DOI: 10.1016/j.epsl.2017.10.044
Scopus记录号: 2-s2.0-85033590064
论文题名: Fast intraslab fluid-flow events linked to pulses of high pore fluid pressure at the subducted plate interface
作者: Taetz S. ; John T. ; Bröcker M. ; Spandler C. ; Stracke A.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 482 起始页码: 33
结束页码: 43
语种: 英语
英文关键词: diffusion modelling
; fluid flow system
; Li chronometry
; plate interface
; seismic slip
; subduction zones
Scopus关键词: Dehydration
; Diffusion
; Diffusion in liquids
; Lithium
; Lithium compounds
; Metamorphic rocks
; Rocks
; Wall rock
; Dehydration reactions
; Metamorphic conditions
; Plate interfaces
; Quantitative models
; Seismic slips
; Subduction zone fluids
; Subduction zone process
; Subduction zones
; Flow of fluids
; diffusion
; fluid flow
; lithium
; modeling
; pore pressure
; slab
; slip rate
; subduction zone
; tectonic plate
; vein (geology)
; New Caledonia [Melanesia]
英文摘要: A better understanding of the subduction zone fluid cycle and its chemical–mechanical feedback requires in-depth knowledge about how fluids flow within and out of descending slabs. Relicts of fluid-flow systems in exhumed rocks of fossil subduction zones allow for identification of the general relationships between dehydration reactions, fluid pathway formation, the dimensions and timescales of distinct fluid flow events; all of which are required for quantitative models for fluid-induced subduction zone processes. Two types of garnet–quartz–phengite veins can be distinguished in an eclogite-facies mélange block from the Pouébo Eclogite Mélange, New Caledonia. These veins record synmetamorphic internal fluid release by mineral breakdown reactions (type I veins), and infiltration of an external fluid (type II veins) with the associated formation of a reaction selvage. The dehydration and fluid migration documented by the type I veins likely occurred on a timescale of 105–106 years, based on average subduction rates and metamorphic conditions required for mineral dehydration and fluid flow. The timeframe of fluid–rock interaction between the external fluid and the wall-rock of the type II veins is quantified using a continuous bulk-rock Li-diffusion profile perpendicular to a vein and its metasomatic selvage. Differences in Li concentration between the internal and external fluid reservoirs resulted in a distinct diffusion profile (decreasing Li concentration and increasing δ7Li) as the reaction front propagated into the host rock. Li-chronometric constraints indicate that the timescales of fluid–rock interaction associated with type II vein formation are on the order of 1 to 4 months (0.150−0.08 +0.14 years). The short-lived, pulse-like character of this process is consistent with the notion that fluid flow caused by oceanic crust dehydration at the blueschist-to-eclogite transition contributes to or even dominates episodic pore fluid pressure increases at the plate interface, which in turn, may trigger slip events reported from many subduction zones. © 2017 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110147
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Institut für Mineralogie, Universität Münster, Corrensstraße 24, Münster, 48149, Germany; Institut für Geologische Wissenschaften, Freie Universität Berlin, Malteserstr. 74-100, Berlin, 12449, Germany; Economic Geology Research Centre, James Cook University, Townsville, 4811, Australia
Recommended Citation:
Taetz S.,John T.,Bröcker M.,et al. Fast intraslab fluid-flow events linked to pulses of high pore fluid pressure at the subducted plate interface[J]. Earth and Planetary Science Letters,2018-01-01,482