Coupled Deformation and Metamorphism, Fabric Development, Rheological Evolution and Strain Localization

耦合变形和变质、织物开发、流变演化和应变定位

• 批准号: 0440063
• 负责人: Scott Johnson
• 金额: --
• 依托单位: University of Maine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0440063&HistoricalAwards=false
• 关键词: Coupled; Deformation; Metamorphism; Fabric; Development

When Earth's tectonic plates interact with one another the rocks that comprise them are deformed, commonly forming great mountain chains. During this deformation, the minerals that make up the rocks can become spatially or crystallographically aligned to form a fabric. The development of rock fabric is a primary factor affecting the strength, or rheological evolution of deforming rocks. Fabric development commonly involves coupling of both physical and chemical processes. For example, crenulation cleavage is the most common type of fabric in multiply deformed rocks, and its formation leads to extreme mineral segregation and rheological anisotropy. It is also commonly associated with the growth of large metamorphic minerals (porphyroblasts), which are used by structural geologists to infer deformation histories and mechanical quantities such as shear strain, shear strain rate and vorticity. Although crenulation cleavage is common throughout the world's mountain chains, and may play an important role in the localization of deformation across a range of scales, the details of its formation, and its possible mechanical significance, remain poorly understood. The investigators and their students are combining field- and laboratory-based studies with computer modeling to address the effects of rock fabric, particularly crenulation cleavage, on the rheological evolution of rocks. The chosen field area is located in the Appalachian mountains of western Maine. The results of this project will be incorporated into web-based educational modules that are intended as resources for earth-science teachers and students at all levels.

当地球的构造板块相互作用时，组成它们的岩石就会变形，通常会形成巨大的山脉。在这种变形过程中，构成岩石的矿物可以在空间上或晶体学上对齐，形成一种结构。岩石组构的发育是影响变形岩石强度或流变演化的主要因素。织物开发通常涉及物理和化学过程的耦合。例如，在多次变形的岩石中，锯齿状解理是最常见的组构类型，它的形成导致极端的矿物分离和流变各向异性。它也通常与大型变质矿物（成斑岩）的生长有关，这些矿物被构造地质学家用来推断变形历史和力学量，如剪切应变，剪切应变率和涡度。虽然锯齿状劈理在世界山脉中很常见，并且可能在一系列尺度的变形局部化中发挥重要作用，但其形成的细节及其可能的力学意义仍然知之甚少。研究人员和他们的学生正在将基于现场和实验室的研究与计算机建模相结合，以解决岩石组构，特别是锯齿状解理对岩石流变演化的影响。选定的领域领域是位于阿巴拉契亚山脉西部缅因州。该项目的成果将纳入以网络为基础的教育模块，作为各级地球科学教师和学生的资源。