Deformation-aided segregation of Fe -S liquid from olivine under deep Earth conditions: Implications for core formation in the early solar system - Archive ouverte HAL Access content directly
Journal Articles Physics of the Earth and Planetary Interiors Year : 2017

Deformation-aided segregation of Fe -S liquid from olivine under deep Earth conditions: Implications for core formation in the early solar system

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Madeleine T. L. Berg
  • Function : Author
Geoffrey D. Bromiley
  • Function : Author
Ian B. Butler
  • Function : Author
Mungo Frost
  • Function : Author
Robert Bradley
  • Function : Author
James Carr
  • Function : Author
Yann Le Godec
Laurent G. J. Montesi
  • Function : Author
Wenlu Zhu
  • Function : Author
Kevin Miller
  • Function : Author
Elisabetta Mariani
  • Function : Author
Daniel Tatham
  • Function : Author
Simon A. T. Redfern
  • Function : Author

Abstract

The planets and larger rocky bodies of the inner solar system are differentiated, and consist of metallic, iron-rich cores surrounded by thick shells of silicate. Core formation in these bodies, i.e. the segregation of metal from silicate, was a key process in the early solar system, and one which left a lasting geochemical signature. It is commonly assumed that extensive silicate melting and formation of deep magma oceans was required to initiate core formation, due to the inability of iron-rich melts to segregate from a solid silicate matrix. Here we assess the role of deformation in aiding segregation of core-forming melts from solid silicate under conditions of planetary deep interiors. Low-strain rate, high-pressure/ temperature deformation experiments and high-resolution 2-D and 3-D textural analysis demonstrate that deformation fundamentally alters iron-rich melt geometry, promoting wetting of silicate grain boundaries and formation of extensive micron to sub-micron width Fe-rich melt bands. Deformation aided Fe-S melt networks noted here contrast those observed in higher finite strain experiments conducted at lower pressure, and may reveal either an alternative mechanism for melt segregation at higher pressures, or an early stage process of melt segregation. Results suggest, however, that core-mantle chemical equilibration cannot be assumed in models of planetary formation, and that instead, the chemistry of rocky planets may record a complex, multi-stage process of core formation. Crown Copyright (c) 2017 Published by Elsevier B.V.
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hal-02329279 , version 1 (20-09-2021)

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Attribution - CC BY 4.0

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Madeleine T. L. Berg, Geoffrey D. Bromiley, Ian B. Butler, Mungo Frost, Robert Bradley, et al.. Deformation-aided segregation of Fe -S liquid from olivine under deep Earth conditions: Implications for core formation in the early solar system. Physics of the Earth and Planetary Interiors, 2017, 263, pp.38-54. ⟨10.1016/j.pepi.2017.01.004⟩. ⟨hal-02329279⟩
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