Mineral Chemistry of Mantle Eclogites

该项目将利用各种分析和理论 更好地了解榴辉岩包裹体起源的方法 非洲南部的金伯利岩。 第一个目标是 表征常量和微量元素， 原生相之间的放射成因同位素关系 私家侦探 将完成并公布一项初步研究结果， 化学成分多样的一套样品，包括主要和 微量元素、氧、Sm-Nd和Rb-Sr同位素。 做 为此，他将需要柯石英的额外氧同位素数据 石榴石的Sm-Nd和Rb-Sr数据。 除了完成 初步研究，他将进行晶体化学 常量、微量元素和氧同位素模拟 这些岩石中的分馏，基于压缩性 测量和额外的结构改进， 温度和升高的温度。 第二个目标是 主要和微量元素的化学特性 在小脉和颗粒中形成的次生相 这些样本中的边界，似乎是 深部交代作用 这将通过电子探针来完成 连同这些样品的分析SEM和TEM显微岩相学， 似乎与主体化学相关的相 榴辉岩 这些研究应该更好地确定 榴辉岩成分的变化，这将产生更大的 了解上地幔的化学动力学。 对这一建议的供资水平从最初的 请拨的123 603美元将减少分析， 使用分析TEM，这是最昂贵的 分析技术。 我们也无法支持全面的- 在这项研究中，虽然我们预计 从其他来源获得学生支持，这可能是部分 适用于这个项目。 支持T。McCormick是 从全职的25%略降至20%。 所附 两年期订正预算约为78 400美元， 这些变化。 按所附订正预算的供资水平， 我们预计，在了解预算方面将取得重大进展， 未来两年上地幔的化学动力学

This project will utilize various analytical and theoretical methods to better understand the origin of eclogite inclusions in kimberlites of southern Africa. The first objective is to characterize the major and trace element and stable and radiogenic isotopic relationships among primary phases. The P.I. will complete and publish the results of a preliminary study on a chemically diverse suite of samples, including data on major and trace elements, and oxygen and Sm-Nd and Rb-Sr isotopes. To do this he will require additional oxygen isotopic data on coesite and Sm-Nd and Rb-Sr data on garnet. In addition to completion of the preliminary study, he will undertake crystal chemical modeling of major and trace element and oxygen isotope fractionation in these rocks, based on compressibility measurements and additional structure refinements at room temperature and elevated temperature. A second objective is to characterize the major and trace-element chemistry of the secondary phases that have formed in small veins and grain boundaries in these samples, and appear to be the result of metasomatism at depth. This will be done by electron microprobe together with analytical SEM and TEM micropetrography of these phases which appear to be chemically related to the host eclogite. These studies should better define the causes of eclogite compositional variation which will yield a greater understanding of the chemical dynamics of the upper mantle. Funding of this proposal at a level reduced from the originally requested $123,603 will result in fewer analyses and reduced usage of the analytical TEM, which is the most expensive of the analytical techniques. We also will be unable to support a full- time graduate student in this study, although we do anticipate having student support from other sources which may be partly applied to this project. Also, support for T. McCormick is slightly reduced from 25% to 20% of full-time. The attached revised budget at approximately $78,400 over two years reflects these changes. At the funding level of the attached revised budget, we anticipate significant progress in understanding the chemical dynamics of the upper mantle over the next two years.