Petrofabric and Compositional Controls of Physical Properties Across the Granulite - Eclogite Transition

麻粒岩-榴辉岩转变过程中物理性质的岩石组构和成分控制

• 批准号: 9118318
• 负责人: David Fountain
• 金额: $ 7.98万
• 依托单位: University of Wyoming
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-02-15 至 1995-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9118318&HistoricalAwards=false
• 关键词: Petrofabric; Compositional; Controls; Physical; Properties

Previous investigation of the garnet granulite-eclogite facies transition exposed on Holsnoy Island, southwest Norway, suggests that seismic velocity and density increases across a sharp (1 m thick) transition. The magnitude of the changes are postulated to be related to compositional changes (silica depletion and relative enrichment of Fe2O3, MgO, and CaO) caused by fluid transport during metamorphism plus fabric development during deformation. Detailed sampling, using paleomag drills, across the exposed reaction fronts will be carried out to test this idea. Resultant mineralogical and chemical compositional determinations will be compared to seismic velocity measurements at high confining pressure in order to understand the factors controlling the variations in velocity. Detailed petrofabric analysis of major mineral phases in eclogites and granulites will be made with standard U-stage methods. Seismic velocity will be calculated from the preferred orientation data and tested against velocities determined in the laboratory at high confining pressure.

先前对挪威西南部霍尔斯诺伊岛上发现的石榴石麻粒岩-榴辉岩相转变的研究表明，地震速度和密度在陡峭(1米厚)的转变过程中增加。这些变化的大小被认为与变质过程中流体输运和变形过程中组构发展引起的成分变化(二氧化硅亏损和Fe2O、MgO和CaO的相对富集性)有关。在暴露的反应前沿，将使用古地标钻探进行详细采样，以检验这一想法。所得到的矿物学和化学成分测定将与高围压下的地震速度测量进行比较，以了解控制速度变化的因素。榴辉岩和麻粒岩中主要矿物相的岩石组构分析将用标准的U-Stage方法进行。地震速度将根据优先取向数据计算，并与实验室在高围压下确定的速度进行对比测试。