US-France Cooperative Research: The Geochemistry of The Beryllium Isotopes

该奖项将支持麻省理工学院的John Edmond博士和他的研究小组与法国奥赛光谱分析中心的Grant Raisbeck博士之间的合作研究。拟议项目的目标是调查铍的同位素的地球化学，以期将Be-10用作测年工具，类似于碳14。长寿命的同位素Be-10是由宇宙射线在大气层和地球表面上部发生的散裂反应产生的。稳定同位素Be-9来源于岩石的风化作用。如果同位素在运输和沉积的循环中表现出一致的行为，那么Be-10/Be-9对可以用类似于碳14/碳12的方式进行测年。然而，时间尺度将更长，即1000万年，而不是5万年。此外，通过宇宙射线轰击岩石产生的Be-10可以用来确定岩石暴露的时间。在这个项目中，主要从委内瑞拉奥里诺科盆地采集和准备样品将由麻省理工学院小组负责。美国和法国的小组都在BE-9的地球化学方面拥有丰富的专业知识。这项研究的结果可能为BE-10作为地质计时器的潜在用途提供有价值的信息。

This award will support collaborative research between Dr. John Edmond and his research group at the Massachusetts Institute of Technology and Dr. Grant Raisbeck, Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, Orsay, France. The objective of the proposed project is the investigation of the geochemistry of the isotopes of beryllium with a view to using Be-10 as a dating tool, similar to Carbon 14. The long lived isotope Be-10 is produced by cosmic ray induced spallation reactions in the atomosphere and in the upper meters of the earth's surface. The stable isotope Be-9 is derived from the weathering of rocks. If the isotopes behave coherently in the cycles of transport and deposition, then the Be-10/Be-9 couple can be used for dating in a manner analogous to Carbon 14/Carbon 12. However the time scales would be much longer, i.e. 10 million years as opposed to 50 thousand. In addition, Be-10 produced in rocks by cosmic ray bombardment could be used to date the exposure of the rock. In this project, sample collection and preparation, principally from the Orinoco Basin in Venezuela, will be the responsibility of the MIT group. Both the U.S. and French groups have extensive expertise in the geochemistry of Be-9. Results of this research may provide valuable information on the potential uses of Be-10 as a geochronometer.