Experimental study on transient phenomena involving interactions between planetary materials and atmosphere

• Project/Area Number: 17K05710
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: Kumamoto University
• Principal Investigator: Isobe Hiroshi 熊本大学, 大学院先端科学研究部(理), 教授 (80311869)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2019: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2018: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2017: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
• Keywords: 溶融微小隕石 / 磁鉄鉱 / 硫化鉄 / 急冷樹枝状結晶 / 酸素分圧 / 大気組成 / 過渡的現象 / 微小隕石 / 酸化鉄 / 樹枝状結晶 / I type 微小隕石 / リキダス相 / I type cosmic spherule / 鉄隕石 / 炭素質コンドライト隕石 / 地球惑星物質

Outline of Final Research Achievements

Micrometeorites are the most abundant planetary materials accumulating to the Earth. Melted micrometeorites can record fO2 of upper atmosphere. Compositions of FeS derived melt in fine spherules are following Fe-S-O phase relations even in a few seconds. Troilite in micrometeorite is melted, oxidized and vaporized depending on oxygen fugacity. Magnetite crystals occur in artificial micrometeorites as a liquidus phase in rapid cooling processes of iron oxide melt produced from metallic iron with fO2 lower than FMQ buffer curve. Oxidation of micrometeorites may be controlled by accumulated interaction with oxygen molecules not only oxygen molecules but also CO2 in the heating path of micrometeorites.

Academic Significance and Societal Importance of the Research Achievements

惑星物質と地球大気との相互作用において、大気中の酸素の存在量のみが金属鉄の酸化反応を規定するものと考えられてきた。しかし、本研究の成果により、磁鉄鉱の形成条件よりも低い酸素分圧条件において惑星物質中の金属鉄が酸化され、溶融微小隕石に極めて類似した組織を示す磁鉄鉱が形成することが示された。これは、酸素分子以外の酸素を含む分子、恐らく二酸化炭素が、金属鉄の酸化をもたらす可能性があることを示している。この知見は、原始地球や他の地球型惑星における大気進化の理解において極めて重要である。

Research Products

• [Journal Article] An experimental study of chondrule formation from chondritic precursors via evaporation and condensation in Knudsen cell: Shock heating model of dust aggregates (2017)
  • Author(s): Imae Naoya、Isobe Hiroshi
  • Journal Title: Earth and Planetary Science Letters Volume: 473 Pages: 256-268
  • DOI: 10.1016/j.epsl.2017.05.040
  • Peer Reviewed
• [Presentation] Fe-S-O系メルト微粒子の急冷による組織形成過程 (2019)
  • Author(s): 磯部博志
  • Organizer: 地球惑星科学関連学会合同大会
• [Presentation] 人工微小隕石作成実験による高層大気酸素分圧条件の再現 (2019)
  • Author(s): 磯部博志
  • Organizer: 日本鉱物科学会年会
• [Presentation] Oxidation behavior of micrometeorites in upper atmosphere based on melting experiments in controlled oxygen fugacity (2019)
  • Author(s): Hiroshi ISOBE
  • Organizer: American Geophysical Union Fall Meeting 2019
  • Int'l Joint Research
• [Presentation] Compositional fluctuation of silicate minerals in formation processes of artificial cosmic spherules (2018)
  • Author(s): Hiroshi Isobe and Minami Ohno
  • Organizer: Japan Geoscience Union, Japan Geoscience Union Meeting
• [Presentation] Reproduce of I type cosmic spherules from iron meteorite powder (2018)
  • Author(s): Huimin Shao, Hiroshi Isobe and Bingkui Miao
  • Organizer: Japan Geoscience Union, Japan Geoscience Union Meeting
• [Presentation] REPRODUCTION OF TYPE I CHONDRULES AND THE IMPLICATIONS (2018)
  • Author(s): N. Imae, K Horie and H. Isobe
  • Organizer: “Experiments and Modeling in Investigation of Extraterrestrial Material” 81st Annual Meeting of The Meteoritical Society
  • Int'l Joint Research
• [Presentation] 大気加熱時の酸素分圧条件による硫化鉄微粒子の酸化・揮発現象 (2018)
  • Author(s): 磯部博志・室園健人
  • Organizer: 日本鉱物科学会年会
• [Presentation] Oxidation and evaporation of iron sulfide fine particles by heating experiments with various oxygen fugacity conditions (2018)
  • Author(s): Hiroshi ISOBE and Kento MUROZONO,
  • Organizer: American Geophysical Union Fall Meeting
  • Int'l Joint Research
• [Presentation] 硫化鉄微粒子の大気突入における溶融急冷過程再現実験 (2017)
  • Author(s): 室園健人・磯部博志
  • Organizer: 地球惑星科学関連学会合同大会
• [Presentation] Oxidation of iron sulfide in artificial micrometeorites (2017)
  • Author(s): Hiroshi Isobe, Takaaki Gondo and Kento Murozono
  • Organizer: The Eighth Symposium on Polar Science
  • Int'l Joint Research
• [Presentation] Oxidation and evaporation of sulfur species at atmospheric entry of iron sulfide fine particles (2017)
  • Author(s): Hiroshi ISOBE and Kento MUROZONO
  • Organizer: American Geophysical Union Fall Meeting 2017
  • Int'l Joint Research