講演情報
[SGC46-01]Iron-silicate partitioning of plutinum group elements under high pressure
*土屋 卓久1、鈴木 勝彦2 (1.愛媛大学地球深部ダイナミクス研究センター、2.海洋研究開発機構)
キーワード：
第一原理計算、白金族元素、レイト・べニア仮説
Platinum Group Elements (PGEs) refer to the six elements ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt). These are extremely important elements in geochemistry, serving as "keys" to unlocking the Earth's formation history and the evolution of the mantle. The most significant geochemical characteristic of PGE is their strong siderophile nature. Due to their extremely high affinity for iron, most of these elements are thought to sink into the core during the early stages of Earth's formation, when the metallic core separated from the rocky mantle. The PGE concentration in Earth's mantle is however known to be higher than theoretical value. This provides strong support for the Late Veneer hypothesis, which proposes that meteorites (planetesimals) rich in PGE rained down on Earth after core-mantle separation was complete.
However, this assumption relies on the PGEs retaining their strong siderophilia under high pressure. If this nature of PGEs decreases under high pressure, the Late Veneer hypothesis would not be required to explain the current PGE concentration in the mantle. In this study, we employed the first-principles thermodynamic integration molecular dynamics method (Xion et al., 2018; 2021; Huang & Tsuchiya, 2025) to determine the partition coefficients of six PGEs between liquid iron and molten silicate, along with their pressure dependence up to the core-mantle boundary condition. Results on the reactions of not only elemental PGEs but also their sulfides will be reported in the presentation.
However, this assumption relies on the PGEs retaining their strong siderophilia under high pressure. If this nature of PGEs decreases under high pressure, the Late Veneer hypothesis would not be required to explain the current PGE concentration in the mantle. In this study, we employed the first-principles thermodynamic integration molecular dynamics method (Xion et al., 2018; 2021; Huang & Tsuchiya, 2025) to determine the partition coefficients of six PGEs between liquid iron and molten silicate, along with their pressure dependence up to the core-mantle boundary condition. Results on the reactions of not only elemental PGEs but also their sulfides will be reported in the presentation.