Tectonics
E. Haji; H. Safari
Abstract
The Saqqez-Baneh area, as a part of the NW Sanandaj-Sirjan zone, is selected for investigation of different deformation stages. In this research, firstly, the lithology of outcropped rock units and visible lineaments were mapped using remote sensing approach. Then, field surveys were carried out for ...
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The Saqqez-Baneh area, as a part of the NW Sanandaj-Sirjan zone, is selected for investigation of different deformation stages. In this research, firstly, the lithology of outcropped rock units and visible lineaments were mapped using remote sensing approach. Then, field surveys were carried out for structural measurements, during which major and minor faults and shear zones (as ductile zones) were measured and mapped. These data were then entered to GIS environment as vector layers (and attributed descriptions), resulting in preparation of a structural map. The results of field surveys along with geometric and kinematic analyses show that the major faults together with their related fault orders formed a curved shape of structures, outcropped rock unit patterns and intrusive localities. Geometric and kinematic analyses demonstrated three stages of movement: with north-south (in ductile environment), northeast-southwest (in ductile to brittle environment) and east-west (in brittle environment). These three stages caused three stages of faulting with trends along N140-150, N70-80 and N10-20 directions, which can be attributed to three orogenic phases in Precambrian and/or late Triassic (Katangai and/or Cimmerian), Cretaceous (Laramide) and Neogene (late Alpine events such as Savian to Pasadenian).
H Safari; M.R Ghassemi; M Bahrami
Abstract
This opinion exist that basement of the Sanandaj-Sirjan Zone was cratonized during Cimmerian and Laramide Orogenic phases and so, therefore it is considered as an aseismic (or low-sesimicity) zone. The Shahreza area in the central part of the zone is selected as a case study area for investigation on ...
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This opinion exist that basement of the Sanandaj-Sirjan Zone was cratonized during Cimmerian and Laramide Orogenic phases and so, therefore it is considered as an aseismic (or low-sesimicity) zone. The Shahreza area in the central part of the zone is selected as a case study area for investigation on seismicity and recent movements and verifying of this hypothesis. We used Geoinformatic techniques (including: Remote Sensing, GIS and field surveying methods) in this research to detect the structures of the area and their kinematics, to locate earthquake foci, to find neotectonic evidences of active faults, and proofs for high seismicity of the area. Our results shows that the Shahreza fault (and Dehaghan fault located in southwest of study area) having a dextral strike-slip mechanism is the main structural trend in the area. This fault zone is truncated and offset by the Nosratabad fault (with strike N50-70E and sinistral strike-slip mechanism). In the intersection area of these main trends, many earthquake foci (with strike-slip focal mechanism) are located. Other than several earthquakes, neotectonic evidences for fault activity are are observed in the Shahreza area.
