Obiettivo Since 1963 alien xenon enriched in the isotopes 132Xe, 131Xe, 134Xe, 129Xe has been observed in CO2 well gases, MORB (Mid-Ocean-Ridge Basalt) glasses basalt, anorthosite from Greenland, and in meteorites. The surprising similarity of the xenon isotopic composition in these distinctly different objects was noted but no explanation has been suggested. Recently, the hypothesis was put forward that the enrichment of the middle isotopes may result from the migration of beta-radioactive precursors produced during the fission of heavy nuclei. The migration of Xe precursors occurred at a relatively high temperature and/or in outer parts of mineral grains. Some experimental evidence of such mechanisms resulted from the analyses of Xe in rocks from the Oklo natural nuclear reactor, of Xe evolved in the ampoule during neutron irradiation of pitchblends, and of Xe in the sandstone from the epicentre of a nuclear test. Because of the proposed origin of alien xenon it was subsequently called CFF-Xe (Chemically Fractionated Fission Xe), but further development and testing of the formation hypothesis is needed. This project aims to improve the currently running mass-spectrometric facility in the Vernadsky Institute of Geochemistry and Analytical Chemistry in Moscow, Russia, in order to obtain additional reliable evidence for CFF-Xe and to enable the in-depth investigation of its origin. It will also study carefully the source of excess 129Xe in MORB basalt, CO2 gases, samples from deep drilling wells, ancient rocks and meteorites, in order to understand the role that CFF-Xe played in the present-day Xe composition. Finally, it will revise concepts on the evolution of the terrestrial atmosphere on the basis of the presence of CFF-Xe.The following results are expected: the formation mechanism of CFF-Xe will be revealed by specially designed laboratory experiments; new data on the presence of CFF-Xe in various natural materials will be obtained; and the role of CFF-Xe in isotope geochemistry will be determined. 129Xe in samples already studied will be reconsidered in the light of CFF-Xe. Results will be reported at a number of international conferences on terrestrial geology and planetary sciences, and published in international science journals. Programma(i) IC-INTAS - International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993- Argomento(i) 52 - Geochemistry Invito a presentare proposte Data not available Meccanismo di finanziamento Data not available Coordinatore Max-Planck Gesellschaft zur Förderung der Wissenschaften e.V. Contributo UE Nessun dato Indirizzo Sanplereheck weg 1 69029 Heidelberg Germania Mostra sulla mappa Costo totale Nessun dato Partecipanti (3) Classifica in ordine alfabetico Classifica per Contributo UE Espandi tutto Riduci tutto Institut de Physique du Globe de Paris Francia Contributo UE Nessun dato Indirizzo 75252 Paris Mostra sulla mappa Costo totale Nessun dato National Academy of Sciences of Ukraine,Institute of Geochemistry, Mineralogy and Ore Formation Ucraina Contributo UE Nessun dato Indirizzo 252680 Kiev Mostra sulla mappa Costo totale Nessun dato Russian Academy of Sciences Russia Contributo UE Nessun dato Indirizzo 117334 Moscow Mostra sulla mappa Costo totale Nessun dato
