Geochemical Journal, Vol. 43 (No. 5), pp. e11-e15, 2009EXPRESS LETTER
Kumiko Fujimoto,1 Shoichi Itoh,1 Shingo Ebata1 and Hisayoshi Yurimoto1,2
1Department of Natural History Sciences, Hokkaido University, Sapporo 060-0810, Japan
2Isotope Imaging Laboratory, Creative Research Institution "Sousei," Hokkaido University, Sapporo 001-0021, Japan
(Received May 28, 2009; Accepted August 24, 2009; Online published August 28, 2009)
Oxygen isotopic compositions of metal grains in a noble-gas-rich chondrite, NWA 801 CR2, have been determined by secondary ion mass spectrometry. The results show bimodal distribution on Δ17O histogram with peaks of Δ17O = 2.3 and -35.0. The 16O-rich peak seems to be due to stellar wind from the protosun. The 16O enrichment is comparable with the most 16O-rich value from chondrite constituents. Difference of oxygen isotopic composition of stellar wind between protosun and the present sun implies how self-pollution by planetary embryos during the planet formation epoch have occurred and whether the present solar photosphere preserves the representative composition of the solar system.
Key words: oxygen isotopes, chondrite, protosun, solar wind, solar system