Microstructural Investigation of Evaporitic Silica

蒸发二氧化硅的微观结构研究

基本信息

批准号：
9418031
负责人：
Peter Heaney
金额：
$ 14万
依托单位：
Princeton University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
1995
资助国家：
美国
起止时间：
1995-03-15 至 1997-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=9418031&HistoricalAwards=false
关键词：
Microstructural Investigation Evaporitic Silica

项目摘要

Heaney 9418031 The funds requested in this proposal will support Professor Peter J. Heaney of Princeton University and his research group in their investigations of microcrystalline silica SiO2 . This work will explore the ways in which silica microstructures reflect the chemistry of the environments in which they formed. Although these kinds of investigations have been intensively pursued for biogenic marine silica, the structural characteristics of silica minerals from evaporitic environments remain relatively unknown. Our ignorance of these phases is especially unfortunate, since evaporitic silica is an important paleoclimatic indicator and is commonly associated with economic ores. By using transmission electron microscopy, powder X-ray diffraction, and electron probe microanalysis, Heaney and coworkers will determine the way in which evaporitic silica forms and transforms over time. These studies will involve three interrelated projects: 1) Microstructural analysis of moganite, a newly recognized silica polymorph; 2) Determination of the crystal structure of the hydrous sodium silicate magadiite and the structural pathway between magadiite and moganite; and 3) Examination of replacement mechanisms between evaporitic silica and preexisting carbonate. This work will establish a microstructural understanding of the diagenetic alteration of silica minerals from evaporitic deposits, and it will reveal silicification mechanisms of shell carbonate at the atomic scale and should shed light on fossilization processes.

Heaney 9418031 本提案要求的资金将支持普林斯顿大学的 Peter J. Heaney 教授及其研究小组对微晶二氧化硅 SiO2 的研究。这项工作将探索二氧化硅微观结构反映其形成环境化学的方式。尽管对生物海洋二氧化硅进行了深入的此类研究，但来自蒸发环境的二氧化硅矿物的结构特征仍然相对未知。我们对这些相的无知尤其不幸，因为蒸发二氧化硅是重要的古气候指标，并且通常与经济矿石有关。通过使用透射电子显微镜、粉末 X 射线衍射和电子探针微量分析，Heaney 和同事将确定蒸发二氧化硅随时间的形成和转变的方式。这些研究将涉及三个相互关联的项目：1）莫干石（一种新认识的二氧化硅多晶型物）的微观结构分析； 2) 水硅酸钠麦钠石晶体结构的测定以及麦钠石与莫干石之间的结构途径； 3）研究蒸发二氧化硅和预先存在的碳酸盐之间的替代机制。这项工作将对蒸发沉积物中硅矿物的成岩蚀变建立微观结构的理解，并将在原子尺度上揭示贝壳碳酸盐的硅化机制，并为化石化过程提供线索。