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Evaporation and Accompanying Isotopic Fractionation of Sulfur from FE-S Melt During Shock Wave HeatingChondrules probably formed by melting and subsequent cooling of solid precursors. Evaporation during chondrule melting may have resulted in depletion of volatile elements in chondrules. It is known that kinetic evaporation, especially evaporation from a melt, often leads to enrichment of heavy isotopes in an evaporation residue. However, no evidence for a large degree of heavy-isotope enrichment has been reported in chondrules for K, Mg, Si, and Fe (as FeO). The lack of isotopic fractionation has also been found for sulfur in troilites (FeS) within Bishunpur (LL3.1) and Semarkona (LL3.0) chondrules by an ion microprobe study. The largest fractionation, found in only one grain, was 2.7 +/- 1.4 %/amu, while all other troilite grains showed isotopic fractionations of <1 %/amu. The suppressed isotopic fractionation has been interpreted as results of (i) rapid heating of precursors at temperatures below the silicate solidus and (ii) diffusion-controlled evaporation through a surrounding silicate melt at temperatures above the silicate solidus. The kinetic evaporation model suggests that a rapid heating rate of >10(exp 4)-10(exp 6) K/h for a temperature range of 1000-1300 C is required to explain observed isotopic fractionations. Such a rapid heating rate seems to be difficult to be achieved in the X-wind model, but can be achieved in shock wave heating models. In this study, we have applied the sulfur evaporation model to the shock wave heating conditions of to evaluate evaporation of sulfur and accompanying isotopic fractionation during shock wave heating at temperatures below the silicate solidus.
Document ID
20040068159
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Tachibana, S.
(Tokyo Univ. Hongo, Japan)
Huss, G. R.
(Arizona State Univ. Tempe, AZ, United States)
Miura, H.
(Tsukuba Univ. Japan)
Nakamoto, T.
(Tsukuba Univ. Japan)
Date Acquired
August 21, 2013
Publication Date
January 1, 2004
Publication Information
Publication: Lunar and Planetary Science XXXV: Chondrules: The Never-Ending Story
Subject Category
Lunar And Planetary Science And Exploration
Meeting Information
Meeting: Lunar and Planetary Science XXXV: Chondrules: The Never-Ending Story
Location: Houston, TX
Country: United States
Start Date: March 15, 2004
End Date: March 19, 2004
Distribution Limits
Public
Copyright
Public Use Permitted.
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