Noble gases in presolar diamonds III: Implications of ion implantation experiments with synthetic nanodiamonds

Gary R. Huss, Ulrich Ott, Alexey P. Koscheev

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

A series of experiments carried out by Koscheev et al. (1998, 2001, 2004, 2005) showed that the bimodal release of heavy noble gases from meteoritic nanodiamonds can be reproduced by a single implanted component. This paper investigates the implications of this result for interpreting the noble gas compositions of meteoritic nanodiamonds and for their origin and history. If the bimodal release exhibited by meteorite diamonds reflects release of the P3 noble gas component, then the composition inferred for the pure Xe-HL end member changes slightly, the excesses of heavy krypton isotopes that define Kr-H become less extreme, evidence appears for a Kr-L component, and the nucleosynthetic contribution to argon becomes much smaller. After correction for cosmogenic neon inherited from the host meteorites, the neon in presolar diamonds shows evidence for pre-irradiation, perhaps in interstellar space, and a nucleosynthetic component perhaps consistent with a supernova source. After a similar correction, helium also shows evidence for presolar irradiation and/or a nucleosynthetic component. For the case of presolar irradiation, due to the small size of the diamonds, a large entity must have been irradiated and recoiling product nuclei collected by the nanodiamonds. The high 3He/21Ne ratio (-43) calls for a target with a (C + O)/heavier-element ratio higher than in chondritic abundances. Bulk gas + dust (cosmic abundances) meet this criteria, as would solids enriched in carbonaceous material. The long recoil range of cosmogenic 3He argues against a specific phase. The excess 3He in presolar diamonds may represent trapped cosmic rays rather than cosmogenic 3He produced in the vicinity of the diamond crystals.

Original languageEnglish
Pages (from-to)1811-1826
Number of pages16
JournalMeteoritics and Planetary Science
Volume43
Issue number11
DOIs
Publication statusPublished - Nov 2008

ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science

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