interiors of other terrestrial planets. This support will assist the development of an early career scientist and will also enhance the training and development of a research engineer in rock mechanics. Educational opportunities for students and postdoctoral researchers will be significant, as they will participate in all phases of the design, calibration, and implementation of the new apparatus. The design of the new apparatus will be made publically available, and the details of its construction will be disseminated via the Internet. Access to these designs will benefit other early career scientists and established researchers as they plan their first labs or expand existing labs.Rock deformation apparatus are not available commercially and efforts to design devices with unique capabilities are essential for the advancement of rock mechanics, and many active areas of study within structural geology and geophysics. One critical feature of the LVT is that it deforms materials in torsion. The benefit of this geometry is that samples can be deformed to extremely large strains. Research at lower pressures and temperatures has emphasized the importance of large strains for developing steady state deformation microstructures. Large strains are needed to generate microstructures that are viscously anisotropic and to reproduce microstructures observed in mantle shear zones; viscous anisotropy and localized deformation are key factors that control the dynamics of plates. Large strains are also needed to investigate the generation of crystallographic fabrics; the relationships between these fabrics and seismic anisotropy are essential for interpreting patterns of flow in the mantle, particularly in the vicinity of plate boundaries. Elevated pressures, which are possible with this apparatus design, expand the range of materials and planetary conditions that can be studied, by suppressing unwantedphase changes, melting, and brittle deformation.