Japan Geoscience Union Meeting 2015

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International Session (Oral)

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

[S-IT03] Structure and dynamics of Earth and Planetary deep interiors

Tue. May 26, 2015 11:00 AM - 12:45 PM 106 (1F)

Convener:*Takashi Yoshino(Institute for Study of the Earth's Interior, Okayama University), Satoru Tanaka(Department of Deep Earth Structure and Dynamics Research Japan Agency for Marine-Earth Science and Technology), Dapeng Zhao(Department of Geophysics, Tohoku University), Masanori Kameyama(Geodynamics Research Center, Ehime University), John Hernlund(Earth-Life Science Institute, Tokyo Institute of Technology), Chair:Satoru Tanaka(Department of Deep Earth Structure and Dynamics Research), Kenji Kawai(Department of Earth Science and Astronomy, Graduate School of Arts and Sciences, University of Tokyo)

11:00 AM - 11:15 AM

[SIT03-22] Liquid iron alloys with light elements at outer core conditions by first-principles calculation

*Koichiro UMEMOTO1, Kei HIROSE2 (1.Earth-Life Science Institute, Tokyo Institute of Technology, 2.ELSI, TITECH; OELE, JAMSTEC)

Keywords:outer core, liquid iron alloys, first principles

Since the density of the outer core deduced from seismic data is about 10% lower than that of pure iron at core pressures and temperatures (P-T), it is widely believed that the outer core includes one or more light elements. Although intensive experimental and theoretical studies have been performed so far, the light element in the core has not yet been identified. Comparison of the density and sound velocity of liquid iron alloys with observations, such as the PREM, is a promising way to determine the species and quantity of light alloying component(s) in the outer core. Here we report the results of a first-principles molecular dynamics study on liquid iron alloyed with different concentrations of light elements, in order to clarify the effects of their impurities on the liquid density and sound velocity under outer core P-T conditions. We also discuss validity of empirical Birch's law between density and sound velocity in liquid iron alloys.