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DOI	10.1016/j.epsl.2021.116913
	Effective rheology of a two-phase subduction shear zone: Insights from numerical simple shear experiments and implications for subduction zone interfaces
	Ioannidi P.I.; Le Pourhiet L.; Agard P.; Angiboust S.; Oncken O.
发表日期	2021
ISSN	0012821X
卷号	566
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
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
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203144
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
推荐引用方式 GB/T 7714	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],2021,566.
APA	Ioannidi P.I.,Le Pourhiet L.,Agard P.,Angiboust S.,&Oncken O..(2021).Effective rheology of a two-phase subduction shear zone: Insights from numerical simple shear experiments and implications for subduction zone interfaces.Earth and Planetary Science Letters,566.
MLA	Ioannidi P.I.,et al."Effective rheology of a two-phase subduction shear zone: Insights from numerical simple shear experiments and implications for subduction zone interfaces".Earth and Planetary Science Letters 566(2021).