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Open Access Article
1 - Structural analysis of elevated Sabzkuh syncline in High Zagros
yasser narimani Elham Asadi MehmandostiHigh Zagros zone located in the northeast of Zagros Fold-Thrust Belt and comprises of NW-trending thrust faults. In Sabzkuh area, these thrust faults as forethrust and backthrust have accompanied with positive and negative triangle zones. These zones cause formation of MoreHigh Zagros zone located in the northeast of Zagros Fold-Thrust Belt and comprises of NW-trending thrust faults. In Sabzkuh area, these thrust faults as forethrust and backthrust have accompanied with positive and negative triangle zones. These zones cause formation of the elevated Sabzkuh syncline on the hanging wall of the Dopoulan and Solaghan-Avardegan Fault as well as the Choghakhor embayment at footwalls of the Main Zagros and Solaghan-Avardegan faults. The horizontal bedding in the Ilam-Sarvak formations in the main faults footwall can be used as an evidence for the formation of the embayment. The elevated Sabzkuh syncline is associated with accommodation of limb wedge thrusts on the fold limbs. These structures show complexity of thrust faults geometry in the high Zagros and imply their initiation from the detachment horizons within the Lower Paleozoic/Hormoz Formation. Manuscript profile -
Open Access Article
2 - Seismic hazard assessment of the city of Khoy using deterministic and probabilistic seismic hazard analysis approaches
Nasim Rahmani AbasfamConstruction of new cities or development of old towns in an area requires geological and geophysical (seismic) studies. The city of Khoy is one of the developing cities that have to be study. Therefore, the Deterministic and Probabilistic Seismic Hazard Analysis (DSHA MoreConstruction of new cities or development of old towns in an area requires geological and geophysical (seismic) studies. The city of Khoy is one of the developing cities that have to be study. Therefore, the Deterministic and Probabilistic Seismic Hazard Analysis (DSHA and PSHA) approaches have been used to assess seismic hazards and earthquake risk in the city. For this purpose, analyses have been carried out considering historic and instrumented earthquakes, geologic and seismotectonic parameters of the region covering a radius of 100 km with the city of Khoy in the center. Therefore, the main faults and fault zones in the study area were studied and length and distance of each fault from the center of the city of Khoy was calculated. At the next step, the Maximum Credible Earthquake (MCE) and Peak Ground Acceleration (PGA) have been measured using both DSHA and PSHA approaches and also equations presented by different researchers. DSHA Results show that the MCE and PGA values are 6.5 and 0.31g, respectively. PSHA results indicated that the MCE evaluated value is 6.1 for a 0.64 probability in a 50-years period. The period of this earthquake is 110 years and its probability will be 0.009 per a year. The occurrence probability of earthquakes with magnitude equal or greater than 7.1 is 10% and for earthquakes with magnitude equal or greater than 6.3 is 50% for the study area. Manuscript profile -
Open Access Article
3 - Determination of stress state and tectonic regime changes in the brittle structures of Chah Yusuf Mountain (East of Gonabad)
فرهاد زارعی Ghaemi GhaemiIn this study, structural elements, such as faults and fractures and their formation mechanisms and relationships with tectonic regime of Chah Yusuf Mountain in East of Gonabad city have been recognized and discussed. Their relation with regional fractures, based on dat MoreIn this study, structural elements, such as faults and fractures and their formation mechanisms and relationships with tectonic regime of Chah Yusuf Mountain in East of Gonabad city have been recognized and discussed. Their relation with regional fractures, based on data’s from satellite image process and field data, is also shown. Major faults in this area were identified by using fault plain features such as striations, stretching vein and cumulative steps of minerals that helped us to determine fault mechanisms. In general, faults were oriented in three main directions: 1) Reversed faulting along N90-120˚, 2) Right lateral strike –slip faults along N140-160˚ and 3) Normal faults along N0-15˚. Based on the obtained data and using the inversion method, the orientation of the principal stress axes (σ1، σ2 and σ3) and the ratio of the principal stress differences R in the studied area were analyzed. The results showed two different tectonic regimes in the formation of regional structures: 1) Compressive tectonic regime, major stress along NNE-SSW, which generated structures of folds and reversed faults. 2) Shear tectonic regime, compressive stress along NE_SW and tensile stress line NW-SE, which generated structures such as strike-slip faults, normal faults, vein and tensile fracture. So, the major stress direction in this region is NNE-SSW, which shows its relation to the Late Cenozoic Arabia –Eurasia oblique continental collision. Manuscript profile -
Open Access Article
4 - Geochemistry and origin of orogenic gold in Qolqoleh area, Kurdistan: using fluid inclusion and stable isotope methods
Taghipour Makizadeh فرهاد احمدنژادThe Qolqoleh gold deposit is located in the northwestern part of the Sanandaj–Sirjan metamorphic belt, about 50 km south-west of Saqqez. The rocks in the vicinity of the Qolqoleh deposit consist predominantly of Mesozoic volcano-sedimentary sequences of phyllite, meta-l MoreThe Qolqoleh gold deposit is located in the northwestern part of the Sanandaj–Sirjan metamorphic belt, about 50 km south-west of Saqqez. The rocks in the vicinity of the Qolqoleh deposit consist predominantly of Mesozoic volcano-sedimentary sequences of phyllite, meta-limestone, cholorite- sericite schist, metavolcanic and granitic intrusive rocks that have undergone greenschist facies metamorphism. Geochemical studies indicate that gold mineralization occur in the sulfide-quartz veins. Based on the number of phases present at room temperature and their microthermometric behavior, three fluid inclusion types were recognized: type I mono phase aqueous inclusions, type II two-phase aqueous inclusions (aqueous + vapor), that based on Th could be subdivided into two groups: type IIa show salinities of 5–13 wt.% NaCl equivalent and Th-tot of 205 to 255 °C. Type IIb with salinities of 15–19 wt.% NaCl equivalent and Th-tot of 335 to 385 C. Type III three-phase shows carbonic–aqueous inclusions (aqueous–LCO2–VCO2) with salinities of 9–13 wt.% NaCl equivalent and Th-tot of 345–385 °C. Furthermore, the mean values of density of ore-forming fluids, pressure and depth of mineralization are 0.79-0.93 gr/cm3, 2 Kbar and 7 Km respectively. On the basis of these data, the Qolqoleh gold deposit is categorized in meso zonal orogenic gold deposit. The δ_0^18 values of the ore-forming fluids are in the range of 7.2‰ to 8‰ and the D values are from -35.27‰ to -40.23‰, which indicate a source of deep-originated metamorphic water that is partially mixed with shallow meteoric water. The change of tectonic regime from compressional to extensional in association with the continuously increasing geothermal gradient, results in remobilization of large amounts of metamorphic fluids. Mixing of ascending orogenic drive fluids with descending meteoric fluids led to deposition of gold by sulfide minerals. Manuscript profile -
Open Access Article
5 - Biotite and amphibole geobarometer as an indicator of exploration potential for Cu-Fe deposits in the Panah-Kuh skarn, West of Yazd
اعظم زاهدی Mohammad BoomeriThe intrusion of Panah-Kuh granodiorite-quartz diorite stock into the limestone-dolomite of the Jamal Formation has led to the skarn formation in the Panah-Kuh area. Skarns have formed in direct contact with intrusions in carbonate rocks. The Panah-Kuh granitic rocks ar MoreThe intrusion of Panah-Kuh granodiorite-quartz diorite stock into the limestone-dolomite of the Jamal Formation has led to the skarn formation in the Panah-Kuh area. Skarns have formed in direct contact with intrusions in carbonate rocks. The Panah-Kuh granitic rocks are mainly metaluminous, calc-alkaline with I-type granitoid characteristics. Biotite and amphibole phenocrysts are the most abundant hydrous mineral in the Panah-Kuh granite. Chemical analysis of biotite and amphibole in granitic rocks in Panah-Kuh shows that the total Al (TAl) content of them can be used as a useful indicator for distinguishing between mineralized and nonmineralized granitic rocks. A good positive correlation is showed between the TAl content and the formation pressure of the granitic rocks estimated by biotite and hornblende geobarometers. These facts suggest that the TAl content of biotite and hornblende can be used to estimate the solidification pressure of the granitic rocks. According to the obtained biotite and amphibole geobarometers, it is estimated that Panah-Kuh Fe-Cu skarn deposit was formed at pressures of 1-2 kb similar to Yaguki, Kamaishi and Tanazawa Fe-Cu deposits in Japan. Therefore, biotite and amphibole geobarometers of granitic rocks may be a useful indicator in the exploration of skarn ore deposits related to granitic rocks. Manuscript profile -
Open Access Article
6 - Rock typing in Asmari Formation using hydraulic flow unit concept, with an impact on Ahvaz Sandstone Member in Mansouri Oilfield
مسلم خداویسی Kavianpour-Sangenoo Namdarian Seyed Reza Moussavi-Harami Mahbobi Kadkhodaei Davood FereidooniThe Asmari Formation (Oligocene-Miocene) is one of the most importance reservoir rocks in the Zagros Basin. This formation in the Mansouri Oilfield is composed of the mixture of silisiclastic - carbonate deposits which silisiclastic deposits are known as the Ahwaz Sands MoreThe Asmari Formation (Oligocene-Miocene) is one of the most importance reservoir rocks in the Zagros Basin. This formation in the Mansouri Oilfield is composed of the mixture of silisiclastic - carbonate deposits which silisiclastic deposits are known as the Ahwaz Sandstone Member. Rock typing is a process in which geological facies determined with their dynamic behavior. Each flow unit is related to flow zone indicator, thus zoning of a reservoir using of flow zone indicators and identification of Flow units can be used to evaluate the reservoir quality based on relationship between porosity and permeability. To evaluate the reservoir quality and determining spatial distribution of petro-physical indexes in the Asmari Formation Sandstone, porosity-permeability relationship as well as their relationship with the rock types is used and finally Flow Units and Rock Types have been identified. In this study, the Asmari Formation Sandstone is divided into four flow units A, B, C and D. Within recognized flow units, flow unit C is the best one in the terms of reservoir quality and flow unit D also has a good reservoir quality. Comparison of determined flow units with porosity logs (neutron, density and sonic), it is observed that sandstone successions of Asmari reservoir affected by diagenetic processes like fracturing, dissolution, dolomitic cementation and hydrocarbon migration before cementation and flow units C and D are more extended, so porosity logs show good reservoir quality in this interval of Asmari succession. Thus it can be deduced that using hydraulic flow units, we can determine rock types groups in wells with core and then extrapolate the results into uncored wells. Manuscript profile -
Open Access Article
7 - Arc-type magmatism in middle part of the Sanandaj-Sirjan Zone (western Iran) and geochemical characteristics of the granitoids of this area
Granitoids of Aligoodarz, Dehno, Boroujerd and Alvand are located in the middle part of the Sanandaj-Sirjan Zone (SSZ), western Iran and intruded the regional metamorphic rocks. Granite, granodiorite and tonalite are the most abundant rock types. Comparison of chemical MoreGranitoids of Aligoodarz, Dehno, Boroujerd and Alvand are located in the middle part of the Sanandaj-Sirjan Zone (SSZ), western Iran and intruded the regional metamorphic rocks. Granite, granodiorite and tonalite are the most abundant rock types. Comparison of chemical composition of Aligoodarz granitoids with those from other areas indicates that they are co-genetic and have petrogenetic relations. All of them show continuous trends on Harker variation diagrams and have similar chondrite-normalized multi elements patterns. Fractionation of biotite, amphibole, feldspar and Fe-Ti oxides had important effect on magma evolution and generation of different magma types. In contrast to other rock types, tonalites show relatively different chemical behavior. They have abundant amphibole and are similar to cumulative rocks. The granitoids in this study are similar to I-type granitoids generated in continental arcs. They have relatively the same age and are the result of intense magmatic activity during Middle Jurassic time in response to the subduction of Neotethys oceanic crust beneath Centeral Iran. Alvand granite has the slightly different composition. It is enriched in Cs, Cr, Rb, K2O and Th but depleted in Ca in comparison with other granitoids. All of these features indicate the role of sedimentary rocks in the petrogenesis of Alvand granite. Comparison of the rare earth elements abundances in SSZ granitoids with those from Andean rocks indicates magma generation at shallow crustal levels. Manuscript profile -
Open Access Article
8 - Calcareous algae of the Shah Kuh Formation (Early Cretaceous) in southwest of Khur (Central Iran)
hamid mirmohammadsadeghi AdabiA complete succession of the Shah Kuh Formation with the age of Early Cretaceous is exposed in southwest of Khur, in Central Iran. In order to study and describe calcareous algae the Shah Kuh Formation a stratigraphic section was selected, sampled and studied in Kuh- e MoreA complete succession of the Shah Kuh Formation with the age of Early Cretaceous is exposed in southwest of Khur, in Central Iran. In order to study and describe calcareous algae the Shah Kuh Formation a stratigraphic section was selected, sampled and studied in Kuh- e Tangal- e Bala, 80 Km southwest of Khur city. Association of calcareous algae consist of Delloffrella quercifoliipora belongs to Triploporellaceae, Montiella elitzae, Neomeris cretacea, Salpingoporella sp. and Terquemella sp. related to Dasycladacea and Permocalculus cf. minutus belongs to Gymnocodiacea. Also 2 genera of Udoteaceae (Arabicodium and Boueina) and 1 species of Solenoporaceae (Marinella Lugeoni) were identified. A species of algae ascribed to uncertain affinities (Lithocodium aggregatum) accompanied by skeletal fragments of colonial octocorals were identified in this research. In studied microfacies, calcareous algae were observed in sediments of lagoon and bar environments. Based on calcareous algae and benthic foraminifera association, the age of Late Barremian- Early Aptian was assigned for the succession of the Shah Kuh Formation in studied section. Manuscript profile
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