JpGU-AGU Joint Meeting 2017

Presentation information

[EE] Poster

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

Sun. May 21, 2017 1:45 PM - 3:15 PM Poster Hall (International Exhibition Hall HALL7)

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)

[SIT22-P37] Sound velocity and density of liquid iron alloys under Earth’s core pressures by laser-shock compression

*Tatsuhiro Sakaiya1, Tadashi Kondo1, Hidenori Terasaki1, Keisuke Shigemori2, Yoichiro Hironaka2 (1.Graduate School of Science, Osaka University, 2.Institute of Laser Engineering, Osaka University)

Keywords:Sound velocity, Shock compression, Iron alloy, Earth's core, Birch's law

Sound velocity at Earth’s core conditions are one of the most important physical properties in Earth science because it can be directly compared with the seismological Earth model (PREM: Preliminary Reference Earth Model) [1]. The composition of solid inner core is estimated from the comparison of the model [1] and the extrapolation of sound velocities as a function of density of iron and iron alloys obtained by the static compression experiment [2, 3]. Birch’s law, a linear sound velocity−density relation [4], is used to extrapolate sound velocities to densities in the core condition. On the other hand, the composition of liquid outer core is estimated from the partitioning and solubility data in the inner core boundary condition for the composition of solid core. There has been some works for the sound velocity of iron and iron alloys on the Earth’s core condition by dynamic techniques using explosive [5], gas gun [5-9], and laser [10-12]. Huang et al. estimated that the outer core composition is Fe with 0.5 wt.% O and 9.5 wt.% S by the comparison of PREM and sound velocities of Fe-S-O system [9]. In this study, we measure the sound velocity and density of liquid iron alloys by shock-compression method using high-power laser.
We conducted shock-compression experiments using a High Intensity Plasma Experimental Research (HIPER) system at the GEKKO-XII laser irradiation facility [13] at the Institute of Laser Engineering, Osaka University. The samples were Fe-Ni alloys, Fe-Si alloys, and pyrrhotite. The sound velocities and densities of shock-compressed iron alloys using the high-power laser were measured by x-ray radiography [10-12] at pressures up to 1000 GPa.
Part of this work was performed under the joint research project of the Institute of Laser Engineering, Osaka University and supported by JSPS KAKENHI Grant Number JP16K05541.

[1] A. M. Dziewonski and D. L. Anderson, Phys. Earth Planet. Inter. 25, 297-356 (1981).
[2] J. Badro et al., Earth Planet. Sci. Lett. 254, 233-238 (2007).
[3] G. Fiquet et al., Phys. Earth Planet. Inter. 172, 125-129 (2009).
[4] F. Birch, Geophys. J. R. Astron. Soc. 4, 295-311 (1961).
[5] J. M. Brown and R. G. McQueen, J. Geophys. Res. 91, 7485-7494 (1986).
[6] J. H. Nguyen and N. C. Holmes, Nature 427, 339-342 (2004).
[7] J. W. Shaner et al., Shock Waves in Condensed Matter, 135-138 (1988).
[8] H. Huang et al., J. Geophys. Res. 116, B04201 (2010).
[9] H. Huang et al., Nature 479, 513-516 (2011).
[10] K. Shigemori et al., Eur. Phys. J. D 44, 301-305 (2007).
[11] K. Shigemori et al., Rev. Sci. Instrum. 83, 10E529 (2012).
[12] T. Sakaiya et al., Earth Planet. Sci. Lett. 392, 80-85 (2014).
[13] C. Yamanaka et al., Nucl. Fusion 27, 19-30 (1987).