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2021
Tabular or sheetlike and planar or curviplanar zones in which rocks are more highly strained than rocks adjacent to the zone are called ductile shear zones. The identification and study of ductile shear zones (Figures 2.1–2.73) are important, because such shear zones define major plate boundaries.
Pamplona, J., Rodrigues, B. C.
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Tabular or sheetlike and planar or curviplanar zones in which rocks are more highly strained than rocks adjacent to the zone are called ductile shear zones. The identification and study of ductile shear zones (Figures 2.1–2.73) are important, because such shear zones define major plate boundaries.
Pamplona, J., Rodrigues, B. C.
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On the origin of shear-band network patterns in ductile shear zones
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2022Ductile yielding of rocks and similar solids localize shear zones, which often show complex internal structures due to the networking of their secondary shear bands. Combining observations from naturally deformed rocks and numerical modelling, this study addresses the following crucial question: What dictates the internal shear bands to network during ...
Arnab Roy, Puspendu Saha, Nibir Mandal
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Fabric development in brittle-to-ductile shear zones
Pure and Applied Geophysics, 1986Brittle-to-ductile shear zones from two separate geological settings are shown to have nucleated on zones of predominantly brittle deformation. The shear zones are not simply foliated cataclasites, since they contain abundant evidence of dynamic recrystallization of constituent minerals.
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2015
Two alternative pathways to generate shearband boudins in a HT shear zone have been observed at the Salgosa outcrop field (NW of Portugal, N4642140 E524687, WGS84) – Parautochthonous of Variscan Central Iberian Zone, Silurian age –: The classical one, associated with relatively thick veins (see final geometry and explanation in Figure 2.15), and a ...
Induni, Guillermo Alvarado +9 more
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Two alternative pathways to generate shearband boudins in a HT shear zone have been observed at the Salgosa outcrop field (NW of Portugal, N4642140 E524687, WGS84) – Parautochthonous of Variscan Central Iberian Zone, Silurian age –: The classical one, associated with relatively thick veins (see final geometry and explanation in Figure 2.15), and a ...
Induni, Guillermo Alvarado +9 more
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What controls the width of ductile shear zones?
Tectonophysics, 2021Abstract It is widely recognized that major brittle faults in the upper crust transition downwards into ductile shear zones that then widen with depth. However, the controls on shear zone width at any specific depth, and the mechanisms that may cause the width to change over time, are less well understood.
T.K. Cawood, J.P. Platt
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On mylonites in ductile shear zones
Journal of Structural Geology, 1980Abstract In this contribution, shear zones are treated as zones of inhomogeneous deformation in which strain softening has occurred. The mylonites which form in ductile shear zones are the softened medium. The development of mylonite microstructures and fabrics are discussed from this point of view.
S.H. White +4 more
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Tectonophysics, 1991
Abstract The geometric character of conjugate ductile shear zones has been defined from the structures developed in a undeformed granitoid corresponding to an homogeneous and isotropic material. In the plane perpendicular to the intersection line of conjugate zones (plane σ 1 σ 3 ) one notes that: (1) the principal direction of finite shortening ...
C. Lamouroux, J. Ingles, P. Debat
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Abstract The geometric character of conjugate ductile shear zones has been defined from the structures developed in a undeformed granitoid corresponding to an homogeneous and isotropic material. In the plane perpendicular to the intersection line of conjugate zones (plane σ 1 σ 3 ) one notes that: (1) the principal direction of finite shortening ...
C. Lamouroux, J. Ingles, P. Debat
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Porosity network of a ductile shear zone
Journal of Structural Geology, 1995Abstract The permeability of ductile shear zones is assumed to be significantly higher than that of surrounding undeformed rocks, although lower than that of fracture systems. This assumption, which results indirectly from geochemical mass balance calculations, is checked in this paper by the tomography of the porosity network in a metre-wide ...
Géraud, Yves +2 more
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How ductile are ductile shear zones?
Geology, 2006Three premises of ductile deformation in the middle and lower crust are widely accepted: (1) rocks flow with power-law viscous rheology, (2) localization in ductile shear zones involves strain softening, and (3) fluid flows into and is channelized within ductile shear zones.
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Terminations of ductile shear zones
Tectonophysics, 1986Abstract We propose a plane strain model for ductile shear zone terminations in rocks that otherwise record no visible shear strain. This model may explain the strain distribution patterns in naturally occurring terminations of shear zone which show, in the XZ plane of finite strain, (1) a decrease in the area of finite strain and in strain ...
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