气候变化领域集成服务门户(CCPortal): Grain boundary diffusion of W in lower mantle phase with implications for isotopic heterogeneity in oceanic island basalts by core-mantle interactions

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DOI	10.1016/j.epsl.2019.115887
	Grain boundary diffusion of W in lower mantle phase with implications for isotopic heterogeneity in oceanic island basalts by core-mantle interactions
	Yoshino T.; Makino Y.; Suzuki T.; Hirata T.
发表日期	2020
ISSN	0012821X
卷号	530
英文摘要	Tungsten isotopes provide important constraints on the ocean-island basalt (OIB) source regions. Recent analyses of μ182W in modern basalts with high 3He/4He originating from the core-mantle boundary region reveal two distinct features: positive μ182W in Phanerozoic flood basalts indicating the presence of primordial reservoir, and negative μ182W in modern OIBs. One possibility to produce large variations in μ182W is interaction between the mantle and outer core. Here, we report grain boundary diffusion of W in lower mantle phases. High pressure experimental results show that grain boundary diffusion of W is fast and strongly temperature dependent. Over Earth's history, diffusive transport of W from the core to the lowermost mantle may have led to significant modification of the W isotopic composition of the lower mantle at length scales exceeding one kilometer. Such grain boundary diffusion can lead to large variations in μ182W in modern basalts as a function of the distance of their source regions from the core mantle boundary. Modern oceanic island basalts from Hawaii, Samoa and Iceland exhibit negative μ182W and likely originated from the modified isotope region just above the core-mantle boundary, whereas those with positive μ182W could be derived from the thick Large Low Shear Velocity Provinces (LLSVPs) far from the core-mantle boundary (CMB). When highly-oxidized slabs accumulate at the CMB oxidizing the outer core at the interface, a large W flux with negative μ182W can be added to the silicate mantle. As a result, the source region of the OIB would be effectively modified to a negative μ182W. © 2019 Elsevier B.V.
关键词	core mantle boundary core mantle interaction grain boundary diffusion high pressure experiment postspinel W isotope
英文关键词	Basalt; Diffusion; Grain boundaries; Isotopes; Reservoirs (water); Shear flow; Silicates; Core-mantle boundary; Core-mantle interaction; Grain-boundary diffusion; High-pressure experiment; postspinel; W isotopes; Structural geology; core-mantle boundary; flood basalt; high pressure; isotopic composition; lower mantle; mantle source; mantle structure; ocean island basalt; tungsten; Hawaii [United States]; Iceland; Samoa; United States
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/202991
作者单位	Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan; Geochemical Research Center, The University of Tokyo, Tokyo, 113-0033, Japan
推荐引用方式 GB/T 7714	Yoshino T.,Makino Y.,Suzuki T.,et al. Grain boundary diffusion of W in lower mantle phase with implications for isotopic heterogeneity in oceanic island basalts by core-mantle interactions[J],2020,530.
APA	Yoshino T.,Makino Y.,Suzuki T.,&Hirata T..(2020).Grain boundary diffusion of W in lower mantle phase with implications for isotopic heterogeneity in oceanic island basalts by core-mantle interactions.Earth and Planetary Science Letters,530.
MLA	Yoshino T.,et al."Grain boundary diffusion of W in lower mantle phase with implications for isotopic heterogeneity in oceanic island basalts by core-mantle interactions".Earth and Planetary Science Letters 530(2020).