Oxygen isotopic and chemical compositions of cosmic spherules collected from the Antarctic ice sheet: Implications for their precursor materials

Toru Yada, Tomoki Nakamura, Takaaki Noguchi, Noriko Matsumoto, Minoru Kusakabe, Hajime Hiyagon, Takayuki Ushikubo, Naoji Sugiura, Hideyasu Kojima, Nobuo Takaoka

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Abstract

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.

Original languageEnglish
Pages (from-to)5789-5804
Number of pages16
JournalGeochimica et Cosmochimica Acta
Volume69
Issue number24
DOIs
Publication statusPublished - Dec 15 2005

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All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology

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