DOI: 10.1016/j.epsl.2020.116601
论文题名: Slab dehydration in warm subduction zones at depths of episodic slip and tremor
作者: Condit C.B. ; Guevara V.E. ; Delph J.R. ; French M.E.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 552 语种: 英语
中文关键词: dehydration
; slow slip
; subduction
; tremor
英文关键词: Dehydration
; Hydration
; Seismographs
; Silicate minerals
; Dehydration reactions
; Depleted MORB mantles
; Episodic slow slips
; Hydrated peridotites
; Non-volcanic tremors
; Pore fluid pressure
; Subduction interface
; Thermodynamic model
; Transport properties
; lithology
; metapelite
; oceanic crust
; P-T conditions
; peridotite
; petrology
; plate boundary
; slip
; subduction zone
英文摘要: Non-volcanic tremor (NVT) and episodic slow slip events (SSEs) have been observed below the seismogenic zone of relatively warm subduction zones for the past 20 years. Geophysical and geologic observations show that this portion of the subduction interface is fluid-rich, and many models for these slip behaviors necessitate high pore fluid pressures. However, whether these fluids are sourced from local dehydration reactions in particular lithologies, or require up-dip transport from greater depths is not known. We present thermodynamic models of the petrologic evolution of four lithologies typical of the plate interface (average MORB, seafloor altered MORB, hydrated depleted MORB mantle, and metapelite) along predicted plate boundary pressure–temperature (P-T) paths at several warm subduction segments where NVT and SSEs are observed at depths between 25-65 km. The models suggest that 1-2 wt% H2O is released at the depths of NVT/SSEs in Jalisco-Colima, Guerrero, Cascadia, and Shikoku due to punctuated dehydration reactions within MORB, primarily through chlorite and/or lawsonite breakdown. These reactions produce sufficient in-situ fluid across a narrow P-T range to cause high pore fluid pressures at NVT/SSE depths. Dehydration of hydrated peridotite is minimal at these depths for most margins, and metapelite releases H2O (<1.5 wt%) gradually over a wide depth range compared to MORB. We posit that punctuated dehydration of oceanic crust provides the dominant source of fluids at the base of the seismogenic zone in these warm subduction zones, and up-dip migration of fluids from deeper in the subduction zone is not required. © 2020 The Authors Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/164927
Appears in Collections: 气候变化与战略
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作者单位: University of Washington, Seattle, WA, United States; Rice University, Houston, TX, United States; Amherst College, Amherst, MA, United States; University of Oregon, Eugene, OR, United States; Purdue University, Lafayette, ID, United States
Recommended Citation:
Condit C.B.,Guevara V.E.,Delph J.R.,et al. Slab dehydration in warm subduction zones at depths of episodic slip and tremor[J]. Earth and Planetary Science Letters,2020-01-01,552