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Higher Himalayan Shear Zone, Zanskar Indian Himalaya: microstructural studies and extrusion mechanism by a combination of simple shear and channel flow

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Title Higher Himalayan Shear Zone, Zanskar Indian Himalaya: microstructural studies and extrusion mechanism by a combination of simple shear and channel flow
 
Creator MUKHERJEE, S
KOYI, HA
 
Subject south tibetan detachment
inverted metamorphism
ductile shear
manaslu leukogranite
collision tectonics
nepalese himalaya
western zanskar
constraints
extension
deformation
zanskar shear zone
higher himalayan shear zone
extrusion
ductile deformation
channel flow model
brittle deformation
 
Description Thin-section studies of the Zanskar Shear Zone (ZSZ) rocks reveal a top-to-SW and subsequent primary and secondary top-to-NE ductile shearing; brittle-ductile and brittle extensions; top-to-SW brittle shear, steep normal faulting and fracturing. In the proposed two-phase model of ductile extrusion of the Higher Himalayan Shear Zone (HHSZ), a top-to-SW simple shearing during 22-18 Ma was followed by a combination of top-to-SW simple shear and channel flow at 18-16 Ma. The second phase simulates a thin ZSZ characterized by a top-to-NE shearing. The channel flow component ceased around 16 Ma, the extruding HHSZ entered the brittle regime but the top-to-SW shearing continued until perturbed by faults and fractures. Variation in the extrusion parameters led to variable thickness of the ZSZ. Shear strain after the extrusion is presumably maximum at the boundaries of the HHSZ and falls towards the base of the ZSZ, which crudely matches with the existing data. The other predictions: (1) spatially uniform shear strain after the first stage, (2) fastest extrusion rate at the base of the ZSZ, and (3) a lack of continuation of the ZSZ along the Himalayan trend are not possible to validate due to paucity of suitable data. Non-parabolic shear fabrics of the ZSZ indicate their heterogeneous deformation.
 
Publisher SPRINGER
 
Date 2011-08-29T13:52:08Z
2011-12-26T12:58:37Z
2011-12-27T05:48:51Z
2011-08-29T13:52:08Z
2011-12-26T12:58:37Z
2011-12-27T05:48:51Z
2010
 
Type Article
 
Identifier INTERNATIONAL JOURNAL OF EARTH SCIENCES, 99(5), 1083-1110
1437-3254
http://dx.doi.org/10.1007/s00531-009-0447-z
http://dspace.library.iitb.ac.in/xmlui/handle/10054/12101
http://hdl.handle.net/10054/12101
 
Language en