DOI: 10.1016/j.epsl.2017.12.012
Scopus记录号: 2-s2.0-85040603990
论文题名: Collisional stripping of planetary crusts
作者: Carter P.J. ; Leinhardt Z.M. ; Elliott T. ; Stewart S.T. ; Walter M.J.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 484 起始页码: 276
结束页码: 286
语种: 英语
英文关键词: accretion
; crust
; impact erosion
; planet composition
; planet formation
; terrestrial planets
Scopus关键词: Erosion
; Geochemistry
; Hydrodynamics
; Melting
; Planets
; Silicates
; accretion
; crust
; Impact erosion
; Planet formation
; Terrestrial planets
; Budget control
; accretion
; chondrite
; crustal structure
; erosion
; fractionation
; geochemistry
; hydrodynamics
; planet
英文摘要: Geochemical studies of planetary accretion and evolution have invoked various degrees of collisional erosion to explain differences in bulk composition between planets and chondrites. Here we undertake a full, dynamical evaluation of ‘crustal stripping’ during accretion and its key geochemical consequences. Crusts are expected to contain a significant fraction of planetary budgets of incompatible elements, which include the major heat producing nuclides. We present smoothed particle hydrodynamics simulations of collisions between differentiated rocky planetesimals and planetary embryos. We find that the crust is preferentially lost relative to the mantle during impacts, and we have developed a scaling law based on these simulations that approximates the mass of crust that remains in the largest remnant. Using this scaling law and a recent set of N-body simulations of terrestrial planet formation, we have estimated the maximum effect of crustal stripping on incompatible element abundances during the accretion of planetary embryos. We find that on average approximately one third of the initial crust is stripped from embryos as they accrete, which leads to a reduction of ∼20% in the budgets of the heat producing elements if the stripped crust does not reaccrete. Erosion of crusts can lead to non-chondritic ratios of incompatible elements, but the magnitude of this effect depends sensitively on the details of the crust-forming melting process on the planetesimals. The Lu/Hf system is fractionated for a wide range of crustal formation scenarios. Using eucrites (the products of planetesimal silicate melting, thought to represent the crust of Vesta) as a guide to the Lu/Hf of planetesimal crust partially lost during accretion, we predict the Earth could evolve to a superchondritic 176Hf/177Hf (3–5 parts per ten thousand) at present day. Such values are in keeping with compositional estimates of the bulk Earth. Stripping of planetary crusts during accretion can lead to detectable changes in bulk composition of lithophile elements, but the fractionation is relatively subtle, and sensitive to the efficiency of reaccretion. © 2017 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110058
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: School of Physics, University of Bristol, H. H. Wills Physics Laboratory, Tyndall Avenue, Bristol, BS8 1TL, United Kingdom; Department of Earth and Planetary Sciences, University of California Davis, One Shields Avenue, Davis, CA 95616, United States; School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol, BS8 1RJ, United Kingdom
Recommended Citation:
Carter P.J.,Leinhardt Z.M.,Elliott T.,et al. Collisional stripping of planetary crusts[J]. Earth and Planetary Science Letters,2018-01-01,484