Uranium Isotopes in Carbonate Sediments: Assessing a Novel Paleoredox Proxy

碳酸盐沉积物中的铀同位素：评估新型古氧化还原代理

• 批准号: 0952394
• 负责人: Ariel Anbar
• 金额: $ 36.85万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2014-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0952394&HistoricalAwards=false
• 关键词: Uranium; Isotopes; Carbonate; Sediments; Assessing

This work tests the application of Uranium (U) isotopes preserved in carbonate sediments as a paleo-redox proxy. Significant variability exists in U isotope composition, due largely to isotope fractionation during redox transformations of U in solution. This suggests that the U isotope composition of seawater may be determined by the redox state of the global ocean. This research will involve laboratory experiments to determine whether U isotopes fractionate during abiotic precipitation of calcite and aragonite, which will serve as a baseline against which to compare any biogenic fractionation. A field component will investigate fractionation of U isotopes in natural carbonates, both biogenic and abiotic. This will include study of how low temperature alteration during deposition and burial might affect the preservation of the primary U isotope signal. Funding provides research opportunities for undergraduates from the Arizona State University Honors College, and supports a PhD thesis.

本工作测试了保存在碳酸盐沉积物中的铀（U）同位素作为古氧化还原指标的应用。存在显着的变化，在U同位素组成，主要是由于同位素分馏过程中的U在溶液中的氧化还原转化。这表明，海水中铀同位素组成可能是由全球海洋的氧化还原状态决定的。 这项研究将涉及实验室实验，以确定是否U同位素在方解石和文石的非生物沉淀过程中分馏，这将作为一个基线，以比较任何生物分馏。现场部分将调查天然碳酸盐中铀同位素的分馏，包括生物和非生物。这将包括研究沉积和埋藏过程中的低温变化如何影响原始铀同位素信号的保存。资金为亚利桑那州立大学荣誉学院的本科生提供研究机会，并支持博士论文。