Composition Of The Noble Gases In Canyon Diablo

Abstract

Five separate fractions of noble gases were extracted and analyzed as a 150g sample of the Canyon Diablo iron meteorite was heated to successively higher temperatures by direct coupling with an RF coil. Isotopic compositions of the light gases, He, Ne and Ar, demonstrate that essentially their entire inventory was produced by spallation reactions. Spallation products are also a prominent feature of the isotopes of Kr and Xe, but in each gas fraction the spallogenic heavy gases were mixed with a nonspallogenic component. The isotopic composition of Kr and Xe trapped in Canyon Diablo are shown to be type-Y, rather than the type-X Kr and Xe that is found with planetary He and Ne in mildly oxidized carbon fractions of chondrites. Large variations are observed in ratios of the light spallogenic noble gases. Spallation products in Kr and Xe tend to correlate with those in Ne, rather than in Ar, suggesting that diffusive fractionation is not responsible for variations in the 21Ne/38Ar ratio. It is suggested that portions of the material in Canyon Diablo may have been preirradiated. Xenon contains a large component of excess 129Xe and 131Xe from neutron capture on Te at energies above 0.4 ev, but there is no indication that the decay of primordial 129I or the incorporation of exotic interstellar dust produced the excess 129Xe or 131Xe in our sample of Canyon Diablo. The maximum amount of excess 136Xe in our sample from fission of the hypothetical superheavy elements is shown to be 600atoms/g if the trapped Xe is atmospheric in composition; however, if the trapped Xe is AVCC, it might be as high as 6,000 atoms/g. © 1982, GEOCHEMICAL SOCIETY OF JAPAN. All rights reserved.

Department(s)

Chemistry

International Standard Serial Number (ISSN)

0016-7002

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2023 J-Stage, All rights reserved.

Publication Date

01 Jan 1982

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