Development of Microstructure and Creep Strength of Marble

大理石微观结构和蠕变强度的发展

• 批准号: 1451022
• 负责人: Brian Evans
• 金额: $ 30万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1451022&HistoricalAwards=false
• 关键词: Development; Microstructure; Creep; Strength; Marble

Carbonate rocks (limestone, dolomite, marble) are important constituents of the Earth's crust. Notably, layers of limestone and dolomite are among the folded and faulted units within the fold-and-thrust belts of the major mountain ranges - the Idaho-Wyoming overthrust belt and the Alpine nappes, for example. These belts contain major hydrocarbon reservoirs. The processes by which the constituent minerals deform is essential in the understanding of how these belts form and how the deep crust deforms. This project explores the detailed mechanisms by which carbonate rocks deform through a series of experiments in which the constituent minerals are deformed over a range of strain rates, confining pressures, and temperatures. A new novel micro-scale strain mapping method when coupled with various high-resolution microscopy methods, will allow for unprecedented understanding of the atomic scale mechanisms of carbonate mineral deformation. Results will be compared to naturally deformed carbonate rocks collected from the Alps. The project would advance desired societal outcomes through: (1) development of a globally competitive STEM workforce through postdoctoral fellow training; (2) increased partnerships through international collaboration; and (3) enhanced infrastructure for education through development of Open Courseware materials.The main goals of this project are to investigate the physics and kinetics of the evolution of microstructure and strength of carbonate rocks during creep, and to identify characteristic elements of microstructure necessary to interpret the mechanical history of naturally deformed rocks. The project, in collaboration with scientists at GFZ German Research Centre for Geosciences and Université Montpellier builds on previous work by this research group and will include testing and observations of the microstructure in samples deformed under conventional triaxial and torsion loading of natural and synthetic marbles at shear strain rates between 10^-3 and 10^-6 per second, confining pressures less than 300 MPa, and temperatures between 500-1000 K. Observations of microstructure will be made using optical microscopes, SEM, TEM, and EBSD to correlate dislocation structure, generation of LPO, dynamic recrystallization, and the evolution of strength. Two novel techniques, micro-scale strain mapping and sequential microanalyses, will be used to understand the kinetics and partitioning of strain amongst the deformation mechanisms. Although lab investigations are important, thorough and fundamental understanding of tectonics will come only by combining and reconciling lab experiments, observations of field- and micro- structure, geophysical investigations, and theoretical and computational treatments. Thus, continued observations of microstructures in naturally deformed marbles are an important part of this project. In collaboration with researchers at Universität of Bern, the team will observe microstructure in mylonites from the Helvetic Nappes, which provides opportunities to investigate the influence of temperature on strain localization, to study the influence of varying quartz and dolomite content on strain localization within the carbonates, and to correlate dislocation microstructure, grain structure, and phase chemistry at locations where deformation conditions are well constrained.

碳酸盐岩（石灰石、白云岩、大理石）是地壳的重要组成部分。值得注意的是，石灰岩和白云岩层位于主要山脉的褶皱和逆冲带（例如爱达荷-怀俄明州逆冲带和阿尔卑斯推覆带）内的褶皱和断裂单元中。这些带含有主要的油气储集层。组成矿物变形的过程对于理解这些带是如何形成的以及深部地壳是如何变形的是必不可少的。本项目通过一系列实验探索碳酸盐岩变形的详细机制，在这些实验中，组成矿物在一系列应变速率、围压和温度下变形。一种新的微尺度应变映射方法与各种高分辨率显微镜方法相结合，将使人们对碳酸盐矿物变形的原子尺度机制有前所未有的了解。结果将与从阿尔卑斯山收集的自然变形的碳酸盐岩进行比较。该项目将通过以下方式促进预期的社会成果：(1)通过博士后培训培养具有全球竞争力的STEM劳动力；(2)通过国际合作加强伙伴关系；(3)通过开发开放课件材料加强教育基础设施。该项目的主要目标是研究碳酸盐岩蠕变过程中微观结构和强度演化的物理和动力学，并确定解释自然变形岩石力学历史所需的微观结构特征元素。该项目是与GFZ德国地球科学研究中心和蒙彼利埃大学的科学家合作进行的，以该研究小组之前的工作为基础，将包括测试和观察在传统三轴和天然大理石和合成大理石的扭转载荷下变形的样品的微观结构，剪切应变率为10^-3至10^-6 /秒，围压小于300 MPa，温度在500-1000 K之间。利用光学显微镜、SEM、TEM和EBSD观察微观结构，分析位错结构、LPO生成、动态再结晶和强度演变。两种新技术，微尺度应变映射和顺序微分析，将用于了解动力学和分配应变之间的变形机制。虽然实验室研究很重要，但只有结合实验室实验、野外和微观结构观测、地球物理调查以及理论和计算处理，才能彻底和基本地理解构造。因此，继续观察自然变形大理岩的微观结构是本项目的重要组成部分。与伯尔尼Universität的研究人员合作，该团队将观察Helvetic推覆体中糜伦岩的微观结构，这为研究温度对应变局部化的影响，研究碳酸盐中不同石英和白云石含量对应变局部化的影响，以及在变形条件受到良好约束的位置将位错微观结构、晶粒结构和相化学联系起来提供了机会。

项目成果

Heterogeneity of inelastic strain during creep of Carrara marble: Microscale strain measurement technique: MICROSCALE STRAIN MEASUREMENT TECHNIQUE

卡拉拉大理石蠕变过程中非弹性应变的不均匀性：微尺度应变测量技术：微尺度应变测量技术

• DOI: 10.1002/2016jb012970
• 发表时间: 2016
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: Quintanilla-Terminel, Alejandra;Evans, Brian
• 通讯作者: Evans, Brian

Microscale and nanoscale strain mapping techniques applied to creep of rocks

应用于岩石蠕变的微米级和纳米级应变映射技术

• DOI: 10.5194/se-8-751-2017
• 发表时间: 2017
• 期刊: Solid Earth
• 影响因子: 3.4
• 作者: Quintanilla-Terminel, Alejandra;Zimmerman, Mark E.;Evans, Brian;Kohlstedt, David L.
• 通讯作者: Kohlstedt, David L.