Japan Geoscience Union Meeting 2018

Presentation information

[EE] Oral

S (Solid Earth Sciences) » S-IT Science of the Earth's Interior & Tectonophysics

[S-IT20] Structure and Dynamics of Earth and Planetary Mantles

Mon. May 21, 2018 10:45 AM - 12:15 PM A05 (Tokyo Bay Makuhari Hall)

convener:Takashi Yoshino(Institute for Planetary Materials, Okayama University), Dapeng Zhao(Department of Geophysics, Tohoku University), Takashi Nakagawa(海洋研究開発機構数理科学・先端技術研究分野), Chairperson:Nakagawa Takashi(JAMSTEC), Yoshino Takashi(Okayama University)

11:30 AM - 11:45 AM

[SIT20-10] Low-pressure analogs of MgSiO3 post-perovskite at ultrahigh pressures by first principles

*Koichiro Umemoto1, Renata Wentzcovitch2 (1.Earth-Life Science Institute, Tokyo Institute of Technology, 2.Department of Applied Physics and Applied Mathematics, Department of Earth and Environmental Sciences, Lamont Doherty Earth Observatory, Columbia University, USA)

Keywords:Post-post-perovskite transitions, first principles, deep interiors of terrestrial exoplanets

MgSiO3 post-perovskite (Mg-PPV) is the final form of this silicate in the Earth’s mantle. However, the fate of Mg-PPV in the mantle of terrestrial exoplanets, where pressures and temperatures are much higher than those on Earth, is still an open question. Knowledge of such transitions will be fundamental for numerical simulations of mantles in terrestrial exoplanets. Previously, by first principles, we predicted a complex series of phase transitions involving dissociation (MgSiO3 -> Mg2SiO4 + MgSi2O5 -> Mg2SiO4 + SiO2 -> MgO + SiO2) and recombination (MgO + MgSiO3 -> Mg2SiO4 or SiO2 + MgSiO3 -> MgSi2O5) reactions among silicates and elementary oxides. These transitions also depend on the chemical compositions of planetary mantles [1,2] and occur at very high pressure (above ~0.5 TPa), which makes experimental validation rather difficult. Here, we search for these low-pressure analogs using first principles calculations. We hope the present study will facilitate experimental validation and encourage researchers of numerical simulations of mantles in terrestrial exoplanets to take dissociations and recombinations of Mg-PPV into account.

[1] S. Q. Wu, M. Ji, C. Z. Wang, M. C. Nguyen, X. Zhao, K. Umemoto, R. M. Wentzcovitch, K. M. Ho, J. Phys. Condensed Matter, 26, 035402 (2014).

[2] K. Umemoto, R. M. Wentzcovitch, S. Q. Wu, M. Ji, C. Z. Wang, and K. M. Ho, Earth Planet. Sci. Lett. 478, 40 (2017).