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DOI	10.1016/j.epsl.2021.116973
	The miscibility of calcium silicate perovskite and bridgmanite: A single perovskite solid solution in hot, iron-rich regions
	Muir J.M.R.; Thomson A.R.; Zhang F.
发表日期	2021
ISSN	0012821X
卷号	566
英文摘要	Calcium silicate perovskite and bridgmanite are two phases believed to coexist throughout the lower mantle, which at some temperature, at least theoretically, dissolve into each other to form a single perovskite solid solution (CaxMg1−xSiO3). This may have large seismic and geochemical implications due to the changes in density, elasticity and element partition coefficients between single and mixed phase perovskites. DFT Molecular Dynamics has been used to estimate the miscibility of bridgmanite and calcium perovskite at pressures between 25 and 125 GPa. At 125 GPa (where mixing is the greatest in our pressure range) to mix 1% of Ca-pv into bridgmanite requires a temperature of 2042 K, 5% 2588 K, 10% 2675 K and 50% 2743 K. Therefore, in a simplified lower mantle chemistry an extensive MgSiO3–CaSiO3 solid solution is not expected to occur. However, a simple model was employed to test whether the presence of other elements might influence this mutual solid solution and it was demonstrated that if sufficient concentrations (>1 at.%) of additional elements are present then miscibility may become favourable. Of the elements likely to be present at these concentrations it appears that ferrous iron promotes, whilst aluminium inhibits, a single-phase perovskite solid solution. To a lesser extent ferric iron may both increase and decrease perovskite miscibility. Modelling for realistic mantle compositions suggests that basaltic lithologies will always retain two perovskite components, whereas a single perovskite solid solution may be preferred in hot and/or iron-rich pyrolytic bulk compositions near the base of the lower mantle. Static calculations indicate perovskite miscibility may cause pyrolytic lithologies (with 12.5% CaSiO3) to possess lower density (−0.14–0.25%), Vs (−1.5–3.5%) and Vp (−0.5–1.2%), and higher VΦ (+ 0.00–0.75%) than predicted for assemblages containing two perovskites. These seismic changes, while preliminary, are similar to those observed in the LLSVPs which are also regions that are likely hotter than the surrounding mantle and thus possess conditions promoting the formation of a single perovskite phase. © 2021 Elsevier B.V.
关键词	bridgmanite calcium silicate perovskite phase mixing
英文关键词	Calcium silicate; Iron; Molecular dynamics; Perovskite; Seismology; Silicates; Solid solutions; Solubility; Bridgmanite; Calcium silicate perovskite; Geochemicals; Iron rich; Lower mantle; Perovskite solid solutions; Phase mixing; Silicate perovskite; Single phase; Two phase; Mixing; calcium; concentration (composition); mantle chemistry; mixing; perovskite; silicate; solid solution
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203232
作者单位	State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 99 West Lincheng Road, Guiyang, Guizhou 50081, China; Department of Earth Sciences, University College London, London, WC1E 6BT, United Kingdom
推荐引用方式 GB/T 7714	Muir J.M.R.,Thomson A.R.,Zhang F.. The miscibility of calcium silicate perovskite and bridgmanite: A single perovskite solid solution in hot, iron-rich regions[J],2021,566.
APA	Muir J.M.R.,Thomson A.R.,&Zhang F..(2021).The miscibility of calcium silicate perovskite and bridgmanite: A single perovskite solid solution in hot, iron-rich regions.Earth and Planetary Science Letters,566.
MLA	Muir J.M.R.,et al."The miscibility of calcium silicate perovskite and bridgmanite: A single perovskite solid solution in hot, iron-rich regions".Earth and Planetary Science Letters 566(2021).