Microscopic oxygen isotopic homogeneity/heterogeneity in the matrix of the Vigarano CV3 chondrite

Takuya Kunihiro, Kazuhide Nagashima, Hisayoshi Yurimoto

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Two-dimensional 18O/16O isotopic analysis of the Vigarano matrix was conducted by secondary ion-imaging using a novel two-dimensional ion-imager. Quantitative oxygen-isotope images (isotopographs) of the Vigarano matrix show that 16O-rich micrograins are scattered within 16O-poor matrix. This heterogeneous O-isotopic distribution indicates that matrix is composed of different O-isotopic components that formed in different locations and/or at different times. However, the O-isotopic composition of groundmass in the matrix is the same as the bulk isotopic composition of the matrix within ±5‰ uncertainty. The spatial resolution and isotopic precision of our technique should allow submicron-size objects (>0.2 μm) with extreme O-isotopic anomalous characteristics (δ18OSMOW ∼250‰) to be detectable in isotopographs. Because the mean grain size of the matrix is ∼0.2 μm, the inability to detect such O-isotopic anomalous objects indicates that isotopically anomalous micrograins (e.g., presolar grains) are extremely rare in the Vigarano matrix and that most objects in the matrix were formed in the solar nebula or in the parent body.

Original languageEnglish
Pages (from-to)763-773
Number of pages11
JournalGeochimica et Cosmochimica Acta
Volume69
Issue number3
DOIs
Publication statusPublished - Feb 1 2005
Externally publishedYes

ASJC Scopus subject areas

  • Geochemistry and Petrology

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