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  • Article title : Using shear band foliations for determining shear sense,kinematics,shear strain and flow viscosity no. in shear zones(northwest of Orumieh).
    Article type : Tectonic & Seismotectonic
    Location : 20th symposium on geosciences

    Fulltext :

         The study of shear band foliation with considering kinematics of flow is a suitable procedure for determining some properties of shear ioncs (shear sense of the zone, strain field, shear strain value, spining flow and orintation of flow eigenvector, constant stress sensitivity of the strain rate or flow viscosity (n), metamorphic facies during deformation of mylonites). Most of the data used in this paper are gathered from microscopic study of oriented sample (normal to monoclinic symmetric axes). In Qulanji sheet, northeast of Orumich, The early stages of the extensional event was associated with development of type III shear band foliation, and occurred during a high grade metamorphic event, while the later stages of the event was associated with development of type IV shear hand fbliation, and has occurred during a lower grade metamorphic event. These evidences show that transcurrent component of shear has increased with time, while divergent component was decreasing. The study of angle (angle between the shear plane and the local orientation of S—surfaces), indicate that shear strain in the shear zones of compressional system ( Mag=4.6O) is more than extensional system( Am=3 .27, Grl= 3.O7, GR2=3.64 and Ga=3.l4). Considering n-value of shear hand foliation, development of compressional mylonites (MAg and Gn units) occurred in amphiholite facies conditions (n=1.9-3) and development of extensional mylonites (Am, Grl Gr2 and R units) occurred in greenschist facies conditions (n<3). l)Deformation of the both mylonites continued down to lower—grade conditions brittle—ductile conditions).

    Celebration date : 16 Wednesday April 2008