Japan Geoscience Union Meeting 2019

Presentation information

[E] Oral

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

[S-IT25] Planetary cores: Structure, formation, and evolution

Thu. May 30, 2019 9:00 AM - 10:30 AM A09 (TOKYO BAY MAKUHARI HALL)

convener:Hidenori Terasaki(Graduate School of Science, Osaka University), Eiji Ohtani(Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University), William F McDonough(University of Maryland College Park), George Helffrich(Earth-Life Science Institute, Tokyo Institute of Technology), Chairperson:George Helffrich(ELSI, Tokyo Institute of Technology), Hidenori Terasaki

9:45 AM - 10:00 AM

[SIT25-04] The sound velocity of liquid Fe-Ni-S-Si alloys under Mercury’s core condition

*Iori Yamada1, Hidenori Terasaki1, Asaka Kamiya1, Ryo Tsuruoka1, Yuji Higo2, Akihiko Machida3 (1.Graduate School of Science, Osaka University, 2.Japan Synchrotron Radiation Research Institute, 3.National Institute for Quantum and Radiological Science and Technology)

Keywords:Mercury, Core, Sound velocity, Light element

Mercury has a large liquid core and it mainly consists of Fe-Ni and possibly contains some light elements. The X-ray spectroscopy measurements by the MESSENGER spacecraft indicates that surface on Mercury contains 1-4wt% S (Nittler et al. 2011). When silicate containing 1-4 wt%S coexists with liquid metal, S and Si tend to dissolve into liquid metal based on partitioning of S and Si between metal and silicate melts. This suggests that both S and Si are likely to be included in the outer core of Mercury (Chabot et al. 2014). Thus, elastic properties of liquid Fe-Ni-S-Si at BL04B1 and BL22XU beamlines, SPring-8 Facility. High pressure was generated using 1500ton Kawai-type or 180 ton cubic multianvi press. The sound velocity was measured using the pulse-echo overlap method. We used two kinds of compositions (Fe-11wt%Ni-6wt%S-4wt%Si and Fe-11wt%Ni-3wt%S-8wt%Si) for Fe-Ni-S-Si sample. The P-wave velocity (VP) was measured up to 16 GPa and 2000 K and it increases with pressure. Temperature dependence on the VP of liquid Fe-Ni (Kuwabara et al. 2016), the VP of liquid Fe-Ni decreases approximately 1.6 % by addition of 6 wt%S and 4 wt%Si and increases approximately 3.1 % by addition of 3wt%S and 8wt%Si. This suggests that the effect of S reduces the VP effectively also in the Fe-Ni-S-Si system.