A Bayet-Goll; R Moussavi-Harami; A Mahboubi
Abstract
Carbonate deposits of members 1 to 2 of the Mila Group (Middle Cambrian) in Central Alborz that call the Deh-Sufiyan Formation in this research, were studied in Shahmirzad, Tueh-Darvar, Mila-Kuh and Deh-Molla sections. The Unit 2 of Deh-Sufiyan Formatrion in Central Alborz of Northern Iran consists mainly ...
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Carbonate deposits of members 1 to 2 of the Mila Group (Middle Cambrian) in Central Alborz that call the Deh-Sufiyan Formation in this research, were studied in Shahmirzad, Tueh-Darvar, Mila-Kuh and Deh-Molla sections. The Unit 2 of Deh-Sufiyan Formatrion in Central Alborz of Northern Iran consists mainly of shallow marine carbonates and contains a variety of limestone conglomerates. Limestone conglomerate is an important component of Unit 2 of Deh-Sufiyan Formatrion, but its origins remain enigmatic. These limestone conglomerates have a diverse set of characteristics that range from clast to matrix supported with scattered flat pebbles. These conglomerates are largely comprised of oligomictic, rounded lime–mudstone clasts of various sizes and shape (equant, oval, discoidal, tabular, and irregular). According to composition and characteristic sedimentary structures and fabric, limestone conglomerates in the Unit 2 of Deh-Sufiyan Formatrion consist of: (1) Intraformational limestone conglomerate beds were formed by depositional processes (2) Limestone pseudoconglomerate beds were produced by diagenetic processes. The common characteristics of the Unit 2 of Deh-Sufiyan Formatrion pseudoconglomerates, such as oligomictic lithology of lime–mudstone clasts, mosaic fabric, disorganized/edgewise fabric, variable and gradational fabric, transitions from adjacent or underlying facies and the complete lack of depositional structures, are typical of pseudoconglomerates formed by early diagenetic sediment deformation under shallow burial conditions. These characteristics are different from those of intraformational limestone conglomerate showing primary depositional features such as normal or inverse grading, internal stratification, (hummocky) cross-stratification and sharp erosional bases. Diagenetic conglomerates in ribbon rocks resulted from soft-sediment deformation of ribbon rocks during early diagenesis. In contrast, the dimension and thickness, sizes of the clasts, clast-rich beds, size ingredient of matrix, tendency to amalgamate with amalgamation scours within depositional conglomerates suggest that high energy and strong erosion above storm wave base was responsible for the disintegration of the carbonate material.
Geophysics
Hamidreza Samadi; Roohollah Kimiaefar; Alireza Hajian
Abstract
One of the most important issues in seismology is to accurately determine the epicenter of earthquake, mainly because the accuracy of dependent studies such as seismic risk analysis, fault mechanism, depends on the accuracy of mentioned parameter. Double difference method is one of the conventional relative ...
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One of the most important issues in seismology is to accurately determine the epicenter of earthquake, mainly because the accuracy of dependent studies such as seismic risk analysis, fault mechanism, depends on the accuracy of mentioned parameter. Double difference method is one of the conventional relative earthquake relocation methods which is used vastly by seismological centers and it is used as the basis of an algorithm that relocates earthquake events about 0.004 second. In the proposed method, Adaptive Neuro-Fuzzy Inference System (ANFIS) is trained based on the former relocated events and generalized for new earthquakes. In the training procedure, the hypocentral information, for the main event and the nearest one (determined by K nearest neighbor search), and the velocity model of the region are considered as inputs and hypocentral information are set as target for the network. Here, with reference to the information of about 8000 earthquakes, as the training events, 490 earthquakes were relocated in about 0.1 (s) where RMS for predicating latitude and longitude of the events were 0.002 and for the depth parameter, RMS was 0.45. It is concluded that the proposed method could be considered as a powerful algorithm for near real time relocation of earthquakes.
Petrology
Seyed Ali Akbar Asadi; Habibollah Ghasemi; Mohsen Mobasheri
Abstract
Sargaz-Abshur (Sikhoran) ultramafic-mafic complex, which is situated in Esfandagheh area, SE Sanandaj-Sirjan metamorphic- magmatic zone, intruded into Upper Paleozoic- Triassic metamorphic rocks and covered by Jurassic sedimentary rocks. This complex consists of harzburgite and porphyroclastic ...
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Sargaz-Abshur (Sikhoran) ultramafic-mafic complex, which is situated in Esfandagheh area, SE Sanandaj-Sirjan metamorphic- magmatic zone, intruded into Upper Paleozoic- Triassic metamorphic rocks and covered by Jurassic sedimentary rocks. This complex consists of harzburgite and porphyroclastic dunites of the residual mantle (tectonites), layered ultramafic-mafic cumulates, large isotropic gabbro intrusion and scattered microgabbroic to diabasic dykes. It does not have extrusive and sedimentary parts of a topical ophiolite sequence (e.g., diabasic swarm dykes, massive and pillow basalts, hyaloclastites, chert, radiolarite and pelagic limestone). The complex is like a large pluton that caused the intensive contact metamorphism of Upper Paleozoic- Triassic rocks through the widespread partial melting of amphibolites, thus it is not an ophiolite sequence. The pluton is mainly comprised of porphyroclastic dunites and layered ultramafic-mafic cumulates. Cr-spinel is enriched or depleted in Cr, having magmatic to residual origins and found in the layered ultramafic (mantle) part of the pluton. The Euhedral Cr-spinel crystalized between olivine grains or as inclusion with massive and layered cumulative textures. It is chromite, magnesiochromite, hercynite in composition, corresponding to Cr-spinels of depleted peridotites from the supra-subduction zone (SSZ), especially those magmas of SSZ that reacted with boninitic magmas. Detailed field works together with previous and new geochronological ages of pegmatite veins related to partial melting of host amphibolite show the alpine type Sargaz-Abshour ultramafic-mafic pluton was ascended as a astenospheric mantle diaper in extensional intra/fore-arc basin of the Andyan type of Sanandaj-Sirjan metamorphic- magmatic zone during the Late Triassic-Early Jurassic (187.2 ± 2.6 Ma).
F. Rezaie; H. Nazari; S. Rahmanian; A. R. Shahidi
Abstract
Due to the fast urban developing and construction of surface and sub-surface structures such as several subway lines, requiring the geotechnical studies on these structures is increasingly emphasized. The metropolitan Tehran, in south of the Central Alborz, lying on the set of Quaternary alluvial deposits ...
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Due to the fast urban developing and construction of surface and sub-surface structures such as several subway lines, requiring the geotechnical studies on these structures is increasingly emphasized. The metropolitan Tehran, in south of the Central Alborz, lying on the set of Quaternary alluvial deposits and surrounded by the active seismic faults such as the Northern Tehran fault in the north and the Parchin and Pishva faults in the south requires investigations to determine the bilateral relationship betweenseismic potential of the peripheral active faults andthe geotechnical characteristics of the alluvial deposits. In this study, using field and laboratory data, geotechnical characteristics of the deposits, material of soil horizons, and different parameters of them along the 27 km length of Tehran 7th subway line have been studied by provided software to calculate: bearing capacity, settlement and liquefaction potential. Based on this study, the members C and D of the Tehran alluvial deposits has relatively high resistance value and measured settlement in all areas is limited to 2.5 cm. The data of SPT indicate any likely occurrence of liquefaction of sand layers in the east - central Tehran during a seismic event.
M Hadi; H Mosaddegh; N Abbassi
Abstract
Carbonate successionsof the Ziarat Formation with introduce the Baghdareh and Gheynarjehsections in the Soltanieh Mountains(southern Zanjan) are rare locality in the western Alborzzone,which are contains of great abundance oflarge benthic foraminifera (LBF), particularly species of Alveolina. In fact, ...
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Carbonate successionsof the Ziarat Formation with introduce the Baghdareh and Gheynarjehsections in the Soltanieh Mountains(southern Zanjan) are rare locality in the western Alborzzone,which are contains of great abundance oflarge benthic foraminifera (LBF), particularly species of Alveolina. In fact, from this succession described some of Alveolinaspecies and their comparative stratigraphic distribution with the Alveolina species in the Tethyanbasinwhich is represent close affinitieswith coeval Alveolinaassemblages described in diVerent studies from this province. Also, this correlation shows Ilerdian-Cusianstages of study area that characterized by A. ellipsoidalis, A. laxa, A. tumida, A.cemali, A.aragonensis, A. pisiformis,A.rotundata, A.subpyrenaica, A. cf. canavari, A. canavari, A.ex gr. cremae species.
M Roohafza; S Alipour; A Abedini
Abstract
Ghareh-bolagh area is located in 20 Km of east of Mahabad, south of West-Azarbaidjan province. Carbonate rocks of Bayandour formation and dolomites of Soltanieh formation in this area are the host of mineralizations from Barium, iron and manganese. Based upon mineralogical investigations, barite, magnetite, ...
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Ghareh-bolagh area is located in 20 Km of east of Mahabad, south of West-Azarbaidjan province. Carbonate rocks of Bayandour formation and dolomites of Soltanieh formation in this area are the host of mineralizations from Barium, iron and manganese. Based upon mineralogical investigations, barite, magnetite, hematite, goethite, limonite, pyrolusite were major mineral assemblages of these mineralizations which that is accompanied by chalcopyrite, malachite, azurite, and calcite in low amounts. The most important geochemical characteristic these mineralizations are relative weak differentiation of LREE from HREE in barite and iron-manganese ores, Eu negative anomalies in iron-manganese ores (0.26-0.76) and Eu positive anomalies in barite (7.7-10.51). Incorporation of the obtained results from investigations of field, petrographic and geochemical (analytic data and correlation coefficients between elements) indicate that factors such as changes in physicochemical conditions of environment (pH, Eh, temperature), activity of complexing ligands, and presence of minor mineral phases (clay minerals, zircon, zenotime, and monazite) played important role in distribution of rare earth elements during mineralization and development of these ores.
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.
A. S Khalifeh Soltani; S. A Alavi; M. R Ghassemi
Abstract
Fractal analysis of drainages and fractures is a useful tool to determine the maturity structure of a region. With the help of fractal geometry, this study investigates the fractal dimension of drainages and fractures in the southwestern part of Lenjan, and examines the role of geological structures ...
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Fractal analysis of drainages and fractures is a useful tool to determine the maturity structure of a region. With the help of fractal geometry, this study investigates the fractal dimension of drainages and fractures in the southwestern part of Lenjan, and examines the role of geological structures after determining the most active part of region. In order for fractal analysis of fractures and drainages, box-counting method has been used. To achieve this, four parts A, B, C and D of high structural density were first detected in the region, and the fractal dimensions of drainages and fractures were then calculated and compared. Results of fractal analysis of fractures suggest that sector B is the most active part of the region, while fractal analysis of drainages indicates greater tectonic activity in sector A. The larger number of earthquakes and higher density of fractures in sector B, however, could indicate it as the most active part of the study area. Therefore, contradicts in different results obtained from the fractal dimension analysis of fractures and drainages can be explained by the varieties in lithology. The structural studies indicate the existence of a dextral transpression zone in the study area. The dextral transpression zone resulted in uplift of sector B by development of positive flower structures in this part of the region. Therefore, increased tectonic activity in part B is due to formation of positive flower structures and consequent tectonic uplift.
M Shafiee Ardestani; M Vahidinia; A Sadeghi
Abstract
In this research, we documented a paleontological study on the basis of planktic foraminifera, in five stratigraphic sections (Type, Padeha village, Shorab, Abderaz village and Qarehso) across the Santonian-Campanian transitional boundary in the eastern Kopeh-Dagh sedimentary basin. In all sections, ...
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In this research, we documented a paleontological study on the basis of planktic foraminifera, in five stratigraphic sections (Type, Padeha village, Shorab, Abderaz village and Qarehso) across the Santonian-Campanian transitional boundary in the eastern Kopeh-Dagh sedimentary basin. In all sections, no M. testudinarius Schlotheim (cosmopolitan species) was identified, which its last occurrence datum (LOD) is widely used to define the base of the Campanian stage. Several planktic foraminiferal biohorizons close to the Santonian/Campanian boundary were recorded, including the LOD’s of Ventilabrella austiniana Cushman, Dicarinella concavata (Brotzen) and Dicarinella asymetrica (Sigal), and the first occurrence datum (FOD) of Contusotruncana patelliformis (Gandolfi). The Santonian/Campanian boundary was placed in the upper part of the Dicarinella asymetrica Total Range Zone at the top of the Abderaz Formation in the type section and other sections in Shorab, Abderaz village, Padeha village, and at the base of the Abtalkh Formation in the Qarehso section. The acquired bio-models for the study sections are quite comparable with that of Gale et al, 2008 in WDS section, North Texas. On the basis of quantitative analysis of the planktic and benthic foraminiferal assemblages, the sparse presence of keeled planktic foraminifera and planktic foraminifera (%P) indicates that a shallow marine condition was prevailing just above the Santonian/Campanian boundary in the type section, Shorab, Abderaz and Padeha village sections. In addition, the abundance of such foraminifera (keeled planktic foraminifera and planktic foraminifera) reflects deeper water depths in the Qarehso section at the same time. Besides, estimation of the planktic to benthic ratio, which is based on the Van der Zwaan equilibrium, confirms that in the base of Campanian at one of the study sections (Qarehso section) the water depth was 160 m.
B Shahbazi; B Rezai; S.M.J Koleini; M Noaparast
Abstract
In this research the effect of bubble surface area flux on flotation rate constant of coal particles was investigated and the results showed that flotation rate constant increased with increasing bubble surface area flux. The obtained Maximum flotation rate constant was 3.30 /min while the particle size ...
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In this research the effect of bubble surface area flux on flotation rate constant of coal particles was investigated and the results showed that flotation rate constant increased with increasing bubble surface area flux. The obtained Maximum flotation rate constant was 3.30 /min while the particle size and bubble surface area flux were -37mm and 25.891/s, respectively. The bubble-particle collision, attachment and detachment efficiency were calculated in order to analyze the results. The obtained Maximum Stokes collision efficiency was 81.57% while the particle size, bubble surface area flux, and flotation rate constant were -500+420mm, 27.431/s, and 1.17/min, respectively. The obtained Maximum Yoon, Stokes and Potential efficiency were 94.66, 56.74 and 45.61%, respectively. Moreover, the obtained maximum detachment efficiency was 34.57% while the particle size, bubble surface area flux and flotation rate constant were -500+420mm, 16.771/s, and 0.85 /min. The collection efficiency increased with increasing of the bubble surface area flux. The collection efficiency was high for the particle size range of -106+37mm and for out of this particle size range it decreased steadily. So, the low efficiency of floating coarse particles can be attributed to the high efficiency of detachment while the low efficiency of floating of the fine particles was due to the low efficiency of collision.
M Kamani; A Uromeihy; M Joorabchi
Abstract
Roads are of linear engineering projects passing various rock units and geological conditions, so it is necessary to engage the engineering geological studies along the way. The studies continue until the end of the construction and operation. In the route selection process, large volumes of data and ...
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Roads are of linear engineering projects passing various rock units and geological conditions, so it is necessary to engage the engineering geological studies along the way. The studies continue until the end of the construction and operation. In the route selection process, large volumes of data and different track conditions are facing. To perform this manually is time consuming and not accurate enough. This study examines the status of engineering geology freeway route Qazvin - Rasht in Roudbar discussed in this context, the factors affecting engineering geology route selection and construction of the freeway, using the Analytical Hierarchy Process (AHP) and Expert Choice software to give weight of these factors, according to their suitability for the construction of freeways, and then layers weighted overlay in GIS software and the final map has been prepared. The final map shows the quality of route engineering geological conditions, which is provided for both surface and subsurface (tunnels) with the least error. Since the procedure for engineering geological survey route is a new method, it requires further investigation and to test in other places in order to be much more modified and corrected. On the other hand, this model can be used for other engineering geological investigations due to high flexibility of this model.
S Shirinmanesh; V Chegini
Abstract
Development of modern energies is one of the most important issues that all countries have focused on and have tried to find a new model in that respect. One of the greatest energy-resources in the world is oceans and tidal currents are one of the specific indicators of oceanic current. The movement ...
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Development of modern energies is one of the most important issues that all countries have focused on and have tried to find a new model in that respect. One of the greatest energy-resources in the world is oceans and tidal currents are one of the specific indicators of oceanic current. The movement of oceans waters caused by tidal current has a great deal of energy. On the other hand, development of new energies causes to search new plan in all countries. In this study, the potential energy obtained from daily, monthly and eventually annually average of 18-years (1990-2007) tidal range difference data in the Chabahar station. The average of tidal range was 2.09 m. The average energy estimated to be 5.5 w/m² and the average power estimated to be 0.44 w/m2. According to the obtained results, producible energy of tidal currents in Chabahar is very low and it has no economic importance.
Z Khosravi; S.M Hosseini-Nezhad
Abstract
The carbonate and terrigenous sedimentary sequence of the Padeha and Bahram formations (late Givetian- late Frasnian) with a total thickness of 126 m have a gradational and conformable contact at Baghin region of W Kerman in Central Iran. The terrigenous facies are mainly consisting of sandstone and ...
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The carbonate and terrigenous sedimentary sequence of the Padeha and Bahram formations (late Givetian- late Frasnian) with a total thickness of 126 m have a gradational and conformable contact at Baghin region of W Kerman in Central Iran. The terrigenous facies are mainly consisting of sandstone and shale deposited in the beach environment. The carbonate rocks including dolomite and limestone have tidal flat, lagoon and barrier (shoal) facies. Based on the index conodonts and brachiopods the late Givetian- late Frasnian age is suggested for this studied section. The conclusions of petrographical studies indicated a shallow carbonate platform of ramp type for these sediments. The stratigraphical study of the Bahram formation at the studied area resulted in identifying 3 sedimentary sequences of the third order, which according to the microfacies and conodonts consist of the following items. The first sequence begins with transgression at the base of the Lower falsiovalis – Upper falsiovalis zone (TST), with continuation of transgression, it reaches the maximum flooding level (mfs) indicated by the coral bindstone facies in a shoal environment and then is followed by the relevant HST parasequences. The second sequence begins at transitans – punctata zone, and finally the TST parasequences with ooid grainstone in a shoal environment reaches the maximum flooding level (mfs) at the Lower rhenana zone and ceases, and then is followed by the HST parasequences. The third sedimentary sequence begins at the base of Upper rhenana-? linguiformis zone, its maximum flooding surface (mfs) is in the middle of the Upper rhenana -?linguiformis zone and is identified by the spiculate wackestone facies in an open sea environment, and it is followed by the HST parasequences. These sequences are limited by the sequential boundaries of SB1 and SB2 types.
K. Mohammadiha; M. Sabzehie; M. Ghahraie pour; J. Radfar
Abstract
A large widespread outcrop of granitoid - mylonitic gabbros complexes is observed in northeastern part of Serow, NW Iran. Those rocks were considered as Precambrian gneiss and metamorphic rocks (Haghipour and Aghanabati, 1977), or alternatively, a complex of acidic to basic igneous rocks which have undergone ...
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A large widespread outcrop of granitoid - mylonitic gabbros complexes is observed in northeastern part of Serow, NW Iran. Those rocks were considered as Precambrian gneiss and metamorphic rocks (Haghipour and Aghanabati, 1977), or alternatively, a complex of acidic to basic igneous rocks which have undergone intense deformation and dynamic metamorphism by shearing (Mohammadiha, 2000; Mohammadi Torkabad, 2001). The basic mylonitic rocks in the studied area are simply composed of plagioclase, hornblende, actinolite, chlorite, and epidote. They display minor remains of primary pyroxenes which are largely replaced by amphibole. Feldspars have been altered to epidote, and secondary plagioclase (more sodic) and roughly sericite. There are some gabbros with clastic and lentiform fabric which were not affected by dynamic deformation in the shear zone. Cataclastic flow, micro fracturing, dislocation creep, recovery, diffusion creep, grain boundary sliding and pressure dissolution are the dominant deformation mechanisms influenced the complexes. The consequent structures are foliation, lineation, undoluse extinction, porphyroclasts with core-mantle structure, micro fractures parallel and unparallel with brecciation, mechanical twining, mica fish structure, banded differentiated structure and kinked foliation. We conclude that the whole observed evidences demonstrate a major dynamic deformation in a brecciated zone in the studied area.
V. Alizadeh; M. Momenzadeh; M. H. Emami
Abstract
Based on Qayen 1:100000 geological map, the copper mineralization of Vorezg in volcanic rocks is attributed to Paleocene-Lower Eocene. Submarine volcanic rocks of the study area are found in two forms of lava and pyroclastics. Based on field and laboratory investigations, the outcropped rocks in Vorezg ...
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Based on Qayen 1:100000 geological map, the copper mineralization of Vorezg in volcanic rocks is attributed to Paleocene-Lower Eocene. Submarine volcanic rocks of the study area are found in two forms of lava and pyroclastics. Based on field and laboratory investigations, the outcropped rocks in Vorezg deposit are andesite, andesite – basalt, basalt and several small exposures of pyroclastic rocks such as tuff. Alkaline volcanic rocks of the area show within plate characteristics. Texture of mineralization is vein-veinlet, disseminated and open space filling amygdales. According to the mineralography studies, main minerals of copper are chalcocite, β-chalcocite, bornite, covellite, digenite and rare native copper. Chalcocite is the most abundant mineral. Intergrowth among copper ores is observed in most cases. Silver was detected as accessory phase (copper element paragenesis) in this ore deposit. Whereas silver has not founded an independent crystalline phase, therefore in the crystal of chalcocite, copper was replaced by Ag. Fluid inclusion studies on trapped fluids in quartz show homogenization temperature average is 230-250 ºC and salinity degree of fluids is 5-6%wt NaCl. On the basis of recognized characteristics, Vorezg ore deposit is comparable with Manto and Volcanic redbed type copper deposits. Recently, these two types of deposits are considered as synonyms.
F. Askari; H. Garivani
Abstract
Tehran is the largest and the most populous city of Iran that have been recently regarded from the risk management point of view because of possibility of the earthquake damages. An important destructive phenomenon that may happen in Tehran during an earthquake is liquefaction. In the last ...
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Tehran is the largest and the most populous city of Iran that have been recently regarded from the risk management point of view because of possibility of the earthquake damages. An important destructive phenomenon that may happen in Tehran during an earthquake is liquefaction. In the last two decades, liquefaction of Tehran, especially its southern part, has been extensively studied. These studies are done in different scales and also with different methods. The goal of this paper is consideration of the most important studies which have been done in Tehran up to now and present a practical conclusion. The above mentioned studies are reviewed in the first part of the paper. After that, a network, divided into squares of 1Km×1Km, has been considered in southern part of the Tehran and liquefaction potential for every square of the network is evaluated. Finally, liquefaction hazard map for this part of the city is presented.
M. Khademi
Abstract
The only geologic evidence of the neotectonic activity of theTorud region is its seismisity which assumed to be related to the Torud seismogenic fault. This fault has been overlain by the Quaternary alluvium in the major part of its length. Therefore, the study of morphotectonical characteristics of ...
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The only geologic evidence of the neotectonic activity of theTorud region is its seismisity which assumed to be related to the Torud seismogenic fault. This fault has been overlain by the Quaternary alluvium in the major part of its length. Therefore, the study of morphotectonical characteristics of the region gives more evidences about its activity. Calculation of three morphotectonic indices including stream length – gradient ( SL) and ratio of valley – floor width to valley height (Vf) of stream channels and mountain front sinuosity (Smf) shows high SL values (425 – 1044) and low Vf (2.68 – 3.34) and Smf (1.05 – 1.44) values and indicate that the region has activity specially at two parts: central part (near the mountain front ) and northwestern part ( near the main divide of the Torud mountains) and therefore the tectonic activity class of the region can be number 1. The activity of the central part can be due to the movements of the Torud fault. The activity of the northwestern part is the result of the uplift of the region which is related to the at least one fault parallel with the Torud fault that has formed the relic mountain fronts at recent past. The distribution of strain of this activity shows the progressive deformation from north northwest to south southeast and from west to east.
N Afsari; F Taghizadeh-Farahmand; M.R Ghassemi
Abstract
The AlborzMountains are part of the Alpine-Himalayan orogenic belt, situated to the south of the Caspian Sea and north of the Central Iran. . The region is undergoing extensive crustal deformation and shortening between the north-central Iran and the rigid SouthCaspianBasin crust. In this study, we used ...
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The AlborzMountains are part of the Alpine-Himalayan orogenic belt, situated to the south of the Caspian Sea and north of the Central Iran. . The region is undergoing extensive crustal deformation and shortening between the north-central Iran and the rigid SouthCaspianBasin crust. In this study, we used the P-wave receiver function modeling to investigate the crustal structure beneath the eastern part of the AlborzMountains from data recorded between 2004-2010 in Sari and Semnan seismic networks of short-period seismographs, permanently deployed across the area. We observed clear conversions (Ps) from the Moho boundary, and we used them to define a model for the crust of the eastern Alborz. Our analysis indicates a thickening of the crust from ~51±2 km beneath the northern part of the eastern Alborz to ~62±2 km beneath the central part of the region, then a thinning of the crust to ~52±2 km towards south of the eastern Alborz Mountains.
R Arjmandzadeh; M.H Karimpour; S.A Mazaheri; J F.Santos; M Medina
Abstract
The dehsalm porphyritic granitoids belong to the Lut Block volcanic-plutonic belt in East - Central Iran. The intrusive rocks range in composition from gabbro - diorite to granite and can be classified as high-K calc alkaline to shoshonitic volcanic arc granites. Elevated contents of Mo, Cu, Au, Pb, ...
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The dehsalm porphyritic granitoids belong to the Lut Block volcanic-plutonic belt in East - Central Iran. The intrusive rocks range in composition from gabbro - diorite to granite and can be classified as high-K calc alkaline to shoshonitic volcanic arc granites. Elevated contents of Mo, Cu, Au, Pb, Zn occur in silica veins within Bt - Px - Quartz monzonite and Hbl - monzonite. The trend of major oxides on Harker diagrams point to the crystal fractionation of Ca - plagioclase and mafic minerals. Primitive mantle - normalized trace element spider diagram display strong enrichments in LILE such as Rb, Sr, Ba, Zr, Cs and depletions in some high field strength elements (HFSE) e.g. Nb, P and Y. On chondrite - normalized plots, display significant LREE enrichments, high La/Yb = 21.5-31 and the lack of Eu. On the basis of Sr/Y and La/Yb ratios, Dehsalm intrusives cover characteristic features of adakites and (87Sr/86Sr)i and εNdi isotope ratios range from 0.70469 to 0.70505 and from +1.5 to +2.5 respectively, and show that the source is related to the mantle melts contaminated slightly by the crustal materials. They are classified into the magnetite series granitoids and have high mineralization potential for Cu-Mo-Au porphyry type deposits. Two-sided asymmetric subduction explains all the tectonic and magmatic occurrences and the mineralization of porphyry type deposits within the Lut Block during the Tertiary.
E Mohammadi; Gh Ghorbani; H Shafaii Moghadam
Abstract
The studied volcanic rocks are situated in NW of the Sabzevar, mainly at southern domains of the Northern Sabzevar ophiolitic belt. Abundant rhyolitic domes (e.g., Sarough, Zard-Kuhi, Kuh-e-Sefid Mehr and Nahr domes) in the southern margin of the Davarzan-Sabzevar ophiolitic belt crosscut the above-mentioned ...
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The studied volcanic rocks are situated in NW of the Sabzevar, mainly at southern domains of the Northern Sabzevar ophiolitic belt. Abundant rhyolitic domes (e.g., Sarough, Zard-Kuhi, Kuh-e-Sefid Mehr and Nahr domes) in the southern margin of the Davarzan-Sabzevar ophiolitic belt crosscut the above-mentioned ophiolitic rocks. The Geochemical signatures of these volcanic rocks including enrichment in LREEs and LILEs relative to HREEs and HFSEs, depletion in TNT (Ta-Nb-Ti) elements, metaluminous to peraluminous and medium to high K-calc-alkaline characteristics, and their positions in discrimination tectonomagmatic diagrams, displayed that these rocks derived from a subduction-related environment. These adakitic domes are characterized by adakitic signatures (e.g., 69.2 wt.% < SiO2، 14.7 wt.% < Al2O3، MgO < 0.35 wt.% ، Sr > 273 ppm, enrichment in LREEs and LILEs, depletion in Y and HREE (Y < 9.7 and Yb < 0.86( and high ratio of Sr/Y > 58 and La/Yb > 12.1 and belong to high silica adakites (SiO2 ≥ 69.2 wt.%, MgO = 0.19-0.31 wt.% ، CaO+Na2O < 7.62 wt.% and Sr = 273-936). Nd-Sr-Pb isotopes characteristics of the adakitic rocks show similarities to a MORB-type and/or PREMA mantle source, highlighting that their magma (s) is originated from a depleted MORB-type mantle source associated with minor contamination with crustal materials. The geochemical and isotopes characteristics of the Sabzevar adakitic rocks display derivation from partial melting of subducted oceanic crust (garnet amphibolite) associated with subsequent fractional crystallization.
B Alizadeh; R. Fouladvand
Abstract
The main goal of this study is to introduce a paleo high in the central part of Binak oilfield using geochemical parameters. Despite the effect of this phenomena on sedimentation, due to its low amplitude of uplift and lack of unconformity, so far remained unknown in this oilfield. Seismic and well log ...
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The main goal of this study is to introduce a paleo high in the central part of Binak oilfield using geochemical parameters. Despite the effect of this phenomena on sedimentation, due to its low amplitude of uplift and lack of unconformity, so far remained unknown in this oilfield. Seismic and well log data reveal that, Binak oilfield is an asymmetrical anticline with Bangestan reservoir of about 22 km long and 10 km wide. To investigate the paleo high in the oil field, geochemical analyses were performed on the cutting samples by Rock Eval 6 Pyrolysis, Vitrinite reflectance measurement and finally Pars Basin Modeler software was used for thermal modeling. The results of Rock-Eval analysis demonstrate that the quantity of total organic carbon decreases in all the Kazhdumi, Lafan, Gurpi and Pabdeh Formations towards the center of this anticline. This phenomenon reveals that the environment and condition of sedimentation have been oxidation and shallow for these formations during their deposit history in the center. This can be explained by development of an uplift along Kharg - Mish basement fault starting at or before Albian to Cenomanian time. The Kazhdumi Formation in well number four indicates a drastic change in the geochemical data in compare to other formations as well as the same formation in well number seven. This can also be correlated to remarkable increase in the activities of Kharg-Mish Fault during Albian. On the other hand significant temperature anomalies are often observed close to the faults and there is a direct relationship between basement fault, high thermal gradient and paleo highs. Therefore, thermal modeling was performed to understand thermal history of this oilfield using PBM (Pars Basin Modeler) software. The results indicate that, the amount of heat flow must be 80, 76, 66 and 60 mW/m2 for well numbers 2, 4, 6 and 7 respectively for achievement of the best fit between calculated Vitrinite reflectances as well as Tmax parameters and the same parameters actually measured by geochemical analyses. Consequently, this study reveals that there is a paleo high in the centre and along the Kharg – Mish Fault of the oil field which caused low content of TOC and naturally lower potential for hydrocarbon generation in the middle part of the oilfield. Finally considering the reservoir in the Binak oilfield, since in the central part is shallower due to the paleo high, there is more Rudist presence and higher oil production in the central part of the oilfield.
F. Farjandi; H. Bastani
Abstract
The aims of present study are investigation of endemic plants in Masjed-Daghi area introducing hyperaccumulator and indicator plants for gold and copper, and also describe the biogeochemical response pattern over a known mineralized site, namely the "Au- Cu" mineralization at Masjed-Daghi area. Masjed_Daghi ...
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The aims of present study are investigation of endemic plants in Masjed-Daghi area introducing hyperaccumulator and indicator plants for gold and copper, and also describe the biogeochemical response pattern over a known mineralized site, namely the "Au- Cu" mineralization at Masjed-Daghi area. Masjed_Daghi is located in Jolfa sheet and it is underlain by Eocene flysch, andesite, trachyandesite, dacite, rhyodacite, Oligocene agglomerate and Quaternary deposits. Pervious researches reported copper porphyry mineralization in this area.Considering variety of vegetation in Jolfa and Masjed_Daghi, indicator plants for Cu, Pb and Zn mineralization in the study area were investigated. Mean metal contents (ppm) and mean biological absorption coefficients for Stachys inflata are:
Cd 0.13- 1.18, Cu 14.8- 1.10, Pb 5.67- 0.52, Re 0.033- 4.4 and Zn 57.4- 2.50;
for Artemisia sp.: Cd 0.373-1.40, Cu 22.06- 0.19, Pb 5.801- 0.12, Re 0.197- 97 and Zn 35.51- 0.48;
for Moltkia coerulea: Cd 0.15- 5, Cu 24.6- 0.78, Pb 0.48- 0.06, Re 0.348- 116 and Zn 125.5- 9.65;
for Astragalus sp.: Cd 0.033- 0.37, Cu 11.44- 0.21, Pb 0.513- 0.04, Re 0.089- 53 and Zn 21.8- 0.83;
for Salvia sp.: Cd 0.047- 0.55, Cu 11.04- 0.46, Pb 2.643- 0.19, Re 0.091- 19 and Zn 70.43- 3.42. This study presents that plants with high metal intake enabled us to obtain invaluable information about natural concentrations of chemical elements in the substrate, and to recognize new potential areas for mineral prospecting. In this study most of these plants have mean biological absorption coefficients exceeding or near to hyperaccumulating criterion >1 for most of the elements investigated. Most of the hyperaccumulator values belong to Stachys inflata and the indicating values belong to Stachys inflata, Artemisia sp., and Salvia sp.
A. Arzani; S.A. Alavi; M. Pooladzadeh; A.R. Golalzadeh; Z. Mehdipoor
Abstract
The area that will be discussed in this study is located between Zagros and Arabian structural zones in Iran in which full fold 3D seismic data has been acquired and interpreted using sophisticated techniques. This paper covers the role of structural sensitive seismic attributes including first and Second ...
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The area that will be discussed in this study is located between Zagros and Arabian structural zones in Iran in which full fold 3D seismic data has been acquired and interpreted using sophisticated techniques. This paper covers the role of structural sensitive seismic attributes including first and Second Derivative attributes, Azimuth attribute, Variance Cube attribute and Seismic Inversion attributes as an advanced stage of the interpretation program in delineating and resolving structural ambiguities in the mentioned field. The result of this study using integrating these attributes shows the interference structural features such as superimposed folding and structural basin in NW nose of the field of study. Hence it seems that an interference folding event to be most probably occurred between Zagros and Arabian structures and made a very gentle refolding belt. Complementary geophysical studies also show a reservoir of good potential in some parts of this belt that located in this field of study.
A Mohebi; A Hezarkhani; M Behzadi; H Mirnejad; H Taghi Zadeh
Abstract
Bondar Hanza porphyry copper deposit occurs 150 km southeast of Kerman, in southern part of the Urmia-Dokhtar zone and in Dehaj-Sardoiyeh zone. This ore deposit has formed in diorite to granodiorite rocks. The present paper deals with the study of fluid inclusion on quartz and hornblende samples as well ...
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Bondar Hanza porphyry copper deposit occurs 150 km southeast of Kerman, in southern part of the Urmia-Dokhtar zone and in Dehaj-Sardoiyeh zone. This ore deposit has formed in diorite to granodiorite rocks. The present paper deals with the study of fluid inclusion on quartz and hornblende samples as well as the measurement of isotopic ratio of oxygen and hydrogen with the aim to recognize characterization of hydrothermal fluids effective in mineralization. The studied veinlets are divided into five groups. Veinlet I: fluid of high pressure (>300 MPa) and medium to high temperature (250°C-300°C) with salinity of 38-45 Wt%NaCl that includes molybdenum mineralization. This veinlet contains halite and anhydrite and has resulted in potassic and sodic-calcic mineralization in deeper parts of the ore deposit. Veinlet II: high pressure (>300 MPa), high salinity (33-47 Wt%NaCl) and high temperature (250°C-420°C), containing copper and molybdenum mineralization as well as potassic alteration. Veinlet III: high salinity (40-56 Wt%NaCl), high pressure (>300 MPa) and high temperature (200°C-500°C), containing copper mineralization. Veinlet IV: medium to low salinity (6-7 Wt%NaCl), medium temperature (approximately 170°C), low pressure (0/7-0/8 MPa), containing no mineralization. The study performed indicate that the boiling occurred in the initial magma, as a result of pressure and temperature changes and mixing with meteoric waters, caused copper and molybdenum mineralization. Results obtained from oxygen and hydrogen isotopic analysis in quartz show δ18O to vary from 3.9 to 6.3 per mil. Considering its formation temperature and based on thermometric study (130-400°C), the amount of δ18o in mineralizing fluid is from 5.26 to 6.19 per mil, being indicative of magmatic origin of mineralization fluids like the other porphyry copper deposits of Iran and the world. While results of hydrogen analysis existed in fluid inclusions of quartz mineral illustrate a range between -88 to -90 per mil, being indicative of a decrease in the amount of mineralizing fluid deuterium. These values are traceable to the effect of meteoric waters, given the propylithic and sodic alterations accompanied with potassic alteration in mentioned veinlet.
M.R Partoazar; B Hamdi; S.A Aghanabati
Abstract
Foraminiferal contents of the Permian strata of the Kuh-e Baghvang in central Iran has been investigated. The section is located some 45Km Northwest of Tabas and south of Shirgeshtvillage. The Permian deposits of the Jamal Fm. with a thickness of 270 meters are underlain by the Sardar Fm. disconformably ...
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Foraminiferal contents of the Permian strata of the Kuh-e Baghvang in central Iran has been investigated. The section is located some 45Km Northwest of Tabas and south of Shirgeshtvillage. The Permian deposits of the Jamal Fm. with a thickness of 270 meters are underlain by the Sardar Fm. disconformably and in turn overlain by the Lower Triassic deposits of Sorkh shale Formation. A total of 124 rock samples have been systematically taken from various layers for an accurate biostratigraphic study. Forty one genera and 48 species of Foraminifera and 10 generaand 12 species of Algae have also been determined through this study. According to the index fossils, geochronology of Member 1 and Member 2 of the Jamal Fm. is attributed to Early Murgabian. Moreover, according to the biostratigraphic study, some index fossils of Fusulinidae have been recorded and the following assemblage zones have been differentiated which are equivalent to international biozones of Leven(1975 and Ishii (1975). Paradunbarula – Geinitzina Assemblage Zone (Murgabian) Dagmarita – Paraglobivalvulina Assemblage Zone (Dzhulfian) Colaniella – Reichelina Assemblage Zone (Changxingian).
