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Abstract The heat extracted from the core by the overlying mantle across the core‐mantle boundary controls the thermal evolution of the core. This in turn leads to the solidification of the inner core in association with the exsolution of light alloying elements into the liquid outer core. Although the temperature (T) at the inner core boundary (ICB) would be adjusted to account for the effects of the light elements, the melting T of Fe places an upper bound at the ICB and it is a vital point in the thermal profile of the core. Here, we determine the melting T of Fe in the multi‐anvil press by characterizing the interface of Fe‐W interaction. Our data place a tighter constraint on the melting curve of Fe between 8 and 21 GPa, that is directly applicable to small planetary bodies and serves as an anchor for melting curve of Fe at higher pressure.
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Regimes of Element Transfer Between Earth's Core and Basal Magma Ocean
Abstract Earth's accretion was highly energetic and likely involved multiple global melting events. Following the Moon‐forming giant impact, extensive mantle melting and the separation of solids and melts under deep mantle pressures likely produced a basal magma ocean (BMO) beneath the solidified mantle. The presence and evolution of the BMO have been proposed to explain key geophysical and geochemical features of the lowermost mantle. Understanding the evolution of the BMO is crucial for testing these hypotheses, but its interaction with the core presents a significant challenge, as the mechanism of this exchange remains unclear. In this study, we develop a theoretical framework to assess the regime of BMO‐core exchange based on the compositions of the BMO and the core. We propose that during solidification, the BMO may evolve into a regime where the reaction at the BMO‐core interface drives compositional convection in liquids on both sides, if the core has a high enough Si content (–, under the assumption that the O content is –). In this scenario, the BMO‐core exchange would be much more efficient than previously estimated, buffering the tendency of FeO enrichment during crystallization and shortening the lifetime of the BMO.
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- Award ID(s):
- 2444522
- PAR ID:
- 10628631
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Solid Earth
- Volume:
- 130
- Issue:
- 7
- ISSN:
- 2169-9313
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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