气候变化领域集成服务门户(CCPortal): Metal-silicate mixing by large Earth-forming impacts

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DOI	10.1016/j.epsl.2021.116888
	Metal-silicate mixing by large Earth-forming impacts
	Landeau M.; Deguen R.; Phillips D.; Neufeld J.A.; Lherm V.; Dalziel S.B.
发表日期	2021
ISSN	0012821X
卷号	564
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.
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
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203176
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
推荐引用方式 GB/T 7714	Landeau M.,Deguen R.,Phillips D.,et al. Metal-silicate mixing by large Earth-forming impacts[J],2021,564.
APA	Landeau M.,Deguen R.,Phillips D.,Neufeld J.A.,Lherm V.,&Dalziel S.B..(2021).Metal-silicate mixing by large Earth-forming impacts.Earth and Planetary Science Letters,564.
MLA	Landeau M.,et al."Metal-silicate mixing by large Earth-forming impacts".Earth and Planetary Science Letters 564(2021).