JpGU-AGU Joint Meeting 2017

Presentation information

[EE] Oral

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

[S-IT22] [EE] Interaction and Coevolution of the Core and Mantle in the Earth and Planets

Sat. May 20, 2017 3:30 PM - 5:00 PM A05 (Tokyo Bay Makuhari Hall)

convener:Taku Tsuchiya(Geodynamics Research Center, Ehime University), Hidenori Terasaki(Graduate School of Science, Osaka University), Madhusoodhan Satish-Kumar(Department of Geology, Faculty of Science, Niigata University), Tetsuo Irifune(Geodynamics Research Center, Ehime University), John Hernlund(Earth-Life Science Institute, Tokyo Institute of Technology), Eiji Ohtani(Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University), Chairperson:Taku Tsuchiya(Geodynamics Research Center, Ehime University)

3:30 PM - 3:45 PM

[SIT22-19] Effects of Fe and Al incorporations on MgSiO3 postperovskite phase boundary

★Invited papers

*Xianlong Wang1,2, Taku Tsuchiya3,4, Zhi Zeng1,2 (1.Institute of Solid State Physics, Chinese Academy of Sciences, 2.University of Science and Technology of China, 3.Geodynamics Research Center, Ehime University, 4.Earth-Life Science Institute, Tokyo Institute of Technology)

Keywords:First-principles method, internally consistent LSDA+U, MgSiO3, postperovskite

MgSiO3 bridgmanite (Br) will undergoes a post-perovskite (PPv) phase transition[1,2,3] in the pressure (P) and temperature (T) conditions corresponding to the Earth’s D” layer. Therefore, The phase change is recognized as the key for understanding the seismological observations in the D” layer. However, to date, it is still a challenging subject to determine the phase transition boundary preciously in the geophysically relevant Fe and Al-bearing compositions. Based on the first-principles methods combined with the internally consistent LSDA+U method and the lattice dynamics approach, the high-P,T thermodynamics of the MgSiO3 phases are directly calculated with incorporation of 6.25 mol% of Fe2+, Fe3+Fe3+, Fe3+Al3+, and Al3+Al3+ [4,5]. Using calculated free energies, we determine the PPv phase boundaries for Fe and Al-bearing compositions. Our results show that at 2500 K, incorporations of Fe3+Fe3+ and Fe3+Al3+ span coexisting domains between Br and PPv significantly with lowering the transition pressure, in contrast to the Fe2+ and Al3+Al3+-bearing cases.

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[3] T. Tsuchiya, J. Tsuchiya, K. Umemoto, and R. M. Wentzcovitch, Earth. Planet. Sci. Lett. 224, 241 (2004).
[4] J. Tsuchiya, and T. Tsuchiya, Proc. Natl. Acad. Sci. USA 105, 19160 (2008).
[5] A. Metsue, and T. Tsuchiya, Geophys. J. Int. 190, 310 (2012).