地球の深いマントルの原始的な水の証拠
Lydia J Hallis1, Gary R Huss2, Kazuhide Nagashima3
1NASA Astrobiology Institute, Institute for Astronomy, University of Hawai'i, 2680 Woodlawn Drive, Honolulu, HI 96822-1839, USA. Hawai'i Institute of Geophysics and Planetology, Pacific Ocean Science and Technology (POST) Building, University of Hawai'i, 1680 East-West Road, Honolulu, HI 96822, USA. lydia.hallis@glasgow.ac.uk.
まとめ
地球の深層マントルは低デュテリウム/水素 (D/H) の比率を有しており,原始的な水分を保持していることを示唆している. この発見は,地表の貯水池とは異なる地球の水の起源を制限するのに役立ちます.
科学分野:
- 地化学
- 宇宙化学
- 惑星科学
背景:
- 地球の水貯蔵庫におけるデュテリウム/水素 (D/H) の比率は,惑星の水源を理解するために重要である.
- 地球の海は,表面と深層の間の水循環のために,原始的なD/H比を反映していないかもしれません.
- 地球の原始的な水分を決定するには 深く隔離された貯水池からのD/H比が必要です
研究 の 目的:
- 深層マントララバにおけるデュテリウム/水素 (D/H) の比率を調査する.
- 地球の原始的なD/Hシグネチャーを保存する 潜在的貯蔵庫を特定する
- 地球の水源を制限するためです
主な方法:
- バフィン島とアイスランドの火山の溶岩の水素同位体 (D/H) の比率の分析.
- 深層マントルのサンプルで δD値を測定する.
主要な成果:
- バフィン島とアイスランドからの溶岩はD/H比が低い (δDは1ミリあたり218よりマイナス).
- これらの強い負の δD値は,独特のD/Hシグネチャーを持つ深層マントルの構成要素を示します.
結論:
- 深いマントルは,原太陽雲から直接継承されたD/H比を持つ成分を含んでいる.
- この深層マントルの貯水池は,地表の海よりも,地球の原始的な水のより正確な表現を提供します.
- この発見は,地球の水増量と進化のモデルに重大な意味を持ちます.
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