DOI: 10.1016/j.epsl.2019.115942
论文题名: Tracing dehydration and melting of the subducted slab with tungsten isotopes in arc lavas
作者: Mazza S.E. ; Stracke A. ; Gill J.B. ; Kimura J.-I. ; Kleine 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: arc volcanism
; slab dehydration
; stable tungsten isotopes
; volatile recycling
英文关键词: Dehydration
; Melting
; Recycling
; Volcanoes
; Alkali basalt
; Arc volcanism
; Cold subduction
; Magmatic process
; Mantle melting
; Shoshonites
; Slab dehydration
; Subduction zones
; Isotopes
; alkali basalt
; dehydration
; isotopic composition
; isotopic fractionation
; lava
; magmatism
; melting
; stable isotope
; subduction zone
; tungsten
; volcanism
; Japan
英文摘要: Tungsten is strongly incompatible during magmatic processes and is fluid mobile in subduction zones. Here we show that W isotope fractionation in arc lavas provide a powerful new tool for tracing slab dehydration and melting in subduction zones. Geochemically well characterized, representative arc-lavas from three subduction zones were chosen for this study to evaluate W isotope fractionation under different sub-arc conditions. Arc-lavas from SW Japan are produced by subducting a young, hot slab, and lavas from the volcanic front and rear arc of the Sangihe and Izu arcs are produced during subduction of a cold slab. The heaviest W isotope compositions (δ184W∼0.06‰) are observed in fluid-rich samples from the volcanic fronts of the Sangihe and Izu arcs. With increasing distance from the volcanic front, more melt-rich samples are characterized by progressively lighter W isotope compositions. Enriched alkali basalts from SW Japan, thought to be the product of mantle melting at a slab tear, and adjacent shoshonites have the lightest W isotope compositions (δ184W∼0‰). The correlation of W isotope fractionation with various indices of fluid release (e.g., Ce/Pb, Ba/Th) suggests that the heavy W isotope signatures record fluid recycling near the volcanic front due to dehydration of the subducted slab. Upon release of the heavy W, the residual slab preferentially retains isotopically light W, which is released during subsequent melting of drier lithologies in hot subduction zones, such as SW Japan. These data suggest that W isotopes can be used as a tracer of slab dehydration, potentially helping to determine the onset of cold subduction zone magmatism and hence, modern-style plate tectonics. © 2019 The Authors Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165151
Appears in Collections: 气候变化与战略
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作者单位: Institut für Planetologie, University of Münster, Münster, 48149, Germany; Department of Geosciences, Smith College, Northampton, MA 01063, United States; Institut für Mineralogie, University of Münster, Münster, 48149, Germany; Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, United States; Japan Agency for Marine-Earth Science and Technology, Yokosuka, 237-0061, Japan
Recommended Citation:
Mazza S.E.,Stracke A.,Gill J.B.,et al. Tracing dehydration and melting of the subducted slab with tungsten isotopes in arc lavas[J]. Earth and Planetary Science Letters,2020-01-01,530