مجله زمین ساخت
پیاپی 5 (بهار 1397)

The aim of this research is determination of structural fractures density (faults and lineaments) and drainages and their fractal pattern of the Hassanabad fault zone in SW of the Qazvin. Remote sensing analysis and data processing techniques in the ArcGIS software have been used to identify the lineaments and active faults in this zone and analyze of the tectonic activities. Lineaments maps was extracted using the appropriate algorithm of spatial data, Landsat 8 satellite images and shaded relief models. The fractal pattern of structural fractures and drainages networks was calculated by square method and using log-log charts for the 14 zones in the study area. The J zone have the maximum fractal value based on fractal dimension of the lineaments (Dj=1/91) and faults (Dj=1/82). The g and J zones have the maximum and minimum fractal values respectively, based on fractal dimension drainage basin, that less values of the fractal dimension indicate uplift of the region. The dimension fractal obtained and field studies of the Hassanabad fault zone indicate more relative activity of the southern and eastern parts of the study area. The southern part is the boundary between the Hassanabad and Kharrood faults and the eastern part is boundary between the Hassanabad fault and the active Ipak fault zone.

The evaluation of Active Tectonics in north of  Esfarāyen city by using morphological evidences and morphotectonic indicators.Esfarāyen city is located on the southern slopes of Aladagh Mountains in northeastern of Iran. The northern part of the city, experienced intense  tectonic activities. Due to the high population density and proximity to the  Bojnord city ,center of North Khorasan Province, the study of tectonic activity in this area is necessity. The study of tectonic movements was done in two parts of morphological evidences and morphotectonic indicators. Based on morphological evidence such as numerous earthquakes, geological  formations , change in direction of faults, the displacement in geological formation and river deviation is indicated that this area is part of tectonic active area. morphotectonic studies were performed by using of compactness indicators, Several morphotectonic indices have also been used for morphotectonic studies, and its values for Gravelius coefficient are 1.99, for the ratio of width to valleys’ height (vf) indicators are0.938,  for screw mountain front (smf) are 1.38, basin’ warping coefficient (AF) are 54.28, river sinusoidal index (s) are1.29 and relative tectonic activities index (Iat) are1.41. The results of all these factors, the area will be tectonically active regions. The studies also showed that the Bidwaz basin in central part of the region  And Roein Basin in West is experienced severe tectonic activities and the Cal Valayt basin Basin in the East region is experiencing  relaxed tectonic movements

The Ravar zone, a wedge-shaped terrane, situated at the southern Tabas block, is confined between two main boundary faults, the Nayband fault in the east and the Kuhbanan fault in the west.  The Mesozoic strata, especially the Jurassic layers, have a variety of facies, distribution, and exposure. Structural restoration and stratigraphical correlation between the Jurassic layers on the basis of the field and lab studies in the Ravar zone, brought new result.  The stratigraphy, structure, and magmatism of the middle Jurassic to late Cretaceous successions are similar to the deposits which have been evolved in the continental rift zone is being transited to a passive margin.  The sedimentary successions are classified into two groups; the clastic deposits of the Hojedk and Baghamshah Formations, and carbonate-evaporate of the Pectinid layers, and alkali basalts of the Ravar Series which are considered as the syn-rift series. The second group composed of lower Cretaceous red marl and evaporate as well as upper Cretaceous marine limestone well-thought-out as the post-rift series. These two series are separated by pronounce angular unconformity and basaltic volcanic rocks in the Ravar zone. Deepening towards the west, indicates that the main ocean, in the Cretaceous time, must be at the west side, somewhere at the west of the Tabas block. The Nain and Dehshir-Baft ophiolites could be the best candidates for the remnants of this ocean.

Khorramabad's anticline with its overturned southern limb and NW-SE trend is located near Khorramabad city, in Zagros fold-thrust belt. Three structural cross sections with NE-SW trend was determined and desired structural data (strike and dip) of structures including fault, parasitic folds, and joints were obtained. For geometric analysis, and to determine the folding type related to the thrust faults, different Jamison`s diagrams were used. Results of this study suggest that the geometry of khoramabad's anticline is similar to Fault Propagation Folding and Faulted Detachment Folding. High Zagros Fault in this area, which is known as Khorramabad Thrust, passes from the south of Khorramabad anticline and is the main factor for generation of Khorramabad anticline

 The Cretaceous limestone in the NE of the Kerman show the several evidences of faulting. In this study, the faulting style was evaluated using paleo stress methods such as multiple inverse, determination of compressive and tensile axis and slip line configuration method.  The results of these methods revealed the effect of two phases of faulting. The position of the maximum compressive axis is exactly separable in the normal and strike-slip faults. The evidences of faults planes, overprinting of slikenlines, displacment of normal faults and tension veins by strike slip faults show the reactivation of normal faults in strike slip fault pattern. In the two phase of faulting the shape of stress ellipsoid is prolate. The internal friction angle was calculated as 45 degrees for both of normal and strike slip faulting. The unscaled Mohr diagram method show the strike slip faulting under the conjugate pattern. The results of this study clearly show a change in the fault pattern from normal to strike slip.

The study area is south west of Zarrinrod in south of Zanjan province. In this study, various indicators including Ratio of valley floor width to valley height index (Vf), Stream length-gradient index (SL), Hypsometric integral index (Hi), Basin shape index (Bs) and Drainage drainage symmetry index ( AF) and the pattern of streams were calculated. The combination of these indexes can be used to determine the relationship between the active tectonics index (Iat). In this study, GIS 10.5 Arc was used to calculate the morphometric indices of topographic maps and DEM of the region. The most drainage  pattern  in this study area is a tree channel. Based on the studies done in the study area, tectonics are divided into two parts with moderate and low activity.

Kinematic and structural studies on the deformed rocks of the Sanandaj-Sirjan metamorphic belt as a part of the Zagros Orogeny show that the deformation was occurred under greenschist- to amphibolite-facies conditions. A dominant top-to-the-SE sense of shear is confirmed by asymmetric boudins, mica fish, mantled porphyroclasts, drag folds, asymmetric crenulation cleavage and quartz c-axis fabrics.  The mean kinematic vorticity number analyses based on the quartz fabrics and rotated porphyroclasts revealed relative contribution of ~44% pure shear and ~56% simple shear components during ductile general shear deformation associated with a transpressional flow regime. The variable quantities of simple shear relative to time reveals that the earlier phases of deformation developed during a pure shear-dominated regime whereas the later stages took place in a simple shear-dominated regime.