M. Aflaki1; M. Mohajjel
Abstract
Laibid (northwest Esfahan) metamorphic rocks are situated in complexly deformed sub zone of the Sanandaj-sirjan zone, in which bounding faults emplaced Permian metamorphosed, beside the younger Triassic-Jurassic metamorphic rocks. Structural study of these units reveals three deformation stages of a ...
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Laibid (northwest Esfahan) metamorphic rocks are situated in complexly deformed sub zone of the Sanandaj-sirjan zone, in which bounding faults emplaced Permian metamorphosed, beside the younger Triassic-Jurassic metamorphic rocks. Structural study of these units reveals three deformation stages of a progressive deformation in this area. The first stage includes tight to isoclinal folds, the second stage includes open to close folds and the third one includes gentle to open folds. From the first to the third stage, fold's wavelength gradually become longer, so that their aspect ratio change respectively from tall and short, for the first stage, to broad, for the second stage, and to wide, for the third one. Superposition of these fold generations caused in coaxial interference patterns. It seems that during Late Jurassic, these three folding stages consequently formed and passively rotated in a continuous deformation condition, by gradually decreasing deformation depth. Dikes alternatively injected into the extensional fractures and through the axial plane foliation and gradually deformed in to the fold, boudin, folded boudin, and boudined fold.
S. Bahiraie; M. Abbasi; M. Almasian
Abstract
Generally the most important factor in the structural evolution of Alborz is thrust and reverse faulting that often has an east-west trend, parallel to the mountain chain. Mosha fault, one of the main faults, in this study covers the area between longitudes 51˚, 30´ to 51˚, 45´ including ...
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Generally the most important factor in the structural evolution of Alborz is thrust and reverse faulting that often has an east-west trend, parallel to the mountain chain. Mosha fault, one of the main faults, in this study covers the area between longitudes 51˚, 30´ to 51˚, 45´ including central-western part of Mosha fault. The stress evolution on the available faults in northeast of Tehran city was studied by means of inversion of 120 striated fault planes and related striations. Finally, two different movement systems were identified. One of them generated dextral reverse faulting and the other one which is younger created sinistral reverse faulting. The dextral system, known to resulted from the movement of the Arabian plate toward the north, is determined to be Miocene and probably older. The sinistral system originates from structural transition of AlborzMountain (progressive deformation in Alborz). Obtained result shows that the movement vector on the thrust Mosha is the consequence of the combination of sinistral and reverse faulting. The ages of stress changes were determined by using the cross cutting
