Collaborative Research: Linking Fluid-rock Interaction and Strain Accumulation in a Naturally Deformed Diamictite, Implications for Hydrolytic Weakening and Reaction Softening

合作研究：将流体-岩石相互作用与自然变形杂岩中的应变积累联系起来，对水解弱化和反应软化的影响

• 批准号: 0838240
• 负责人: Dyanna Czeck
• 金额: $ 16.64万
• 依托单位: University of Wisconsin-Milwaukee
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0838240&HistoricalAwards=false
• 关键词: Collaborative; Research; Linking; Fluid; rock

Understanding the strength and mechanical behavior of the continental lithosphere is a first-order issue in tectonics. Mechanical behavior of the lithosphere depends mostly on the development of weak and strong layers. In the laboratory, insight into this process can be gained through the study of reactions and deformation mechanisms in minerals, fluid flow, and fabric evolution. The wide range of temporal and spatial scales at work in deforming lithosphere presents challenges in extrapolating results from laboratory studies to natural mountain belts. Through a study of deformed diamictites, rocks composed of mainly mud and cobbles, these researchers will evaluate processes that reduced the rock strength and resulted in concentrated deformation. The deformation will be addressed through measurements of the shape changes that the cobbles have undergone. These studies will improve our understanding of how strong and weak parts of the crust evolve during mountain building, and processes that localize deformation into fault zones and partly control nucleation of large earthquakes. The investigators will integrate field, microtextural, and microchemical analyses of variably deformed and altered granitic gneiss and quartzite to quantify relationships between progressive strain, deformation mechanisms, and fluid-chemical processes. The diamictite displays a km-scale gradient in bulk deformation intensity, providing a record of hydrolytic weakening and reaction softening processes. Strain will be estimated for different clast types and sizes using the Rf/?Ö technique. Volume change will be estimated from geochemical changes and microstructural relations. Deformation mechanisms will be evaluated from petrographic studies of microstructures, combined with electron backscatter diffraction analysis of lattice preferred orientation and subgrain boundaries. Amounts and locations of water and related species, which control hydrolytic weakening, will be evaluated using Fourier transform infrared spectroscopy and synchrotron infrared radiation. Cathodoluminescence will provide data on locations of quartz neocrystallization and healed microcracks. Changes in bulk chemical composition of clasts and matrix will be quantified using X-ray fluorescence, X-ray spectral mapping and scanning electron microscopy. This combination of techniques will provide new information on the interactions between deformation, fluids, and chemical processes during progressive strain.

了解大陆岩石圈的强度和力学行为是构造学中的首要问题。 岩石圈的力学行为主要取决于弱层和强层的发育。 在实验室中，可以通过研究矿物、流体流动和织物演化的反应和变形机制来深入了解这一过程。 岩石圈变形的时间和空间尺度范围广泛，这给将实验室研究结果外推到自然山带带来了挑战。 通过对变形混积岩（主要由泥和卵石组成的岩石）的研究，这些研究人员将评估降低岩石强度并导致集中变形的过程。 将通过测量鹅卵石所经历的形状变化来解决变形问题。 这些研究将提高我们对造山过程中地壳强弱部分如何演化的理解，以及将变形局部化到断层带并部分控制大地震成核的过程。 研究人员将对不同变形和蚀变的花岗片麻岩和石英岩进行现场、微观结构和微观化学分析，以量化渐进应变、变形机制和流体化学过程之间的关系。 混积岩在体积变形强度上表现出公里级的梯度，提供了水解弱化和反应软化过程的记录。 将使用 Rf/?Ö 技术估计不同碎屑类型和尺寸的应变。 体积变化将根据地球化学变化和微观结构关系来估计。 变形机制将通过微观结构的岩相学研究，结合晶格择优取向和亚晶界的电子背散射衍射分析来评估。 将使用傅里叶变换红外光谱和同步加速器红外辐射来评估控制水解减弱的水和相关物种的数量和位置。 阴极发光将提供有关石英新结晶和愈合微裂纹位置的数据。 碎屑和基质的大量化学成分的变化将使用 X 射线荧光、X 射线光谱图和扫描电子显微镜进行量化。 这种技术的组合将提供有关渐进应变过程中变形、流体和化学过程之间相互作用的新信息。