Presentation Information
[SGC46-01]Iron-silicate partitioning of plutinum group elements under high pressure
*Taku Tsuchiya1, Katsuhiko Suzuki2 (1.Geodynamics Research Center, Ehime University, 2.JAMSTEC)
Keywords:
Ab initio calculations,Platinum group element,Late Veneer hypothesis
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.