Collaborative Research: COMPRES Grand Challenge for Experimental Study of Plastic Deformation under Deep Earth Conditions

地球材料的定量流变测量只在相对较低的压力条件下进行，对应于~60公里或更小的深度。该项目的主要目的是通过技术发展，将这一极限扩展到至少800公里，不仅覆盖上地幔，还包括过渡带和下地幔。我们建议与地球科学材料特性研究联盟（COMPRES）合作建立一个新的机构间项目，利用国家设施和教育项目的基础设施来运作，并将这些设施的能力扩展到更广泛的科学界。通过机构间合作，我们将开发两种新型设备（改进的立方设备（D-DIA）和旋转Drickamer设备（RDA）），并进一步改进使用多砧设备（MA）的成熟变形技术。D-DIA和RDA（以及MA）都可以很容易地安装到同步辐射设施中，以便在高压和温度条件下进行应力和应变的定量测量。D-DIA适用于定量流变学测量，包括剪切局部化和由此产生的不稳定性，而RDA具有在高压下进行大应变变形实验的独特能力，这是研究晶格优选取向的重要特征。这些装置将用于获得高压、高温条件下（~15-25 GPa, ~2000 K）地球和行星材料流变特性和变形诱导微观结构的第一个定量数据集。这些测量的结果将有助于更好地理解(i)整个地幔流变特性的径向和横向变化，（ii）流变行为与包括相变在内的化学反应的相互作用，以及（iii）变形引起的微观结构的性质，如晶格优先取向（导致地震各向异性）。这样开发的独特设施将可供大型矿物和岩石物理团体使用，并将大大加强矿物和岩石物理研究对广泛的固体地球科学的贡献。

Karato0136181Quantitative rheological measurements on Earth materials have been conducted only under relatively low-pressure conditions corresponding to the depth of ~60 km or less. The main thrust of this project is to extend this limit, through technical developments, at least to ~800 km covering not only the upper mantle but also the transition zone and the lower mantle. We propose to establish a new inter-institutional program coordinated with COMPRES (Consortium for Materials Property Research in the Earth Sciences) by utilizing the infrastructure for operation of national facilities and educational program, and we will expand the capabilities of these facilities for the broader scientific community. Through inter-institutional collaboration, we will develop two new types of apparatus (a modified cubic apparatus (D-DIA) and a rotational Drickamer apparatus (RDA)) in addition to further improvements to the well-established deformation techniques using a multianvil apparatus (MA). Both D-DIA and RDA (as well as MA) can readily be fitted to synchrotron radiation facilities to allow quantitative measurements of stress and strain at high-pressure and temperature conditions. D-DIA is suited for quantitative rheology measurements including shear localization and resultant instabilities while RDA has a unique capability of large strain deformation experiments at high-pressures, an important feature for study of lattice preferred orientation. These apparatus will be used to obtain the first quantitative data set on rheological properties and deformation-induced microstructures of Earth and planetary materials under high-pressure, high-temperature conditions (to ~15-25 GPa, ~2000 K). The results of such measurements will contribute to better understand (i) the radial and lateral variation of rheological properties for whole mantle, (ii) the interaction of rheological behavior with chemical reactions including phase transformations, and (iii) the nature of deformation-induced microstructures such as lattice preferred orientation (which causes seismic anisotropy). The unique facility thus developed will be accessible to a large mineral and rock physics community and will significantly enhance the contribution of mineral and rock physics research to a wide range of solid Earth sciences.