Oxygen Isotopes of Chondritic Components

摘要: We review the oxygen isotopic compositions of chondrite components (refractory inclusions, chondrules, and matrix) their inter- intra- crystalline distributions. Primary compositions, acquired before planetesimal accretion, are easily disturbed by parent-body processes such as aqueous alternation thermal metamorphism. or original refractory inclusions (Ca-, Al-rich amoeboid olivine aggregates) distribute along a slope-1 line on three-oxygen isotope diagram over range −60‰ 17 O ≈ δ 18 16 O-rich O-, during inclusion formation. On other hand, primary minerals most chondrules have small variations enriched in relative to suggesting that chondrule formation occurred nebular gas. However, rare been found, some overlap timing solar nebula. Oxygen matrix grains same chondrules. The similarity distributions suggests was originally mechanical mixture dusts co-generated with inclusions. Presolar clearly distinct from those materials trace component matrices. Based these characteristics, more than 99.5% solid nebula formed locally nebula, remainder interstellar space. astrophysical setting early Solar System is also discussed. Refractory around inner edge seem elsewhere Efficient, large-scale radial mixing may an essential process chondritic planetesimals.