Asymmetric boudins that are widespread in the SehGhalatoun area in the Neyriz, southwestern Iran are good indicators to estimate the kinematic vorticity number (Wk) and sense of shear. This area is part of the Sanandaj-Sirjan HP-LT metamorphic belt located within the Zagros orogenic belt. Boudins have been analyzed on the meso- and micro-scales. Domino and shearband boudins are developed in deformed quartzitic layers associated with quartzo-feldspathic gneiss, amphibolite, mica-schist and marble. Shearband boudins with backward rotation and domino boudins with forward rotation, mantled porphyroclasts, drag folds, and asymmetric folds which all display a dextral sense of shear. The mean kinematic vorticity number was estimated by using the asymmetric boudin hyperbolic distribution method and quartz caxis patterns. The estimated mean kinematic vorticity number is Wk = Wm = 0.85 ± 0.04, which indicates 34% pure shear and 66% simple shear components of deformation. The estimated mean deformation temperature based on the opening angle of the quartz c-axis fabrics is 530 ± 50 °C. These quantitative analyses suggest a sub-simple shear deformation developed at the epidote-amphibolite to amphibolite facies conditions at depth along the SanandajSirjan HP-LT metamorphic belt, which is associated with a transpressional flow regime with shortening perpendicular to the shear zone boundary
کلید واژگان :boudin, Sanandaj-Sirjan HP-LT metamorphic belt, kinematic vorticity number, Zagros
ارزش ریالی : 600000 ریال
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