Critical Studies of Uranium and Trace Element Coral- Geochemistry to Determine their Reliability as Paleoclimate Recorders

对铀和微量元素珊瑚地球化学进行批判性研究，以确定其作为古气候记录器的可靠性

• 批准号: 9304187
• 负责人: Devendra Lal
• 金额: $ 3.82万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-07-01 至 1996-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9304187&HistoricalAwards=false
• 关键词: Critical; Studies; Uranium; Trace; Element

The proposal seeks to carry out basic studies to determine the siting of U, Be, Sr and other cations in recent and old corals. A specific aim of the work is to determine whether these elements exist partly or primarily as adsorbed onto organic matter, or are exclusively sited within the lattice. This knowledge is an essential prerequisite for using corals as paleorecorders of wide- ranging geophysical and geochemical information, e.g., oceanic 234U/238U and 10Be/9Be ratios, seawater metal concentrations and atmospheric 14C/12C ratios. Our studies will attempt to assess whether coral compositions can be used for examining variability in the geophysical parameter(s) of interest, and should help determine the reliability of coral 14C/12C ratios, and also suggest suitable methods to extract such information in a reliable manner, free of effects due to diagenesis. For example, if our studies show that certain cations in corals are primarily adsorbed on organic matter, the concentrations of those cations would be subject to exchange with the environment. To use such elements for paleoenvironment studies, it would be necessary to extract cations from the aragonite lattice only. We also propose to examine the suitability of corals for determining surface oceanic 10Be/9Be ratios in the past. 10Be is produced by cosmic ray nuclear interactions in the atmosphere. The 10Be half-life of 1.5 my promises to allow dating corals of several millions of years' age from analyses of samples of 50 gm weight. The proposal is clearly exploratory in character, aiming at enhancing the potential of corals as recorders of global paleoclimatic and paleo-oceanographic parameters.

该提案旨在进行基础研究，以确定 铀、铍、锶和其他阳离子在现代和古老珊瑚中的位置。 一 工作的具体目标是确定这些要素是否 部分或主要以吸附在有机物质上的形式存在，或 专门位于晶格内。 这种知识是一种 使用珊瑚作为广泛的古记录器的必要先决条件， 测量地球物理和地球化学信息，例如，海洋 ~（234）U/~（238）U和~（10）Be/~（9）Be比值、海水金属浓度和 大气中14 C/12 C比值。 我们的研究将试图评估 珊瑚组成是否可用于检查 感兴趣的地球物理参数，并应有助于确定 珊瑚14 C/12 C比值的可靠性，并建议合适的 以可靠的方式提取此类信息的方法， 成岩作用的影响。 例如，如果我们的研究表明， 珊瑚中的某些阳离子主要吸附在有机物上， 这些阳离子的浓度将受到交换 与环境的关系。 利用这些元素研究古环境 研究，这将是必要的提取阳离子从 只有文石晶格。 我们亦建议研究 用于测定海洋表层10 Be/9 Be比值的 过去 10 Be是由宇宙射线核相互作用产生的， 气氛 1.5我承诺允许约会的10 Be半衰期 数百万年前的珊瑚 50克重。 该提案显然是探索性的， 特性，旨在提高珊瑚作为记录者的潜力 全球古气候和古海洋学参数。