Density-Pressure Profiles of Fe-Bearing MgSiO3 Liquid: Effects of Valence and Spin States, and Implications for the Chemical Evolution of the Lower Mantle
Density-Pressure Profiles of Fe-Bearing MgSiO3 Liquid: Effects of Valence and Spin States, and Implications for the Chemical Evolution of the Lower Mantle
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DOI：
10.1029/2018gl077149
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发表时间：
2018-05-16
影响因子：
5.2
通讯作者：
Park, Jeffrey
中科院分区：
文献类型：
--
作者：
Karki, Bijaya B.;Ghosh, Dipta B.;Park, Jeffrey
密度是控制地球内部化学状态的关键属性。我们的知识有关的熔体组成的密度是目前穷人在深地幔条件。在这里，我们报告的结果从第一性原理分子动力学模拟的Fe轴承MgSiO3液体考虑不同的价态和自旋态的铁在整个地幔压力条件。我们的模拟预测，在硅酸盐液体中的亚铁和三价铁的高自旋到低自旋的转变逐渐发生在100 GPa左右的压力。计算出的铁引起的熔体密度变化（铁含量为25%时增加约8%）主要是由于Mg和Fe之间的原子质量差异，
Density is a key property controlling the chemical state of Earth's interior. Our knowledge about the density of relevant melt compositions is currently poor at deep-mantle conditions. Here we report results from first-principles molecular-dynamics simulations of Fe-bearing MgSiO3 liquids considering different valence and spin states of iron over the whole mantle pressure conditions. Our simulations predict the high-spin to low-spin transition in both ferrous and ferric iron in the silicate liquid to occur gradually at pressures around 100GPa. The calculated iron-induced changes in the melt density (about 8% increase for 25% iron content) are primarily due to the difference in atomic mass between Mg and Fe, with smaller contributions (