TY - JOUR
T1 - Oxygen isotopic and chemical compositions of cosmic spherules collected from the Antarctic ice sheet
T2 - Implications for their precursor materials
AU - Yada, Toru
AU - Nakamura, Tomoki
AU - Noguchi, Takaaki
AU - Matsumoto, Noriko
AU - Kusakabe, Minoru
AU - Hiyagon, Hajime
AU - Ushikubo, Takayuki
AU - Sugiura, Naoji
AU - Kojima, Hideyasu
AU - Takaoka, Nobuo
N1 - Funding Information:
We are grateful to Mr. J. Mikada and Ms. A. Nakazawa for collecting some of the samples in this study and to Prof. Minoru Sekiya for discussion. We thank Dr. S. Tachibana for giving us the artificial forsterite and Mr. T. Akaki for lending the thin sections of Allende meteorite. We give great thanks to Drs. Michael E. Zolensky, Susan Taylor, Cécile Engrand and an anonymous referee for constructive reviews for this paper. We are particularly grateful to Drs. Akira Yamaguchi and Naoya Imae for helping us with the operation of SEM-EDS and EPMA in National Institute of Polar Research. We wish to express special thanks to Drs. Christine Floss, Wallis F. Calaway and Michael R. Savina for improving this paper in both English and discussion. This study is partially supported by the Research Fellowships of the Japan Society for the Promotion of Science for Young Scientists, given to T.Y., by the research fund of NIPR, by the cooperative program of the Institute for Cosmic Ray Research, University of Tokyo, and by the Scientific Research Grant-in-Aid of the Ministry of Education, Culture, Sports, Science and Technology (No. 11440163 to H.K. and No.13740318 to T.N.).
PY - 2005/12/15
Y1 - 2005/12/15
N2 - Bulk chemical compositions and oxygen isotopic compositions were analyzed for 48 stony cosmic spherules (melted micrometeorites) collected from the Antarctic ice sheet using electron- and ion-microprobes. No clear correlation was found between their isotopic compositions and textures. The oxygen isotopic compositions showed an extremely wide range from -28‰ to +93‰ in δ18O and from -21‰ to +13‰ in Δ17O. In δ18O-δ17O space, most samples (38 out of 48) plot close to the terrestrial fractionation line, but 7 samples plot along the carbonaceous chondrite anhydrous mineral (CCAM) line. Three samples plot well above the terrestrial fractionation line. One of these has a Δ17O of +13‰, the largest value ever found in solar system materials. One possible precursor for this spherule could be 16O-poor planetary material that is still unknown as a meteorite. The majority of the remaining spherules are thought to be related to carbonaceous chondrites.
AB - Bulk chemical compositions and oxygen isotopic compositions were analyzed for 48 stony cosmic spherules (melted micrometeorites) collected from the Antarctic ice sheet using electron- and ion-microprobes. No clear correlation was found between their isotopic compositions and textures. The oxygen isotopic compositions showed an extremely wide range from -28‰ to +93‰ in δ18O and from -21‰ to +13‰ in Δ17O. In δ18O-δ17O space, most samples (38 out of 48) plot close to the terrestrial fractionation line, but 7 samples plot along the carbonaceous chondrite anhydrous mineral (CCAM) line. Three samples plot well above the terrestrial fractionation line. One of these has a Δ17O of +13‰, the largest value ever found in solar system materials. One possible precursor for this spherule could be 16O-poor planetary material that is still unknown as a meteorite. The majority of the remaining spherules are thought to be related to carbonaceous chondrites.
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U2 - 10.1016/j.gca.2005.08.002
DO - 10.1016/j.gca.2005.08.002
M3 - Article
AN - SCOPUS:29644444124
SN - 0016-7037
VL - 69
SP - 5789
EP - 5804
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
IS - 24
ER -