| DOI: | 10.1002/grl.50186
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| 论文题名: | Compositional instability of Earth's solid inner core |
| 作者: | Gubbins D.; Alfè D.; Davies C.J.
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| 刊名: | Geophysical Research Letters
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| ISSN: | 0094-9207
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| EISSN: | 1944-8938
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| 出版年: | 2013
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| 卷: | 40, 期:6 | | 起始页码: | 1084
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| 结束页码: | 1088
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| 语种: | 英语
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| 英文关键词: | Convection
; Inner core
; Light elements
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| Scopus关键词: | Compositional instability
; Concentration gradients
; Convective stability
; Inner core
; Light elements
; Oxygen concentrations
; Sulfur concentrations
; Thermal convections
; Chemical elements
; Heat convection
; Oxygen
; Seismology
; Silicon
; Sulfur
; Thermal conductivity
; alloy
; concentration (composition)
; convective system
; core (planetary)
; instability
; numerical model
; oxygen
; Rayleigh number
; seismic property
; silicon
; stabilization
; sulfur
; temperature effect
; thermal conductivity
; viscosity
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| 英文摘要: | All models that invoke convection to explain the observed seismic variations in Earth's inner core require unstable inner core stratification. Previous work has assumed that chemical effects are stabilizing and focused on thermal convection, but recent calculations indicate that the thermal conductivity at core temperatures and pressures is so large that the inner core must cool entirely by conduction. We examine partitioning of oxygen, sulfur, and silicon in binary iron alloys and show that inner core growth results in a variable light element concentration with time: oxygen concentration decreases, sulfur concentration decreases initially and increases later, and silicon produces a negligible effect to within the model errors. The result is a net destabilizing concentration gradient. Convective stability is measured by a Rayleigh number, which exceeds the critical value for reasonable estimates of the viscosity and diffusivity. Our results suggest that inner core convection models, including the recently proposed translational mode, can be viable candidates for explaining seismic results if the driving force is compositional. Key Points Partitioning of O and S between inner and outer cores is time dependent Inner core is unstable to compositional convection, contrary to previous studies Thermal effects are stabilising, making composition the only driving force. ©2013 American Geophysical Union. All Rights Reserved. |
| URL: | https://www.scopus.com/inward/record.uri?eid=2-s2.0-84876923939&doi=10.1002%2fgrl.50186&partnerID=40&md5=05c070799bf1ef1f7ee49b0de7c9c4c7
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| Citation statistics: |
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| 资源类型: | 期刊论文
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/6471
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| Appears in Collections: | 气候减缓与适应
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作者单位: | School of Earth and Environment, University of Leeds, Leeds LS2 9JT, United Kingdom
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| Recommended Citation: | |
Gubbins D.,Alfè D.,Davies C.J.. Compositional instability of Earth's solid inner core[J]. Geophysical Research Letters,2013-01-01,40(6).
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