气候变化领域集成服务门户(CCPortal): Silicon-Depleted Present-Day Earth's Outer Core Revealed by Sound Velocity Measurements of Liquid Fe-Si Alloy

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DOI	10.1029/2020JB019399
	Silicon-Depleted Present-Day Earth's Outer Core Revealed by Sound Velocity Measurements of Liquid Fe-Si Alloy
	Nakajima Y.; Kawaguchi S.I.; Hirose K.; Tateno S.; Kuwayama Y.; Sinmyo R.; Ozawa H.; Tsutsui S.; Uchiyama H.; Baron A.Q.R.
发表日期	2020
ISSN	21699313
卷号	125 期号:6
英文摘要	Here we determined the P wave velocity of liquid Fe84Si16 up to 56 GPa based on inelastic X-ray scattering measurements in a laser-heated diamond-anvil cell. We found that silicon significantly increases the P wave velocity of liquid iron under high pressure. The equation of state (EoS) of liquid Fe-Si is obtained from the present sound velocity measurements. When extrapolating the present data to core pressures with the EoS, the silicon concentration must be limited to less than 1.9+1.2−0.5 wt.% in the outer core to explain its P wave velocity. In contrast, if silicon is the sole light element, 4.0+1.0−0.6 to 4.8+0.9−1.4 wt.% is necessary to account for the outer core density deficit. Thus, a liquid Fe-Si cannot explain both the density and sound velocity simultaneously, suggesting that silicon is not the predominant light element in the core. Recent core formation models have predicted that the initial core contained 2 to 9 wt.% Si, which makes the P wave velocity much faster than that observed in the present-day outer core. The core may have changed its composition by crystallizing SiO2 or (Mg,Fe)SiO3. It is possible that the initial core with <4 wt.% Si and ~5 wt.% O segregated from silicate under moderately oxidizing conditions and its composition evolved into a silicon-poor one (<1.9 wt.% Si), which is compatible with the seismological observations. Such moderate Si content in the original core could also account for the high MgO/SiO2 and 30Si/28Si ratios in Earth's mantle relative to chondritic values. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	High pressure; Light element; Outer core; Sound velocity
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187798
作者单位	Department of Physics, Kumamoto University, Kumamoto, Japan; Materials Dynamics Laboratory, RIKEN SPring-8 Center, Hyogo, Japan; Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan; Japan Synchrotron Radiation Research Institute (JASRI), Hyogo, Japan; Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan; Institute for Study of the Earth's Interior, Okayama University, Tottori, Japan; Geodynamics Research Center, Ehime University, Ehime, Japan
推荐引用方式 GB/T 7714	Nakajima Y.,Kawaguchi S.I.,Hirose K.,et al. Silicon-Depleted Present-Day Earth's Outer Core Revealed by Sound Velocity Measurements of Liquid Fe-Si Alloy[J],2020,125(6).
APA	Nakajima Y..,Kawaguchi S.I..,Hirose K..,Tateno S..,Kuwayama Y..,...&Baron A.Q.R..(2020).Silicon-Depleted Present-Day Earth's Outer Core Revealed by Sound Velocity Measurements of Liquid Fe-Si Alloy.Journal of Geophysical Research: Solid Earth,125(6).
MLA	Nakajima Y.,et al."Silicon-Depleted Present-Day Earth's Outer Core Revealed by Sound Velocity Measurements of Liquid Fe-Si Alloy".Journal of Geophysical Research: Solid Earth 125.6(2020).