Tectonics
Rojan Hemati; Manouchehr Ghorashi; Ali Solgi; Abdollah Saidi
Abstract
The Zagros suture zone is one of Key regions. Continent - Continent collision between Arabian plate and Iranian Block. This region is coincided by High Zagros and Zagros Simply Fold Zones in Western side and in other side is the Sanandaj- Sirjan Zone. The region of this research in situated in Northern ...
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The Zagros suture zone is one of Key regions. Continent - Continent collision between Arabian plate and Iranian Block. This region is coincided by High Zagros and Zagros Simply Fold Zones in Western side and in other side is the Sanandaj- Sirjan Zone. The region of this research in situated in Northern part of suture zone. The Zagros suture is oriented parallel to the other collision Structures as passive and active margins of Neo- Tethys Basin and also to Magmatic Arc (Urmiyeh - Dokhtar Arc).The main Faults in this region which we can mention by name are Zagros Main Thrust Fault and Zagros Main Recent Fault, Which they are also parallel to others structures. This region of suture zone in highly deformed and structures as folds, faults and nappes are the evident of a long compression Tectonics. The aim of this research firstly is analysing of folds and secondly is calculation of shortening rate of crust in this part of collision Zone. Three structural section (Eslam Abad- e- Gharb - Mahidasht, Kamyaran and Gazorkhani) have been balanced and the rate of shortening which is obtained respectively is 6252m , 6530m and 2040m.
Tectonics
Zeynab Taslimi; Abdollah Saidi; Mehran Arian; A. Solgi; Manouchehr Ghoreshi
Abstract
The Alborz Mountains has been separated the subsiding Caspian Basin from the foreland basin of Central Iran. This mountain range from east to northwest, has changed greatly in structural trend formed spirally. Two orogenic phases, Cimmerian and Alpine events caused more changing in sedimentary basin ...
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The Alborz Mountains has been separated the subsiding Caspian Basin from the foreland basin of Central Iran. This mountain range from east to northwest, has changed greatly in structural trend formed spirally. Two orogenic phases, Cimmerian and Alpine events caused more changing in sedimentary basin of Palo Tethys and Neotethys and it caused the complexity of abundant structural in other way too. The aim of this research is to investigate and analysis of existence structures in east central Alborz from northwest of Damghan (South of Toyeh) to South of Sari (North Alborz fault). The Structural features Analysis indicate that the Alborz Mountains are a fold and thrust belt. During the intense shortening of Alborz crust in the studied area the initial model of folds have been modified or destroyed. Some of these folds could take place in flexural flow folds or Drug folds classes since one limb of folds on the surface of low-angel thrust faults was thrusted recumbently. The thrust faults with south and north dipping is the main controller for variety structures in this part of Alborz. Based on geological and structural properties, construction of folding structures initiated during the Alpine orogeny since the late Eocene (37 million years) and the most shortening and faulting had occurred during at the Late Miocene. Data presented here demonstrate that shortening percent in the study area of Alborz Mountains is about 36.27% and the Rate of Shortening is estimated about 0.93 mm/y.
Tectonics
Zahra Mohammadyasl; Abdollah Saidi; Mehran Arian; Ali Solgi; taher Farhadinejud
Abstract
The Studied area is located in the small part of the structural zone of Urumieh- Dokhtar Magmatic Arc, at 60km far from south of Qom and 12km far from south east of Kahak. In the beginning, 1:25000 map of the area was prepared, because, region is located in two 1:100000 scale map sheet of Kahak and Aran, ...
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The Studied area is located in the small part of the structural zone of Urumieh- Dokhtar Magmatic Arc, at 60km far from south of Qom and 12km far from south east of Kahak. In the beginning, 1:25000 map of the area was prepared, because, region is located in two 1:100000 scale map sheet of Kahak and Aran, and more rock units were separated. In the next step, in a several step of the field observations, 17 samples of regional volcanic rocks were taken for XRF and ICP chemical analysis, and they main Oxides, heavy metals and rare elements were identife. Most of the samples have been located in the Calk- alkaline series, and some in the Tulleit series. In the lithology diagrams, these samples respectively are arranged in the range of Andesite, Dacite, Trachy Andesite and Rhyolite Rocks. Due to the anomalies and the amount of Nb in the samples of the region, they formation can be related to the subduction zone. On the other hand, the depletion of Nb and Ti is special in magmatism in the subduction zone. Because in the subduction regions released fluids from floating lithospheric rich in LILE, increases in the mantle wedge. Since in the study area rocks exhibit calc- alkaline with moderate to high potassium, it can be concluded that the stones are related to active continental margin associated with subduction.
M. Jamali; M. R. Ghassemi; M. Lotfi; A. Solgi
Abstract
Kuh-e-Ahan is a high-standing single relief within a rather flat plain, which is located in the north of the Tabas block, near the intersection of the Nayband and Kalmard faults and there are great outcrops of fe-oxide, along with eastern-western faults and fractures in Kooh-e-Ahan area.. ...
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Kuh-e-Ahan is a high-standing single relief within a rather flat plain, which is located in the north of the Tabas block, near the intersection of the Nayband and Kalmard faults and there are great outcrops of fe-oxide, along with eastern-western faults and fractures in Kooh-e-Ahan area.. The present study uses structural and remote sensing methods to discover the mechanism for evolution of the Kuh-e-Ahan, and to understand style of mineralization in the mountain, emphasizing on the role of fractures and major faults. In our remote sensing approach, we used DEM data and Aster satellite images and their filtering in main directions to detect displacements and sudden offsets of lithologic units and changes in drainage patterns. In our field studies, we studied mechanism of the faults, emphasizing on the faults within the Kuh-e-Ahan mining district. The results show N-S faults (Nayband fault trend) and NE-SW faults (Kalmard trend) have a general right-lateral mechanism, and the E-W faults are left-lateral with a reverse component. Structural model developed in this study suggest that strike-slip displacement on conjugate fault provided the space required for ascend and development of hydrothermal mineral deposits within the mine district.
Tectonics
Golnaz Abbasi; Ali Solgi; Mohsen Pourkermani; Hosein Motamedi; alireza farrokhnia; Keivan Orang
Abstract
We used 2D seismic profiles, field observation and well data to constrain the structural evolution of the Saveh basin during the late-lower Miocene to late Pliocene. During this time period almost 8-9 kilometers of Upper Red Formation (URF) and the Pliocene conglomerates were deposited in the basin depocenter. ...
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We used 2D seismic profiles, field observation and well data to constrain the structural evolution of the Saveh basin during the late-lower Miocene to late Pliocene. During this time period almost 8-9 kilometers of Upper Red Formation (URF) and the Pliocene conglomerates were deposited in the basin depocenter. During the late- lower Miocene (to early- middle Miocene ?), Syn-depositional activity of west-east-northwest-southeast trending high-angle fault zones, with an extensional component, created accommodation space for deposition of lower Upper Red Formation. Since the late- middle Miocene (or late Miocene), initiation of a compressional phase has resulted in regional deformation.The deposition of upper part of the URF and the Pliocene conglomerates was contemporaneous with compressional deformation. During this stage, the middle part of the URF acted as an effective detachment horizon and detachment folds, such as the Saveh and Taraz Naeen anticlines, were formed. The thinning of the Pliocene conglomerates towards the crestal point of these folds indicates late structural growth. According to the top Qom depth map, there are no traps with fault independent closure within the Saveh basin. The top of the Qom Formation is estimated at -4250 m in the Taraz Naeen anticline.
R. Gholipour; A. Solgi; Y. Sattarzadeh-Ghadim; A. Sorbi
Abstract
Geomorphic indices of active tectonics are useful tools to analyze of the active tectonics in a large area. These indices have the advantage of being calculate from the software and remote sensing packages over large area as a reconnaissance tool to identify geomorphic anomalies possibly related to active ...
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Geomorphic indices of active tectonics are useful tools to analyze of the active tectonics in a large area. These indices have the advantage of being calculate from the software and remote sensing packages over large area as a reconnaissance tool to identify geomorphic anomalies possibly related to active tectonics. This is particulary valuable in Ajichai basins where relatively little work on active tectonics based on this method was done, so this method is new and useful. Based upon valuable of the stream length-gradient index(SL), drainage basins asymmetry(Af), hypsometric integral (Hi), ratio of valley-floor width to valley height (Vf), drainage basins index shape (Bs), and index of mauntain front sinuosity (Smf), we used an overall index (Iat), that is a combination of the other indices that divides the landscape into four classes of relative tectonic activity. The moderate class of Iat is mainly in the class 2 (high), with 1045.46 Km2 ,11.26 percent, class 3 (moderate), with 2940.67 Km2 ,31.67 percent and with 5297.30 Km2 ,57.06 percent occupying of all zone. The stream network asymmetry (T) was also studied using morphometric measures of Transverse Topographic Symmetry. Analysis of the drainage basins and sub-basins in the study area results in a field of T-vectors that defines anomalous zone of the basins asymmetry. A comparison of T index clearly consist with the values and classes of active tectonics indices and the overall Iat index.
S. M. Hamidzadeh; A. Babazadeh; B. Asgari – Pirbaluti; A. Solgi
Abstract
The Asmari Formation was measured and sampeled in Ghar-e Agha Seyyed at Farsan area in order to determine sedimentary environment based on facies analysis. In the study area, the Asmari Formation has a thickness of 183 m and conformably underlained the Pabdeh Formation. Based on microfacies studies, ...
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The Asmari Formation was measured and sampeled in Ghar-e Agha Seyyed at Farsan area in order to determine sedimentary environment based on facies analysis. In the study area, the Asmari Formation has a thickness of 183 m and conformably underlained the Pabdeh Formation. Based on microfacies studies, 8 microfacies were recognized such as:1) Porcelanouse foraminifera – bioclastic – red algal wackestone / packstone, 2) Rotalia grainstone, 3) Bioclastic –red algal grainstone, 4) Red algal – coral boundstone, 5) Red algal wackestone (Floatstone), 6) Red algal –large hyaline foraminifera – intraclast packstone, 7) Red algal – bioclastic - large hyaline foraminifera wackestone / packstone, 8) Large hyaline foraminifera packstone. These microfacies represent three facies belts including Inner ramp, Middle ramp and Outer ramp. On the other hand, based on the presence of benthic foraminifera, the age of the Asmari Formation is related to Oligocene (Rupelian – Chatian).
A. Solgi; A. R. Farrokhnia; F. Zahmati
Abstract
The Haft kel anticline is one of the oil fields located in Dezful embayment of the Zagros folded zone. In this study, the most important factors influencing the fracture distribution and hydrocarbon entrapments of Asmari formation were considered, and to investigate the fractures, subsurface data and ...
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The Haft kel anticline is one of the oil fields located in Dezful embayment of the Zagros folded zone. In this study, the most important factors influencing the fracture distribution and hydrocarbon entrapments of Asmari formation were considered, and to investigate the fractures, subsurface data and analytical methods were used. These methods include inscribed circle, curvature analysis of the axial zone and changes in thickness of overburden sediments. Results of the inscribed circles and thickness maps of the overburden sediments show that the greatest concentration and development of fractures is in the hinge zone and in the eastern part of the anticline. In addition, the highest density of fractures is found to be in the outer arcs of the axial curvature sand decreases with depth. Evidences show that the most important factors controlling the fracture distribution are the geometry and the folding mechanism(flexural-slip).
M Hamidian Shirazi; A Saeedi; A Solgi; K Yazdjerdi
Abstract
The Zagros orogen is located along the central part of the of Alpine-Himalayan orogenic belt, and is one of the world’s youngest orogenic systems. Geological and deformational characteristics of this orogen are completely different from other parts of the Alpine orogenic belt. Of the most obvious ...
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The Zagros orogen is located along the central part of the of Alpine-Himalayan orogenic belt, and is one of the world’s youngest orogenic systems. Geological and deformational characteristics of this orogen are completely different from other parts of the Alpine orogenic belt. Of the most obvious structural features of the Zagros orogen are the occurrence of large-scale folds. The lack of geometrical uniformity along their axes is the most important character of these folds. General trend of the structures formed in the Zagros region (folds and major faults) is northwest–southeast, which is locally deflected due to different reasons such as effects of large fault zones. In some places, the changes in the initial pattern of folds may be related to more than one tectonic parameter. The simultaneous operation of two or more parameters such as faulting or salt penetration can also significantly change the fold patterns. The Ahmadi anticline, which is located 50 km east of Shiraz, is one of such folds where this property (i.e. changes in fold pattern) can be investigated. The fold has a box fold model with the axis trending NNW-SSE, and is located south of the Main Zagros Thrust Fault, as well as close and parallel to it. It is also situated in the Zagros folded zone and forms the northern boundary of the Sarvestan plain. The Ahmadi anticline is an open and symmetric fold, trending along NNW-SSE direction. Along the anticline, the fold axis is never straight and has been deflected at several points. The most significant fold axis deflection is observed along the eastern termination of the anticline, where the fold axis is deflected by about 62 degrees toward south.
F Baratpour; M Arian; A S
Abstract
Situated 15 km NW of the Izeh city, Tukak and Kamarun anticlines are located in northwest of the Izeh zone in the Zagros fold-and-thrust belt. The Tukak anticline measures about 17 km length by 3.3 km width on the Asmari formation outcrop, while the Kamarun anticline shows a maximum length and width ...
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Situated 15 km NW of the Izeh city, Tukak and Kamarun anticlines are located in northwest of the Izeh zone in the Zagros fold-and-thrust belt. The Tukak anticline measures about 17 km length by 3.3 km width on the Asmari formation outcrop, while the Kamarun anticline shows a maximum length and width of about 15 km and 3.5 km, respectively, on the same formation. The SE termination of the Kamarun anticline and the NW termination of the Tukak anticline form together an en-echelon array. Both anticlines represent nearly symmetrical box-fold geometry, in which the Pabdeh formation is the oldest outcrop in each anticlinal core and the Asmari formation constitutes most of their surface outcrop. Based on surface geology, 4 cross-sections across the Tukak anticline and 3 cross-sections across the Kamarun anticline (D-D' is a common section crossing the en-echelon plunges), and one longitudinal section through both structures were constructed. Since the Bangestan horizon is taken to indicate a position upper than sea level, the cross-sections were used to construct the UGC map on the Upper Khami horizon. In Tukak anticline, which is bigger than the Kamarun anticline, the UGC map of the Upper Khami horizon illustrates vertical and horizontal closures of 250 m and about 4.3 km2, respectively.
M Haj Manuchehri; M Arian; M Ghorashi; A Solgi; A Sorbi
Abstract
Geomorphic indices of active tectonics are useful tools to analyze the influence of active tectonics. These indices have the advantage of being calculated from ArcGIS and Remote Sensing software packages over large areas as a reconnaissance tool to identify possible geomorphic anomalies related to active ...
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Geomorphic indices of active tectonics are useful tools to analyze the influence of active tectonics. These indices have the advantage of being calculated from ArcGIS and Remote Sensing software packages over large areas as a reconnaissance tool to identify possible geomorphic anomalies related to active tectonics. This method is particularly new and useful in areas where relatively little work has been carried out on active tectonics based on this method. Based upon the values of stream length-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), ratio of valley-floor width to valley height (Vf), index of drainage basin shape (Bs), and index of mountain front sinuosity (Smf), we used an integrated index (Iat) that is a combination of the other indices. This index divides the landscape into four classes of relative tectonic activity. According to the Iat results, sub-basins 4 and 6 show zones of low tectonics activity (Class 4), sub-basins 1, 2, 7, 9, 10, 11, 12, 14, 15 and 19 fit to areas of moderate tectonic activity (Class 3), and high tectonic activity is represented by sub-basins 3, 5, 8, 13, 16, 17 and 18 (Class 2). The Tranverse Topographic Symmetry (T) was also studied using morphometric measurements, which finally gave a plot of T-vectors defining anomalous zones of basin asymmetry. A comparison between T index and map of relative tectonic activity showed a consistent coincidence between areas of higher Iat classes with zones of greater asymmetry.
Z Maleki; M Arian; A Solgi; M.A Ganjavian
Abstract
The Karbasi anticline is located to the west-northwest of the Jahrom town, and 40 km to the northwest of Aghar gas anticline in interior Fars region. The anticline has an asymmetric structure, and some faults with large strike separations are observed in it. Because of the importance of comparison between ...
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The Karbasi anticline is located to the west-northwest of the Jahrom town, and 40 km to the northwest of Aghar gas anticline in interior Fars region. The anticline has an asymmetric structure, and some faults with large strike separations are observed in it. Because of the importance of comparison between the folds, and understanding folding patterns in different systems, analysis and description of basic elements of fold style is considered as a major components in structural studies. The aim of this study is to analyze the elements of fold style in the Karbasi anticline located in the interior Fars, in order to contribute to the exploration goals of hydrocarbon. The software used in this study include Tectonics FP, Global Mapper, and software related to Geo Modelling. Analysis of fold style elements in the different parts of the Karbasi anticline indicates changes in the pattern of folding. The changes in the western part of the Karbasi anticline is different from other parts of the anticline. Based on prepared stereoplots, fold axis and axial plane show major changes in the western part of the anticline. In the study area Dashtak Formation as a middle detachment unit plays a major role in development of the geometry of folds. Based on our results, it seems the western part of the anticline is affected by more deformation. It is probable that in this part, the Nezam-Abad fault has caused rotation of the western plunge of the fold towards north, and has affected the Karbasi anticline. Based on the modeling done for the study area, a secondary fault is indicated related to the Nezamabad fault.
M Sarhangi; A Solgi; A Sorbi; B Fayyazi; Sh Soltani
Abstract
In this paper, the relative active tectonics of the Mordaq-Chai basin has been discussed according to the geomorphic indices using Global Mapper software. The calculated indices are as follows: stream length–gradient index (SL), hypsometric integral (Hi), ratio of valley floor width to valley height ...
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In this paper, the relative active tectonics of the Mordaq-Chai basin has been discussed according to the geomorphic indices using Global Mapper software. The calculated indices are as follows: stream length–gradient index (SL), hypsometric integral (Hi), ratio of valley floor width to valley height (Vf), index of drainage basin shape (Bs),index of mountain front sinuosity (Smf), asymmetry factor (AF), and transverse index of basin topographic symmetry (T). Using above indices results, led to calculation of relative tectonic activity index (Iat).The results show that the Mordaq-Chai basin’s relative tectonic activity index falls into two groups: the first one includes the areas around the Sahand volcano crater (upper part of sub-basin one) and the Goshayesh Valley (upper part of sub-basin three), both of which have high levels of relative tectonic activity. The second one includes high lands located at northern part of the Maragheh fault towards the Kordeh-Deh village (sub-basins one and two), the opening of the Mordaq-Chai river into the Malekan plain (from the Ekiz village to the Sheikh-o-eslam village in central of sub-basin 3) and the southern portion of the Sahand Volcano’s crest (central part of sub-basin one), which all have moderate levels of relative tectonic activity.
N Bagha; M Ghorashi; M Arian; M Pourkermani; A Solgi
Abstract
Structural development, caused by active tectonics leads to deformation of morphology features. The Mosha-North Tehran fault zone, located in south edge of the Central Alborz consists of significant tectonic structures. Hence, study on morphotectonic signs is a proper method for evaluation of relative ...
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Structural development, caused by active tectonics leads to deformation of morphology features. The Mosha-North Tehran fault zone, located in south edge of the Central Alborz consists of significant tectonic structures. Hence, study on morphotectonic signs is a proper method for evaluation of relative tectonic activities in the area. In this research, six main morphometric indices such as stream length-gradient (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), ratio of valley-floor width to valley height(Vf), drainage basin shape (Bs), and mountain front sinuosity(Smf)were considered. The computations and probes of these indices indicate three classes of relative tectonic activity in the study area from low to high level. Consequently, the drainage basins with high class of tectonic activity mostly coincide with the main faults in south edge of the Central Alborz.
S Bahiraee; M Arian; M Qorashi; A Solgi
Abstract
The Mosha fault is the most important fault structures in the south of Central Alborz. According to the activity of this fault, confirmation of the morphological evidences, and large historical earthquakes occurred by its activity, also proximity to Tehran metropolitan, the study of this area is very ...
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The Mosha fault is the most important fault structures in the south of Central Alborz. According to the activity of this fault, confirmation of the morphological evidences, and large historical earthquakes occurred by its activity, also proximity to Tehran metropolitan, the study of this area is very important. Therefore, as a parameter, evaluation of the fault movement potential helps us in seismological study of the area. In this paper, we have used the model presented by Lee et al. (1997) to evaluate movement potential. The model is based on the relationship between fault geometrical characteristics and regional tectonic stress field. To use the equations of this model, structural data of 13 stations along the Mosha fault were collected to identify the position of the principal axes of stress. Then, we obtained the direction of maximum principal stress of the Mosha fault and also for each section separately by using Inversion method and they were placed in equations.
P Didar; N Nezafati; M.H Emami; A Solgi
Abstract
In the south of Mashhad city, situated in the Khorasan-eRazaviProvince, NE Iran, there are a number of granitic intrusive bodies intersected by several pegmatite veins. These granitic bodies are of orogenic (collisional), peraluminous, S- type and host the pegmatites in an area of 40km2. This paper presents ...
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In the south of Mashhad city, situated in the Khorasan-eRazaviProvince, NE Iran, there are a number of granitic intrusive bodies intersected by several pegmatite veins. These granitic bodies are of orogenic (collisional), peraluminous, S- type and host the pegmatites in an area of 40km2. This paper presents the geological, geochemical, and mineralogical investigations on the pegmatite veins in order mainly to examine their economic value for lithium and lithium bearing minerals. For this purpose, the pegmatite veins of the area were first mapped and sampled. In this regard, more than 100 samples from the pegmatites and associated granites were taken and investigated using polarized microscopy, SEM, XRD, and ICP. According to the field observations and laboratory examinations, seven individual pegmatite facies were recognized, all of which of LCT (Li, Cs, Ta) type (based on Cerny-2005-classification). The studied pegmatites contain three main types of mica including muscovite, lepidolite, and biotite and host from 430 to 1150 ppm lithium. Beside lithium bearing mica, presence of some other minerals such as garnet (almandine-spessartite), tourmaline (schorl-dravite series and schorl-elbaite series), and apatite are of interest, especially because of their potential for hosting REEs. The average of A/CNK index for the pegmatites is 1.3 to 1.6, while the average of Mg/Li is 3.9 to 24.1. The average of lithium for the facies of "quartz + tourmaline ± muscovite" is 19.3ppm, while the average of Li for the facies of "quartz+ potassium feldspar + plagioclase + muscovite + lepidolite + biotite + tourmaline" is 177.2 ppm. The low Mg/Li ratio, the high content of lithium, and the mineralization of lepidolite introduce the pegmatites of Mashhad as a significant potential for lithium, what that is being introduced for the first time from these pegmatites.
H Haji Hosseinlou; A Solgi; M Mohajjel; M Pourkermani
Abstract
The Khoy shear zone (KSZ) is exposed 130 Km north of Uremia and 650 km west of Tehran. Structural analysis in the Khoy Shear Zone (KSZ) indicated that they consist of NW-SE oriented various metamorphic rocks. They contain NW-SE trending moderate to steeply dipping mylonitic foliation to the NE. Stretching ...
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The Khoy shear zone (KSZ) is exposed 130 Km north of Uremia and 650 km west of Tehran. Structural analysis in the Khoy Shear Zone (KSZ) indicated that they consist of NW-SE oriented various metamorphic rocks. They contain NW-SE trending moderate to steeply dipping mylonitic foliation to the NE. Stretching lineation plunge shallowly to moderately towards NE. Thrust faults are oriented the same as mylonitic foliation. Ductile fabrics are superimposed by brittle structures. Orientation of the structures indicates that the main stress trend is NE-SW. Four deformation stages (D1-D4) identified in KSZ. The first two stages are ductile that superimposed by the two other ductile-brittle stages. Shear sense indicators such as S/C fabrics, shear bands, shear folds, book-shelf structures, fishes and mantled porphyroclasts indicate that the KSZ deformed via dextral transpression tectonic regime. The Khoy area contains both NW-SE striking dextral strike-slip and SW verging NE dipping ductile reverse shear fabrics. Ductile shear fabrics are overprinted by subsequent younger both thrust and strike-slip fault systems. Abundant syn-tectonic granitoids were intruded in the Khoy area during convergent. The shear deformation fabrics are well identified in both deformed intrusive and metamorphic-ophiolite complex. The geometry and kinematics of shear fabrics indicate a deformation partitioning in both ductile and brittle conditions during a progressive transpression tectonic regime. The KSZ deformed during an oblique convergence scenario between the Arabian and West Alborz- Azerbayjan blocks in NW Iran.