DOI: 10.1016/j.epsl.2020.116680
论文题名: On the fate of impact-delivered metal in a terrestrial magma ocean
作者: Maas C. ; Manske L. ; Wünnemann K. ; Hansen U.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 554 语种: 英语
中文关键词: differentiation
; impact
; magma ocean
; metal settling history
; metal-silicate equilibration
; rotating convection
英文关键词: Dispersions
; Drops
; Geochemistry
; Oceanography
; Silicates
; Chemical heterogeneities
; Degree of dispersion
; Geochemical signatures
; Metal-silicate equilibrations
; Numerical experiments
; Planetary rotation
; Possible mechanisms
; Spherical geometries
; Metals
; differentiation
; heavy metal
; isotopic analysis
; magma chamber
; mantle chemistry
; mantle convection
; planetary rotation
; rotating flow
; silicate
; terrestrial environment
英文摘要: Impacts on Earth crucially influenced core formation and the subsequent evolution of Earth's mantle and may have contributed to late accretion of material. However, to what extent the present-day geochemical signature of Earth's mantle reflects the processes of core formation and late accretion, and how much of material delivered by giant impacts and by impacts of smaller projectiles during late accretion was incorporated into the core remains unclear. To improve the insight into these processes, it is of key importance to comprehend how impact-delivered metal droplets are dispersed and subsequently settle in a terrestrial magma ocean. Settling and mixing are potentially strongly influenced by the convective and rotational state of the magma ocean. Therefore, by means of numerical experiments in spherical geometry, we study how the convective state of the magma ocean and the potentially strong planetary rotation affect the settling of impact-delivered material in a deep global magma ocean. We reveal crucial differences in metal dispersion and in settling history depending on the impactor's target latitude. For an impact at either pole, the metal dispersion within the magma ocean is spatially limited while the metal droplets settle fast. Impacts at lower latitudes allow for a higher degree of dispersion, being accompanied by a slower metal settling. Consequently, metal-silicate equilibration may differ depending on the target latitude, being limited to certain localized domains of the magma ocean. We further demonstrate that the volume fraction undergoing metal-silicate equilibration seems to depend linearly on the impactor's diameter and may be largely underestimated in previous studies. Overall, we present a possible mechanism for heterogeneous metal-silicate equilibration and the generation of chemical heterogeneities and isotopic anomalies in Earth's mantle due to the influence of planetary rotation, potentially shaping the geochemical signatures that are observed today. © 2020 The Authors Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165583
Appears in Collections: 气候变化与战略
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作者单位: Institut für Geophysik, Westfälische Wilhelms-Universität Münster, Corrensstr. 24, Münster, D-48149, Germany; Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Berlin, D-10115, Germany; Institut für Geologische Wissenschaften, Freie Universität Berlin, Malteserstr., 74-100, Berlin, D-12249, Germany
Recommended Citation:
Maas C.,Manske L.,Wünnemann K.,et al. On the fate of impact-delivered metal in a terrestrial magma ocean[J]. Earth and Planetary Science Letters,2021-01-01,554