Low Temperature Dynamic Recrystallization: Processes and Rheological Consequences

低温动态重结晶：过程和流变后果

• 批准号: 0208150
• 负责人: Jan Tullis
• 金额: $ 21.12万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2005-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0208150&HistoricalAwards=false
• 关键词: Low; Temperature; Dynamic; Recrystallization; Processes

EAR-0208150Jan TullisLower crustal and upper mantle rocks commonly show localized ductile shear zones, characterized by a finer grain size than the host rocks; such strain localization implies a strain weakening process. Dynamic recrystallization accompanying dislocation creep is a major process tending to reduce grain size, and several distinct mechanisms of dynamic recrystallization have been identified; for quartz these define three 'regimes' of dislocation creep, with distinctly different microstructures as well as mechanical behavior. The low temperature, higher stress process of grain boundary bulging produces strain weakening and localization in both quartz and feldspar, whereas the higher temperature process of subgrain rotation does not. Previous work on olivine has focussed on high temperature, low stress creep, although there are indications of bulging recrystallization and strain localization at lower temperatures. The goals of this project are to quantify the constitutive behavior and piezometer relation for bulging recrystallization in quartz, and for olivine to verify the existence of this process, determine the conditions over which it operates, and quantify the strain weakening it produces. The results should allow more accurate modelling of lithospheric deformation.

EAR-0208150Jan Tull下地壳和上地幔岩石通常表现为局部韧性剪切带，其特征是粒度比寄主岩石更细；这种应变局部化意味着应变弱化过程。动态再结晶伴随位错蠕变是倾向于减小晶粒度的主要过程，已经确定了几种不同的动态再结晶机制；对于石英来说，这三种机制定义了位错蠕变的三个‘区域’，具有明显不同的微观结构和力学行为。晶界膨胀的低温、高应力过程在石英和长石中都产生应变弱化和局部化，而亚晶旋转的高温过程不产生应变弱化和局部化。以前对橄榄石的研究主要集中在高温、低应力蠕变上，尽管有迹象表明在较低温度下会发生鼓胀重结晶和应变局部化。该项目的目标是量化石英中膨胀重结晶的本构行为和压力计关系，并对橄榄石验证这一过程的存在，确定其工作条件，并量化其产生的削弱应变。这些结果应该可以更准确地模拟岩石圈的变形。