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Mass fractionation of noble gases in diffusion-limited hydrodynamic hydrogen escapeThe theory of mass fractionation by hydrogen is presently extended to atmospheres in which hydrogen is not the major constituent. This theoretical framework is applied to three different cases. In the first, it is shown that the fractionation of terrestrial atmospheric neon with respect to mantle neon is explainable as a consequence of diffusion-limited hydrogen escape from a steam atmosphere toward the end of the accretion process. In the second, the anomalously high Ar-38/Ar-36 ratio of Mars is shown to be due to hydrodynamic fractionation by a vigorously escaping and very pure hydrogen wind. In the last case, it is speculated that the currently high Martian D/H ratio emerged during the hydrodynamic escape phase which fractionated Ar.
Document ID
19900046693
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Zahnle, Kevin
(NASA Ames Research Center Moffett Field, CA, United States)
Pollack, James B.
(NASA Ames Research Center Moffett Field, CA, United States)
Kasting, James F.
(Pennsylvania State University University Park, United States)
Date Acquired
August 14, 2013
Publication Date
April 1, 1990
Publication Information
Publication: Icarus
Volume: 84
ISSN: 0019-1035
Subject Category
Lunar And Planetary Exploration
Accession Number
90A33748
Distribution Limits
Public
Copyright
Other

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