Japan Geoscience Union Meeting 2015

Presentation information

International Session (Oral)

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

[S-IT06] Early Earth - from accumulation to formation -

Sun. May 24, 2015 4:15 PM - 6:00 PM 303 (3F)

Convener:*Tatsuya Sakamaki(Department of Earth Science, Tohoku University), Akio Suzuki(Department of Earth and Planetary Materials Science, Faculty of Science, Tohoku University), Seiji Kamada(Graduate school of Science, Tohoku University), Bjorn Mysen(Geophysical Laboratory, Carnegie Inst. Washington), Chair:Akio Suzuki(Department of Earth and Planetary Materials Science, Faculty of Science, Tohoku University)

5:15 PM - 5:30 PM

[SIT06-18] Thermal equations of state of MgSiO_{3} post-bridgmanite phase

*Takeshi SAKAI1, Haruhiko DEKURA1, Naohisa HIRAO2 (1.Geodynamics Research Center, Ehime University, 2.Japan Synchrotron Radiation Research Institute)

Keywords:post-bridgmanite, equation of state, LHDAC, Ab initio calculation

MgSiO3 post-bridgmanite phase exists at the lowermost mantle of the Earth. Thus many studies on the equation of state of the phase were done at the lowermost mantle P-T conditions (Caracas and Cohen, 2008; Guignot et al., 2007; Oganov and Ono, 2004; Ono et al., 2006; Tsuchiya et al., 2004; Mosenfelder et al., 2009). On the other hand, super-Earths which have a few times of the Earth's mass have been found in the extra solar system one after another. MgSiO3 post-bridgmanite is an abundant silicate phase in such huge terrestrial planet's mantle (Tsuchiya and Tsuchiya, 2011). Although the pressure condition of super-Earth's mantle reaches several hundred GPa, previously reported EoSs of post-bridgmanite by the laser heated diamond anvil cell (LHDAC) experiment were limited up to around 150 GPa. Moreover, the post-bridgmanite is expected to exist in Uranus's and Neptune's rocky cores and also early Earth's proto-core. The direct determination of the compression behavior of post-bridgmanite at multi-megabar pressure is, therefore, important to understand the super-Earth's interior and so on.
Here we report PPv EoSs up to 258 GPa and 2140 K based on the LHDAC experiment and up to 1 TPa and 6000 K by ab initio calculation based on the density-functional theory in the same manner as Tsuchiya et al. (2004). The experimental EoS agrees excellently with the calculated ab initio volume data within 1% up to 400 GPa and 6000 K. The volume differences between the present result and the EoS based on shock experiment data (Mosenfelder et al. 2009) was also 1% at 400 GPa and 300 K. The present EoSs show internal consistency among LHDAC, shock and ab initio data up to 400 GPa within 1% in volume. Our new EoSs are applicable to not only the Earth's core-mantle boundary region but also the super-Earth's mantle and early Earth's proto core.