Premium
Thermodynamical Modeling of Liquid Fe‐Si‐Mg‐O:Molten Magnesium Silicate Release From the Core
Author(s) -
Helffrich George,
Hirose Kei,
Nomura Ryuichi
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl089218
Subject(s) - silicate , liquidus , mantle (geology) , metal , solubility , geology , magnesium , fractional crystallization (geology) , crystallization , mineralogy , materials science , thermodynamics , geochemistry , chemical engineering , chemistry , metallurgy , physics , alloy , engineering
We developed a thermodynamic model to explore the joint solubility of Mg, Si, and O in liquid Fe on the basis of high‐pressure metal‐silicate partitioning data in the literature, with more Mg kept in the metal when Si and O are present. With <1.7 ± 0.5 wt% Mg, the metal in the young Earth's core retains Mg as the core evolves and crystallizes SiO 2 . Higher Mg concentrations require either the late addition of metal that equilibrated with silicate in a super‐liquidus magma ocean or the assimilation of silicate into the core at the time of a giant impact. Above 1.7 wt% Mg, (Mg,Fe)‐silicate melts also exsolve from the core and transfer core‐hosted elements to the mantle. Fractional crystallization of the core‐derived silicate melts in the core or at the core‐mantle boundary could, additionally, yield a persistent molten silicate layer that could also contribute to ultralow velocity zone formation in the lowermost mantle.