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Title: 炭素質隕石に記録された二種類の起源を持つ水
Other Titles: The dual origin of water in carbonaceous asteroids revealed by CM chondrites
Authors: 圦本, 尚義1 Browse this author →KAKEN DB
Piani, Laurette Browse this author
Authors(alt): Yurimoto, Hisayoshi1
Keywords: 原始惑星系円盤
Protoplanetary disk
hydrogen isotope
Issue Date: 24-Mar-2020
Publisher: 低温科学第78巻編集委員会
Journal Title: 低温科学
Volume: 78
Start Page: 259
End Page: 264
Abstract: 炭素質小惑星は太陽系内側部の水の主な供給者かもしれない,そして,地球に水をもたらした源か もしれない.始原隕石,例えば炭素質隕石,の水素同位体は小惑星形成時の水の貯蔵庫の起源を考え る時に有用である.この時,集積前の状態と集積後の母天体プロセスを区別するには微小部分の同位 体分析が必要である.我々は6個のCMコンドライトに対し水素同位体分析を行い,D/H比の高い 有機物に混じっているD/H比の低い水成分(ÙD=-350±40‰)を見つけた.このD/H比の低い水 は原始太陽系円盤内側領域の水を代表していると考えられる.また,Parisコンドライトの水質変質 が少ない部分から,水質変質前にすでに存在していた含水物質(ÙDParis≥-69±163‰)が見つかった. このParisコンドライトの含水物質のD/H比の高い特徴は,原始太陽系円盤外側領域から内側領域 への氷の輸送が太陽系形成初期数百万年間以内に活発であったことを示している.
Carbonaceous asteroids represent the principal source of water in the inner Solar System and may have been one of the main contributors in the delivery of water to Earth. Hydrogen isotopes in water-bearing primitive meteorites,for example,carbonaceous chondrites,constitute a unique tool for deciphering the sources of water reservoirs at the time of asteroid formation. However, fine-scale isotopic measurements are required to unravel the effects of parent body processes on the pre-accretion isotopic distributions. Here, we report in situ micrometer-scale analyses of hydrogen isotopes in six CM carbonaceous chondrites, revealing a dominant deuterium-poor water component (ÙD=-350± 40‰) mixed with deuterium-rich organic matter. We suggest that this deuterium-poor water corresponds to a ubiquitous water reservoir in the inner protoplanetary disk. A deuterium-rich water signature has been preserved in the least altered part of the Paris chondrite(ÙDParis≥-69±163‰)in hydrated phases possibly present in the CM rock before alteration. The presence of the deuterium-enriched water signature in Paris may indicate that transfers of ice from the outer to the inner Solar System were significant in the first million years of Solar System history.
Type: bulletin (article)
Appears in Collections:低温科学 = Low Temperature Science > 第78巻

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