Hydrology
Mohamad Hosein Mahmudy Gharaie; Najmeh Rokhashmah; Asadollah Mahboubi; Seyed Reza Moussavi Harami
Abstract
The aims of this study are water quality assessment for drinking and industrial usages with refer to affective factors on water chemistry in North of Quchan plain, Razavi Khorasan province. 17 groundwater samples were collected for major cations (Ca2+, Na+, Mg2+, K+) and anions (HCO3-, SO42-, Cl-) analysis. ...
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The aims of this study are water quality assessment for drinking and industrial usages with refer to affective factors on water chemistry in North of Quchan plain, Razavi Khorasan province. 17 groundwater samples were collected for major cations (Ca2+, Na+, Mg2+, K+) and anions (HCO3-, SO42-, Cl-) analysis. According to Piper diagram, chemical composition of water samples is 29.4% Ca-SO4, 23.5% Na-SO4, 23.5% Mg-SO4, 11.8% Na-HCO3 and 5.8% Mg-HCO3. Based on Gibbs diagram, the main controlling process of the water composition is mainly water-rock interactions (weathering), rather than evaporation and precipitation. Schoeller diagram shows that most of water samples are categorized in moderate and acceptable classes. Also, based on water quality index (WQI), 70.59 % water samples are suitable for drinking usage. Increasing in SO42- concentration reduced the water quality for drinking purposes. Langelier index (LSI) shows 82.35 % water samples are scale forming and 17.65 % are corrosive. Scale forming of the water are due to high TH induced by carbonate dissolution (of Mozdouran and Tirgan Formations). In addition, corrosive property of some water samples is due to gypsum dissolution (from Shoorigeh Formation) and increasing of sulfate concentration in the groundwater.
Tectonics
Mohammad Hossein Tahriri; Hamid Saffari
Abstract
The Doruneh fault system with more than 700 km length, after the main Zagros fault, is known as the largest fault in Iran. In this research, this fault system is divided into 3 main parts because the mechanisms of its different parts are different. The western part is reported to have a left lateral ...
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The Doruneh fault system with more than 700 km length, after the main Zagros fault, is known as the largest fault in Iran. In this research, this fault system is divided into 3 main parts because the mechanisms of its different parts are different. The western part is reported to have a left lateral strike-slip mechanism with a reverse component, the middle part is a left lateral strike-slip mechanism, and the eastern part is reported to have a reverse mechanism. In this study, seismicity parameters and their temporal and spatial changes along this fault system are analyzed using seismic data collected from 1980 to 2023 and based on the maximum likelihood method. In this regard, the temporal changes of b-value shows two significant drops, which indicate two relatively strong Torbat-e Heydarieh earthquakes in 2010 and the Fariman earthquake in 2017. Despite the fact that the scientific community is not yet able to accurately predict earthquakes, according to the studied method and with the continuous monitoring and analysis of various earthquake parameters, especially b-value, it is not far from expected to predict the occurrence of possible earthquakes in the future.
Tectonics
Mohammad R. Ghassemi; Ali Aghanabti; Abdollah Saeidi
Abstract
Correlation of the orogenic and epeirogenic events in Iran with the events that have been identified in different parts of the world and in different tectonic environments, has caused some confusion in the Iranian geological literature. After a brief review of the nature of known orogenic processes in ...
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Correlation of the orogenic and epeirogenic events in Iran with the events that have been identified in different parts of the world and in different tectonic environments, has caused some confusion in the Iranian geological literature. After a brief review of the nature of known orogenic processes in the world, examining issues related to the abovementioned correlations, and considering the tectonic history of various parts of Iran, we have tried to systematically describe and name the important orogenic and epeirogenic events of the country. Most Precambrian orogenic events in Iran are dubious due to unknown age and poorly constrained tectonic setting of the rock units attributed to Precambrian. Paleozoic in Iran has been mostly associated with epeirogenic events, and the only sign of a real orogenic event goes back to the Late Carboniferous in northern Iran. The important Mesozoic and Cenozoic orogenic events have shaped the modern tectonic configuration of Iran. The Paleotethys suture in northern and central Iran formed during the Gorgani orogeny, development of the Central Iranian active margin (Sanandaj-Sirjan) occurred in the Ekbatani orogeny, ophiolite obduction in Central Iran and Zagros developed during the Late Cretaceous events, and collision of the Iranian plate with the Helmand block resulted in the Sistani orogeny. The creation of the Zagros and Alborz Mountain ranges started from Oligocene and Miocene times, respectively, and the deformation due to their shortening continues to this day.
Tectonics
MohammadAmir Alimi
Abstract
The Bahlgerd shear zone in the northern margin of Bagheran Mountain is separated Eocene flysch from the Cretaceous ophiolite sequence and Quaternary sediments by southern Birjand and Bahlgerd faults. In the deformation evaluation , sigmoidal array arrays located in sandstone units have been used as strain ...
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The Bahlgerd shear zone in the northern margin of Bagheran Mountain is separated Eocene flysch from the Cretaceous ophiolite sequence and Quaternary sediments by southern Birjand and Bahlgerd faults. In the deformation evaluation , sigmoidal array arrays located in sandstone units have been used as strain markers. Based on the geometry of these arrays, the mathematical equations and R-θ' diagrams of the strain parameters were estimated. The mean values of shear strain (γ), volume change (∆) and convergence across the zone (K) are 0.45, -0.26 and 0.85, respectively. The plotting strain ellipses on the logarithmic Flinn diagram are in the field of flattening, which indicates the simultaneous simple shear and compaction in the region and show a volume reduction of up to 30%. Also, in the Bahlgerd shear zone, the value of θ'> 45 ° and cleavages are created in the direction perpendicular to the opening of the veins, which conforms to the characteristics of the compactional simple shear model. The horizontal strain parameters in the transpression model have similar values the compactional simple shear model. Based on the calculated convergence parameter (0.39), Behlgard shear zone is in the category of slightly convergence zones in which the amount of shortening
Economic Geology
Seyed Mehran Heidari; Sara Safavy; Afshin Akbarpour; Azra Hassanlou; Bahram Mohaghegh
Abstract
Saveh-Razan copper (± gold) area, with WNW direction in the northwest of Urmia-Dokhtar magmatic belt, with the highest reaction to right-sided shear zones and structural trend change during the Oligomyocene, leads to the placement of semi-deep Oligomyocene diorite massifs in shallow rock depths. ...
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Saveh-Razan copper (± gold) area, with WNW direction in the northwest of Urmia-Dokhtar magmatic belt, with the highest reaction to right-sided shear zones and structural trend change during the Oligomyocene, leads to the placement of semi-deep Oligomyocene diorite massifs in shallow rock depths. It is an Eocene volcano. By creating different types of mass-related hydrothermal alteration (propylitic, intermediate-advanced argillaceous, and phyllite) along the fractures, the system concentrates the mineralizations in quartz-sulfide veins, hydrothermal incisions, and concentrated sulfide-bearing filaments. Common features of metallurgy in this area are fluid homogenization temperature between 250 to 350 ° C and salinity range of 6-28% by weight of salt, containing CO2 gas and liquid phase of liquid and the presence of sulfides such as pyrite, chalcopyrite, burnite, chalcocite and sulfosalts in related reserves. There is also more gold than silver. Therefore, these features are most similar to the mass-related intermediate-type epitermal deposits that form in calcoalkalkene magmatic arcs.
Petrology
Atefeh Nimroozi; gholamreza ghadami; Jamshid Hassanzadeh; Mohammad posti
Abstract
The study area is located near Abarkoh city and in Sanandaj –Sirjan zone. The volcanic activity of this region is in the form of dacite and rhyolite domes and lava flow and in the petrographic studies includes coarse plagioclase, quartz and hornblende. The volcanic rocks are considered as the separate ...
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The study area is located near Abarkoh city and in Sanandaj –Sirjan zone. The volcanic activity of this region is in the form of dacite and rhyolite domes and lava flow and in the petrographic studies includes coarse plagioclase, quartz and hornblende. The volcanic rocks are considered as the separate units interlayered with calcareous sedimentary units. Geochemical classification confirms the rhyolitic and dacitic composition of the volcanic unites and show their belonging to the calc-alkaline magmatic series, which is the characteristic of the subduction tectonic setting. Significant characteristics observed in spider and multi-element diagrams, such as their enrichment in LREE, high LREE / HREE ratio, Nb and Ti trough, and enrichment of Pb, Rb and Th elements demonstrate the continental crustal contribution to the development of the volcanics and their formation in the subduction environment in the active continental margin setting. Tectonic setting diagrams confirm this idea and determined a continental arc setting for the volcanic rocks of the area. The dating studies on zircon minerals yield the age of about 17.7.2 ± 7.6 ma equivalent to Jurassic for this part of the Sanandaj-Sirjan zone, which matches with the subduction stage of the Neotethyan Ocean below the central Iran zone.
Tectonics
Zeynab Taslimi; Abdollah Saidi; Mehran Arian; A. Solgi; Manouchehr Ghoreshi
Abstract
The Alborz Mountains has been separated the subsiding Caspian Basin from the foreland basin of Central Iran. This mountain range from east to northwest, has changed greatly in structural trend formed spirally. Two orogenic phases, Cimmerian and Alpine events caused more changing in sedimentary basin ...
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The Alborz Mountains has been separated the subsiding Caspian Basin from the foreland basin of Central Iran. This mountain range from east to northwest, has changed greatly in structural trend formed spirally. Two orogenic phases, Cimmerian and Alpine events caused more changing in sedimentary basin of Palo Tethys and Neotethys and it caused the complexity of abundant structural in other way too. The aim of this research is to investigate and analysis of existence structures in east central Alborz from northwest of Damghan (South of Toyeh) to South of Sari (North Alborz fault). The Structural features Analysis indicate that the Alborz Mountains are a fold and thrust belt. During the intense shortening of Alborz crust in the studied area the initial model of folds have been modified or destroyed. Some of these folds could take place in flexural flow folds or Drug folds classes since one limb of folds on the surface of low-angel thrust faults was thrusted recumbently. The thrust faults with south and north dipping is the main controller for variety structures in this part of Alborz. Based on geological and structural properties, construction of folding structures initiated during the Alpine orogeny since the late Eocene (37 million years) and the most shortening and faulting had occurred during at the Late Miocene. Data presented here demonstrate that shortening percent in the study area of Alborz Mountains is about 36.27% and the Rate of Shortening is estimated about 0.93 mm/y.
Petrology
Ashraf Torkian; Sara Damchin-Mashak; Zohreh Yarali; Maryam Souri
Abstract
The studied area is located in N-Sonqor and in the Sanandaj-Sirjan zone. Field relationships and petrographic evidence show that volcanic rocks of the north of Bashirabad comprise of trachydacite to trachyandesite (and altered basaltic trachyandesite) and in the south of this area, it consists of andesite ...
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The studied area is located in N-Sonqor and in the Sanandaj-Sirjan zone. Field relationships and petrographic evidence show that volcanic rocks of the north of Bashirabad comprise of trachydacite to trachyandesite (and altered basaltic trachyandesite) and in the south of this area, it consists of andesite to trachyte. Their texture is mainly porphyry. Geochemical data {total abundance of (Na2O+K2O), enrichment of large lithophile ion elements and rare light earth elements) indicate that these rocks belong to the alkaline series. Spider diagrams show enrichment in LREE and depletion HREE, and parallel patterns in all volcanic samples confirm their common origin. According to modeling magmatic processes, fractional crystallization, assimilation and crustal contamination have played an important role in the magma forming the studied rocks. The discriminating diagrams the tectonic setting the Bashirabad volcanic rocks indicate their subduction-related volcanic arc that was formed in an active continental margin environment with local tensions.
Stratigraphy and Palaeontology
Tayaebe Sarbandi Farahani; Mehdi Yazdi; Mahmoud Reza Majidifard
Abstract
The present study deals with the ammonites from the upper part of the Chaman Bid Formation, member 4 (Middle-Upper Jurassic) at the type locality. Lithostratigraphicall, it is consites alternation of limestone and marls.Following ammonite families are present: Perispinctidae, Ataxioceratidae, Haploceratidae, ...
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The present study deals with the ammonites from the upper part of the Chaman Bid Formation, member 4 (Middle-Upper Jurassic) at the type locality. Lithostratigraphicall, it is consites alternation of limestone and marls.Following ammonite families are present: Perispinctidae, Ataxioceratidae, Haploceratidae, Oppeliidae and Aspidoceratidae, which indicate the Biozones: Hybonoticeras hybobotum , Semiformiceras semiforme , Semiformiceras fallauxi , Microcanthoceras ponti and Micracanthoceras micracanthum Zones. Paleobiogeographicall, the ammonite fauna is closely related with the Submeditteranean Provice, with few affinities to South Tethys (Ethiopian province ),migrated during the Tithonian. Following taxa are reported for the first time fromthe Tithonian strataNorth Iran: Zappalia cf. zapalensis, Paraulacosphinctes transitorios, P. seneoides.
Sedimentology
Ali Hossein Jalilian; Mohammad Ali Kavoosi
Abstract
The Hauterivian-Barremian Gadvan Formation represents a depositional sequence in the central and eastern regions of the Zagros Mountains. Field surveys and petrography of 30 thin-sctions of this Formation in the Khaneh-Kat anticline togheter with wireline logs (gamma-ray and sonic) and 25 thin-sections ...
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The Hauterivian-Barremian Gadvan Formation represents a depositional sequence in the central and eastern regions of the Zagros Mountains. Field surveys and petrography of 30 thin-sctions of this Formation in the Khaneh-Kat anticline togheter with wireline logs (gamma-ray and sonic) and 25 thin-sections analysis of two drilled wells in the Dashtak and Bandubast gas fields (Interior Fars area) indicate important events in the basin evolution, especially the changes in the sedimentation regime and platform evolution during the time period. The key point is upward grading of the thick-bedded layers, feature forming Berriasian-Valanginian carbonates into shale, marl and argillaceous limestone interbeds of the Gadvan Formation. The vertical changes is consisten with a prominent decrease in carbonate production and a definite change in the nature of the Fars platform. The intense bioturbation and mostly mud-dominated texture of skeletal limestone microfacies with significant occurrence of molluscs, green algae and benthic foraminifera in the cyclic alternations of shales and limestones indicate that the Gadvan Formation was deposited in a mixed carbonate-siliciclastic platform. The platform formed as the result of increased siliciclastics influx from the southern areas of the Zagros fold-thrust belt (clastic drowning of the platform) and the change of the Fahlyian oolithic-algal ramp into an environment consisting of an open lagoon and a muddy shelf. In the drilled wells, these changes correspond to a significant increase in gamma-ray and sonic wireline logs. The Khalij Member shows the regional continuity, implies a decrease of the (relative) siliciclastics supply and increase of carbonate production in the mixed platform. Considering the relative tectonic quiescence of the Interior Fars area during the Early Cretaceous, the mentioned changes can be the result of the interplay between tropical climate and short-term fluctuations in the context of global sea level rise.
Petrology
Sakine Moradi; Muhammad Reza Ghorbani; Shao- Yang Jing
Abstract
The Kahak mafic volcanic rocks in the central part of the Urumieh-Dokhtar Magmatic Arc are composed of basalts and basaltic andesite and show sub alkaline to transitional affinity. They are calc-alkaline based on the tholeiitic index (THL). U-Pb zircon dating yields ...
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The Kahak mafic volcanic rocks in the central part of the Urumieh-Dokhtar Magmatic Arc are composed of basalts and basaltic andesite and show sub alkaline to transitional affinity. They are calc-alkaline based on the tholeiitic index (THL). U-Pb zircon dating yields almost 60 (Middle Paleocene) and 24 to 19 Ma (Late Oligocene–Early Miocene) for andesitic basalt and basaltic rocks respectively. These rocks are identified by LREE and LILE enrichment and HFSE depletion with relatively negative or without Eu anomalies and E-MORB like pattern in multiple spider diagrams that.attributed to the subduction of the Neotethyan oceanic slab beneath the central Iranian microcontinent. Based on petrography, trace and rare earth elements, and isotopic features, fractional crystallization played a significant role during magma evolution in these rocks. Trace element modeling suggests that the studied mafic rocks were derived by partial melting within the spinel lherzolite mantle. Isotopic ratios also show that they resulted from lithospheric mantle metasomatized by released fluids from subducted slab sediments. The studied samples might have formed in the extensional regime followed by slab rollback and undergone a continental arc to back-arc basin transition during the Paleocene to Miocene. This basin might have been closed in the middle Miocene.
Tectonics
Babak Samani
Abstract
In this research, using deformed chert nodules in the calcareous units of Sarvak Formation in Pyun anticline, quantitative strain values in different parts of this anticline have been investigated. In a perpendicular fold axis survey, the anticline was divided into seven different areas. At least 40 ...
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In this research, using deformed chert nodules in the calcareous units of Sarvak Formation in Pyun anticline, quantitative strain values in different parts of this anticline have been investigated. In a perpendicular fold axis survey, the anticline was divided into seven different areas. At least 40 nodules were measured in each area and finite strain analysis was carried out using Rf/Ø and polar methods. The results of strain studies show an increase mode in strain values from the fold limbs (Rs = 1.7) to the fold hinge (Rs = 2.9). Kinematic vorticity analysis shows the range between 0.68<Wk<0.91 and the effect of both simple and pure shear strain components and the occurrence of the strain partitioning in the Pyun anticline. The amounts of kinematic vorticity number indicate the increase of pure shear strain components in the hinge of anticline and the predominance of simple shear strain components in the limbs of the Pyun anticline. According to the results of strain analyses the amounts of bulk shortening was estimated about 47- 50 percent in the Pyun anticline.
Economic Geology
Raziyeh Mahabady; Farajollah Fardoost
Abstract
Abgareh copper deposit located in 140 km southwest of shahrood and part of a volcanic-sedimentary Torud-Chah shirin belt that has facies in the northern edge Structural-sedimentary zones of Central Iran. Field and petrographical studies, deposit area, consist of andesite, basaltic andesite and basalt ...
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Abgareh copper deposit located in 140 km southwest of shahrood and part of a volcanic-sedimentary Torud-Chah shirin belt that has facies in the northern edge Structural-sedimentary zones of Central Iran. Field and petrographical studies, deposit area, consist of andesite, basaltic andesite and basalt and contains less includes tuffit crystal that indicate middle–upper Eocene with with argillitic, sericitic, silicic, carbonatic, chloritic and iron oxides alterations. According to the field observations and mineralogical studies, the mineralization in the region was carried out in two stages: hypogene and supergene and weathering. Hypogen zone minerals are generally pyrite, chalcopyrite and bornite. Because of existence in oxidizing-supergene environment , nearly almost Cu-bearing minerals of the main stage of mineralization have been replaced by secondary Cu minerals such as chalcocite, covellite, malachite and chrysocolla. Fluid inclusion data shows in the temperature range from 145 to 217 °C and salinity between 3.73 and 9.84 Wt%NaCl and depths less than 390 m. The host rocks, ore mineralogy, ore structures and textures, and fluid inclusions characteristics and comparison with similar epithelial deposits indicate that the Abgareh vein system is formed in a low-sulfidation epitermal environment.
Geological Environment and Engineering
Neda Khajooee; Sourosh Modabberi; Behnoush Khosh manesh Zadeh; Fatemeh Razavian
Abstract
Population growth and increasing urbanization expose city dwellers to higher degrees of urban pollutants, especially when they spend long time in enclosed environments with inadequate ventilation. This study is the first research on inorganic pollutants in indoor dust particles of Tehran city, which ...
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Population growth and increasing urbanization expose city dwellers to higher degrees of urban pollutants, especially when they spend long time in enclosed environments with inadequate ventilation. This study is the first research on inorganic pollutants in indoor dust particles of Tehran city, which applies geochemical indices to estimate the intensity of dust pollution by potentially harmful elements. A number of 31 indoor dust samples were passively collected from inside the residential and office buildings in the central and densely populated districts of the city and were analyzed by ICP-Ms at the Universitat Rovira i Virgili, Tarragona, Spain. Single geochemical indices of the Contamination Factor, Geoaccumulation Index, Enrichment Factor, and cumulative indices of Pollution Load and Potential Ecological Risk Indices were calculated. The results of elemental analysis showed that the concentration of arsenic, cadmium, copper, mercury, lead and zinc in Tehran indoor dust is higher than that in some cities in the world. On the other hand, cobalt, chromium, nickel and vanadium present low concentrations in the analyzed indoor dust samples. This result was confirmed by the cumulative indices as well as the contamination factor. In contrast, some other factors showed a low to medium degree of pollution for the above-mentioned elements. Based on the obtained concentration of elements in the dust samples, it can be argued that the geochemical indices indicating low to moderate pollution are not applicable and trustable in the current study.
Tectonics
mohammad khalaj
Abstract
Anarak metamorphic complex located east of Nain city. Based on geological, chronological and paleomagnetical data, the complex consists of different metamorphic units from different varity of source. This metamorphic complex also composed of ophiolitic bodies which crop out in the complex as thrust sheets. ...
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Anarak metamorphic complex located east of Nain city. Based on geological, chronological and paleomagnetical data, the complex consists of different metamorphic units from different varity of source. This metamorphic complex also composed of ophiolitic bodies which crop out in the complex as thrust sheets. This study is concerned with structural investigation of metamorphic rocks around Anarak, specially on a Z shape folding in the chahgorbeh mountains. Based on field surveys and microscopic investigations there are at least 3 deformationnal phases in the morghab and chahgorbeh units, all of them occurred in ductile conditions possibly related to “Variscan metamorphism” (late carboniferous). In the basic and ultramafic rocks of chahgorbeh unit, the first deformational phase accompanied with HP/LT metamorphic conditions at amphibolite facies. This phase is accompanied with a relatively low grade metamorphism-green schist facies in the metamorphic pelletic rocks of Morghab and Chahgorbeh units and leads to generation of a low grade (S1) foliation. This phase followed by increasing of intensity of deformation and milonitic foliation and sheath folds developed in the rock units through second phase of deformation. Third phase of deformation continusly affected the pre- deformed rocks in a more low- grade metamorphic and deformational condition than earlier phases.
Economic Geology
Negar Kaboudmehri; Hossein Kouhestani; Mir Ali asghar Mokhtari; Afshin Zohdi
Abstract
The Toryan occurrence is located in the Central Iran zone, 120 km northwest of Zanjan. Pb–Zn mineralization at Toryan occurred as laminated and lens-shaped parallel to lamination of grey sandstone units of the Upper Red Formation. Mineralization often formed around and within the fragments of the ...
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The Toryan occurrence is located in the Central Iran zone, 120 km northwest of Zanjan. Pb–Zn mineralization at Toryan occurred as laminated and lens-shaped parallel to lamination of grey sandstone units of the Upper Red Formation. Mineralization often formed around and within the fragments of the plant fossils, and shows disseminated, replacement, solution seems, intergranoular cement, framboidal, and vein-veinlet textures. At Toryan, ore horizon has 1 m thickness and approximately 350 m length and contains three zones include the red oxidized zone, the bleached zone and the mineralized reduced zone. Galena, sphalerite, pyrite and arsenopyrite are the main ore minerals at Toryan occurrence. Cerussite and goethite are formed during supergene and wethering processes. Comparison of trace elements and REE patterns of barren red and grey host sandstones and mineralized samples indicate that mineralized samples show lower concentrations of trace elements and REE. Based on tectonic setting, sedimentary environment, host rock, presence of plant fossils, geometry, ore texture and mineralogy and alteration, Toryan occurrence can be classified as sediment-hosted Cu deposits of Redbed type, and is comparable with another Redbed type of Cu and Pb–Zn deposits in the Avaj-Zanjan-Tabriz-Khoy belt.
Petrology
Reza Jamal Omidi; Saeid Hakimi Asiabar; Shahrooz Haghnazar; Mansour Vosoghi Abedini
Abstract
Tarom mountains are located at the southwestern end of the Alborz mountain range with an approximate northwest-southeast direction. Tashvir region is a part of the northern margin of the Tarom mountains. Most igneous rocks in this area include basalt, andesitic basalt, and interlayers of tuff. Enrichment ...
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Tarom mountains are located at the southwestern end of the Alborz mountain range with an approximate northwest-southeast direction. Tashvir region is a part of the northern margin of the Tarom mountains. Most igneous rocks in this area include basalt, andesitic basalt, and interlayers of tuff. Enrichment of LIL elements with positive anomalies of Ce, P, Sm, and depletion of Nb, Ta, Zr, Hf, and Th, elements and also K2O/Na2O and Ba/Rb ratios in the rock samples of Tashvir area, indicate magma contamination with the lower crust. The evidence of crustal contamination and the ratio of Nb/Y and Zr/Y in the samples indicate that the basalts of the Tashvir region belong to the source of the plume. Alkaline, shoshonitic, and peraluminous nature, REE enrichment (i. e. Ba, Rb, and Sr), low titanium content, origin, and depth of magma indicate they're belonging to the rift environment. In this study, in addition to determining the characteristics of igneous rocks in the Tashvir area, the results of several previous studies are plotted on the map of the Tarom mountains. Accordingly, the tectonic setting of the Tarom range is divided into two parallel sub-regions with magmatic arc and rift-type eruptions, which expansion of this rift zone has stopped before it evolve as a back-arc basin.
Petrology
Amir Esna-Ashari; Massimo Tiepolo
Abstract
The Malayer-Boroujerd plutonic complex (MBPC) is part of the Sanandaj-Sirjan continental arc of Iran resulted from subduction of Neotethys oceanic crust below Central Iran microcontinent. A number of adakitic samples have recently been reported in the MBPC. This study shows that among the various petrogenetic ...
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The Malayer-Boroujerd plutonic complex (MBPC) is part of the Sanandaj-Sirjan continental arc of Iran resulted from subduction of Neotethys oceanic crust below Central Iran microcontinent. A number of adakitic samples have recently been reported in the MBPC. This study shows that among the various petrogenetic processes responsible for the formation of adakitic rocks, two have been suggested in the genesis of those from the MBPC. i) interaction of crust-derived magma with ultramafic rocks and ii) crystallization of amphibole from a more basic magma. The former process leads to formation of intermediate to basic magma that subsequently crystallized amphibole in the ultramafic rocks. Amphibole growth was associated with textural and chemical changes toward the rim. Chemical modeling shows that amphibole growth was coeval with assimilation of olivines that their residue are remained as inclusions in the amphibole. The magma that formed the rim of amphiboles had higher Th, Zr, Ta and LREE but lower Ti and HREE than the core-forming magma. Assimilation of olivine during the amphibole growth prevented a decrease in Ni and Co content of the remained magma. Comparable chemistry of the rim-forming melt and MBPC adakitic rocks suggest that they are of the same origin.
Petrology
Mohsen Moayyed; Farzaneh ValinasabZarnagh; Ahmad Jahangiri; Hosein Azizi
Abstract
there are Discontinuous outcrops of volcanic rocks in the northern regions of Maku. The volcanic rocks were metamorphosed in the green schist facies. These volcanic complex were bimodal and compose of acidic and basic lava and pyroclastic rocks. The lava of this unit covers the Cambrian and equivalent ...
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there are Discontinuous outcrops of volcanic rocks in the northern regions of Maku. The volcanic rocks were metamorphosed in the green schist facies. These volcanic complex were bimodal and compose of acidic and basic lava and pyroclastic rocks. The lava of this unit covers the Cambrian and equivalent of Lashkarak rock units and is progressively covered by Devonian dolomitic units. The geochemical data of metabasic and metarhyolite rocks signify transitional to alkaline nature of the primary magma and they have a negative gradient of REE and LREE / HREE ratio of those rocks are high and enriched inHFS elements. Metarhyolite rocks are similar to the rift setting rhyolites (A1-Type). Geochemical data indicate that the studied rocks are due to fractional crystallization of basic magma with crustal contamination, and in particular, the studied rocks have a genetic relationship and originate from a commen magma. The magma of the studied rocks generated by 3-10 percent partial melting of an enriched garnet peridotitic mantle source in an intra-continental extensional rift setting. This tectonic setting is concordant with the known extensional rift setting governed on other parts of Iran during the early Paleozoic, primary stages of generation and development of the Paleotethys.
Geophysics
Vahid Maleki; mohammad reza Hatami; Ali Asghar Mottaghi
Abstract
In this study, we investigate the seismicity of eastern Alborz based on precise location of the earthquakes during the last two decades. In order to reduce the effect of outliers and low quality data on earthquake location results, during phase reading, weighing has been done. Manual readings of seismic ...
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In this study, we investigate the seismicity of eastern Alborz based on precise location of the earthquakes during the last two decades. In order to reduce the effect of outliers and low quality data on earthquake location results, during phase reading, weighing has been done. Manual readings of seismic phases for the desired area have been provided with a seismic data bank in which 5461 phases S and 8523 phases have been read, compared to seismic phases read in The Iranian Seismological Center (IRSC) shows a significant increase. Initial location is based on phase picking and initial weights using a nonlinear probabilistic method (Lomax et al, 2000). After calculation of initial location, the double difference method (waldhauser et al, 2000) is used to enhance the earthquake location quality. The earthquake waveform correlation tool is used to re-find the earthquakes. Transparency correlations are performed for events with a similarity of over 70% in a given time window for phase P and S. As a result, using this technique, the phase reading error for the same events reaches its lowest level, resulting in seismic events in re-location with a much higher accuracy than the initial location and location based only on the catalog data. Results of waveform cross correlation shows that in this area, earthquakes with high similarity occurring at in different times. Investigating the location of earthquakes on the Firoozkouh fault and then Chashm fault and Astaneh Fault in the cross sections.
Economic Geology
Zafari Zafar Abad; Ebrahim Tale Fazel; Mehrdad Barati; Abbas Oroji
Abstract
The Yenganli gold deposit is one of the important indices of the Takab orefeild is located in the southern Zarshuran deposit and 42 km north of Takab Province. Based on structural subdivision of Iran, this deposit is situated between the Sanandaj-Sirjan zone and Uremia-Dokhtar magmatic arc and is related ...
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The Yenganli gold deposit is one of the important indices of the Takab orefeild is located in the southern Zarshuran deposit and 42 km north of Takab Province. Based on structural subdivision of Iran, this deposit is situated between the Sanandaj-Sirjan zone and Uremia-Dokhtar magmatic arc and is related to sedimentary-hydrothermal activities of the Takab orefield. The Yeganli deposit in the western part of the NW-SE-trending Iman Khan anticline and is similar to the Zarshuran deposit is composed of three Neoproterozoic lithostratigraphic unites, including, schist and serpentinite (Iman-Khan unit), limestone and dolomite (Chaldagh unit) and black shale and siltstone (Zarshuran unit). Mineralization occurs as vein-type, disseminated and breccia with a NNE-trending and 5 km2 thickness in the Zarshuran shale and siltestone and Chaldagh limestone host rocks.
Tectonics
shima afkhami; Ahmad Alavi; Mohammad Reza Yamini; Mohamad Reza Ghasemi
Abstract
The main purpose of this study is to investigate and structureral analyzes of Sirri oil field by subsurface geophysical data. In order to Seismic interpretation from 3 seismic lines (LL3, LL4 and LL5) picked up by Iranian Offshore Oil Company and SIC-1 well Data was used. In addition to interpreting ...
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The main purpose of this study is to investigate and structureral analyzes of Sirri oil field by subsurface geophysical data. In order to Seismic interpretation from 3 seismic lines (LL3, LL4 and LL5) picked up by Iranian Offshore Oil Company and SIC-1 well Data was used. In addition to interpreting the geological horizons and understanding the stratigraphic-structural evolution of the region they have also been used. The study area is located in the south of Iran and in the Persian Gulf. In this study, the geological analysis of the area has been studied by two-dimensional seismic surveying method and petrophysical images (up to Darian Formation) and Petrel software. The results show that the rising of the salt dome related to the Hormuz series has affected the overlying Formations in these field, and has created a dome shaped state for most of the Formations. Rising of the salt and folding of the sediments eventually resulted in faulting of the sediments. During the study and measurement of the angle between the edges, it was found that 15.2% of the folds are open and 84.8% are of the soft folds.
Petrology
Abdolhamid Ansari
Abstract
The Chahargonbad batholite is located close to Sirjan and southeast of Urumieh-Dokhtar magmatic zone. The batholite's composition is acidic to intermediate that is intruded into the Eocene volcanic rocks. Although the main volume of these rocks consisted of granodiorite and monzogranite, this mass ...
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The Chahargonbad batholite is located close to Sirjan and southeast of Urumieh-Dokhtar magmatic zone. The batholite's composition is acidic to intermediate that is intruded into the Eocene volcanic rocks. Although the main volume of these rocks consisted of granodiorite and monzogranite, this mass contains numerous mafic microgranular enclaves with a combination of diorite and monzodiorite. Also, microgranular dykes have cut the mafic mass. Existence of field evidence such as mafic microgranular enclaves with spherical to oval shapes, bell and rod shaped mafic microgranular enclaves, the presence of synplutonic mafic dykes, as well as textural disequilibrium evidences indicate the absence of plagioclase with oscillatory zoning and repeated analytical levels, and Osley quartz in the presence of enclaves. As they grow, they are minerals and evidence for magmatic mixing. Enclaves show higher values than the host rock in most of the basic elements, such as Al2O3, CaO, MgO, Fe2O3, TiO2, P2O5. The elements (REE), host granite rocks and associated enclaves show relatively differentiated REE patterns with sloping LREE patterns and flat MREE and HREE patterns. Based on the tectonomagmatic environment determination diagrams, all samples from the Chahargonbad (studied area) are located in the arc island setting due to subduction and show the characteristic of active continental margin setting.
Tectonics
Mohammad Amir Alimi
Abstract
This paper presents the results of a field study aiming to describe and to interpret origin of the vein network in the south of Birjand. Adjacent to Birjand ophiolite in eastern Iran, the Paleocene-Eocene flysch facies was deposited in the Birjand foreland area concomitant with the Alpine orogeny (Laramide). ...
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This paper presents the results of a field study aiming to describe and to interpret origin of the vein network in the south of Birjand. Adjacent to Birjand ophiolite in eastern Iran, the Paleocene-Eocene flysch facies was deposited in the Birjand foreland area concomitant with the Alpine orogeny (Laramide). The sandstone unit of this facies contain two orthogonal sets of quartzite veins. The N310-340 striking veins (set 1) are arranged parallel to the Bagheran Kuh range front and perpendicular to the vein set 2 (N215-240). The paleostress reconstruction in the Paleocene-Eocene shows that the regional compression direction N240 is perpendicular to the Bagheran Kuh range front. Structurally, to create orthogonal veins, σ1 should be perpendicular to the layering and σ2 and σ3 should be horizontal. This situation was created in the middle Eocene-Oligocene. The post-collision extensions of this period caused a decrease in regional pressure in the region. As a resault, the maximum principal stress (σ1), was changed to a vertical state and intermediate stress (σ2) was parallel to the orogenic pressure. In these conditions, orthogonal tensile openings (state I) were formed as a result of the local inversion of stress and fluid pressure in the flysch facies.
Stratigraphy and Palaeontology
Toran Khamoshi; Ahmad Lotfabad Arab; Mohammad Reza Vaziri
Abstract
In order to study the Lower Cretaceous deposits' coral fossils, the Baghin section was chosen and sampled. This section consists of a sequence of green marl, limestone and shaly limestone deposits. In this section, diverse groups of microfossils (orbitolinids, algae and ostracods) and macrofossils ...
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In order to study the Lower Cretaceous deposits' coral fossils, the Baghin section was chosen and sampled. This section consists of a sequence of green marl, limestone and shaly limestone deposits. In this section, diverse groups of microfossils (orbitolinids, algae and ostracods) and macrofossils (corals, echinoids, bivalves, brachiopods, gastropods,…) are present. The presence of diverse collection fossils, especially large orbitolinid foraminifera indicated a favorable environmental conditions and absence of planktonic foraminifera indicated shallow environmental conditions. Also, the presence of platycopid and podocopid ostracods and corals confirm the shallow, warm, light and suitable paleoecological conditions.
