AOAs oxygen isotopes

A The relationship between chondrules, CAIs, and AOAs The contrasting mineralogy of CAIs and chondrules indicates that they formed at different nebular temperatures and perhaps in different nebular environments. This is confirmed by oxygen isotope studies which show that there are significant oxygen isotope compositional differences between chondrules and refractory CIAs and AOAs. Chondrules from C and O chondrites also have different oxygen isotope compositions and appear to have formed in different nebular environments. In contrast, CAIs from all chondrite types and AOAs are isotopically similar and share the... 

The alternative hypothesis, that of a nucleosynthetic component carried into the early solar system by 0-rich presolar dust (see discussion in Clayton 1993) remains plausible after all, as mentioned in the Introduction, trace amounts of presolar dust is known to exist in the matrices of chondrites. However, all the high spatial (ion microprobe) measurements of the many types of primitive refractory materials discussed here have failed to find any very extreme oxygen isotopic anomalies such as might be expected if pure 0 dust (e.g. from a supernova) were incorporated into CAIs or AOAs along with local condensates. Even among the -100 true interstellar oxide grains that... 

Itoh S., Rubin A. E., Kojima H., Wasson J. T., and Yurimoto H. (2002) Amoeboid olivine aggregates and AOA-bearing chondrule from Y-81020 CO 3.0 chondrite distribution of oxygen and magnesium isotopes. In Lunar Planet. Sci. XXXni, 1490. The Lunar and Planetary Institute, Houston (CD-ROM). 

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