DOI: 10.1016/j.epsl.2021.116913
论文题名: Effective rheology of a two-phase subduction shear zone: Insights from numerical simple shear experiments and implications for subduction zone interfaces
作者: Ioannidi P.I. ; Le Pourhiet L. ; Agard P. ; Angiboust S. ; Oncken O.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 566 语种: 英语
中文关键词: dislocation creep
; effective rheology
; subduction zone
; two-phase media
英文关键词: Elasticity
; Friction
; Geodynamics
; Strain rate
; Dislocation creep
; Effective rheology
; Large-scales
; matrix
; Shear zone
; Simple shear
; Subduction interface
; Subduction zones
; Two phase
; Two phase medium
; Creep
; dislocation creep
; experimental study
; finite element method
; melange
; rheology
; shear zone
; subduction
; viscosity
英文摘要: Inspired by exhumed subduction shear zones that commonly exhibit block-in-matrix characteristics (mélanges), we create synthetic models with different proportions of strong clasts within a weak matrix and compare them to natural mélange outcrops. Using 2D Finite Element visco-plastic numerical simulations in simple shear kinematic conditions, we determine the effective rheological parameters of such a two-phase medium, comprising blocks of basalt embedded within a wet quartzitic matrix. We treat our models and their structures as scale-independent and self-similar and upscale published field geometries to km-scale models, compatible with large-scale far-field observations. Like in the laboratory deformation experiments, we vary confining pressures, temperatures and strain rates to evaluate effective rheological estimates for a natural subduction interface. As expected, the block-in-matrix ratio affects deformation and strain localization, with the effective dislocation creep parameters (A, n, and Q) varying between the values of the strong and the weak phase, in cases where both materials deform by viscous creep. At conditions where the blocks are frictional and the matrix viscous, the mélange deforms effectively by dislocation creep but the locally frictional deformation of the blocks leads to higher stresses. This results in an effective value of the stress exponent, n, greater than that of both pure phases, as well as an effective rate-dependent viscosity lower than that of the weak phase. In combination with an appropriate evolution law for the block concentration of a mélange, our effective rheology parameters may be used in large scale geodynamic models as a proxy for a heterogeneous subduction interface. © 2021 Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165522
Appears in Collections: 气候变化与战略
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作者单位: GFZ German Research Centre for Geosciences, Potsdam, D-14473, Germany; Department of Geological and Atmospheric Sciences, Iowa State University, Ames, IA, United States; Sorbonne Université, CNRS-INSU, Institut des Sciences de la Terre Paris, ISTeP UMR 7193, Paris, F-75005, France; Université de Paris, Institut de Physique du Globe de Paris, CNRS, Paris, F-75005, France
Recommended Citation:
Ioannidi P.I.,Le Pourhiet L.,Agard P.,et al. Effective rheology of a two-phase subduction shear zone: Insights from numerical simple shear experiments and implications for subduction zone interfaces[J]. Earth and Planetary Science Letters,2021-01-01,566