Mechanisms of shear localization in the continental lithosphere: inference from the deformation microstructures of peridotites from the Ivrea zone, northwestern Italy

Jin, Denghui; Karato, Shun‐ichiro; Obata, Masaaki

doi:10.1016/s0191-8141(97)00059-x

Cited by 160 publications

(104 citation statements)

References 47 publications

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“…A temperature above 600 • C is also in accord with the general assumption that dynamic recrystallization of olivine in (100), (010) and (001) the regime of dislocation creep at reasonable strain rates of 10 −13 to 10 −15 s −1 requires temperatures above about 650 • C as based on observations from natural systems (e.g. Skrotzki et al, 1990;Altenberger, 1995;Jin et al, 1998) and the extrapolation from experimentally derived flow laws for dislocation creep of olivine ( Fig. 9; Chopra and Paterson, 1981;Hirth and Kohlstedt, 2003).…”

Section: Deformation Processes and Conditions Recorded By Olivine Andsupporting

confidence: 51%

“…Hilairet et al, 2007;Chernak and Hirth, 2010) microfabrics can yield information on the deformation mechanisms, as well as the stress and strain-rate conditions during burial and exhumation (e.g. Skrotzki et al, 1990;van der Wal, 1993;Altenberger, 1995;Jin et al 1998;Zhang et al, 2000;Jung and Karato, 2001;Piepenbreier and Stöckhert, 2001;Stöckhert, 2002;Andreani et al, 2005;Auzende et al, 2006;Jung et al, 2006;Wassmann et al, 2011;Matysiak and Trepmann, 2012). The aim of this study is to use the successively overprinted and modified microfabrics of the partly serpentinized peridotite mylonites to differentiate between the potential record of independent grain-scale deformation processes and implications on the stress conditions.…”

Section: Introductionmentioning

confidence: 99%

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The microstructural record of porphyroclasts and matrix of partly serpentinized peridotite mylonites – from brittle and crystal-plastic deformation to dissolution–precipitation creep

Bial

Trepmann

2013

Solid Earth

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Abstract. We present microfabrics in high-pressure, metamorphic, partly serpentinized peridotite mylonites from the Voltri Massif, in which porphyroclasts and matrix record independent deformation events. The microfabrics are analysed using polarization microscopy and electron microscopy (SEM/EBSD, EMP). The mylonites contain diopside and olivine porphyroclasts originating from the mantle protolith embedded in a fine-grained matrix consisting mainly of antigorite and minor olivine and pyroxene. The porphyroclasts record brittle and crystal-plastic deformation of the peridotite at upper-mantle conditions and differential stresses of a few hundred MPa. After the peridotites became serpentinized, deformation occurred mainly by dissolutionprecipitation creep resulting in a pronounced foliation of the antigorite matrix, crenulation cleavages and newly precipitated olivine and pyroxene from the pore fluid at sites of dilation, i.e. in strain shadows next to porphyroclasts and folded fine-grained antigorite layers. Antigorite reveals a pronounced associated shape preferred orientation (SPO) and crystallographic preferred orientation (CPO) with the basal (001) cleavage plane oriented in the foliation plane. In monomineralic antigorite aggregates at sites of stress concentration around porphyroclasts, a characteristically reduced grain size and deflecting CPO as well as sutured grain boundaries indicate also some contribution of crystal-plastic deformation and grain-boundary migration of antigorite. In contrast, the absence of any intragranular deformation features in newly precipitated olivine in strain shadows reveals that stresses were not sufficiently high to allow for significant dislocation creep of olivine at conditions at which antigorite is stable. The porphyroclast microstructures are not associated with the microstructures of the mylonitic matrix, but are inherited from an independent earlier deformation. The porphyroclasts record a high-stress deformation of the peridotite with dislocation creep of olivine in the upper mantle probably related to rifting processes, whereas the serpentinite matrix records dominantly dissolution-precipitation creep and low stresses during subduction and exhumation.

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Section: Deformation Processes and Conditions Recorded By Olivine Andsupporting

confidence: 51%

Section: Introductionmentioning

confidence: 99%

The microstructural record of porphyroclasts and matrix of partly serpentinized peridotite mylonites – from brittle and crystal-plastic deformation to dissolution–precipitation creep

Bial

Trepmann

2013

Solid Earth

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“…This hypothesis is supported by numerous observations of grain size reduction in strongly deformed lithospheric mantle shear zones [ Vissers et al, 1995;Jin et al, 1998]. Stress versus strain rate (or constitutive) relationships have been determined in the laboratory for olivinerich rocks both in the dislocation and GSS (diffusion) creep regimes [Karato et al, 19813;Hirth and Kohlstedt, 1995a,b].…”

Section: Introductionmentioning

confidence: 49%

A simple parameterization of strain localization in the ductile regime due to grain size reduction: A case study for olivine

Braun¹,

Chéry²,

Poliakov³

et al. 1999

J. Geophys. Res.

147

137

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Abstract.We propose a simple parameterization of the transition between dislocation creep and grain-size-sensitive creep under conditions characteristic of the lithospheric mantle and derived from the results of laboratory experiments on olivine-rich rocks. Through numerical modeling and linear stability analysis, we determine the conditions under which this transition takes place and potentially leads to strain localization. We pay particular attention to the effect of cooling rate and strain rate which are likely to be dominant parameters in actively deforming tectonic areas. We conclude that at constant temperature, strain localization can only take place if the rheology of the material is nonlinearly related to grain size; that strain localization is facilitated by syndeformation cooling; that there is only a narrow region in the strain rate versus cooling rate parameter space where localization is likely to take place; and that grain growth inhibits strain localization at fast cooling rates but may lead to "grain growth localization" at low cooling rates. We draw attention to the potential consequences of our analysis of strain localization for the style of plate motions at the Earth's surface.

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“…To account for the e¡ects of frictional sliding [31] and mylonitic shear localization behavior [41] in the upper part of the subduction zone, we implemented a static fault, with an arc-shaped geometry, as a reasonable approximation of the actual subduction geometry [42]. In general, the fault has to be mobile and advected as in [14,43] in order to adjust to the stress and £ow ¢eld.…”

Section: Implementation Of a Lithospheric Faultmentioning

confidence: 99%

A thermo-mechanical model of horizontal subduction below an overriding plate

Hunen

Berg

Vlaar

2000

Earth and Planetary Science Letters

112

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Subduction of young oceanic lithosphere cannot be explained by the gravitational driving mechanisms of slab pull and ridge push. This deficiency of driving forces can be overcome by obduction of an actively overriding plate, which forces the young plate either to subduct or to collide. This mechanism leads to shallow flattening of the slab as observed today under parts of the west coast of North and South America. Here this process is examined by means of numerical modeling. The convergence velocity between oceanic and continental lithospheric plates is computed from the modeling results, and the ratio of the subduction velocity over the overriding velocity is used as a diagnostic of the efficiency of the ongoing subduction process. We have investigated several factors influencing the mechanical resistance working against the subduction process. In particular, we have studied the effect of a preexisting lithospheric fault with a depth dependent shear resistance, partly decoupling the oceanic lithosphere from the overriding continent. We also investigated the lubricating effect of a 7 km thick basaltic crustal layer on the efficiency of the subduction process and found a log^linear relation between convergence rate and viscosity prefactor characterizing the strength of the oceanic crust, for a range of parameter values including values for basaltic rocks, derived from empirical data. A strong mantle fixes the subducting slab while being overridden and prevents the slab from further subduction in a Benioff style. Viscous heating lowers the coupling strength of the crustal interface between the converging plates with about half an order of magnitude and therefore contributes significantly to the subduction process. Finally, when varying the overriding velocity from 2.5 to 10 cm yr 31 , we found a non-linear increase of the subduction velocity due to the presence of non-linear mantle rheology. These results indicate that active obduction of oceanic lithosphere by an overriding continental lithosphere is a viable mechanism for shallow flat subduction over a wide range of model parameters. ß

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Mechanisms of shear localization in the continental lithosphere: inference from the deformation microstructures of peridotites from the Ivrea zone, northwestern Italy

Cited by 160 publications

References 47 publications

The microstructural record of porphyroclasts and matrix of partly serpentinized peridotite mylonites – from brittle and crystal-plastic deformation to dissolution–precipitation creep

The microstructural record of porphyroclasts and matrix of partly serpentinized peridotite mylonites – from brittle and crystal-plastic deformation to dissolution–precipitation creep

A simple parameterization of strain localization in the ductile regime due to grain size reduction: A case study for olivine

A thermo-mechanical model of horizontal subduction below an overriding plate

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