期刊名称:Proceedings of the National Academy of Sciences
印刷版ISSN:0027-8424
电子版ISSN:1091-6490
出版年度:2019
卷号:116
期号:21
页码:10238-10243
DOI:10.1073/pnas.1821712116
出版社:The National Academy of Sciences of the United States of America
摘要: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 S i O 2 does not crystallize out of molten Fe-Si-O at the core-mantle boundary.