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Higher Himalaya in the Bhagirathi section (NW Himalaya, India): its structures, backthrusts and extrusion mechanism by both channel flow and critical taper mechanisms

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Title Higher Himalaya in the Bhagirathi section (NW Himalaya, India): its structures, backthrusts and extrusion mechanism by both channel flow and critical taper mechanisms
 
Creator MUKHERJEE, S
 
Subject Ductile shear
Brittle shear
Higher Himalayan Crystalline
Backthrusting
South Tibetan Detachment System
Channel flow
Critical taper mechanism
Extrusion
Exhumation
CENTRAL THRUST ZONE
GARHWAL HIGHER HIMALAYA
DUCTILE SHEAR ZONES
CENTRAL NEPAL
EXHUMATION HISTORY
CONTINENTAL SUBDUCTION
CRUSTAL ARCHITECTURE
DEFORMATION FEATURES
THERMAL EVOLUTION
DETACHMENT SYSTEM
 
Description The Higher Himalayan Crystalline (HHC) in the Bhagirathi river section (India) on fieldwork reveals two extensional ductile top-to-N/NE shear sub-zones-the 'South Tibetan Detachment System' and the 'Basal Detachment'aEuro"besides a preceding top-to-S/SW ductile shear. A top-to-N/NE brittle shear was identified as backthrusts from the HHC (except its northern portion) that occur repeatedly adjacent to numerous top-to-S/SW brittle shears as fore-thrusts. The northern portion of the HHC-the Gangotri Granite-exhibits infrequent total six extensional and compressional brittle shear senses. The backthrusts could be due to a low friction between the lower boundary of the HHC (i.e. the Main Central Thrust-Zone) and the partially molten hot rock materials of the HHC. Subduction of the Eurasian plate towards S/SW below the Indian plate more extensively in the Garhwal sector could be the second possible reason. Presence of two ductile extensional shear sub-zones may indicate channel flow (or several exhumation mechanisms) of the HHC in a shifting mode (similar to Mukherjee et al. in Int J Earth Sci 101:253-272, 2012). The top-to-S/SW extensional brittle shear exclusively within the upper (northern portion) of the HHC and a top-to-S/SW brittle shear within the remainder of it is a possible indicator of critical taper deformation mechanism. Thus, this work provides the field evidences of possibly both channel flow and critical taper conditions from a Higher Himalayan section, besides that by Larson et al. (Geol Soc Am Bull 122:1116-1134, 2010).
 
Publisher SPRINGER
 
Date 2014-10-15T15:15:54Z
2014-10-15T15:15:54Z
2013
 
Type Article
 
Identifier INTERNATIONAL JOURNAL OF EARTH SCIENCES, 102(7)1851-1870
http://dx.doi.org/10.1007/s00531-012-0861-5
http://dspace.library.iitb.ac.in/jspui/handle/100/15128
 
Language en