Tectonics
Marzieh Rostami; Morteza Talebian; Abbas Bahroudi
Abstract
Anticline axes in both orogenic belts of the Zagros and Kopeh Dagh are offset by NW-SE trending transvers faults. These faults are rotating anticlockwise due to their oblique orientation relative to maximum stress vector, causing shortening across the belt and elongation along the strike. The transverse ...
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Anticline axes in both orogenic belts of the Zagros and Kopeh Dagh are offset by NW-SE trending transvers faults. These faults are rotating anticlockwise due to their oblique orientation relative to maximum stress vector, causing shortening across the belt and elongation along the strike. The transverse faults move right laterally and known as prominent faults of Bajgiran, Quchan, Shokranlou, Baghan in central Kopeh Dagh; and Kazerun, Karehbas, Sabzpushan, Sarvestan in central Zagros. Faults in two regions, however, show different pattern of offset. We proposed two different physical models, consist of rotating blocks at the base overlaid by sand with and without silicon layers, resembling variation of stratigraphy in two belts. In the Zagros model, where we have more incompetent layers, offset on the basement faults causes bending of the fold axes at the surface prior to any offset. While in the Kopeh Dagh, where we have less incompetent layers, the fold axes are offset with no major change in their orientation.
F Porghiasian; E Gholami; M.M Khatib
Abstract
In this study, value of shear strain for the Koch fault zone was determined based on the angle of foliations with the edge of the Koch fault zone. The Koch fault zone with N-S trend is located in northeast of Birjand, at the end northwest of the Sistan structural zone. In the Koch fault zone shear strain(γ) ...
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In this study, value of shear strain for the Koch fault zone was determined based on the angle of foliations with the edge of the Koch fault zone. The Koch fault zone with N-S trend is located in northeast of Birjand, at the end northwest of the Sistan structural zone. In the Koch fault zone shear strain(γ) was calculated based on the foliations, which are from the types of fracture cleavage. Shear strain in central part of the Koch fault zone reaches to 4 degrees, its maximum. The value of shear strain reaches to 2 degrees in southern and northern parts of the Koch fault. The value of shear strain decreases from central part of the Koch fault towards the northern and southern parts. The latter indicates the growth of the fault from the central to the northern and southern parts.
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