期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 116, 期 21, 页码 10238-10243出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1821712116
关键词
high pressure; melting; alloys; core composition
资金
- NSF [EAR1551348, EAR-1764140, EAR-0744154]
- NASA Connecticut Space Grant [NNX15AI12H]
- Center for Functional Nanomaterials, which is a US Department of Energy Office of Science Facility, at Brookhaven National Laboratory [DE-SC0012704]
- Yale University
- NASA [NNX15AI12H, 804102] Funding Source: Federal RePORTER
Seismic observations suggest that the uppermost region of Earth's liquid outer core is buoyant, with slower velocities than the bulk outer core. One possible mechanism for the formation of a stably stratified layer is immiscibility in molten iron alloy systems, which has yet to be demonstrated at core pressures. We find immiscibility between liquid Fe-Si and Fe-Si-O persisting to at least 140 GPa through a combination of laser-heated diamond-anvil cell experiments and first-principles molecular dynamics simulations. High-pressure immiscibility in the Fe-Si-O system may explain a stratified layer atop the outer core, complicate differentiation and evolution of the deep Earth, and affect the structure and intensity of Earth's magnetic field. Our results support silicon and oxygen as coexisting light elements in the core and suggest that SiO2 does not crystallize out of molten Fe-Si-O at the core-mantle boundary.
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