Stable Isotope Geochemistry of Quartz, Clay Minerals and Zeolites Under Sedimentary/Diagenetic/Low Grade Metamorphic Conditions

沉积/成岩/低级变质条件下石英、粘土矿物和沸石的稳定同位素地球化学

• 批准号: 8720387
• 负责人: Samuel Savin
• 金额: $ 17.1万
• 依托单位: Case Western Reserve University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-02-15 至 1991-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8720387&HistoricalAwards=false
• 关键词: Stable; Isotope; Geochemistry; Quartz; Clay

Fundamental data on the oxygen isotopic behavior of sedimentary/diagenetic/low-grade metamorphic silicate minerals (quartz, clays and zeolites) are needed. The research includes calibration of mineral-water oxygen isotopic fractionations for quartz and for zeolites and calibration of intracrystalline isotopic fractionations in clays. It also includes research on techniques for the oxygen isotopic analysis of zeolites and on the kinetics of isotopic exchange between zeolites and water. The quartz-water oxygen isotope fractionation will be calibrated at approximately 0, 25, 50 and 75 degrees C by growing quartz crystals in aqueous solution under carefully controlled conditions. The results, when combined with published fractionation data for 200 degrees C and above, should yield reliable metamorphic temperature range. In addition to providing information about quartz, the results will be useful in our attempts to estimate other mineral-water isotopic fractionations. Studies aimed at measuring and calibrating intra-crystalline isotopic fractionations in clays will be based both on partial fluorination and on thermal dehydroxylation. This will permit an estimate of both the temperature of the clay formation and the isotopic composition of the clay-forming fluid. The ability to do this would be especially useful in the isotopic study of sandstones, where cogenetic mineral pairs are very rarely encountered. The proposed studies of the isotopic behavior of zeolites will indicate the degree to which the isotopic compositions of various minerals in this common diagenetic/low-grade-metamorphic group provide useful information about the conditions of their formation and enhance applications of oxygen isotope techniques to the understanding of low temperature processes.

需要有关沉积/成岩/低品位变质硅酸盐矿物（石英、粘土和沸石）氧同位素行为的基本数据。 该研究包括石英和沸石矿泉水中氧同位素分馏的校准以及粘土中晶内同位素分馏的校准。 它还包括沸石氧同位素分析技术以及沸石和水之间同位素交换动力学的研究。 通过在严格控制的条件下在水溶液中生长石英晶体，石英-水氧同位素分馏将在大约 0、25、50 和 75 摄氏度进行校准。 该结果与已发表的 200 摄氏度及以上的分馏数据相结合，应能得出可靠的变质温度范围。 除了提供有关石英的信息外，这些结果还将有助于我们尝试估计其他矿泉水同位素分馏。 旨在测量和校准粘土中晶内同位素分馏的研究将基于部分氟化和热脱羟基。 这将允许估计粘土形成的温度和粘土形成流体的同位素组成。 做到这一点的能力在砂岩的同位素研究中特别有用，因为在砂岩的同位素研究中很少遇到同生矿物对。 对沸石同位素行为的拟议研究将表明，这种常见成岩/低级变质岩群中各种矿物的同位素组成在多大程度上提供了有关其形成条件的有用信息，并增强了氧同位素技术在理解低温过程中的应用。