JpGU-AGU Joint Meeting 2020

Presentation information

[E] Poster

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

[S-IT31] Planetary cores: Structure, formation, and evolution

convener:Hidenori Terasaki(Faculty of Science, Okayama University), Eiji Ohtani(Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University), Gerd Steinle-Neumann(Bayerisches Geoinstitut, Universitaet Bayreuth), William F McDonough(Department of Earth Science and Research Center for Neutrino Science, Tohoku University, Sendai, Miyagi 980-8578, Japan)

[SIT31-P02] Mercury core size constrained from elastic properties of Fe-Ni-S-Si liquid

Iori Yamada1, *Hidenori Terasaki1, Ryo Tsuruoka1, Asaka Kamiya1, Tadashi Kondo1, Yoshinori Tange2, Yuji Higo2 (1.Graduate School of Science, Osaka University, 2.JASRI)

Keywords:Mercury, Sound velocity, iron-alloy, Core

Surface on Mercury is found to contain 1–4 wt% of sulfur from X-ray spectroscopy of the MESSENGER spacecraft (Nittler et al. 2011). The S content on the surface suggests that certain amounts of S and Si are likely to be contained in the Mercury core based on partitioning of S and Si between metal and silicate melts (Chabot et al. 2014).

In this study, we measured the VP of liquid Fe–Ni–S–Si up to 17 GPa and investigated the effect of pressure and alloying of S+Si on the VP to constrain the radius of Mercury core. High pressure experiments were performed using 1500 ton Kawai-type multianvil press at BL04B1 beamline, SPring-8 synchrotron facility. The P-wave velocity was measured using the pulse-echo overlap method.

The VP of Fe-Ni-S-Si liquids of this study locate in between reported VP of Fe-Ni-S and Fe-Ni-Si. Thus, there is an offset between S and Si effects on the VP. Based on the obtained elastic properties of liquid Fe-Ni-S-Si, we estimated the Mercury core radius which satisfies the observed total mass and moment of inertia of Mercury and discuss possible core composition.