CSEDI Collaborative Research: Grand Challenge for Experimental Study of Plastic Deformation Under Deep Earth Conditions

该研究计划的目标是开发和利用实验能力，研究岩石在地球深部条件下的塑性特性。 在地质时代，我们看到大陆被撕裂，板块边界被地震和火山打断。 然而，在地球的广大地区，这些过程进展顺利，缓慢。 虽然地震表现了地球变形的动力学特征，但大陆的缓慢运动提供了驱动力。 这种大规模运动的启动过程是整个地幔岩石的塑性变形。 板块构造论的基础是这样一种观点，即岩石在地球深部的高压和高温下会缓慢而稳定地变形。 这项研究计划将继续建立实验能力，以量化岩石的塑性特性作为地球深度的函数。 该计划在高压设备开发和国家同步加速器设施的交界处工作，可以提供强烈的X射线探针。 这一联盟承诺的实验能力，增加了地球的深度范围，我们可以访问，高精度测量，从以前的研究的100倍。 来自该计划的数据将使地球演化模型的测试和修改成为可能。这些变形设施，使新的方向，在地幔压力和温度，包括弹性波衰减地震频率，反应动力学，热扩散率，和晶格优选取向的关系，变形几何形状，地震各向异性的流动历史的地球材料研究。它们还为研究下一代发电厂等极端条件下的材料强度和塑性提供了潜在的设施和技术诀窍。应力、应变、压力和温度是变形实验中需要测量的主要变量。在国家同步加速器（高级光子源和国家同步加速器光源）的帮助下，研究人员开发了进行这些测量的工具。他们还建造了第一代高压设备，将“大容量高压”技术引入变形机。他们现在能够在比10年前高1到2个数量级的压力下进行精确的流变学实验。下一阶段是充分利用现有的流体静力高压设备，包括制造多晶金刚石的先进技术，以达到下地幔条件。 该计划的目标是：1）将变形实验的压力范围增加到30 - 40 GPa，深入到下地幔，2）通过硬件和软件开发的结合提高应力和应变的测量分辨率，3）能够同时测量样品的属性，如晶粒的优选取向和声速，4）探索先进的技术，如同步加速器社区开发的技术，但可能对地球科学目标有用。 这些通常是高风险，但高回报的工具，如白色光束劳厄衍射，可以产生非常详细的信息，个别晶粒内的多晶体。

The goal of this research program is to develop and utilize experimental capabilities for studying the plastic properties of rocks at conditions of the deep Earth. Over geologic time we see that continents have been ripped apart with plate boundaries punctuated by earthquakes and volcanoes. However, over the vast regions of the Earth, these processes proceed smoothly and slowly. While earthquakes express the dynamic character of Earth deformation, the slow movement of the continents provides the driving force. The enabling process for this large-scale motion is the plastic deformation of rocks throughout the Earth's mantle. The foundation of plate tectonics rests on the contention that rocks deform slowly but surely at the high pressure and temperature of the deep Earth. This research program is to continue to build experimental capabilities to quantify the plastic character of rocks as a function of depth in the Earth. This program works at the juncture of high-pressure apparatus development and national synchrotron facilities that can provide intense x-ray probes. This union promises experimental capabilities that increase the depth range of the Earth that we can access, with high precision measurement, by a factor of 100 from previous studies. The data that will come from this program will enable testing and modifying of models of Earth evolution. These deformation facilities enable new directions in Earth material research at mantle pressure and temperature including elastic wave attenuation at seismic frequencies, reaction kinetics, thermal diffusivity, and relationship of lattice preferred orientation to deformation geometry, which links seismic anisotropy to flow history. They also provide a potential facility and technical knowhow for studying material strength and plasticity at extreme conditions such as those generated in the next generation power plants.Stress, strain, pressure, and temperature are the primary variables that need to be measured during a deformation experiment. With the aid of the national synchrotrons (the Advanced Photon Source and the National Synchrotron Light Source), the investigators have developed the tools to make these measurements. They have also built the first generation of high-pressure apparatus for introducing 'large - volume high pressure' technology into deformation machines. They are now able to make accurate rheology experiments at pressures 1 to 2 orders of magnitude higher than could be achieved 10 years ago. The next phase is to take full advantage of the current hydrostatic high-pressure equipment, including advanced technologies for making polycrystalline diamonds, to reach lower mantle conditions. The goals of this program are to 1) increase the pressure range for deformation experiments to 30 - 40 GPa, well into the lower mantle, 2) improve measurement resolution of stress and strain with a combination of hardware and software developments, 3) enable simultaneous measurements of a sample properties such as preferred orientation of grains and acoustic velocity, 4) explore advanced techniques such as those developed by the synchrotron community but may be useful to earth science goals. These are often high risk, but high return tools such as white beam Laue diffraction that could yield very detailed information about the individual grains within a polycrystal.