DOI: 10.1016/j.epsl.2019.115887
论文题名: Grain boundary diffusion of W in lower mantle phase with implications for isotopic heterogeneity in oceanic island basalts by core-mantle interactions
作者: Yoshino T. ; Makino Y. ; Suzuki T. ; Hirata T.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 530 语种: 英语
中文关键词: 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
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. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165369
Appears in Collections: 气候变化与战略
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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
Recommended Citation:
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]. Earth and Planetary Science Letters,2020-01-01,530