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DOI	10.1029/2020JB020365
	Structure and Density of H2O-Rich Mg2SiO4 Melts at High Pressure From Ab Initio Simulations
	Yuan L.; Steinle-Neumann G.; Suzuki A.
发表日期	2020
ISSN	21699313
卷号	125 期号:10
英文摘要	Water has a strong effect on silicate melt properties, yet its dissolution mechanism in depolymerized melts, typical for mantle composition, remains poorly understood. Here we report results of first-principles molecular dynamics simulations for hydrous Mg2SiO4 melts with 6, 16, and 27 wt% H2O at pressure and temperature conditions relevant to the upper mantle and mantle transition zone. The results show that hydrogen bonds not only to the network-forming cation Si but also to Mg which—nevertheless—remains the most important network modifier. There is no evidence to support the hypothesis based on experimental data that water may cause an increase in melt polymerization for ultramafic magmas; the ratio of non-bridging oxygen per Si increases with the addition of the oxygen from H2O. The partial molar volume of water is independent on concentration in our simulations which allows us to examine the density of hydrous melt systematically. The critical water content—at which melts are neutrally buoyant compared to the surrounding mantle—is ~4 wt% H2O for a pyrolite composition, much lower than the high water content (>10 wt%) observed in petrological experiments and estimated thermodynamically for low-degree partial melts formed in the vicinity of the mantle transition zone. ©2020. The Authors.
英文关键词	density; density functional theory; high pressure; hydrous silicate melts; structure
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187575
作者单位	Department of Earth and Planetary Materials Science, Tohoku University, Sendai, Japan; Bayerisches Geoinstitut, Universität Bayreuth, Bayreuth, Germany
推荐引用方式 GB/T 7714	Yuan L.,Steinle-Neumann G.,Suzuki A.. Structure and Density of H2O-Rich Mg2SiO4 Melts at High Pressure From Ab Initio Simulations[J],2020,125(10).
APA	Yuan L.,Steinle-Neumann G.,&Suzuki A..(2020).Structure and Density of H2O-Rich Mg2SiO4 Melts at High Pressure From Ab Initio Simulations.Journal of Geophysical Research: Solid Earth,125(10).
MLA	Yuan L.,et al."Structure and Density of H2O-Rich Mg2SiO4 Melts at High Pressure From Ab Initio Simulations".Journal of Geophysical Research: Solid Earth 125.10(2020).