火星深部に存在する岩石よりも重いマグマの正体は？～国際宇宙ステーション「きぼう」日本実験棟搭載の静電浮遊炉で火星内部の謎に迫る～

2025-03-04 愛媛大学

＜関連情報＞

• https://www.ehime-u.ac.jp/data_relese/pr_20250304_grc/
• https://www.ehime-u.ac.jp/wp-content/uploads/2025/03/pr_20250304_grc.pdf
• https://www.nature.com/articles/s43247-025-02117-3

火星のコア・マントル境界における鉄に富むかんらん岩メルトの重力的安定性 Gravitational stability of iron-rich peridotite melt at Mars’ core-mantle boundary

Yoshio Kono,Chihiro Koyama,Nozomi M. Kondo,Koji Ohara,Hideharu Kuwahara,Ryoichi Nakada,Yuki Watanabe,Hirohisa Oda &Takehiko Ishikawa
Communications Earth & Environment  Published:03 March 2025
DOI:https://doi.org/10.1038/s43247-025-02117-3

Abstract

Possible existence of dense iron-rich silicate melt layer above Mars’ core is important in understanding the nature and evolution of Mars. However, gravitational stability of iron-rich silicate melt in the Mars’ interior has not been well constrained, due to experimental difficulties in measuring density of iron-rich peridotitic melt. Here we report density measurements of iron-rich peridotitic melts up to 2465 K by using electrostatic levitation furnace at the International Space Station. Our experimentally obtained densities of iron-rich peridotitic melts are markedly higher than those calculated by first principles simulation, and are distinct from those estimated by extrapolating a density model for SiO₂-rich basaltic melts. Our determined density model suggests that peridotitic melt with the Fe/(Mg+Fe) ratio more than 0.4-0.5 has higher density than that at the base of the Mars’ mantle, which indicates gravitational stability of the iron-rich peridotitic melt at the core-mantle boundary in Mars.