Japan Geoscience Union Meeting 2016

Presentation information

International Session (Oral)

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

[S-IT06] Interaction and Coevolution of the Core and Mantle

Mon. May 23, 2016 3:30 PM - 5:00 PM 304 (3F)

Convener:*Satoru Tanaka(Department of Deep Earth Structure and Dynamics Research Japan Agency for Marine-Earth Science and Technology), Taku Tsuchiya(Geodynamics Research Center, Ehime University), Chair:Taku Tsuchiya(Geodynamics Research Center, Ehime University), Madhusoodhan Satish-Kumar(Department of Geology, Faculty of Science, Niigata University)

3:30 PM - 3:45 PM

[SIT06-19] Sound velocity Fe3S at high pressure and high temperature based on inelastic X-ray scattering

*Seiji Kamada1,2, Takanori Sakairi2, Tatsuya Sakamaki2, Eiji Ohtani2, Hidenori Terasaki3, Hiroshi Fukui4, Alfred Q.R. Baron5, Akio Suzuki2, Hiroshi Uchiyama6, Satoshi Tsutsui6 (1.Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 2.Department of Earth Science, Graduate school of Science, Tohoku University, 3.Dpartment of Earth and Space Science, Graduate School of Science, Osaka University, 4.Graduate School of Material Science, University of Hyogo, 5.RIKEN, 6.JSRI)

Keywords:High pressure and temperture, Inelastic X-ray Scattering, Planetary core

Mars, the 4th planet from the sun, has been investigated since 1960s. In spite of the investigations, the interior of Mars have not been understood well. Although the surface of Mars has been investigated by Opportunity and Curiosity in the project of NASA, the structure and seismic properties of the Martian core have not been understood well. The core of Mars have been thought to include sulfur as a light element. Sohl and Spohn (1997) proposed the seismic wave velocity and density profiles of the interior of Mars. However, there were almost no data of seismic wave velocity of the Martian core materials such as FeS and Fe3S. Therefore, we have measured sound velocities of Fe3S under high pressures and temperatures in order to discuss the Martian core. In addition, the InSight project of NASA will observe seismic wave velocity and probably be able to give some information of the Martian core.
There have been only a limited number of works for VP of Fe and Fe alloys with light elements, especially Fe alloys with sulfur. Recently, sound velocities of Fe, Fe-Ni, FeS, FeS2, FeO, Fe3C, Fe-Ni-Si alloys have reported based on an inelastic X-ray scattering (IXS) (Fiquet et al., 2001; Antonangeli et al., 2004; Fiquet et al., 2004; Badro et al., 2007; Fiquet et al., 2009; Antonangeli et al., 2010). In the Fe-S system, VP of FeS, the end member of the Fe-FeS system, and FeS2, more sulfur-rich compound, have been studied but these compounds are not appropriate for the core materials of Mars because Fe-S system has a lot of intermediates such as Fe3S2, Fe2S, Fe3S under high pressures (Fei et al., 1997, 2000). In addition, Fe3S coexists with ε-Fe as a subsolidus phase from 20 GPa to at least 200 GPa (Kamada et al., 2010, 2012). Therefore, it is essential to study the VP of Fe3S to understand seismic properties of the Martian core. We have measured sound velocities of Fe3S under high temperature and pressure at BL35XU of SPring-8.
In this study, a synthesized Fe3S was used as a starting material. A symmetric diamond anvil cell was used to generate high pressures. IXS and XRD experiments were performed at the beamline 35XU of SPring-8, Japan (Baron et al., 2000). VP of Fe3S were measured up to 45 GPa and 1900 K. We will discuss temperature effect on VP of Fe3S and the Birch’s law and seismic wave velocity profile of the Martian core.