title: Existence of an 16O-rich gaseous reservoir in the solar nebula.
abstract: Carbonaceous chondrite condensate olivine grains from two distinct petrographic settings, calcium-aluminum-rich inclusion (CAI) accretionary rims and amoeboid olivine aggregates (AOAs), are oxygen-16 (16O) enriched at the level previously observed inside CAIs. This requires that the gas in the nebular region where these grains condensed was 16O-rich. This contrasts with an 16O-poor gas present during the formation of chondrules, suggesting that CAIs and AOAs formed in a spatially restricted region of the solar nebula containing 16O-rich gas. The 16O-rich gas composition may have resulted either from mass-independent isotopic chemistry or from evaporation of regions with enhanced dust/gas ratios, possibly in an X-wind environment near the young Sun.
authors.affiliation: Hawaii Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96822, USA. sasha@higp.hawaii.edu
authors.forename: Alexander N
authors.initials: AN
authors.lastname: Krot
authors.forename: Kevin D
authors.initials: KD
authors.lastname: McKeegan
authors.forename: Laurie A
authors.initials: LA
authors.lastname: Leshin
authors.forename: Glenn J
authors.initials: GJ
authors.lastname: MacPherson
authors.forename: Edward R D
authors.initials: ER
authors.lastname: Scott
mesh_terms: D000535:Aluminum / Q000032:analysis; D002118:Calcium / Q000032:analysis; D019443:Cosmic Dust; D019418:Evolution, Chemical; D005740:Gases; D058085:Iron Compounds; D017616:Magnesium Compounds; D019110:Meteoroids; D008903:Minerals / Q000032:analysis; D010100:Oxygen / Q000032:analysis*; D010103:Oxygen Isotopes / Q000032:analysis; D017640:Silicates; D016082:Solar System
chemical_list: D019443:Cosmic Dust; D005740:Gases; D058085:Iron Compounds; D017616:Magnesium Compounds; D008903:Minerals; D010103:Oxygen Isotopes; D017640:Silicates; C034475:olivine; D000535:Aluminum; D010100:Oxygen; D002118:Calcium