Microstructure in Marble: Evolution of Strength in Natural and Laboratory Deformation

大理石的微观结构：自然变形和实验室变形强度的演变

• 批准号: 1118562
• 负责人: Brian Evans
• 金额: $ 43.48万
• 依托单位: Massachusetts Institute of Technology
• 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: 2011-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1118562&HistoricalAwards=false
• 关键词: Microstructure; Marble; Evolution; Strength; Natural

Strain localization is common in crustal orogenic belts, where shear zones are often found within carbonate rocks. Many field studies indicate that localization is accompanied by striking changes in such aspects of rock structure as grain size, lattice (crystallographic) preferred orientation, major and accessory phase chemistry, pore geometry, and phase dispersion. Previous laboratory studies indicate that creep strength changes over large intervals of strain, and that grain size, grain shape, and lattice preferred orientation evolve concurrently. Recent work also showed that the kinetics of recrystallization scaled with the rate of work done during deformation, that lattice preferred orientation could be strongly affected by the shape and dispersion parameters of accessory phases, and that Mg solid solutes influenced both grain-boundary mobility and the transition from diffusion to dislocation creep. In order to understand localization and evolution of strength during natural deformation, the size of each effect and the relative kinetics of the candidate mechanisms must be known. This project will make observations of deformation microstructure in carbonate rocks from shear zones in the Swiss Alps, and in samples deformed in the laboratory and in collaboration with workers at the Universities of Liverpool and Manchester, UK. Mechanical tests will include simple-shear, torsion, and conventional triaxial loading of natural and synthetic marbles at strain rates of 10^-2-10^-6 ^-1, confining pressures less than 300 MPa, and temperature between 500-1000 K. Two new techniques, microstrain mapping, and sequential microanalysis at high shear-strains, will be used to understand the kinetics and partitioning of strain amongst the various deformation mechanisms.By combining thorough fieldwork, careful experiments, and detailed observations, the aim is to bridge some of the gaps between laboratory and field studies. In addition to increasing knowledge of tectonics and mechanical properties of rocks, the laboratory work will improve the database for the mechanical behavior of carbonate rocks, which are of considerable interest in such engineering applications as enhanced recovery of oil in limestone reservoirs, sequestration of carbon dioxide in fractured and sedimentary carbonate formations, and designing engineered underground structures.

应变定位在地壳造山带中很常见，在碳酸盐岩石中经常发现剪切区。许多现场研究表明，定位伴随着晶粒尺寸，晶格（晶体学）优选方向，主要和附属相化学，孔几何形状和相位分散的岩石结构方面的惊人变化。先前的实验室研究表明，蠕变强度在较大的应变间隔内发生变化，晶粒尺寸，晶粒形状和晶格首选方向同时发展。最近的工作还表明，重结晶的动力学随着变形过程中所做的工作速率缩放，晶格首选方向可能会受到辅助阶段的形状和分散参数的强烈影响，并且MG固体溶质都会影响晶粒 - 结合型迁移率，并且从扩散到脱离蠕动。为了理解自然变形过程中强度的定位和演变，必须知道每种效应的大小和候选机制的相对动力学。该项目将观察瑞士阿尔卑斯山剪切区的碳酸盐岩石岩石中的变形微观结构，以及在实验室中畸形的样品以及与英国利物浦和曼彻斯特大学的工人合作的样品。 Mechanical tests will include simple-shear, torsion, and conventional triaxial loading of natural and synthetic marbles at strain rates of 10^-2-10^-6 ^-1, confining pressures less than 300 MPa, and temperature between 500-1000 K. Two new techniques, microstrain mapping, and sequential microanalysis at high shear-strains, will be used to understand the kinetics and partitioning of strain amongst the various变形机制。通过结合彻底的现场工作，仔细的实验​​和详细的观察，目的是弥合实验室和现场研究之间的一些差距。除了增加岩石构造学和机械性能的知识外，实验室工作还将改善碳酸盐岩石机械行为的数据库，碳酸盐岩石的机械行为，这在诸如在石灰石储层中增强石油恢复的工程应用，二氧化碳在易碎的碳二氧化物中的序列化的碳纤维储层中，在易碎的碳酸盐中恢复了碳酸盐和沉积的碳酸盐和沉积的地下和设计构造和构造工程，并进行了设计。