|
|||||
|
|
Oxygen isotopic and chemical compositions of cosmic spherules collected from the Antarctic ice sheet: Implications for their precursor materials |
|
| Authors: | Toru Yada Tomoki Nakamura Noriko Matsumoto Hajime Hiyagon Naoji Sugiura Nobuo Takaoka |
| Institution: | 1 Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan 2 Department of Earth and Planetary Sciences, Graduate School of Science, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581, Japan 3 Department of Minerals and Biological Sciences, Ibaraki University, Bunkyo 2-1-1, Mito, Ibaraki 310-8512, Japan 4 Institute for Study of the Earth’s Interior, Okayama University, 827 Yamada, Misasa, Tottori 682-0193, Japan 5 National Institute of Polar Research, Department of Polar Science, Graduate University for Advanced Studies, 1-9-10 Kaga, Itabashi, Tokyo 173-8515, Japan |
| 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. |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ | |