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

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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.