DOI: 10.1016/j.epsl.2020.116085
论文题名: Thermal and magnetic evolution of a crystallizing basal magma ocean in Earth's mantle
作者: Blanc N.A. ; Stegman D.R. ; Ziegler L.B.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 534 语种: 英语
中文关键词: basal magma ocean dynamo
; early Earth dynamo
; molten silicates
英文关键词: Interactive devices
; Magnetism
; Silicates
; Core-mantle boundary
; Early Earth
; Magma ocean
; Magnetic activity
; Melting point depressions
; Partition coefficient
; Plausible mechanisms
; Strong dependences
; Heat flux
; basalt
; core-mantle boundary
; crystallization
; geodynamo
; magma chamber
; mantle source
; partial melting
; silicate
; temperature effect
; trace element
英文摘要: We present the thermochemical evolution of a downward crystallizing basal magma ocean (BMO) overlying the liquid outer core and probe its capability to dissipate enough power to generate and sustain an early dynamo. A total of 61 out of 112 scenarios for a BMO with imposed, present-day heat flux, QBMO, values of 15, 18, and 21 TW and radiogenic heat, Qr, values of 4, 8, and 12 TW fully crystallized during the age of the Earth. Most of these models are energetically capable of inducing magnetic activity for the first 1.5 Gyrs, at least, with durations extending to 2.5 Gyrs; with final core-mantle boundary (CMB) temperatures of 4400 ± 500 K -well within current best estimates for inferred temperatures. None of the models with QBMO = 12 TW achieved a fully crystallized state, which may reflect a lower bound on the present-day heat flux across the CMB. BMO-powered dynamos exhibit strong dependence on the partition coefficient of iron into the liquid layer and its associated melting-point depression for a lower mantle composition at near-CMB conditions -parameters which are poorly constrained to date. Nonetheless, we show that a crystallizing BMO is a plausible mechanism to sustain an early magnetic field. © 2020 Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/164872
Appears in Collections: 气候变化与战略
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作者单位: Institute for Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, United States
Recommended Citation:
Blanc N.A.,Stegman D.R.,Ziegler L.B.. Thermal and magnetic evolution of a crystallizing basal magma ocean in Earth's mantle[J]. Earth and Planetary Science Letters,2020-01-01,534