The Geochemical Cycles of 9-Be and 27-Al and Other Reactive Trace Elements

9-Be和27-Al及其他反应性微量元素的地球化学循环

• 批准号: 8717227
• 负责人: Christopher Measures
• 金额: $ 15.61万
• 依托单位: Massachusetts Institute of Technology
• 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: 1987-12-01 至 1990-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8717227&HistoricalAwards=false
• 关键词: Geochemical; Cycles; 27; Al; Other

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 continue investigations of the geochemical cycles of the isotopes of Be and Al with a view to developing them as geochronometers. It is proposed to participate in the South Atlantic Ventilation Experiment expedition to extend coverage into the South Atlantic and to examine the evolution of the isotope distributions as the Atlantic water masses propagate from their northern sources areas. Support is also requested for collaboration with Raisebeck's group in Orsay in a delineation of the continental cycles of the Be isotopes using our expertise and his dedicated Be-10 accelerator.

这个项目开始是为了建立 海洋中Be和Al稳定同位素的系统学 目的是利用它们的宇宙成因放射性同位素， 地质年代学工具 这里有一个明确的类比C- 14. 碳参与地球化学循环，因此 衰变对放射性同位素分布的影响是 被非放射性过程覆盖。 然而，稳定 同位素C-12只受生物过程的影响， 因此可以用来校正它们对无线电的影响- 同位素 这种方法的成功是非常有利的 事实上，碳同位素具有共同的、混合良好的 水库，大气层。 后者被认为不是 本项目的目标是 确定是否停留时间和化学行为的 海水中的这些元素是这样的， 在海洋储备中取得的成就。 如果这是真的， 对海洋沉积物进行直接的放射性测年是可行的 在0到1500万年之间。 请求提供支助，以继续调查 Be和Al同位素的地球化学循环， 发展成地质年代计。 提出要 参与南大西洋通风实验 探险队将覆盖范围扩大到南大西洋， 研究同位素分布的演变， 大西洋水团从它们的北方源头扩散 地区 还要求支持与下列机构的合作： 莱塞贝克小组在奥赛的大陆划界 利用我们的专业知识和他的专业知识 Be-10加速剂。