DOI: 10.1016/j.epsl.2021.116888
论文题名: Metal-silicate mixing by large Earth-forming impacts
作者: Landeau M. ; Deguen R. ; Phillips D. ; Neufeld J.A. ; Lherm V. ; Dalziel S.B.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 564 语种: 英语
中文关键词: Earth's formation
; liquid impacts
; metal-silicate equilibration
; mixing
; planetary impacts
; turbulent thermal
英文关键词: Buoyancy
; Earth (planet)
; Isotopes
; Liquids
; Mass transfer
; Metals
; Silicates
; Earth formation
; Geochemicals
; Impactors
; Liquid impacts
; Metal silicates
; Metal-silicate equilibrations
; Planetary impact
; Scalings
; Temperature and pressures
; Turbulent thermal
; Mixing
; equilibrium
; experimental study
; formation mechanism
; geochemistry
; impact
; impact structure
; inertia
; mass transfer
; metal
; mixing
; silicate
; turbulence
英文摘要: Geochemical and isotopic observations constrain the timing, temperature and pressure of Earth's formation. However, to fully interpret these observations, we must know the degree of mixing and equilibration between metal and silicates following the collisions that formed the Earth. Recent fluid dynamical experiments provide initial estimates of this mixing, but they entirely neglect the inertia of planet-building impactors. Here we use laboratory experiments on the impact of a dense liquid volume into a lighter liquid pool to establish scaling laws for mixing as a function of the impactor speed, size, density and the local gravity. Our experiments reproduce the cratering process observed in impact simulations. They also produce turbulence down to small scales, approaching the dynamical regime of planetary impacts. In each experiment, we observe an early impact-dominated stage, which includes the formation of a crater, its collapse into an upward jet, and the collapse of the jet. At later times, we observe the downward propagation of a buoyant thermal. We quantify the contribution to mixing from both the impact and subsequent thermal stage. Our experimental results, together with our theoretical calculations, indicate that the collapse of the jet produces much of the impact-induced mixing. We find that the ratio between the jet inertia and the impactor buoyancy controls mixing. Applied to Earth's formation, we predict full chemical equilibration for impactors less than 100 km in diameter, but only partial equilibration for Moon-forming giant impacts. With our new scalings that account for the impactor inertia, the mass transfer between metal and silicates is up to twenty times larger than previous estimates. This reduces the accretion timescale, deduced from isotopic data, by up to a factor of ten and the equilibration pressure, deduced from siderophile elements, by up to a factor of two. © 2021 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165554
Appears in Collections: 气候变化与战略
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作者单位: Université de Paris, Institut de Physique du Globe de Paris, CNRS, Paris, 75005, France; Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA, United Kingdom; ISTerre, CNRS, Université Grenoble Alpes, Grenoble, 38058, France; Department of Earth Sciences, University of Cambridge, Cambridge, CB3 0EZ, United Kingdom; BP Institute, University of Cambridge, Cambridge, CB3 0EZ, United Kingdom; Laboratoire de Géologie de Lyon, Université Lyon 1, Villeurbanne, 69622, France
Recommended Citation:
Landeau M.,Deguen R.,Phillips D.,et al. Metal-silicate mixing by large Earth-forming impacts[J]. Earth and Planetary Science Letters,2021-01-01,564