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DOI | 10.1038/s41561-020-0560-y |
Iron isotope fractionation at the core-mantle boundary by thermodiffusion | |
Lesher, Charles E.1,2,3; Dannberg, Juliane2,4; Barfod, Gry H.1; Bennett, Neil R.2; Glessner, Justin J. G.3; Lacks, Daniel J.5; Brenan, James M.6 | |
2020-04-06 | |
发表期刊 | NATURE GEOSCIENCE
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ISSN | 1752-0894 |
EISSN | 1752-0908 |
出版年 | 2020 |
卷号 | 13期号:5 |
文章类型 | Article |
语种 | 英语 |
国家 | Denmark; USA; Canada |
英文摘要 | The D" layer at the base of the Earth's mantle exhibits anomalous seismic properties, which are attributed to heat loss from and chemical interaction with the underlying molten Fe-rich outer core. Here we show that mass transfer due to temperature variations within the D" layer could lead to resolvable fractionation of iron isotopes. We constrain the degree of isotope fractionation by experiments on core-forming Fe alloy liquids at 2100-2300 K and 2 GPa, which demonstrate that heavy Fe isotopes preferentially migrate towards lower temperature and vice versa. We find that this isotope fractionation occurs rapidly due to the high mobility of iron, which reaches 0.013 +/- 0.002 parts per thousand (2 sigma) per degree per amu at steady state. Numerical simulations of mantle convection capturing the evolution of a basal thermal boundary layer show that iron isotope fractionation immediately above the core-mantle boundary can reach measurable levels on geologic timescales and that plumes can entrain this fractionated material into the convecting mantle. We suggest that such a process may contribute to the heavy Fe isotope composition of the upper mantle inferred from mantle melts (basalts) and residues (peridotites) relative to chondrites. That being the case, non-traditional stable isotope systems such as Fe may constrain the interactions between the core and mantle. Iron isotopic fractionation at the core-mantle boundary due to thermal diffusion may partly explain the iron isotope composition of the upper mantle, according to high-temperature experiments and numerical simulations. |
领域 | 地球科学 ; 气候变化 |
收录类别 | SCI-E |
WOS记录号 | WOS:000523950000001 |
WOS关键词 | LIQUID-IRON ; DIFFUSION ; TEMPERATURE ; OXYGEN ; MELT ; HETEROGENEITY ; BENEATH ; METAL ; LAYER ; BASE |
WOS类目 | Geosciences, Multidisciplinary |
WOS研究方向 | Geology |
URL | 查看原文 |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/249281 |
专题 | 地球科学 气候变化 |
作者单位 | 1.Aarhus Univ, Dept Geosci, Aarhus, Denmark; 2.Univ Calif Davis, Dept Earth & Planetary Sci, Davis, CA 95616 USA; 3.Univ Calif Davis, Interdisciplinary Ctr Plasma Mass Spectrometry, Davis, CA 95616 USA; 4.Univ Florida, Dept Geol Sci, Gainesville, FL USA; 5.Case Western Reserve Univ, Dept Chem & Biomol Engn, Cleveland, OH 44106 USA; 6.Dalhousie Univ, Dept Earth & Environm Sci, Halifax, NS, Canada |
推荐引用方式 GB/T 7714 | Lesher, Charles E.,Dannberg, Juliane,Barfod, Gry H.,et al. Iron isotope fractionation at the core-mantle boundary by thermodiffusion[J]. NATURE GEOSCIENCE,2020,13(5). |
APA | Lesher, Charles E..,Dannberg, Juliane.,Barfod, Gry H..,Bennett, Neil R..,Glessner, Justin J. G..,...&Brenan, James M..(2020).Iron isotope fractionation at the core-mantle boundary by thermodiffusion.NATURE GEOSCIENCE,13(5). |
MLA | Lesher, Charles E.,et al."Iron isotope fractionation at the core-mantle boundary by thermodiffusion".NATURE GEOSCIENCE 13.5(2020). |
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