Collaborative Research: The role of Grain Boundary Migration in Water Weakening of Naturally Deformed Quartz

合作研究：晶界迁移在自然变形石英水弱化中的作用

• 批准号: 2120302
• 负责人: Sven Morgan
• 金额: $ 43.33万
• 依托单位: Regents of the University of Michigan - Dearborn
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2120302&HistoricalAwards=false
• 关键词: Collaborative; Research; role; Grain; Boundary

This research is designed to understand how sub-microscopic amounts of water, in minerals, can affect their strength. The overall effect of this tiny amount of water, in rocks, can have a big significance to how plates interact. For example, the Indian plate is colliding with the Asian plate to produce the Himalayas, but the strong Indian plate is not deforming while the weaker Asian plate is folding, faulting, experiencing earthquakes, and rising to produce the tallest mountains on Earth. The uplift of the Tibetan Plateau (which is five times the area of France) to an elevation of over 3 miles high (4.8 km) is remarkable. One possibility for this huge difference in plate strength is that deep rocks of the Indian plate are “dry” (no sub-microscopic water) whereas deep rocks of the Asian plate are “wet” (they contain some sub-microscopic water). Therefore, it is important to understand how and when this tiny amount of water gets into the rocks. This research project involves collecting rocks, in the mountains of California, along a 5 km transect where it is already known that rocks undergo the transition from strong to weak behavior. Detailed chemical analyses with advanced micro-imaging techniques will be conducted to determine exactly how and where along the transect the water gets into and out of the effected minerals. This research will support the education of one post-doctoral researcher, 4-6 undergraduate researchers, as well as 12 inner city Detroit High School (César Chávez Academy High School) students and three High School teachers who will travel to California with the research team to sample and learn about how water affects mountain building and plate tectonics. The effects of water on shaping this part of Earth are visually evident (previous glaciers, pre-historic and historic lake beds) and the effects of climate change, drought and fires, and human intervention (water piped to Los Angeles) will also be examined. The goal of this project is to determine if grain boundary migration allows water to enter the quartz crystal lattice and cause weakening. Oxygen isotope data will be used as the main proxy for tracking water infiltration. Harkless Formation quartzite samples will be collected along a 5 km transect, oriented perpendicular to the contact with the Eureka Valley-Joshua Flat-Beer Creek pluton in the White-Inyo Range of California. Contact metamorphism is first observed at 2.9 km from the pluton and concordancy occurs abruptly at 1.1 km where the Harkless folds 90° and is intensely attenuated. This abrupt transition is assumed to be a “rolling hinge”, that progressed outward as the pluton expanded during emplacement. Samples will be collected across this transition between regional structures and the forceful concordance of country rocks with the intrusion. Standard petrography and scanning electron microscopy techniques with advanced analysis including electron backscatter diffraction and cathodoluminescence, will be used to document; 1) where exactly grain boundary migration begins, where it becomes pervasive and, 2) where the crystallographic preferred orientation begins to develop and how it develops across the transition. Using a focused Secondary Ion Mass Spectrometer beam with a small spot size (6-10µm pit size), grain boundaries will be analyzed between unmigrated and migrated parts of the grains to determine the oxygen isotope signatures for tracking water infiltration and delineating the potential sources of this water. Fourier-transform infrared spectroscopy will also be used to document the overall concentrations of water (OH) on a microscopic scale in associated minerals. Trace element data will be input into several TitaniQ models to determine the temperatures during deformation and the overall Ti diffusional partial re-equilibration during the cooling history. This overall strategy will help correlate rock/mineral strength and deformation behavior with sub-microscopic water phenomena in minerals from intense heating and pressure during mountain building processes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

这项研究旨在了解矿物质中的亚显微镜水如何影响其强度。这种少量水在岩石中的总体影响对板的相互作用具有很大的意义。例如，印度板块与亚洲板碰撞以产生喜马拉雅板，但是强壮的印度板并没有变形，而较弱的亚洲板块折叠，断裂，经历地震并升起以产生地球上最高的山脉。藏族高原的升高（是法国地区的五倍）高度高3英里（4.8公里）。这种巨大差异的一种可能性是，印度板块的深岩石是“干”（没有亚显微镜水），而亚洲板块的深岩石是“湿”的（它们含有一些亚显微镜水）。因此，重要的是要了解这种少量水进入岩石的方式以及何时。该研究项目涉及在加利福尼亚山区的岩石沿5公里的样带收集岩石，在那里已经知道，从强行为到弱行为的过渡下，岩石是在岩石下的。将对先进的微成像技术进行详细的化学分析，以确定水如何以及沿何处的水进入和从有效的矿物出来。这项研究将支持一名博士后研究人员，4-6名本科研究人员，以及12名内城底特律高中（CésarChávezAcidemy高中）的学生和三名高中老师的教育，他们将与研究团队一起前往加利福尼亚州，以采样并了解水的山间建筑物和板块建筑物。水对地球这一部分的影响是视觉上的证据（以前的冰川，史前和历史悠久的湖泊床）以及攀岩变化，干旱和火灾的影响，以及人类干预（流向洛杉矶的水）。该项目的目的是确定晶界迁移是否允许水进入石英晶体晶格并导致弱化。氧同位素数据将用作跟踪水浸润的主要代理。将沿着与尤里卡山谷 - 乔舒亚（Eureka Valley-Joshua）flat-flat-beer creek pluton在加利福尼亚州白色Inyo系列的尤里卡山谷（Eureka Valley-Joshua Flat-Beer Creek Pluton）接触时，将沿着5公里的样带，垂直于5公里的样品收集无量的石英岩样品。接触变质首先是在距木形2.9公里处观察到的，一致性在1.1 km处突然发生，而无harkless折叠为90°，并诚实地减弱。假定这种突然的过渡是“滚动铰链”，随着岩体在扩展过程中的扩展，它向外前进。在区域结构之间的这种过渡和国家岩石与入侵之间的有力一致性之间，将收集样本。标准岩石摄影和扫描电子显微镜技术，具有先进的分析，包括电子反向散射衍射和阴极发光，用于记录； 1）晶界开始迁移的地方，其中它变得普遍，2）晶体学首选方向开始发展以及它如何在整个过渡中发展。使用斑点尺寸较小的聚焦二级离子质谱仪梁（凹坑尺寸为6-10μm），将在谷物的未迁移和迁移部分之间进行分析，以确定用于跟踪水渗透并描述潜在水源来源的氧同位素特征。傅立叶转换红外光谱也将用于在相关矿物中以微观尺度记录水的总浓度（OH）。痕量元素数据将被输入几个泰坦基模型，以确定在冷却历史记录期间变形过程中的温度和整体Ti扩散率部分重新启动。这种总体策略将有助于将岩石/矿物强度和变形行为与山区建筑过程中强烈的加热和压力的矿物质的岩石/矿物强度和变形行为与亚微观水现象相关联。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛影响的审查标准来评估通过评估而被认为是珍贵的支持。