Fe–FeO and Fe–Fe 3 C melting relations at Earth's core–mantle boundary conditions: Implications for a volatile-rich or oxygen-rich core

Abstract : Eutectic melting temperatures in the Fe–FeO and Fe–Fe3C systems have been determined up to 150 GPa. Melting criteria include observation of a diffuse scattering signal by in situ X-Ray diffraction, and textural characterisation of recovered samples. In addition, compositions of eutectic liquids have been established by combining in situ Rietveld analyses with ex situ chemical analyses. Gathering these new results together with previous reports on Fe–S and Fe–Si systems allow us to discuss the specific effect of each light element (Si, S, O, C) on the melting properties of the outer core. Crystallization temperatures of Si-rich core compositional models are too high to be compatible with the absence of extensive mantle melting at the core–mantle boundary (CMB) and significant amounts of volatile elements such as S and/or C (>5 at%, corresponding to >2 wt%), or a large amount of O (>15 at% corresponding to ∼5 wt%) are required to reduce the crystallisation temperature of the core material below that of a peridotitic lower mantle.
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Earth and Planetary Science Letters, Elsevier, 2017, 473, pp.94 - 103. 〈10.1016/j.epsl.2017.05.024〉
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Soumis le : mardi 21 novembre 2017 - 11:16:54
Dernière modification le : mercredi 19 septembre 2018 - 01:24:42

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G. Morard, D. Andrault, D. Antonangeli, Y. Nakajima, A. Auzende, et al.. Fe–FeO and Fe–Fe 3 C melting relations at Earth's core–mantle boundary conditions: Implications for a volatile-rich or oxygen-rich core. Earth and Planetary Science Letters, Elsevier, 2017, 473, pp.94 - 103. 〈10.1016/j.epsl.2017.05.024〉. 〈hal-01643217〉

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