Integrated analysis of crystallography and dynamics of hydrogen in deep mantle minerals by high-intensity neutron scattering and high-resolution transmission electron microscopy

2021 Fiscal Year Final Research Report

• Project/Area Number: 17H01172
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: Kyoto University (2019-2021); Okayama University (2017-2018)
• Principal Investigator: OKUCHI Takuo 京都大学, 複合原子力科学研究所, 教授 (40303599)
• Co-Investigator(Kenkyū-buntansha): 富岡 尚敬 国立研究開発法人海洋研究開発機構, 超先鋭研究開発部門(高知コア研究所), 主任研究員 (30335418) ; 瀬戸 雄介 神戸大学, 理学研究科, 講師 (10399818)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: 中性子散乱 / 透過電子顕微鏡 / マントル含水鉱物 / 水素配置解析 / 水素拡散ダイナミクス

Outline of Final Research Achievements

Hydrogen is involved in the Earth's oceans as liquid water. Hydrogen is also involved as cations in solid minerals occurring in the Earth's mantle. There are two types of hydrogen cations involved in these mantle minerals; hydrogen as a stoichiometric component, or hydrogen as a non-stoichiometric component filling the defects of the other cations. In this project, crystallography of hydrogen in a series of mantle minerals of mostly the latter type is established by applying neutron scattering analysis using strong pulsed neutron sources. In addition, chemical dynamics of hydrogen in crystal structures of some hydrous mantle minerals is determined by applying quasi-elastic neutron scattering analysis.

Free Research Field

鉱物学

Academic Significance and Societal Importance of the Research Achievements

45億年の地球史において、海の材料という特別な役割を持つ元素が水素です。しかし海にある水素は全地球質量の僅か100万分の25であり、地球は水素には恵まれていないように見えます。ここで地球の隠れた主役である岩石に着目します。実験室で高温高圧の条件を再現して、内部の岩石が含む鉱物をつくり、中性子を使ってそこに入り込む水素を調べました。その結果、地球の水素が鉱物に大量に溶け込む様子がわかり、その水素が鉱物中を動き回る過程も見えてきました。