M. H. Kazemzadeh; A. Sadeghi; M. H. Adabi; H. Ghalavand
Abstract
In order to determine biostratigraphy, depositional environment and sequence stratigraphy of the Kalat Formation in the Sheikh Syncline (north east of Bojnurd), Four stratigraphic sections including South Sheikh, North Sheikh, Qaleh Zu and Ziarat were selected and sampled. The thickness of the Kalat ...
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In order to determine biostratigraphy, depositional environment and sequence stratigraphy of the Kalat Formation in the Sheikh Syncline (north east of Bojnurd), Four stratigraphic sections including South Sheikh, North Sheikh, Qaleh Zu and Ziarat were selected and sampled. The thickness of the Kalat Formation in the South Sheikh, North Sheikh, Qaleh Zu and Ziarat sections were 25, 16, 25 and 5m respectively, and its lithology consists mainly of brown to yellow limestones. The reason of changes in thickness in studied sections is tectonic factors, subsidence and different rates of sedimentation. The layer of conglomerate in the base part of the Kalat Formation at South Sheikh and Qaleh Zu sections and the layer of sandstone in the base part of the Kalat Formation at Ziarat section were recognized. In the biostratigraphic studies, 15 species belonging 23 genera of foraminifera were recognized and one biozone including Siderolites calcitrapoides-Sirtina orbitoidiformis assemblagezone was identified. The age of the Kalat Formation in all of studied sections based on the above biozone and fossil contents Maastrichtian were determined. Petrographic analysis led to recognition two silliciclastic and eight carbonate facies belonging to four depositional environments including tidal flat, restricted and semi-restricted lagoon, shoal and open marine. Based on the recognized facies and its gradual trend, abundance of shoal facies, absence of reefs and sediment of turbidite flows such as Falling and sliding sediments, the sedimentation of the Kalat Formation was occurred on the homoclinal ramp setting. Based on the vertical changes of facies and recognized depositional environments, one third-order depositional sequences was represented. This depositional sequence consists mainly of shoal facies rich in bioclast, intraclast, benthic foraminifera, echinoid, rudist (Hyporite) and bivalve. MFS of this sequence is represented by open marine facies rich in echinoid.
E. Asadi Mehmandosti; Sh. Alivand; H. Ghalavand; A. R. Rostami
Abstract
Nuclear magnetic resonance (NMR) is a test method that has had basic influence on the accuracy of reservoir parameters prediction. In this study, petrophysical properties of the Ilam Formation in one oil field of the Abadan plain were investigated by Nuclear magnetic resonance method, and core analysis ...
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Nuclear magnetic resonance (NMR) is a test method that has had basic influence on the accuracy of reservoir parameters prediction. In this study, petrophysical properties of the Ilam Formation in one oil field of the Abadan plain were investigated by Nuclear magnetic resonance method, and core analysis and thin sections data were used to validate the test results for the first time. The Nuclear magnetic resonance method was used to determine reservoir parameters such as porosity, permeability and rebuilding of capillary pressure curve in studied oil field. Correlation between petrophysical results of Nuclear magnetic resonance method, core data and microscopic thin sections indicates effectiveness of this method in determining the reservoir parameters. In addition, evaluation of the Ilam Formation carbonate with NMR method indicates that the studied reservoir at depths of 2890 to 2846 m has suitable reservoir quality in terms of hydrocarbon storages in studied oil field in Abadan plain.
Petrology
Marzieh Asadi-Avargane; Mehdi Rezaei-Kahkhaei; Habibollah Ghasemi
Abstract
The Qarah Chay Neogene caldera is located at 30 km SE Quchan in the Binalud Zone. The volcanic rocks of the caldera are mainly dacite in composition and composed of plagioclase and amphibole. The rocks present a variety of porphyry, microlitic porphyry, sieve, trachytic and glomeroporphyritic textures. ...
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The Qarah Chay Neogene caldera is located at 30 km SE Quchan in the Binalud Zone. The volcanic rocks of the caldera are mainly dacite in composition and composed of plagioclase and amphibole. The rocks present a variety of porphyry, microlitic porphyry, sieve, trachytic and glomeroporphyritic textures. Based on the spider diagrams normalized to chondrite and primitive mantle, the study rocks show enrichments in Large Ion Lithophile Elements (LILEs) and depletion in Heavy Rare Earth Elements (HREEs) and High Field Strength Elements (HFSEs). Their’s calc-alkaline affinity and the obvious negative HFSE anomalies (such as Ti, Nb and P), and positive Pb anomaly are similar to those magmas related to active continental margin. Moreover, their high concentrations of Sr, Sr/Y, Na2O/K2O, and low concentrations of K and MgO are the same as high silica adakites. Considering the above points, the parental magma(s) of the Qarah Chay Caldera formed from the partial melting of eclogite during the subduction of oceanic lithosphere of Sabzevar under the southern edge of the eastern Alborz zone in Neogene. It seems that the major Quchan and Dareh Gaz strike slip faults played a main role for the caldera formation.
Tectonics
Mohammad Moumeni Taromsari; Maryam Dehbozorgi; Reaza Nozaem; Ali Yassaghi
Abstract
Kalmard fault is considered as one of the fundamental faults in central Iran zone. The Ozbak Kuh mountains with a NE-SW strike are located in central Iran in the Kalmard fault zone. Hence, analyze the folds and faults in this deformed zone can aid in the understanding of structural evolution of this ...
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Kalmard fault is considered as one of the fundamental faults in central Iran zone. The Ozbak Kuh mountains with a NE-SW strike are located in central Iran in the Kalmard fault zone. Hence, analyze the folds and faults in this deformed zone can aid in the understanding of structural evolution of this area in central Iran. In this study, field operations and geometric-kinematic analysis of folds and faults, also study of their structural evolution are integrated in order to provide a better understanding of the structural evolution of the Ozbak Kuh area. The results display that before Cretaceous period the Ozbak-Kuh area was influenced by a compressional regime with a prependicular trend with respect to the Kalmrad fault that it caused the formation of folds and faults paralell to folds axial plane trends, after that compressional regime changing to a dextral strike slip regime in Cenozoic in direction of NE- SW, all structures in the study area such as, faults, folds axial plain and other related structures were influenced by the aforementioned strike slip stress. Generally the geometric- kinematic pattern of faults in the study area regarding to the major and R, P, R', and X faults is kind of simple shear and contraction parallel to deformed zone. In this pattern the simple shear is dominant and compression is trivial component. The mechanism of the faults in the study area shows that the deformation of the Ozbak Kuh mountains is toward the final stages of simple shear. The multiple steps of deformation, simple shear movements and intensity of deformation in the study area caused that the strike of all structures is to be in direction of NE-SW that it is parallel to the main fault zone.
E. Zarei; E. Ghasemi-Nejad; A. Dehbozorgi
Abstract
The Gurpi Formation was studied from different aspects at two sections, Farhadabad and Kavar, in southwest and southeast of Ilam where it is composed of 205 m and 158 m of grey to blue marl and shale beds and occasionally thin beds of argillaceous limestones with two formal members of Seymareh (Lopha) ...
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The Gurpi Formation was studied from different aspects at two sections, Farhadabad and Kavar, in southwest and southeast of Ilam where it is composed of 205 m and 158 m of grey to blue marl and shale beds and occasionally thin beds of argillaceous limestones with two formal members of Seymareh (Lopha) and Emam-Hassan. In order to reconstruct paleoclimate during depositional course of the formation, paleontological and palynological data (ratio of specialist to generalist foraminifera (e.s/e.g) and warm-temperate waters dinocysts and spore and pollen grains) were used statistically. The results show that the Gurpi Formation is mainly deposited in a warm-humid climate with two sharp decreases happening in temperature in early Maastrichtian and Danian.
H Alizadeh; M Aryan; M Lotfi; M Ghorashi; M Ghorbani
Abstract
The Dehaj-Sardoiyeh Belt, which is a part of the Urmia-Dokhtar Volcanic-Plutonic Zone, consists of several economic porphyry copper deposits. This area is located on the right lateral shear zone surrounded by the Rafsanjan fault in the north and the Shahr-e Babak fault in the south. In this research, ...
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The Dehaj-Sardoiyeh Belt, which is a part of the Urmia-Dokhtar Volcanic-Plutonic Zone, consists of several economic porphyry copper deposits. This area is located on the right lateral shear zone surrounded by the Rafsanjan fault in the north and the Shahr-e Babak fault in the south. In this research, spatial relationship among sixteen porphyry copper deposits, faults and fractures was studied. The results show a strong relationship between the Photo lineament factor and location of the porphyry copper deposits. The direction of lineament factor (d/D) was found to be highly correlated with the location of porphyry deposits. The results can be used in exploring preliminary porphyry deposits with regard to the geometry and mechanisms of the faults and fractures.
M Aflaki; E Shabanian; Z Davoodi
Abstract
Mahneshan–Mianeh Cenozoic basin, in southern part of SE–termination of North Tabriz Fault, is located between two distinct NW and N Iran tectonic domains affected by different Quaternary tectonic and stress regimes, with a transitional boundary. Determining ...
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Mahneshan–Mianeh Cenozoic basin, in southern part of SE–termination of North Tabriz Fault, is located between two distinct NW and N Iran tectonic domains affected by different Quaternary tectonic and stress regimes, with a transitional boundary. Determining the Quaternary state of stress in the area of interest is a key to locate the locus of this transition between the two tectonic domains. In this study, Quaternary stress state of the area was studied using the inversion of fault kinematics data (with well-known sense and chronology) measured in 25 sites in the Mahneshan–Mianeh Cenozoic basin. Our results indicate a homogenous modern compressional stress field characterized by a NE-trending horizontal maximum stress axis (~N055) prevailing through Quaternary, and coherent with the direction of the Arabia–Eurasia convergence in Iran.
N Zaheri; A.R Zzarasvandi; M Karevani; M Karevani; H Pourkaseb; F Rastmanesh
Abstract
The Aligudarz region is located in middle part of the Sanandaj-Sirjan Zone. During and before the Jurassic time, a variety of Cu, Fe, Zn-Pb and Ba mineralization are formed in this area due to tectono-magmatic activities. This diversity of mineralizations with volcano-plutonic activities caused some ...
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The Aligudarz region is located in middle part of the Sanandaj-Sirjan Zone. During and before the Jurassic time, a variety of Cu, Fe, Zn-Pb and Ba mineralization are formed in this area due to tectono-magmatic activities. This diversity of mineralizations with volcano-plutonic activities caused some complexities and ambiguities in geology-metallogeny evolution of the region. In this way, the aim of this study was investigation of geological evolution and its relation with mineralization and tectono-magmatic evolution of the Aligudarz region. The field and petrographic observations show that mineralization composition consist of barite with sulfide minerals (chalcopyrite, pyrite and covellite) and Fe-oxides in the Farsesh deposit withPermian carbonate host rock in the Farsesh area; sphalerite, galena and chalcopyrite in the Jurassic phylite, slate and meta-sandstone host rocks (Gol-e Zard deposit) and Cu mineralization associated with andesite rocks. In order to approach these aims, sampling for petrographical and geochemical studies with ICP-MS was done from each ore body separately. In addition, the granitoid rocks of the region were considered. In the Gol-e Zard Zn-Pb deposit, REE pattern represent enrichment of LREEs and La/Lu>1. The metamorphic host-rocks show positive Ce and negative Eu anomalies, whereas sphalerite, galena, chalcopyrite and quartz show negative Eu and Ce anomalies. Lack of Eu anomalies indicates high Oxygen fugacity during the precipitation of these minerals. Therefore, according to similarity of REE pattern in host-rock and ores of the Gol-e Zard deposit, it seems REEs extracted from host rock and then added to mineralizing fluid. The chondrite normalized pattern of REEs in barite ores and its host rocks in the Farsesh deposit show LREE enrichment. The positive Eu and negative Ce anomalies indicate that hydrothermal fluids are the main fluids, which caused precipitation of barite inthe host rock. REE pattern of andesite rocks show the same magmatic source for these rocks. LREE enrichment in andesite samples, lack of Eu and Ce anomalies indicate that clinopyroxene and plagioclase were crystallized in the same time and Ce+3 extracted with other REEs from depositional environment. The chondrite normalized pattern of granite rocks in the region show LREE enrichment, negative Eu anomaly and lack of Ce anomaly, which can indicate that diffraction process was controlled by plagioclase crystallization during the granitoid generation. The chondrite normalized spider diagram show the same trend of depletion of HFSE and HRRE and enrichment of LREE and LILE for all of the samples, which represent occurrence of magmatism in the study area and indicate all of these mineralizations are related to the subduction zone. These studies indicate that there is geodynamically a genetic relation between mineralizing fluids and volcano-plutonic activities of the region during or before the Jurassic system.
K. Nezhadafzali; R. Lak; M. Ghoreshi
Abstract
Mud volcano is a natural and spectacular phenomenon that usually appear in form of a dome but some are found as a basin. Mud volcanoes comprise a mixture of water, gas and mud. They are found in most parts of the world, particularly in the Alps and Himalayas belts. In Iran, most of the mud volcanoes ...
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Mud volcano is a natural and spectacular phenomenon that usually appear in form of a dome but some are found as a basin. Mud volcanoes comprise a mixture of water, gas and mud. They are found in most parts of the world, particularly in the Alps and Himalayas belts. In Iran, most of the mud volcanoes appear in coastal plains of the Caspian and Oman Seas. Mud volcanoes are known as indicators of oil and gas resources, and they are used to predict the existence of oil and gas reservoirs in Earth subsurface. The Napag mud volcano, as the largest and most active one in Iran, is located on the northern coast of the Oman Sea and is an interesting natural occurrence in the country. It is associated with a 39-m-high cone-shaped hill and several active and inactive vents. Mud eruption with different rates occurs usually every 3-5 minutes, and flows out from the western disrupted side of the edifice downslope toward the surrounding plain. In this research, a sediment sample was taken from the mud-flow during the field work, then analyses was analyzed for major, accessory and trace elements using ICP-OES machine in the laboratory. In addition, an analysis of the grain size of the sediment sample was carried out and the data were processed by the SPSS software. Results show that the sediment particles are of clay and silt in size. Al and Fe elements constitute 89.8 and 4.4 % of the sediment, and their high frequency is related to the high percentage of clay in the sediment. The evolution of the Napag mud volcano was investigated in three different stages: (1) Explosive, (2) Effusive (fast eruption with high rate), (3) Extrusive (slow and gradual eruption of material with high viscosity).
Sedimentology
S. A. Moallemi; M. A. Salehi; A. Zohdi
Abstract
In this study, the sandstones of the Razak Formation at the Finu and Hanudun outcrops and at Sarkhun Field north of Bandar-Abbas have been investigated by petrography and geochemistry analyses to discriminate provenance for determination of tectonic setting, parent rock and palaeoweathering and for comparison ...
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In this study, the sandstones of the Razak Formation at the Finu and Hanudun outcrops and at Sarkhun Field north of Bandar-Abbas have been investigated by petrography and geochemistry analyses to discriminate provenance for determination of tectonic setting, parent rock and palaeoweathering and for comparison with the Ahwaz Sandstone of Asmari Formation. The Razak Formation mainly consists of marl, sandstone, conglomerate and sandy limestone. The results of geochemical investigation of major and trace elements indicated that the sedimentation of the Razak Formation took place in an active continental margin. Provenance analysis shows that the siliciclastic sediments of the Razak Formation were largely derived from mafic and intermediate igneous, low- to high-grade metamorphic and sedimentary rocks. Chemical weathering indices suggested that their source area underwent a moderate degree of chemical weathering in an arid climate. It seems that the sediments of the Razak Formation are results of erosion from a mixture of ophiolitic-igneous rocks belonging to the Neo-Tethys oceanic crust, metamorphic rocks and other sedimentary strata deposited in Zagros sedimentary basin during foreland basin evolution. Wedge thickness of the Razak Formation changes from the hinterland thrust basin towards the Zagros trough and ridge basin and finally disappears in the coastal Fars region. The presence of polymictic conglomerate and coarse-grained sandstone with abundant rock fragments could be considered as additional evidence for the source of Razak Formation from the Zagros imbricated zone.
K Rezaeeparto; H Rahimpour Bonab; A Kadkhodaie; M Arian; E Hajikazemi
Abstract
Dariyan Formation (Aptian-Albian) is one of the main reservoir units in the South West of Iran which is equivalent to Shuaiba Fm,. Since the first step in the evaluation study of reservoir rock is studying the microfacies, depositional environments and diagenesis processes, in this research we have discussed ...
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Dariyan Formation (Aptian-Albian) is one of the main reservoir units in the South West of Iran which is equivalent to Shuaiba Fm,. Since the first step in the evaluation study of reservoir rock is studying the microfacies, depositional environments and diagenesis processes, in this research we have discussed these parameters in Dariyan reservoir in Salman oil field A, B, C, D and E wells. On the basis of petrographic studies classification of carbonate rocks by Dunham’s method and nomination of microfacies by Flugel’s classification was done and 7 basic microfacies have been identified: Mudstone, Mudstone to fossiliferous wackestone, Orbitolinid wackestone to packstone, Bioclast packstone to grainstone with restricted microfauna, Echinoderm wackestone to packstone, Planktonic wackestone to packstone, Mudstone to Planktonic/echinoderm wackestone, that belong to open marine sedimentary environment, shoal and lagoon. The study of vertical and lateral facies changes and comparing them with modern and ancient sedimentary environments show that Dariyan Formation in this area is deposited in a leeward mud dominated carbonate ramp. Due to numerous diagenetic processes observed in the formation, of their direct impact on the quality of the reservoir to the conclusion that micritization, cementation, compaction (mechanical), neomorphism, and pyritification to block the pores and pore through in the reservoir porosity and permeability decrease while, compaction (chemical), dolomitization, and fracture caused voids and communication between them. Finally, the porosity and permeability of the reservoir increased and led to higher quality.
Tectonics
zahra kamali; hamid nazari; ahad fazeli; faramarz alah vardi migoni; mohamad ali shokri; firooz jafari; hossin iranshahi
Abstract
The Dorud fault, as one of the most important seismic in segments of Zagros main recent fault, near the Arjng area it have northwest-southeast trend and continuity extended in Boroujerd area. Geophysical impressions in 5 profiles, and three resistivity, magnetometric and radionuclide parallel profile ...
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The Dorud fault, as one of the most important seismic in segments of Zagros main recent fault, near the Arjng area it have northwest-southeast trend and continuity extended in Boroujerd area. Geophysical impressions in 5 profiles, and three resistivity, magnetometric and radionuclide parallel profile and parts of one profile were performed. After the completion of field operations and data acquisition, GPR and magnetometer data were final processed in Radexproler and Geosoft software’s, respectively and with combining them in PA software, clearer interpretation of the subsurface structures, especially faults and discontinuities area were obtained. Among these, the F1 fault was considered as the main fault and F2 was the branching branch of the faulty branching out of it. For this reason, the Drood fault in this range is a fault zone with branching fissures branching out to the northeast This fault zone is located at the level of Silakhor plain with a length of several tens of kilometers, a variable height between 50 cm and 7 meters and with approximate dip 60-75 degree toward the north. all of these fault branches have a mechanism and according to their normal slip component.
M yavari; M Yazdi; M.H Adabi; H Ghalavand
Abstract
Dariyan Formation deposited in two different sedimentary settings. In some places it consists of shallow Limestone with algae and Orbitolina and in the other places in addition to limestone, it represents black shales and marls associated with planktonic foraminifera and radiolarian. In this research ...
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Dariyan Formation deposited in two different sedimentary settings. In some places it consists of shallow Limestone with algae and Orbitolina and in the other places in addition to limestone, it represents black shales and marls associated with planktonic foraminifera and radiolarian. In this research Draiyan Formation was studied in order to microfacies, depositional model and sequences stratigraphy of two sections so called, Kuh-e Gadvan and Kuh-e Banesh in high Zagros belt. Detailed petrographic studies led to the recognition of five main facies belts including: lagoon, bar, shallow open marine, outer ramp and deep marine. According to the vertical and lateral variations of facies, the Dariyan Formation deposited on a carbonate ramp platform and intrashelf basin. Depositional sequences have been presented on the basis of analysis of facies, fauna assemblages, Gama and Neutron logs. Three 3rd orders depositional sequences have been recognized during deposition of sediments. There is Type I sequence boundary in the top of third sequence and the other two sequences was considered as Type II sequence. Sea level fluctuations of the studied area correlated with Arabian platform and these changes follow of regional factors.
P Sadeghi-Farshbaf; M.M Khatib; H Nazari
Abstract
The aim of this research is to investigate triggering of fault slip due to stress perturbation caused by hydraulic fracturing. The importance of this issue is to study the observed destructive effects of dam construction at locations adjacent to the superficial faults. Therefore, we use the Matlab programming ...
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The aim of this research is to investigate triggering of fault slip due to stress perturbation caused by hydraulic fracturing. The importance of this issue is to study the observed destructive effects of dam construction at locations adjacent to the superficial faults. Therefore, we use the Matlab programming and SimDesigner system as an analytical extension. Concentrated stresses are applied after defining the nodes for fracture surfaces. By having the fault surface, analyses start to reach an equilibrium state. By defining the reaction forces in boundary condition, comparison of nodal dislocations become possible. The basis for vertical stress calculation is the upper rock layer and for horizontal stress is Coulomb failure stress. We estimate the stress perturbation through theory of tip stress about tensile fractures. The resultant stress field obtained from combination of fractural and regional stresses gives primary condition to study triggered fault slip and related earthquake magnitude. The results show a maximum 2 meters of cumulative slip along the fault surface close to the hydraulic fracturing. Based on moment magnitude of earthquake calculations, this slip gives a magnitude of 3.8 upon the Richter scale. This process needs the increased precision for nodal dislocations and optimized finite elements in order to better improve the future works.
Petrology
Ahmad Khaiatzadeh; Ahmad Abbasnejad; Hojjatolah Ranjbar; Hamid Ahmadipour; Behnam Abbasnejad
Abstract
Damavand is one of the most potential volcanoes of Iran for future eruption. Such indicators as having a slightly- eroded cone, presence of many thermal springs, eruption activity in Late Quaternary, as well as the progression of the generating tectonic regime, all, attest this claim. The intensity of ...
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Damavand is one of the most potential volcanoes of Iran for future eruption. Such indicators as having a slightly- eroded cone, presence of many thermal springs, eruption activity in Late Quaternary, as well as the progression of the generating tectonic regime, all, attest this claim. The intensity of eruption is anticipated to be about 3-5 in Volcanic Explosivity Index (VEI) scale. As a result, such hazards as tephra (ash), nuee ardente, lava flow and lahar may pose problems. Thus, this study deals with zoning these hazards. For zoning, Digital Elevation Models (DEM= 30 m), Landsat ESTM+ pictures as well as Arc GIS, ENVI and VORIS softwares were employed, and for construction of nuee ardente- hazard zoning, Malin and Sheridan (1982) model were used. Atmospheric data for the spread of ashes were taken for NCER/NCAR center. Lava flow routes were determined using a simulation model which is based on the assumption that topography plays the main role on the route of flow, and lavas flow from a point to the nearby one if their differences are positive. In order to construct lahar hazard map, locations of main troughlines on the cone and around the volcano were determined and lahar invasion areas were determined using a proper buffer zone. Based on this study, volcanic ash plume will form at the east of volcano and a number of towns and villages would be threatened. Lava flows and nuee ardentes would threaten some villages around the cone. Lahars would flow via throughlines on the cone and arrive the main vallies around it (Hezar and Delichai). They would threaten many residential areas in their route. The prepared hazard maps are useful and necessary for management of these hazards.
H. Nazari; J-F. Ritz
Abstract
The Taleghan Fault is located at the southern side of Taleghan valley in Central Alborz, 50 km north west of the Tehran mega city. Usually described as a south-dipping reverse fault, it could be the source of some of the strongest historical earthquakes recorded in the Tehran region, notably the 958 ...
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The Taleghan Fault is located at the southern side of Taleghan valley in Central Alborz, 50 km north west of the Tehran mega city. Usually described as a south-dipping reverse fault, it could be the source of some of the strongest historical earthquakes recorded in the Tehran region, notably the 958 AD (estimated magnitude M 7.7). The fault stands out as one of the major active structure menacing the cities of Tehran and Karadj, representing together 12 millions inhabitants. In order to analyze the recent activity of the fault, a morphological study was carried out along the fault combining satellite imagery, aerial photographs and Digital Elevation Model. We found out an active branch that had never been described whereas the fault classically mapped appears inactive. Detailed field work along the branch allows us to show that the fault had its vertical component recently reverted from reverse movement to normal movement. One of the measured ratios of accumulated horizontal / vertical displacements associated to the left lateral and normal movement is 2.5-5. The strike, estimated dip and rake in the eastern part are 105°, 60° and 40° respectinely making it a left lateral- normal strike slip fault in this part of the Central Alborz.
M. Nouradiny; S. Rahmati; M. Yazdi
Abstract
The studied sections are located in southwestern of central Iran. Main lithology of these sections are including shale, sandstone and limestone. Four biozones had been recognized base on Conodont. That contain Idiognathodus delicates Zone, Streptognathodus oppletus Zone, Sweetognathus whitei Zone. And ...
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The studied sections are located in southwestern of central Iran. Main lithology of these sections are including shale, sandstone and limestone. Four biozones had been recognized base on Conodont. That contain Idiognathodus delicates Zone, Streptognathodus oppletus Zone, Sweetognathus whitei Zone. And Neostreptognathodus pequopensis Zone. Based on recognized conodont, the age reveal for Sardar Formation is Bashkirian- early Gzhelian and the Permian deposits are Artinskian (khan formation age equivalent). In this sections Carboniferous- Permian boundary has been seen paraconformity. Comparison this area with neighborhood showed after Kasimovian we have upward and erosion in these areas and with started melting due to glacial epoch in lower Permian so these areas covered with water although we have shallow basin comparable with another areas in Central Iran.
A Asghari Moghaddam; R Barzegar
Abstract
The Tabriz plain with an area of more than 700 km2 is extended from the eastern limit of Tabriz city to the salt flats of UrmiaLake. There are two types of aquifers in this plain with different quality of groundwater. The unconfined aquifer, which is extended all over the plain, in recharge areas near ...
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The Tabriz plain with an area of more than 700 km2 is extended from the eastern limit of Tabriz city to the salt flats of UrmiaLake. There are two types of aquifers in this plain with different quality of groundwater. The unconfined aquifer, which is extended all over the plain, in recharge areas near the plain margins has good quality water but in the central part of the plain along the Aji Chay river as well as in the west margin of the Plain is saline. The multi-layer confined aquifers, which lie down in central and western parts of the Plain bearing more or less good quality groundwater. The arsenic concentration of these aquifers is also different; the water samples analyzed from the chemical point of view especially with respect to concentration of arsenic show two different groups of groundwater. The aim of this study is considering of arsenic spatial distribution and factors controlling high arsenic concentration in the aquifers. For this purpose 16 water samples, with evenly distributed in the Plain, were collected from the aquifers, two water samples for each well, one for analyzing major ions and the other for trace elements. They were analyzed in hydrology lab at the TabrizUniversity. The arsenic concentration in unconfined aquifer and in recharge areas of the plain boundary is low and in confined and deep wells is high. Arsenic concentration compared on the basis of their dependency on hydrogeological conditions, nitrate and phosphate concentrations and pH and the results interpreted by factor analysis and hydrogeochemical methods. Attendance of nitrate and phosphate by positive factor and arsenic by negative factor can show the reduction conditions in groundwater system, which caused the arsenic mobilization. In spite of high arsenic concentrations in the water samples, the saturation index of arsenic minerals is very low and under saturation. The arsenic existing in groundwater resources of the area originate from the geological formations and its concentrations depend highly on the hydrogeological and environmental reduction conditions, residence time of water in underground layers and depth of the sampling wells.
G. R. Elyasi; M. Karimi; A. Bahroudi; A. Adeli Sarcheshme
Abstract
Piles of maps from different sources with varying scales and formats and different styles and absence of a proper solution for integrating vast amount of information has resulted in a complexity for preparing mineral potential map. Using GIS not only organizes the information related to mineral exploration ...
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Piles of maps from different sources with varying scales and formats and different styles and absence of a proper solution for integrating vast amount of information has resulted in a complexity for preparing mineral potential map. Using GIS not only organizes the information related to mineral exploration but also has the ability to produce and integrate information layers in different models with more precision and speed and supports spatial decision makings. In this article mineral potential map of Now Chun copper prospect has been produced for determination of drilling points. Used layers in this study include rock type, structure, alteration, mineralization indicators, anomaly zone of chargeability and apparent resistivity and metal factor, anomaly of copper and molybdenum and Cu-Mo additive indexes. After information preparation, Factor maps were weighted and integrated in the inference network. Integration use of Fuzzy logic and index overlay operators in inference network can eliminate defects in other models and provide more flexible integration of factor maps. Regarding to produce mineral potential map, mineral potential zones of porphyry copper were located in north-east parts of studied area. Eventually, the degree of correlation between mineral potential map and those operated exploration boreholes have been estimated for two different classes, 63.16 % and 64.52 %. Comparison between the high potential points indicated by our mineral potential maps with those previous drilled boreholes reveals about 26% discorrelation. It means that if such present study had been done before any drilling operation, it could have saved 200,000$ just for drilling expenditure.
S Alipour; A Abedini; Sh Abdali
Abstract
The Heydar-Abad laterite horizon is located at 65 km south of Urmia, West Azarbaidjan province. This horizon was developed as stratiform bed within the carbonate rocks of the late Permian Ruteh Formation. Based on the petrographical and mineralographical studies,the ores of this horizon contain micro-granular, ...
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The Heydar-Abad laterite horizon is located at 65 km south of Urmia, West Azarbaidjan province. This horizon was developed as stratiform bed within the carbonate rocks of the late Permian Ruteh Formation. Based on the petrographical and mineralographical studies,the ores of this horizon contain micro-granular, fluidal-collomorphic, panidiomorphic-granular, spastoidic, pelitomorphic, nodular, and ooidic textures and have an authigenic origin. According to the mineralogical investigations, the ores of this horizon include minerals such as diaspore, corundum, hematite, magnetite, goethite, rutile, paragonite, margarite, amesite, berthierine, montmorillonite, chlorite, chloritoid, muscovite-illite, quartz, pyrite, anhydrite, calcite, and dolomite. The presence of high quantities of silicate minerals indicates immaturity and poor draining system during the development of this residual horizon. The results of chemical analyses show that Eu and Ce anomalies in the ores are within the ranges of 0.67 to 2.74 and 0.86 to 2.16, respectively. The calculations of values of enrichment factor of elements in two selected profiles reveal that two processes of leaching and fixation are major regulators of concentrations of REEs in ores of this horizon. The results obtained from the mineralogical and geochemical studies show that changes of pH of weathering solution, fluctuations of level of ground-waters, alteration intensity, and function of carbonate bedrocks as a geochemical barrier, adsorption, and scavenging have played an important role in distribution of the rare earth elements (REEs) in this deposit. The correlation coefficients show that the secondary phosphates, rutile and muscovite-illite are potential hosts for REEs in the ore.
B Derikvand; A Yassaghi
Abstract
The folding style analysis is one of the initial investigations on hydrocarbon reservoirs anticlines. Nader Anticline is located in the western part of the Eastern Kopeh Dagh zone and on hanging wall of the North Kopeh Dagh Reverse Fault. The structural analysis of the anticline is carried out along ...
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The folding style analysis is one of the initial investigations on hydrocarbon reservoirs anticlines. Nader Anticline is located in the western part of the Eastern Kopeh Dagh zone and on hanging wall of the North Kopeh Dagh Reverse Fault. The structural analysis of the anticline is carried out along eight structural transects across the fold. This analysis showed that the Nader Anticline has two culminations with an en echelon arrangement. These culminations as well as the other folds in the study area are cross cut by a series of NW- and N- trending strike-slip faults. The Nader Anticline first culmination is analyzed as fault propagation fold geometry, while its second culmination is examined as fault detachment fold geometry. Since the Nader Hidden Fault cuts the north limb of the first culmination; the geometry of this culmination can also be considered as faulted detachment fold. The study area faults though have different trends but they dominantly have strike-slip mechanism or strike-slip component and thus, can be considered as Riddle shear faults. Geometric and kinematic analysis of these faults showed that a series of these faults could be considered as shear fractures related to a NW-trending PDZ, while the other faults can be examined as Riddle shears related to a N-trending PDZ. Such development of the Riddle shears faults as well as en echelon arrangement of the Nader Anticline culminations imply that the study area is structurally evolved during a NW-trending oblique-slip fault system more likely related to transpressional activity of the North Kopeh Dagh Reverse fault zone.
Alireza Shahidi; E. Barrier; M.-F. Brunet; A. Saidi
Abstract
In northern Iran the Eo-Cimmerian orogeny resulting from this collision is associated with a regional unconformity and a major change in sedimentation. From Norian to middle Bajocian (Shemshak group), 030° trending extension is indicated by syndepositional normal faults. We assign this extensional ...
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In northern Iran the Eo-Cimmerian orogeny resulting from this collision is associated with a regional unconformity and a major change in sedimentation. From Norian to middle Bajocian (Shemshak group), 030° trending extension is indicated by syndepositional normal faults. We assign this extensional tectonics to the rifting phase preceding the oceanic opening of the South Caspian Basin. Dalichai and Lar formations, late-Bajocian to Neocomian in age, conformably cover the Shemshak in central Alborz. They are contemporaneous with the opening of the South Caspian marginal basin. In Alborz, the lower part of the Cretaceous sequence is associated with E-W to WNW-ESE trending normal fault systems associated with magmatism related to an N-S to NNE-SSW trending extension during this period. The Cretaceous-Palaeogene boundary is marked by a major regional unconformity. This unconformity is related to a major inversion of the southern margin of the South Caspian basins. During the early-middle Eocene, southern Alborz is characterized by a rapid subsidence of the Karaj basin. Syndepositional E-W to WNW-ESE trending normal faults are common in the Karaj Formation. They are associated with a well-determined N-S to NNE-SSW extension. We assign the Karaj basin to a back-arc basin related to the NE subduction of the neo-tethyan oceanic lithosphere beneath the southern margin of Eurasia.
H.R Mohammadi; H Mansouri; H Jalalifar
Abstract
The purpose of this paper is to investigate the performance of photogrammetric method for determining the orientation of the discontinuities. The application of photogrammetric method for surveying discontinuities is applied as useful method. In the scanline method because of topographic constraints, ...
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The purpose of this paper is to investigate the performance of photogrammetric method for determining the orientation of the discontinuities. The application of photogrammetric method for surveying discontinuities is applied as useful method. In the scanline method because of topographic constraints, disontinuities in the top part of the bench can not be measured. In addition, in this method when the angle between the discontinuities and scanline approaches to 90 degrees the discontinuities have more chance to sample. The discontinuities in a rock outcrop in the Golgohar mine No. 1 in Sirjan were sampled using the two described methods. In the scanline method, 42 discontinuities and in the photogrametric method, 258 discontinuities were sampled. In the scanline method, two joint sets and in the photogrametric method three joint sets were recognized. The two joint sets J1 and J2 are similar in the two methods showing a small difference. However, the joint set J3, which is the most critical joint set in the view of slope stability, was only sampled by the photogrametric method. Since the photogrammetric method uses many points in the plane of discontinuity, it is more precise for determining the mean orientation of discontinuities.
H Amini; M Fattahi; M.R Ghassemi
Abstract
The Doruneh fault is the second longest fault systems in Iran. This fault is 700 km long and extended from the Afghanistan-Iran border to the central Iran desert. Despite of its length, and position in the convergence zone between the Arabian and Eurasian plates and its seismic potential, only one historical ...
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The Doruneh fault is the second longest fault systems in Iran. This fault is 700 km long and extended from the Afghanistan-Iran border to the central Iran desert. Despite of its length, and position in the convergence zone between the Arabian and Eurasian plates and its seismic potential, only one historical earthquake (M>7) and two instrumental (M>6) earthquakes are recorded on this fault. Therefore, study of this fault is very important for evaluation of its seismic hazard. In our study, we used the Landsat images, aerial photographs, topography maps, geological maps and field work data to identify and estimate the amount of displacements of rivers, rock units, and some alluvial fans along this fault. Three branches of the Doruneh fault investigated in this study, named as the north, middle and south branches according to their geographical locations. This study demonstrates that both of the maximum and minimum fault displacements have occurred on the southern branch. Furthermore, the amount of displacements of the rivers, which have cut the alluvial fans during the Quaternary period, suggests that this branch, particularly between 57˚00΄ and 58˚50΄E, is more active than the other branches. Although, several slip rates were previously determined using different methods for some parts of this fault by the authors and other researchers, we suggest further dating and geodetic methods in the same regions and other part of the fault to estimate and compare the slip rate of different branches of this important fault.
M. A. A. Mokhtari; H. Moinvaziri; M. R. Ghorbani; M. Mehrpartou; G. Hosseinzadeh
Abstract
Kamtal skarn zone is located in the 20km north of Kharvana in the Eastern Azarbaijan. Skarn-type metasomatic alteration is the result of Kamtal monzonitic intrusion into the Upper Cretaceous impure carbonates. Kamtal skarn include exoskarn and endoskarn zones. Exoskarn is the major zone that its thickness ...
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Kamtal skarn zone is located in the 20km north of Kharvana in the Eastern Azarbaijan. Skarn-type metasomatic alteration is the result of Kamtal monzonitic intrusion into the Upper Cretaceous impure carbonates. Kamtal skarn include exoskarn and endoskarn zones. Exoskarn is the major zone that its thickness varies between 100-600m. Field and mineralogical studies demonstrate that exoskarn zone composed of garnet rich sub-zone (garnet skarn), epidote rich sub-zone (epidote skarn) and marble sub-zone. Garnet is the most important calc- silicate mineral within the garnet skarn sub-zone. They are mainly grossularitic in composition (Ad33-35), but along the fractures, andraditic composition (Ad66-73) is predominant. Clinopyroxene is the other dominant mineral within garnet skarn sub-zone that has diopsidic composition (Di82.8-85.7). In the epidote skarn sub-zone, epidote is the predominant mineral while garnet and clinopyroxene present in some places and have low concentration. Petrographic studies indicate that marly limestone was the primary rocks of the garnet skarn sub-zone while clay-bearing marl was the primary rocks of the epidote skarn sub-zone. Skarnification process can be categorized into two discrete stages: 1) prograde and 2) retrograde stages. Prograde stage began immediately after the initial emplacement of the Kamtal monzonitic magma into the enclosing impure carbonate rocks. The effect of heat flow from the intrusion caused the enclosing rocks to become isochemically marmorized in almost homogeneous limestone layers and bimetasomatized (skarnoid–hornfels) in thin interlayers of clay-rich carbonates. Invasion of segregated fluid phase of Kamtal intrusion into the fractures and micro-fractures of the marmorized and skarnoid–hornfelsic rocks incorporate considerable amounts of Fe, Si and Mg into the metasomatic aureole. During retrograde stage, due to relatively low temperature hydrothermal fluids and processes such as hydrolysis, carbonation and sulfidation, considerable amounts of hydrous calc-silicates, sulfides, oxides and carbonates replaced the anhydrous calc-silicates. Garnet and clinopyroxene are the most abundant mineral assemblage in Kamtal skarn zone, which were formed in temperature lower than 550°C. Lack of wollastonite in this mineral assemblage, intergrowth of garnet and clinopyroxene crystals and lack of any reaction rim between these crystals, and lack of emplacement texture indicate that they formed contemporaneously within the temperature and ƒO2 ranges of 430–550ºC and 10-26–10-23, respectively.
