气候变化领域集成服务门户(CCPortal): Deep fractionation of Hf in a solidifying magma ocean and its implications for tungsten isotopic heterogeneities in the mantle

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DOI	10.1016/j.epsl.2021.116873
	Deep fractionation of Hf in a solidifying magma ocean and its implications for tungsten isotopic heterogeneities in the mantle
	Deng J.; Stixrude L.
发表日期	2021
ISSN	0012821X
卷号	562
英文摘要	Recent geochemical studies document a wide range of 182W anomalies in mantle-derived rocks, the origin of which is unknown. Here we explore the consequences of basal magma ocean crystallization while 182Hf was extant. We determine the partition coefficient of Hf between bridgmanite and silicate melt DHf throughout the pressure-temperature regime of Earth's lower mantle from first principles molecular dynamics coupled with thermodynamic integration. The calculations are based on Hf4+ entering the Mg-site, which we show is energetically preferable to the Si-site. We find that DHf increases by more than an order of magnitude from 25 GPa to 140 GPa, making Hf much more compatible with increasing pressure. The larger DHf at greater depths produces a strong fractionation of 182Hf between crystallized bridgmanite and silicate melt. We use a simple geochemical model to show that heterogeneous tungsten anomalies are a natural outcome of the formation and crystallization of a basal magma ocean, with the crystallized products enriched in 182W, while the remaining liquid is depleted by a similar amount. Our results show that the observed large variability of 182W/184W in terrestrial samples may be due to the solidification of a basal magma ocean. © 2021 Elsevier B.V.
关键词	ab initio calculation silicate melt partitioning tungsten anomaly
英文关键词	Geochemistry; Molecular dynamics; Oceanography; Silicates; Tungsten; Ab initio calculations; Earth lower mantle; First principles molecular dynamics; Geochemicals; Magma ocean; Partition coefficient; Silicate melt partitioning; Silicate melts; Temperature regimes; Tungsten anomaly; Calculations; crystallization; hafnium; heterogeneity; isotopic composition; isotopic fractionation; magma; mantle; partition coefficient; silicate melt; tungsten
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/203068
作者单位	Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, 90095, United States
推荐引用方式 GB/T 7714	Deng J.,Stixrude L.. Deep fractionation of Hf in a solidifying magma ocean and its implications for tungsten isotopic heterogeneities in the mantle[J],2021,562.
APA	Deng J.,&Stixrude L..(2021).Deep fractionation of Hf in a solidifying magma ocean and its implications for tungsten isotopic heterogeneities in the mantle.Earth and Planetary Science Letters,562.
MLA	Deng J.,et al."Deep fractionation of Hf in a solidifying magma ocean and its implications for tungsten isotopic heterogeneities in the mantle".Earth and Planetary Science Letters 562(2021).