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Simple shear is not so simple! Kinematics and shear senses in Newtonian viscous simple shear zones

DSpace at IIT Bombay

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Title Simple shear is not so simple! Kinematics and shear senses in Newtonian viscous simple shear zones
 
Creator MUKHERJEE, S
 
Subject simple shear
shear zone
shear sense
Poiseuille flow
viscosity
extrusion
Newtonian fluid
HIMALAYAN INVERTED METAMORPHISM
CONTINENTAL COLLISION ZONES
CHANNEL FLOW
TECTONIC EVOLUTION
EXHUMATION HISTORY
DUCTILE EXTRUSION
NEPAL HIMALAYA
CONSTRAINTS
SEQUENCE
BHUTAN
 
Description This work develops an analytical model of shear senses within an inclined ductile simple shear zone with parallel rigid boundaries and incompressible Newtonian viscous rheology. Taking account of gravity that tends to drive the material downdip and a possible pressure gradient that drives it upward along the shear zone, it is shown that (i) contradictory shear senses develop within two sub-zones even as a result of a single simple shear deformation; (ii) the highest velocity and least shear strain develop along the contact between the two sub-zones of reverse shear; (iii) for a uniform shear sense of the boundaries, a zone of reverse shear may develop within the top of the shear zone if the pressure gradient dominates the gravity component; otherwise it forms near the bottom boundary; (iv-a) a 'pivot' defined by the intersection between the velocity profile and the initial marker position distinguishes two sub-zones of opposite movement directions (not shear sense); (iv-b) a pivot inside any non-horizontal shear zone indicates a part of the zone that extrudes while the other subducts simultaneously; (v) the same shear sense develops: (v-a) when under a uniform shear of the boundaries, the shear zone remains horizontal and the pressure gradient vanishes; or alternatively (v-b) if the shear zone is inclined but the gravity component counterbalances the pressure gradient. Zones with shear sense reversal need to be reinterpreted since a pro-sheared sub-zone can retro-shear if the flow parameters change their magnitudes even though the same shear sense along the boundaries is maintained.
 
Publisher CAMBRIDGE UNIV PRESS
 
Date 2014-10-15T15:16:24Z
2014-10-15T15:16:24Z
2012
 
Type Article
 
Identifier GEOLOGICAL MAGAZINE, 149(5)819-826
http://dx.doi.org/10.1017/S0016756811001075
http://dspace.library.iitb.ac.in/jspui/handle/100/15129
 
Language en