Japan Geoscience Union Meeting 2014

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International Session (Oral)

Symbol P (Space and Planetary Sciences) » P-PS Planetary Sciences

[P-PS02_28AM2] Mars

Mon. Apr 28, 2014 11:00 AM - 12:10 PM 418 (4F)

Convener:*Takehiko Satoh(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), Masaki Ishiwatari(Department of Cosmosciences, Graduate school of Science, Hokkaido University), Ayako Matsuoka(Research Division for Space Plasma, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), Yoshiyuki O. Takahashi(Center for Planetary Science), Sho Sasaki(Department of Earth and Space Sciences, School of Science, Osaka University), Hideaki Miyamoto(The University Museum, The University of Tokyo), Chair:Takehiko Satoh(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency)

11:40 AM - 11:55 AM

[PPS02-P05_PG] Equation of state of (Fe,Ni)3S phase - Implications for Mars internal structure

3-min talk in an oral session

Shunsuke AKAGI1, *Takeshi SAKAI1, Naohisa HIRAO2 (1.Geodynamics Research Center, Ehime University, 2.Japan Synchrotron Radiation Research Institute)

Keywords:Mars core, equation of state, Mars lower mantle

The existence of lower mantle (MgSiO3-perovskite layer) has an important role on Mars thermal evolution. The layer thickness of Mars lower mantle depends on the depth of the core-mantle boundary (CMB). The depth of CMB is related to the Mars core density. Although the structure model of Mars core was discussed based on the equation of state of pure iron and FeS (e.g., Urakawa et al., 2004), Fe3S phase and also the effect of nickel on the density should be considered. We newly established the equation of state (EoS) of (Fe0.89,Ni0.11)3S up to about 40 GPa by high pressure experiment using diamond anvil cell. Considering EoSs of γ-Fe (Tsujino et al., 2013), γ-FeNi (Tsujino, 2012), Fe3S (Seagle et al., 2006), and (Fe0.89,Ni0.11)3S, the effects of nickel and sulfur on the density was determined. Then, we determined the Mars core density corresponding to the composition model based on SNC meteorites. Our new model shows relatively thin lower mantle compare to previous one. Moreover, if Mars core contains 16 wt.%S and 7 wt.%Ni (Sanloup et al., 1999) and if Mars has an entirely liquid core (Fei and Bertka, 2005), there is a possibility of disappearance of Mars lower mantle.