Oxygen Isotopic Abundances in Calcium-Aluminum-Rich Inclusions from Ordinary Chondrites: Implications for Nebular Heterogeneity

The oxygen isotopic compositions of two calcium-aluminum-rich inclusions (CAIs) from the unequilibrated ordinary chondrite meteorites Quinyambie and Semarkona are enriched in $^{16}$O by an amount similar to that in CAIs from carbonaceous chondrites. This may indicate that most CAIs formed in a rest...

Full description

Saved in:
Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 1998-04, Vol.280 (5362), p.414-418
Main Authors: McKeegan, Kevin D., Leshin, Laurie A., Russell, Sara S., MacPherson, Glenn J.
Format: Article
Language:English
Subjects:
Aluminum - analysis
Astronomy
Calcium - analysis
Chondrites
Chondrules
Contour lines
Cosmochemistry. Extraterrestrial geology
Crystallization
Data lines
Earth sciences
Earth, ocean, space
Exact sciences and technology
Fall lines
Inferences
Isotope geochemistry
Isotope geochemistry. Geochronology
Isotopes
Meteorites
Meteorites. Tectites. Impactites
Meteoroids
Mineralogy
Minerals
Nebulae
Oxygen
Oxygen - analysis
Oxygen Isotopes
Radioisotopes
Solar nebulae
Space life sciences
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The oxygen isotopic compositions of two calcium-aluminum-rich inclusions (CAIs) from the unequilibrated ordinary chondrite meteorites Quinyambie and Semarkona are enriched in $^{16}$O by an amount similar to that in CAIs from carbonaceous chondrites. This may indicate that most CAIs formed in a restricted region of the solar nebula and were then unevenly distributed throughout the various chondrite accretion regions. The Semarkona CAI is isotopically homogeneous and contains highly $^{16}$O-enriched melilite, supporting the hypothesis that all CAI minerals were originally $^{16}$O-rich, but that in most carbonaceous chondrite inclusions some minerals exchanged oxygen isotopes with an external reservoir following crystallization.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.280.5362.414