In situ Study of Lattice Preferred Orientation at Mantle Conditions

地幔条件下晶格择优取向的原位研究

• 批准号: 1045629
• 负责人: Donald Weidner
• 金额: $ 38.11万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-02-15 至 2015-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1045629&HistoricalAwards=false
• 关键词: situ; Study; Lattice; Preferred; Orientation

The solid portion of the Earth is extremely dynamic on a million year time scale. Plastic flow of the solid leaves a history in the form of alignment of the crystalline building blocks of rocks. Unraveling this history requires understanding the processes that create this fabric through experiments at the pressure and temperature conditions of the Earth's interior. Here we capitalize on new facilities that have been developed at the National Synchrotron Light Source to probe mineral systems subjected to the deforming conditions of the deep Earth. The goal is to better understand these processes, to define the time scale for changing the induced fabric, and to define the control of the pressure and temperature conditions on the efficiency of producing these fabrics.The dynamic history of the Earth can now be constrained by the anisotropy of seismic wave velocities. Texture in the rocks of the deep Earth is understood to give rise to this anisotropy and it is the plastic flow of the rocks that creates the texture. This breakthrough in understanding was enabled by laboratory investigations of rock deformation at mantle conditions. The former approaches generally resolve the end-product of large deformation. The efficiency of fabric production as a function of the environmental variables is still not well defined. The degree to which small strains will create elastic anisotropies has not been experimentally quantified. We lack a clear understanding of the interactions of the grains during the texture formation such as the relative roles of recrystallization and dislocation glide. New studies need to occur at mantle pressures and temperatures to assure that the proper processes are active. The research of this proposal will provide important information about plastic deformation of solids in general. It will provide metrics that can be used to evaluate the amount of deformation and the mechanism of deformation. This provides potential tools for assessing the failure state of structural materials in engineering applications. Preliminary experiments with sinusoidal stress fields indicate that the techniques proposed here have a strong probability of success and are well defined by theoretical models.

地球的固体部分在百万年的时间尺度上是极其动态的。 固体的塑性流动以岩石的结晶构造块的排列的形式留下了历史。 要解开这段历史，需要通过在地球内部的压力和温度条件下进行实验，了解形成这种结构的过程。 在这里，我们利用国家同步加速器光源开发的新设施来探测受到地球深处变形条件影响的矿物系统。 我们的目标是更好地理解这些过程，以定义的时间尺度为改变的诱导fabrics.The地球的动力学历史，现在可以约束地震波速度的各向异性的效率，并确定控制的压力和温度条件。 据了解，地球深部岩石的纹理会产生这种各向异性，而正是岩石的塑性流动产生了这种纹理。 这一认识上的突破是通过对地幔条件下岩石变形的实验室研究实现的。 前一种方法一般都能解决大变形的最终产物。 作为环境变量的函数的织物生产效率仍然没有很好地定义。 小应变将产生弹性各向异性的程度尚未在实验上量化。 对于织构形成过程中晶粒间的相互作用，如再结晶和位错滑移的相对作用，我们缺乏清晰的认识。 需要对地幔压力和温度进行新的研究，以确保适当的过程是活跃的。这一建议的研究将提供有关一般固体塑性变形的重要信息。 它将提供可用于评估变形量和变形机制的度量。 这为工程应用中评估结构材料的失效状态提供了潜在的工具。正弦应力场的初步实验表明，这里提出的技术具有很强的成功概率，并通过理论模型得到了很好的定义。