COLLABORATIVE RESEARCH: Crystal Chemistry of Metapelite Minerals in a Petrologic Context

这项建议要求继续支持一项旨在了解矿物晶体化学与变质品位和组合之间关系的研究计划。以前得到支持的工作表明，黑云母中的铁含量和八面体有序性随着变质程度和给定组合中共存矿物的变化而变化。拟议的工作将在两个主要方向上扩展这些结果：通过更仔细地研究与先前研究的黑云母共存的其他矿物，以及通过在一系列不同的氧化条件下检查其他新的岩石套件。将使用透射光和反射光岩相学、主元素分析的电子探针、铁氧化还原和现场占有率的穆斯堡尔谱以及氧的快中子活化分析来研究样品。我们的目标是用现代方法为几种常见的溶液相提供一个更全面的数据库，说明较差的相特征对岩石学模型的影响(并对这些模型提出可能的改进)，最后，推导出我们将研究的几种溶液相的“独特”阳离子取代模型。

This proposal requests continuing support for a research program aimed at achieving an understanding of the relationship between mineral crystal chemistry and metamorphic grade and assemblage. Previously-supported work has demonstrated that the ferric iron content and octahedral ordering in biotite vary as a function of both metamorphic grade and co-existing minerals in a given assemblage. Proposed work will expand on these results in two main directions: by looking more closely at the other minerals which coexist with the previously-studied biotites, and by examining other new suites of rocks over a range of different oxidation conditions. Samples will be studied using transmitted and reflected light petrography of phase determination, electron microprobe for major element analysis, Mossbauer spectroscopy for iron redox and site occupancies, and fast neutron activation analysis of oxygen. Our goals are to provide a more comprehen- sive data base for several common solution phases by modern approaches, to illustrate the effects of poor phase characteri- zation on petrologic models (and suggest possible improvements to such models), and finally, to derive "unique" cation substitution models for several of the solution phases we will study.