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Diffusion-controlled magnesium isotopic fractionation of a single crystal forsterite evaporated from the solid stateThough the origin of calcium- and aluminum-rich inclusions (CAI's) in carbonaceous chondrites is till a disputed issue, evaporation is no doubt one of the most important processes for the formation of CAI's in the early solar nebula. The mechanism for production of large isotopic mass fractionation effects in magnesium, silicon, oxygen, and chromium in CAI's can be better understood by examining isotopic fractionation during the evaporation of minerals. New evaporation experiments were performed on single-crystal forsterite. The magnesium isotopic distribution near the evaporating surfaces of the residues using a modified AEI IM-20 ion microprobe to obtain rastered beam depth profiles was measured. A theoretical model was used to explain the profiles and allowed determination of the diffusion coefficient of Mg(++) in forsterite at higher temperatures than previous measurements. The gas/solid isotopic fractionation factor for magnesium for evaporation from solid forsterite was also determined and found to be nearly the same as that for evaporation of liquid Mg2SiO4.
Document ID
19940016382
Document Type
Conference Paper
Authors
Wang, Jianhua (Chicago Univ. Chicago, IL, United States)
Davis, Andrew M. (Chicago Univ. Chicago, IL, United States)
Hashimoto, Akihiko (Harvard-Smithsonian Center for Astrophysics Cambridge, MA., United States)
Clayton, Robert N. (Chicago Univ. Chicago, IL, United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1993
Publication Information
Publication: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z
Subject Category
INORGANIC AND PHYSICAL CHEMISTRY
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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