Results 261 to 270 of about 35,897 (307)

Progressive development of structures in a ductile shear zone

Journal of Structural Geology, 1987
Abstract In the Singhbhum Shear Zone of eastern India successive generations of folds grew in response to a progressive ductile shearing. During this deformation a mylonitic foliation was initiated and was repeatedly transposed. The majority of fold hinges were formed in an arcuate manner at low angles to the Y-axis in an E-W trending subhorizontal ...
S.K Ghosh, null Sudipta Sengupta
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Secondary cleavages in ductile shear zones

Journal of Structural Geology, 1984
Abstract Secondary cleavages developed at late stages in ductile shear zones show several features that are inconsistent with progressive simple shear in the zone. These are: the orientation of a single secondary cleavage oblique to the shear zone boundaries; conjugate sets with opposite senses of shear, and multiple sets with the same sense of shear.
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A dynamic model for aseismic ductile shear zones

Earth and Planetary Science Letters, 1979
Abstract A model for the dynamics of aseismic strike-slip shear zones is proposed under conditions of constant rate out-side the zone and with an almost perfectly rigid plastic rheology for the rock. It is shown that a necessary condition for the activation of the shear zone is the existence of an initial strength defect.
J.P. Poirier, J.L. Bouchez, J.J. Jonas
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Progressive refolding in ductile shear zones

Journal of Structural Geology, 1983
Abstract The foliation formed in a ductile shear zone can become folded by continuing shear in the zone without the foliation having to enter the shortening sector of the flow field. If the foliation lies parallel to the shear plane, infinitesimal variations in the rate of shear strain cause compensating rotations that may amplify into folds.
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Strain within ductile shear zones

Tectonophysics, 1976
Abstract The intensity of strain has been measured from the change in shape of clusters of mafic and felsic minerals within a ductile shear zone of short finite length from Botswana and a much longer planar shear zone from North Uist, Scotland. The strain measurements from North Uist have been supported by measurements of the anisotropy of magnetic ...
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Transient discontinuities in ductile shear zones

Journal of Structural Geology, 1980
Abstract Earthquake fault ruptures sometimes extend to deep crustal levels and beyond, where moderate- to high-grade metamorphic conditions must prevail in mylonitic shear zones. Evidence for such transient loss of continuity in mylonite belts tends to be obliterated by continued aseismic shearing and accompanying metamorphic processes, but in parts ...
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Shear Senses and Viscous Dissipation of Layered Ductile Simple Shear Zones

Pure and Applied Geophysics, 2015
Velocity profiles and shear heat profiles for inclined, layered Newtonian simple shear zones are considered. Reverse fault-like simple shear of the boundaries and upward net pressure gradient act together in such shear zones. As the velocity of the boundary increases, the point of highest velocity shifts from the lower layer of less viscosity into the ...
MULCHRONE, KF, MUKHERJEE, S
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Nucleation of ductile shear zones on dilatant fractures

Geology, 1986
Small shear zones in granitic rocks of the Sierra Nevada, California, and near Roses (Rosas), northeast Spain, display features which indicate that dilatant fracturing preceded the localization of ductile shear deformation. Many zones have sharp, nearly planar boundaries between their highly deformed interiors and the undeformed wall rock.
Paul Segall, Carol Simpson
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Ductile Shearing in Attur Shear Zone and its Relation with Moyar Shear Zone, South India

Gondwana Research, 2000
Abstract In the eastern part of southern Peninsular India, the charnockitic hills of the Madras block are cut across by the E-W trending Attur shear zone (ASZ) which is characterised by a thick (1 to 1.5 km) phyllonite zone, showing intense mylonitisation due to ductile shearing.
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Ductile instability — Shentangyu ductile shear zone and tremolite glass in Huairou, Beijing

Physics and Chemistry of the Earth, 1990
Abstract This report discusses the phenomenon of brittle-ductile transition at the same depth owing to the changing strain rate according to the sheath folds and accompanying glassy substances found in the Shentangy ductile shear zone. Deformation stages are identified, and also mineral textures, structural forms of rocks and material compositions ...
null Shao Ji'an, null Fu Yingqi, null Zang Qijia, null Wang Yufang   +3 more
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