Geochemical Cycles of 9-Be and 27-Al

9-Be 和 27-Al 的地球化学循环

• 批准号: 8915831
• 负责人: Christopher Measures
• 金额: $ 8.81万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-01-01 至 1992-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8915831&HistoricalAwards=false
• 关键词: Geochemical; Cycles; 27; Al

This project began as an attempt to establish the systematics of the stable isotopes of Be and Al in the oceans with a view to using their cosmogenic radio-isotopes as geochronologic tools. There is an explicit analogy here to C-14. Carbon is involved in the biogeochemical cycle; hence the effect of decay on the distribution of the radio-isotope is overprinted by non- radiogenic processes. However the stable isotope C-12 is affected only by the biogenic processes and hence can be used to correct for their effects on the radio-isotope. The success of this approach is greatly facilitated by the fact that the carbon isotopes share a common, well-mixed reservior, the atmosphere. The latter is known not to be the case for Be and Al. The objective of this project is to establish whether the residence time and chemical behaviours of these elements in seawater is such that isotope equilibrium is achieved in the oceanic reserviour. If this were true, then direct radiometric dating of marine sediments would be feasible in the range 0 to -15 million years. Support is requested to complete the first phase of the investigations concerning the geochemical cycle Al with a view to developing Al and Be isotopes as geochronometers. The effort will extend coverage into several new basins in the South Atlantic and examine the evolution of the isotope distribution as the Atlantic water masses propagate from their northern source 8915831 Measures This project began as an attempt to establish the systematics of the stable isotopes of Be and Al in the oceans with a view to using their cosmogenic radio-isotopes as geochronologic tools. There is an explicit analogy here to C-14. Carbon is involved in the biogeochemical cycle; hence the effect of decay on the distribution of the radio-isotope is overprinted by non- radiogenic processes. However the stable isotope C-12 is affected only by the biogenic processes and hence can be used to correct for their effects on the radio-isotope. The success of this approach is greatly facilitated by the fact that the carbon isotopes share a common, well-mixed reservior, the atmosphere. The latter is known not to be the case for Be and Al. The objective of this project is to establish whether the residence time and chemical behaviours of these elements in seawater is such that isotope equilibrium is achieved in the oceanic reserviour. If this were true, then direct radiometric dating of marine sediments would be feasible in the range 0 to -15 million years. Support is requested to complete the first phase of the investigations concerning the geochemical cycle Al with a view to developing Al and Be isotopes as geochronometers. The effort will extend coverage into several new basins in the South Atlantic and examine the evolution of the isotope distribution as the Atlantic water masses propagate from their northern source areas.

这个项目开始作为一个尝试建立系统 海洋中Be和Al的稳定同位素， 利用宇宙成因放射性同位素作为地质年代学 工具. 这里有一个明确的类比C-14。 碳是 参与地球化学循环;因此衰变的影响 关于放射性同位素的分布是由非- 放射成因过程 稳定同位素C-12 仅受生物过程的影响，因此可以使用 来校正它们对放射性同位素的影响。 成功 这一方法的优点是， 碳同位素有一个共同的、混合良好的储存库， 气氛 后者是已知的情况下，不是这样的， 本项目的目标是确定 停留时间和化学行为的这些元素在 海水是这样的，同位素平衡是在 海洋保护区 如果这是真的，那么直接辐射测量 海洋沉积物的年代测定在0至 - 一千五百万年 请求提供支助，以完成 地球化学循环Al的研究， 发展铝和铍同位素作为地质年代计。 的 努力将覆盖范围扩大到几个新的盆地， 研究同位素的演化 随着大西洋水团从它们的 北方源 8915831 措施 这个项目开始作为一个尝试建立系统 海洋中Be和Al的稳定同位素， 利用宇宙成因放射性同位素作为地质年代学 工具. 这里有一个明确的类比C-14。 碳是 参与地球化学循环;因此衰变的影响 关于放射性同位素的分布是由非- 放射成因过程 稳定同位素C-12 仅受生物过程的影响，因此可以使用 来校正它们对放射性同位素的影响。 成功 这一方法的优点是， 碳同位素有一个共同的、混合良好的储存库， 气氛 后者是已知的情况下，不是这样的， 本项目的目标是确定 停留时间和化学行为的这些元素在 海水是这样的，同位素平衡是在 海洋保护区 如果这是真的，那么直接辐射测量 海洋沉积物的年代测定在0至 - 一千五百万年 请求提供支助，以完成 地球化学循环Al的研究， 发展铝和铍同位素作为地质年代计。 的 努力将覆盖范围扩大到几个新的盆地， 研究同位素的演化 随着大西洋水团从它们的 北方源区。