DOI: 10.1016/j.epsl.2019.116046
论文题名: Deep fluid release in warm subduction zones from a breached slab seal
作者: Smit M.A. ; Pogge von Strandmann P.A.E.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 534 语种: 英语
中文关键词: arc magmatism
; earthquakes
; eclogite
; gabbro-to-eclogite transition
; warm subduction zones
英文关键词: Budget control
; Earthquakes
; Gasoline
; Petrology
; Seismology
; Arc magmatism
; Channel systems
; Eclogites
; Gabbroic rocks
; Geochemical evolution
; Mineral reactions
; Subduction zones
; Ultrahigh pressure
; Metamorphic rocks
; earthquake
; eclogite
; gabbro
; igneous geochemistry
; magmatism
; petrology
; seismic data
; slab
; subduction zone
; terrane
; texture
英文摘要: Petrological models and seismic data from subduction zones with geotherms of 7 K km−1 or higher suggest that slabs in these systems dehydrate effectively in the forearc. A large fluid flux is nevertheless released from these slabs at and beyond subarc depth, suggesting that large amounts of H2O can remain slab-bound to much greater depth than expected. We propose that this is due to a transient sealing effect exerted by the subducting lower crust. To test this concept, the petrological and geochemical evolution of such gabbroic crust is investigated through a textural, petrological and Li-chronometric analysis of eclogitized gabbros from an exhumed ultrahigh-pressure terrane. The samples record pristine transitions from dry, rigid gabbro to hydrated eclogite and eclogite mylonite, which occurred when these rocks resided at 90-110 km depth. The observations characterize step-by-step the deformation and overstepped mineral reactions that following the influx of external fluids along a developing network of permeable shear zones. Lithium chronometry indicates that the gabbroic rocks were breached and permeated within a few weeks at a very specific depth within the 90-110 km interval—depths where, in warm subduction zones, large fluid-filled channel system emanate from the slab. The data support a model in which fluids produced in the deserpentinizing slab mantle are trapped at high pore pressure beneath the slab Moho and are ultimately released at subarc depth where the lower crust fails and develops highly permeable fluid vents. The subducting lower crust thus may play an important role in regulating H2O and element budgets, and controlling slab rheology in warm subduction zones. © 2019 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165271
Appears in Collections: 气候变化与战略
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作者单位: Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 2020-2207 Main Mall, Vancouver, V6T 1Z4, Canada; Institute of Earth and Planetary Sciences, University College London and Birkbeck, Gower Street, London, WC1E 6BT, United Kingdom
Recommended Citation:
Smit M.A.,Pogge von Strandmann P.A.E.. Deep fluid release in warm subduction zones from a breached slab seal[J]. Earth and Planetary Science Letters,2020-01-01,534