Marine Geochemistry of Lithium Isotopes

锂同位素海洋地球化学

• 批准号: 8716251
• 负责人: Lui-Heung Chan
• 金额: $ 17.35万
• 依托单位: Louisiana State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-11-01 至 1991-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8716251&HistoricalAwards=false
• 关键词: Marine; Geochemistry; Lithium; Isotopes

A new method has been developed for the measurement of lithium isotope ratios in geological material, as a result of an initial study funded by NSF. The mass spectrometric technique involves the thermal ionization of lithium tetraborate and is capable of producing 6Li/7Li ratios with an uncertainty of 1.3 0/00 (one standard deviation). The results of a preliminary survey indicate important variation of th eisotope composition of Li in the marine environment and demonstrate the usefulness of Li isotope ratio as a tracer for mass exchange in the ocean. This proposal summarizes the findings of the initial research and requests support for a comprehensive investigation of the marine isotope geochemistry of lithium. Efforts will be directed at determining the isotopic composition of the sources and sinks of Li in the ocean and the isotopic fractionation associated with the mass transfer processes. The main emphasis is on the utilization of Li isotope systematics in the understanding of (1) the control on the Li isotopic composition of seawater, (2) the direction and magnitude of Li transfer during seawater-basalt interaction and (3) the process by which Li is enriched in marine sediments. These considerations address the problem of mass balance of Li in the ocean and is of fundamental importance in the characterization of the geochemical cycle of Li.

一项由美国国家科学基金会资助的初步研究已经开发出一种测量地质物质中锂同位素比率的新方法。质谱技术涉及四硼酸锂的热电离，能够产生6Li/7Li比，不确定度为1.3 0/00（一个标准偏差）。初步调查结果显示了海洋环境中锂同位素组成的重要变化，并证明了锂同位素比率作为海洋物质交换的示踪剂的有效性。本提案总结了初步研究的结果，并请求支持对锂的海洋同位素地球化学进行全面调查。将致力于确定海洋中锂源和汇的同位素组成以及与传质过程有关的同位素分馏。重点是利用Li同位素系统学来认识(1)海水中Li同位素组成的控制；(2)海水与玄武岩相互作用过程中Li转移的方向和幅度；(3)海洋沉积物中Li的富集过程。这些考虑解决了海洋中锂的质量平衡问题，对描述锂的地球化学循环具有重要意义。