Variations in the O-isotope composition of gas during the formation of chondrules from the CR chondrites

Schrader DL, Nagashima K, Krot AN, Ogliore RC and Hellebrand E (in press)

Geochimica et Cosmochimica Acta
Volume 132, 1 May 2014, Pages 50–74


The compositional and O-isotope data suggest that BO chondrules experienced more extensive, but incomplete exchange with the ambient gas than porphyritic chondrules. We suggest that CR chondrules formed from relatively 16O-enriched solids in the presence of relatively 16O-depleted gaseous H2O. The O-isotope compositions of chondrule olivine likely result from differences in the O-isotope composition of both the chondrule precursors and the ambient gas during chondrule formation. The inferred O-isotope composition of this gas (Δ17O ranges from ∼−3‰ to +3‰) is inconsistent with a high abundance of water from the outer Solar System, which has been predicted to be isotopically heavy.