Original Research Paper
F Shirezadeh Esfahani; N Kohansal Ghadimvand; A Kangazian; S.H Hejazi; V Hairapetian
Abstract
The Vazhnan Formation in the Shahreza-Abadeh belt, apparently extending from latest Carboniferous to Asselian, consists of conglomerate, limestone, sandstone and shale, which is correlative to the Dorud Formation of the Alborz Mountains and the Zaladou Formation of Central Iran. This work is presenting ...
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The Vazhnan Formation in the Shahreza-Abadeh belt, apparently extending from latest Carboniferous to Asselian, consists of conglomerate, limestone, sandstone and shale, which is correlative to the Dorud Formation of the Alborz Mountains and the Zaladou Formation of Central Iran. This work is presenting some results on revision of the lithostratigraphy of the Vazhnan Formation in the Tang-e-Darchaleh section (northeast of the Shahreza town). Introduction of this interval in the Banarizeh section (north of the Abadeh town) and correlation of the Vazhnan Formation in the sections understudied are other purposes. Based on the results of this study, Vazhnan Formation in the Tang-e-Darchaleh (as the type section) and Banarizeh (as the reference section) section is distinguished with the distinct eroded surface at the base and rests disconformably on the sandstones of Late Carboniferous, corresponding to the Sardar Formation. The upper part of this interval is disconformably overlain by the Surmaq Formation (late Early–Middle Permian) in the Banarizeh section. Field investigations revealed that the contact between the Vazhnan and Surmaq Formations in the Tang-e-Darchaleh section is faulted. The vertical and lateral changes of the lithofacies in the Vazhnan Formation indicate the depositional system which is evolved from a distal into a homoclinal ramp setting.
Original Research Paper
M Khademi; F Ghaemi; S.K Hosseini; F Ghaemi
Abstract
In this paper, the feedback or interaction between tectonic and surface processes in the Binaloud Mountains and Neyshabour plain has been investigated. To achieve this, we have used topographic data, recorded earthquake data provided by the Geophysical Institute of Tehran University (Mashhad center) ...
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In this paper, the feedback or interaction between tectonic and surface processes in the Binaloud Mountains and Neyshabour plain has been investigated. To achieve this, we have used topographic data, recorded earthquake data provided by the Geophysical Institute of Tehran University (Mashhad center) and field surveying results. Surface processes affect the propagation of tectonic thrust wedges in orogenic belts. In regions where tectonic processes have led to an increase in the surface slopes due to development of mountain highs, surface processes will justify the uplifted areas by smoothing the slopes, eventually shedding off a massive load of clastic sediments into the foreland basin. Because of their huge weight and volume, these sediments prevent the forward propagation of the wedge and therefore increase the accumulation rate of stress in the orogenic wedge. Also the increase of fault-plane dips in the orogenic wedge will make the slip along the fault planes hard or even impossible. Formation of out-of-sequence faults and back-rotation of preexisting thrust faults may be considered as results of these accumulated stresses. North Neyshaboor thrust fault is a later or secondary structure and can be considered as an out-of-sequence thrust because it cuts other thrust sheets and limbs of folds. Our research shows that the high volume of Paleogene/Neogen sediments in the Neyshabour foreland basin has prevented the forwards (southwestward) propagation of the Binaloud mountain range as the orogenic wedge. Releasing of the accumulated forces has therefore led to the development of the North Neyshaboor out-of-sequence fault and back-rotation of former thrust faults.
Original Research Paper
R Entezari; S.A Alavi; M.R Ghassemi
Abstract
Metamorphic rock assemblage of southern Salmas area is located in the northwestern terminal part of Sanandaj-Sirjan zone, and includes various rock types. This study uses field observations plus mineralogy and petrography of samples to describe and interpret the microstructures in the area. Different ...
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Metamorphic rock assemblage of southern Salmas area is located in the northwestern terminal part of Sanandaj-Sirjan zone, and includes various rock types. This study uses field observations plus mineralogy and petrography of samples to describe and interpret the microstructures in the area. Different rock units are classified into three groups based on their parent rocks, and consist of 1) metabasite, 2) quartz-feldespathic, and 3) marble. Most of these rocks have mylonitic texture but the grade and the intensity of mylonitization are different. Presence of mylonitic foliation and lineation along with other microstructures such as various porphyroclasts, mica fish, S-C fabric, and S-C' fabric demonstrate different mylonitic zones in this area. Due to differences in strain rate, parent rock type, and depth of deformation, we could distinct three mylonitic zones in the metamorphic complex. Most of these mylonitic samples show features characteristic of low to medium grade mylonites, in which mylonitization grade increases from west to east and center of the study area. Presence of ultramylonites in the central part of the area indicates increases in strain rate. Also presence of high-grade mylonites (T> 650 ºC) and migmatite imply that the deformation occurred at depths of middle to lower crust. We could discern two metamorphic phases (M1 and M2) and six deformation phases (D1, D2, D3, D4, D5, D6). Compressional deformation phase D1 occurred after Precambrian magmatism, then a metamorphic phase (M1) impressed these rocks by the Latest Cambrian. During Late Permian to Early Cretaceous, two deformation phases (D1 and D2) with a major simple shear component strongly affected the metamorphic complex, leading to the development of mylonitic zones. Synchronous with the deformation phase D2, a retrograde metamorphic phase (M2) affected the complex. At Late Cretaceous to Early Paleocene, deformation phase (D4) caused obduction of ophiolites over the metamorphic complex. Eventually, two brittle deformation phases (D5 and D6) affected all older rocks.
Original Research Paper
SH Habibimood; M.N Gorgij; KH Khosrotehrani; A Saidi; S.A Aghanabati
Abstract
The studied section is located in the vicinity of the village Daghal on the Zabol – Nehbandan road, 100 kilometersfrom Zabol. The strata under study are 55.57 meters thick here and lie nonconformably on the igneous rocks while the upper contact is now known. In this study the mentioned strata are ...
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The studied section is located in the vicinity of the village Daghal on the Zabol – Nehbandan road, 100 kilometersfrom Zabol. The strata under study are 55.57 meters thick here and lie nonconformably on the igneous rocks while the upper contact is now known. In this study the mentioned strata are divided into four units lithologically. The results of macroscopic and microscopic studies and the microfacies analysis show that the strata were deposited in four sub-environments including, lagoon, tidal channel, submarine fans and open marine. The thickness and extent of the marine sub-environment is greater than the other sub-environments. The study of microfacies and their constituent sub-environments implies that the mentioned section is formed in a homoclinal carbonate ramp. This study indicates that during the late cretaceous there was a relatively shallow sea covered the area. The existence of microfossils such as Orbitoeides, Omphalosyclus and globutruncana indicates the age of Maastrichtian for the rock unit studied.
Original Research Paper
S Bayetgoll
Abstract
The integration of ichnologic data with sedimentology analyses allows for discrimination between delta and open marine deposits of the Nayband Formation (Upper Triassic) in the Central Iran, Kerman. Relying on the facies characteristics and stratal geometries, the siliciclastic successions are divided ...
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The integration of ichnologic data with sedimentology analyses allows for discrimination between delta and open marine deposits of the Nayband Formation (Upper Triassic) in the Central Iran, Kerman. Relying on the facies characteristics and stratal geometries, the siliciclastic successions are divided into two facies associations, FA (open marine), FB (fluvial-dominated delta). The river-dominated deltaic assemblage includes facies that have been deposited in prodelta, distal delta front, proximal delta front, and mouth bar environments. The overall sedimentological and ichnological characteristics suggest deposition facies association A within the river-dominated deltaic environment. The open-marine facies association includes facies that have been deposited in shelf-offshore, offshore transition, distal lower shoreface and proximal lower shoreface environments. Facies association A and B of the Nayband Formation display markedly different suites of ichnofossils throughout the different depositional subenvironments. The fluvial-dominated delta successions are characterized by numerous physical and chemical stresses that can strongly influence the behavior of burrowing organisms. Three trace fossil assemblages are identified in the fluvial-dominated delta deposits. High rates of fluvial discharge, high water turbidity, seasonally high rates of deposition and phytodetrital pulses in river-dominated deltas may cause marked variations in the temperature, oxygenation and salinity of the fluvial-dominated delta successions. All of these factors in combination lead to reduction in diversity and abundance of infauna, small trace fossil size, and sporadic distribution of burrowing and lower intensities of bioturbation of trace fossil suite of river-dominated deltaic successions. Open marine deposits contain ichnological signatures characterized by moderate to intense bioturbation, high assemblage diversities and larger trace fossil size compared with the river-dominated delta successions. The occurrence of diverse and robust trace fossil suites attributable to the Zoophycos, Cruziana and Skolithos ichnofacies point to unstressed environmental conditions in open marine setting.
Original Research Paper
F Mousivand; E Rastad; M.H Emami; J Peter; M Solomon
Abstract
The Bavanat (Jian) pelitic-mafic- / Besshi-type Cu-Zn-Ag volcanogenic massive sulfide deposit locates in the Bavanat area, South Sanandaj-Sirjan zone. Mineralization occurs as two stratigraphic ore horizons discontinuously within the Surian metamorphosed volcano-sedimentary complex through more than ...
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The Bavanat (Jian) pelitic-mafic- / Besshi-type Cu-Zn-Ag volcanogenic massive sulfide deposit locates in the Bavanat area, South Sanandaj-Sirjan zone. Mineralization occurs as two stratigraphic ore horizons discontinuously within the Surian metamorphosed volcano-sedimentary complex through more than 35 km in the area. Stratigraphicaly, from footwall toward hangingwall, four ore facieses were distinguished within the Bavanat (Jian) orebodies including: 1) vein-veinlets or stringer, 2) vent complex, 3) bedded-banded, and 4) hydrothermal-exhalative sediments. The ores have various primary and secondary textures and structures, although most of the primary ones were obscured during metamorphism and deformation. The relict primary textures include massive, semi-massive, banded, brecciated, disseminated and vein-veinlet ores. In the stringer and specially in the vent complex facies, chalcopyrite replaced pyrite indicating influx of a hot copper-rich fluid into the pyrite-rich massive ores during zone refining process. Also, a metal and mineralogical zonation is obsereved in the Bavanat deposit. The major wall rock alterations in the Bavanat deposit from center to margins are silicic, quartz-chlorite, chloritic, chlorite-carbonate and chlorite-sericite, which show zonal pattern. Based on electron microprobe studies, chlorite is of iron-rich type. The abundant pyrrhotite in the Bavanat deposit might be due to low oxygen and sulfur fogacity, and occurrence of abundant chlinochlor in the alteration zones may indicate low pH (between 4.3 and 5.3) conditions for the ore-forming fluids. The high amounts of Cu and Zn, and low amounts of Pb, along with fluid inclusion studies results indicate high temprature (300-350 °C) for the ore fluids. Based on this study, the ore fluids responsibe for formation of the Bavanat deposit were hot, reduced and acidic, which entered into a confined marine basins, followed by ore deposition.
Original Research Paper
M Raziani; M Vahidinia; A Sadeghi
Abstract
This study on the planktonic foraminifera of the Surgah Formation was carried out .three biozones are proposed for the Late Turonian – Early Santonian interval in Surgah anticline (Southwest Ilam).Based on planktonic/benthonic foraminiferal ratios and “van der zwaan” equation, a general ...
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This study on the planktonic foraminifera of the Surgah Formation was carried out .three biozones are proposed for the Late Turonian – Early Santonian interval in Surgah anticline (Southwest Ilam).Based on planktonic/benthonic foraminiferal ratios and “van der zwaan” equation, a general deepening of depositional environment is indicated from Late Turonian – Early Santonian ages.During the early late Turonian, A (deeper) upper bathyal environment of about 1000 m water depth is indicated (96-98 % planktonic foraminifera, with a relatively large number of keeled and non – keeled specimens).The middle late to latest Turonian interval is characterized by 70 – 90 % planktonic foraminifera with keeled specimens dominating and rarely none – keeled and very rarely heterohelix, pointing to an upper bathyal depositional environment ( 500 m water depth), eutrophication to oligotrophication conditions. During early Coniacian , water depth falling slowly and characterized by 65 – 80 planktonic foraminifera with keeled forms dominating, oligotrophication conditions.Then in late Coniacian water depth rising (1000 m water depth), none – keeling dominating that pointing to eutrophication conditions. A (shallow) upper bathyal environment (400 m water depth), dominated by keeling foraminifera, oligotrophication condition, during the early santonian, is indicated by 45-60 % planktonic foraminifera but there are a short time of raising water depth before upper surgah that is indicated by 90% planktonic foraminifera, with dominated by none-keeling foraminifera specimens, eutrophication condition. In general, an open marine deep water environment (upper bathyal) is indicated by the Late Turonian to early Santonian planktonic foraminiferal faunas, influenced by periods of eutrophication to oligotrophication repeatedly.
Original Research Paper
GH Abbasi; M Ebrahimi; M Sharifi; N Shirdashtzadeh; J Ahmadian
Abstract
The studied volcanic rocks to the northeast of the Gavkhuni playa lake are composed of rhyolite, trachydacite, trachyandesite and pyroclastic rocks including lithic tuff and volcanic breccia. Rhyolitic rocks have flow structure and hyalophyric texture with glassy to cryptocrystalline ...
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The studied volcanic rocks to the northeast of the Gavkhuni playa lake are composed of rhyolite, trachydacite, trachyandesite and pyroclastic rocks including lithic tuff and volcanic breccia. Rhyolitic rocks have flow structure and hyalophyric texture with glassy to cryptocrystalline matrix in which quartz and feldspar crystal are present. The dominant texture in trachydacitic and trachyandesitic rocks in porphyritic texture in which plagioclase and rarely sanidine phynocrysts are set in a glassy to microcrystalline groundmass containing feldspar microlites. In trachydacites, quartz is present as small crystals and rarely as microphynocrysts. Plagioclase phynocrysts in trachydacitic and trachyandesitic rocks display sieve-texture. Amphibole and biotite are the mafic minerals of the volcanic rocks and they are partialy, at rims, or completely altered to Fe-Ti oxides. All of the studied rocks are high- K calc-alkaline in nature. According to the geochemical data, the volcanic rocks are depleted in high field strength elements such as Nb, Ti and Ta and enriched in large ion lithophile elements like Cs, K, Ba, Rb and Th which are characteristics of subduction related volcanic rocks. Nb negative anomaly is characteristic of continental rocks and indicates the continental crust involvement in the magmatic processes. The rocks are enriched in Cs, Rb, Ba and Pb indicating mantle metasomatism by fluids released from subducting oceanic lithosphere. Therefore, magma contamination and mantle metasomatism have affected the magma from which the volcanic rocks of the Gavkhuni playa lake have were generated. The calc-alkaline magmatism in the study area was associated with the closure of the Neotethyan Ocean.
Original Research Paper
F Vaez-Javadi
Abstract
The East Yurt mine, SE Azadshahr, Golestan Province contains well preserved plant macrofossils containing nineteen species allocated to thirteen genera of various orders viz., Equisetales, Filicales, Cycadales, Bennettitales, Ginkgoales, and Coniferales. The plant macrofossils in this area are studied ...
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The East Yurt mine, SE Azadshahr, Golestan Province contains well preserved plant macrofossils containing nineteen species allocated to thirteen genera of various orders viz., Equisetales, Filicales, Cycadales, Bennettitales, Ginkgoales, and Coniferales. The plant macrofossils in this area are studied for the first time. Based on the occurrence of Pterophyllum bavieri, Pterophyllum nathorsti,and Baiera muensteriana a Rhaetian age is suggested for this assemblage. Since, there was no differentiation between formations in geological map, these flora confirms spreading of the Kalariz Formation in this area. The East Yurt mine flora is correlated to the plant macrofossil assemblages of Minoodasht, Narges-Chal, Zirab, Tazareh, Ashtar, Abiek, and Jajarm (Alborz Mountains), Ghadir Member of the Nayband Formation in the Parvadeh mines (Tabas Block), and Darbid-Khun (Kerman Basin). Moreover, this assemblage evidenced in Europe (Germany, Austria, Sweden, Greenland, France, Denmark), China, Turkistan, and the Central Asia. Therefore, there were close floristic relationships between North and Central-East Iran (Kerman Basin and Tabas Block) and these area were palaeogeographically closely related, probably forming a uniform paleoenvironment and palaeoclimate during the Late Triassic. Furthermore, Iran was located at the Middle Asia Province among the Euro-Sinian Region of Vakhrameev climatic belt subdivisions and the South-western Region of Dubroskina’s subdivisions during this time.
Original Research Paper
R Hajialioghli; H Fakharinezhad; M Moazzen
Abstract
The study area (Siyah-Cheshmeh), is located to the south Maku in the Khoy-Maku ophiolite zone. The various outcropped metamorphic rocks include serpentinites, metabasites (green schist, amphibolite) and meta-pelitic rocks (slate, mica-schist) with interlayers of marble and quartzite. The amphibolites ...
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The study area (Siyah-Cheshmeh), is located to the south Maku in the Khoy-Maku ophiolite zone. The various outcropped metamorphic rocks include serpentinites, metabasites (green schist, amphibolite) and meta-pelitic rocks (slate, mica-schist) with interlayers of marble and quartzite. The amphibolites can be classified as actinolite-amphibolite, epidote-actinolite- amphibolite, biotite-amphibolite, amphibolite and garnet-amphibolite. They have fine- to coarse-grained granoblastic texture. On the basis of whole rock chemistry, the protolith composition of the amphibolites has been determined as basalts with tholeiitic and less commonly, calc-alkaline affinities, developed in an island arc setting. The negative anomaly of Nb as well as small enrichments in LILE and LREE support arc related and tholeiitic signatures for the protolith. Considering the unknown age of the studied amphibolites, it is difficult to propose an appropriate tectonic model for formation of the investigated rocks. If the amphibolites are related to the Khoy-Maku ophiolitic complex, then they would be the result of subduction of the northern branch of the Neotethys ocean basin, development of an island arc and eventually metamorphism of the rocks due to closure and collision. Since the age is not clear, it is not possible to conclude unequivocally if the rocks are results of the Neotethys subduction system or they are related to an older, possibly a Precambrian subduction system. Dating the rocks will help to propose a suitable model for their formation.
Original Research Paper
A Mohammadi; B Nekouie Sadri; S.S Hashemi; A Bayatani
Abstract
In 21st century, geologists of the developed countries paid special attention to the usage of criteria for evaluation of geodiversity and introduction of the country’s geoheritage to conserve this valuable heritage and its usage in sustainable way. Conservation and utilization of geoheritage or ...
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In 21st century, geologists of the developed countries paid special attention to the usage of criteria for evaluation of geodiversity and introduction of the country’s geoheritage to conserve this valuable heritage and its usage in sustainable way. Conservation and utilization of geoheritage or mining heritage is carried out in the framework of introducing a national or global region as geopark. Geopark is an under protection area that in addition to the geosite richness contains historical, cultural, and natural (ecosites) places. Making use of efficient management and proper training of local people and emphasizing on recreational teaching of geological and environmental concepts, it can attract tourists to fill their time through interpretation of all attractions in a way that this measurements cause improvement in economic-social situation of the local people as well as all people in the country. The study area is located around the world heritage site, namely Takht-e-Soleiman in the northwest of Iran that is rich from geodiversity, biodiversity and historical-cultural diversity points of view. However, the study area is economically poor. Accordingly, establishment of a geopark in the region can increase job creation, prevent immigration of villagers to the cities and flourish economic life of the region. In this study, two methods used for evaluation of criteria each of them includes some parameters and sub-parameters. Based on calculated scores for each site and making use of interpolation methods in GIS environment, the geopark territory and the best geotrail were selected.
Original Research Paper
M Hamidian Shirazi; A Saeedi; A Solgi; K Yazdjerdi
Abstract
The Zagros orogen is located along the central part of the of Alpine-Himalayan orogenic belt, and is one of the world’s youngest orogenic systems. Geological and deformational characteristics of this orogen are completely different from other parts of the Alpine orogenic belt. Of the most obvious ...
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The Zagros orogen is located along the central part of the of Alpine-Himalayan orogenic belt, and is one of the world’s youngest orogenic systems. Geological and deformational characteristics of this orogen are completely different from other parts of the Alpine orogenic belt. Of the most obvious structural features of the Zagros orogen are the occurrence of large-scale folds. The lack of geometrical uniformity along their axes is the most important character of these folds. General trend of the structures formed in the Zagros region (folds and major faults) is northwest–southeast, which is locally deflected due to different reasons such as effects of large fault zones. In some places, the changes in the initial pattern of folds may be related to more than one tectonic parameter. The simultaneous operation of two or more parameters such as faulting or salt penetration can also significantly change the fold patterns. The Ahmadi anticline, which is located 50 km east of Shiraz, is one of such folds where this property (i.e. changes in fold pattern) can be investigated. The fold has a box fold model with the axis trending NNW-SSE, and is located south of the Main Zagros Thrust Fault, as well as close and parallel to it. It is also situated in the Zagros folded zone and forms the northern boundary of the Sarvestan plain. The Ahmadi anticline is an open and symmetric fold, trending along NNW-SSE direction. Along the anticline, the fold axis is never straight and has been deflected at several points. The most significant fold axis deflection is observed along the eastern termination of the anticline, where the fold axis is deflected by about 62 degrees toward south.
Original Research Paper
F Chegeni; D Baghebani; S.H Vaziri; T Mohtat; N Kohansal Ghadimvand
Abstract
For the purpose of biozonation of the Pabdeh Formation (Middle-Upper Eocene) based on planktonic foraminifera, a stratigraphic section in the southern slope of the Mishan Mountain and another in the Eshgar Mountain were studied. The thickness of these sections is 162.5 and 150 meters, respectively. The ...
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For the purpose of biozonation of the Pabdeh Formation (Middle-Upper Eocene) based on planktonic foraminifera, a stratigraphic section in the southern slope of the Mishan Mountain and another in the Eshgar Mountain were studied. The thickness of these sections is 162.5 and 150 meters, respectively. The Pabdeh Formation in the southern slope of the Mishan Mountain consists of marl, marly limestone, shale and limestone, and in the Eshgar Mountain includes alternating cream limestone and thin-bedded marl. In this study, most of the identified microfauna are Planktonic foraminifera. Identified Planktonic and benthic foraminifers in the southern slope of the Mishan Mountain include 18 genera and 8 species, and in the Eshgar Mountain include 21 genera and 10 species. Also four biozones are introduced of which one belongs to the Mishan Mountain and three belong to the Eshgar Mountain as follow: Hantkenina nuttalli Range Zone; Hantkenina nuttalli Turborotalia cerro-azulensis Interval Zone; Turborotalia cerro-azulensis Range Zone; Turborotalia cerro-azulensis/ Hantkenina sp. Assemblage Zone.
Original Research Paper
S Aghajani Marsa; M Emami; M Lotfi; k Gholizadeh; M Ghasemi Siani
Abstract
The mineralized veins at Nikuyeh are located south of the Tarom-Hashtjin metallogenic province in Alborz-Azarbayejan belt (West Alborz). Rhyodacite and andesite/andesitic basalt volcanic rocks are hosting the vein mineralization in the Nikuyeh ore district. Hydrothermal alteration in host rocks consists ...
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The mineralized veins at Nikuyeh are located south of the Tarom-Hashtjin metallogenic province in Alborz-Azarbayejan belt (West Alborz). Rhyodacite and andesite/andesitic basalt volcanic rocks are hosting the vein mineralization in the Nikuyeh ore district. Hydrothermal alteration in host rocks consists of propylitic, sericitic, argillic and silicic. Mineralization in Nikuyeh occurs in both hypogene and supergene forms in three stages: early stage includes pyrite, magnetite, chalcopyrite and bornite; middle stage includes galena, sphalerite and minor chalcopyrite, and late stage includes malachite, cerussite, covellite, hematite and goethite. Fluid inclusion studies on quartz and calcite show homogenization temperatures ranging between 185°C to 312°C and 133°C to 251°C, respectively. The salinities range from 0.5 to 5.5 wt% NaCl eq. in quartz and 0.3 to 5.4 wt% NaCl eq. in calcite. Boiling is supported by the occurrence of coexisting vapor-rich and liquid-rich inclusions, hydrothermal breccias, microcrystalline quartz, chalcedony and bladed calcite. Boiling and cooling are considered as the main mechanisms for ore deposition. Ore mineralogy, alteration assemblages and fluid inclusion data allow mineralization in Nikuyeh ore district to be classified as low sulfidation epithermal type.
Original Research Paper
M Talebian; M Shahpasand-Zadeh; Y jamour; M.R Sepahvand; A Arabpour
Abstract
Determination of inter-seismic deformations such as fault slip-rate can usually be achieved by using geodetic observations, earthquake geology and paleo-seismology, as well as mechanical, empirical and numerical modeling. In these models, combination of the fault seismic parameters and the GPS data can ...
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Determination of inter-seismic deformations such as fault slip-rate can usually be achieved by using geodetic observations, earthquake geology and paleo-seismology, as well as mechanical, empirical and numerical modeling. In these models, combination of the fault seismic parameters and the GPS data can help estimate the fault slip-rate, the elastic thickness of the lithosphere, the earthquakes recurrence time, the relaxation time of the asthenosphere, the elapsed time of earthquake and the locking depth of the fault. In this study, we utilize the geodetic data of the North Tabriz Fault (NTF) by using random Bootstrap sampling and conducting numerical modeling by code writing in the R and MATLAB softwares. In this concern, the fault slip-rate and elastic layer thickness are estimated to be ~4-6.5±1 mm/yr and ~5-25 km, respectively, for the NW segment of the NTF. Similarly, model results for the SE segment of the fault indicate a slip-rate of ~3.5-5.5±1 mm/yr and elastic layer thickness of ~8-16 km. For the NW segment of the NTF, the asthenosphere relaxation time, earthquake recurrence time and elapsed time are estimated to be ~160-185 years, ~650-950 years and ~200-1400 years, respectively. Model results for the SE segments of the NTF indicate an asthenosphere relaxation time of ~220-340 years, an earthquake recurrence time of ~750-1050 years and an elapsed time of ~200-1500 years, respectively. The results are well consistent with the other paleoseismological and geological results.
Original Research Paper
M.R Hosseinzadeh; S Maghfouri; M Moayyed; A Rahmani
Abstract
The Khalifehlu Cu-Au deposit is located ~7 km North of Khoramdareh, in the central part of the Tarom magmatic zone. Rock units exposed in the area consist of volcanic, subvolcanic and intrusive rocks, which are associated with Eocene tectonics and Magmatism. Volcanism started with large-scale ...
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The Khalifehlu Cu-Au deposit is located ~7 km North of Khoramdareh, in the central part of the Tarom magmatic zone. Rock units exposed in the area consist of volcanic, subvolcanic and intrusive rocks, which are associated with Eocene tectonics and Magmatism. Volcanism started with large-scale andesitic-trachyandesitic lavas and pyroclastics; continued by rhyolite domes, and culminated by a quartzmonzonite porphyry. Copper-gold mineralization at the Khalifehlu is intimately associated with the breccias and veins. The highest grade and most extensive mineralization occurs in silicic veins. Two stages of mineralization are identified at the Khalifehlu area that progressed from regional breccia (phase 1 from stage 1) to Au- bearing silicic- sulfide vein- veinlet (phase 2 from stage 1) to oxide-dominant breccias (phase 1 from stage 2) to specularite vein- veinlet (phase 2 from stage 2). Gold occurs with sulfide minerals as disseminations, as well as in the veins and breccia cemented during phase 2 from stage 1. The wall–rock alteration in the Khalifehlu deposit exhibits a clear concentric zoning pattern. The vuggy quartz and argillic alteration are spatially and closely associated with high-grade gold mineralization, and are mainly developed along veins and in breccias. Propylitic alteration is widespread around the ore bodies. Pyrite, chalcopyrite, bornite, covollite, chalcocite, hematite and native gold are present in the ores. The ore minerals show disseminated, vein-veinlet, replacement, fibrous and breccia textures. We suggest near-surface emplacement of volatile-rich quartzmonzonite porphyry, followed by extensive brecciation and hydrothermal alteration-mineralization. The geology, alteration, and mineralization in the Khalifehlu deposit is similar to high-sulfidation type epithermal deposits.
Original Research Paper
S Enayati Kolaie; M Yazdi; M.A.A Mokhtari
Abstract
Tazeh-Kand Cu mineralization area is located in ~20 km northeast of Tabriz, eastern Azarbaijan province. The area is a part of Central Iranian geo-structural zone in the eastern margin of the Tabriz 1:100000 geological map. Lithological units in this area composed of green- grey sandstones (redox zone), ...
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Tazeh-Kand Cu mineralization area is located in ~20 km northeast of Tabriz, eastern Azarbaijan province. The area is a part of Central Iranian geo-structural zone in the eastern margin of the Tabriz 1:100000 geological map. Lithological units in this area composed of green- grey sandstones (redox zone), red sandstones and marl (oxidized zone), salt domes and conglomerate (Miocene) along with dacitic domes (Pliocene). Based on petrographical investigations, the host sandstones are sub- mature to immature lithic arkos and were deposited in a tidal environment. Cu mineralization in this area occurred as stratiform type within the redoxed sandstones. The thickness of mineralized horizons vary between 30cm to 1m which are crops out up to 500m in some horizons. Concentration of Cu mineralization has direct relation with organic matter concentration. Mineralized horizons composed of three zones include: mineralized redox zone, bleached zone and red oxidized zone. Mineralogical investigations show that this mineralization composed of primary sulfide minerals include pyrite, chalcocite and digenite along with supergene minerals include covellite, malachite and Fe- hydroxides. Texturally, these minerals present as lenticular, disseminated, replacement, inter- grain cement and solution seems textures. According to petrographical and mineralogical results such as pyrite and primary chalcocite bearing redox sandstone, structural and textural evidences, stratigraphy, mineralization controlling factors, presence of organic matter as a redox material, permeability of host rock and salt diapirism, mineralization in the Tazeh-Kand area is mostly similar to RedBed type mineralization which is formed during the early to late diagenesis.
Original Research Paper
S Abbasi; B Hamdi; M.R Majidifard
Abstract
Study of conodont fauna from the Illanghareh Formation in Illanghareh, Illanlu and Pir-Eshag sections provide new data on the stratigraphy of this formation in the North West Iran. Illanghareh section is a terrigenous-carbonate rock sequence, consists mainly of quartzarenite sandstone, shale, and carbonate ...
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Study of conodont fauna from the Illanghareh Formation in Illanghareh, Illanlu and Pir-Eshag sections provide new data on the stratigraphy of this formation in the North West Iran. Illanghareh section is a terrigenous-carbonate rock sequence, consists mainly of quartzarenite sandstone, shale, and carbonate rocks. This sequence generally represents shallow-water Polygnathid-Icriodid biofacies and yielded five biozones: varcus, Older than rhenana, rhenana – linguiformis, Middle triangularis – Late trachytera, postera – expansa. Tectonic activities and erosion caused the Middle Devonian strata in the base of Illanghareh section to be omitted and the varcus Biozone is not recorded. Upper Devonian (Upper Famennian) rock units change into Carboniferous strata with a sedimentary gap though it is not recognizable in the field and no evidence of erosional surface is recognized. It is however, shown between Late Famennian and Late Turnaisian via conodonts recorded. The biozone bilineatus- bolandensis was also recorded in lower part of Carboniferous strata studied here.
Original Research Paper
M Daryapeyma Hormozi; H Biabangard; S Bagheri; M.R Bakhshi Mohebi
Abstract
Dasht Kuh volcanic complex is located to ~75 km to the north of Iranshahr. It consists of two parts: A (main body) and B (the isolated part in the northern Dasht Kuh). Based on the geological maps of the area, the volcanic bodies intruded the flysch type rocks of the East Iran in Cretaceous; the rocks ...
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Dasht Kuh volcanic complex is located to ~75 km to the north of Iranshahr. It consists of two parts: A (main body) and B (the isolated part in the northern Dasht Kuh). Based on the geological maps of the area, the volcanic bodies intruded the flysch type rocks of the East Iran in Cretaceous; the rocks are separated from Eocene conglomerate across a fault zone. The Dasht Kuh volcanic complex essentially consists of basalt, andesite, basaltic andesite and trachybasalt. The main rock-forming minerals are plagioclase, pyroxene, hornblende, and sanidine with dominant porphyritic texture. Minor pyroclastic materials occur in the lower parts of the complex.Samples rocks from of Dasht Kuh in the rare earth elements diagram relative to abundance of these elements in the Chondrite, shows a significant negative slope observed that the samples are enriched in light rare earth elements (LREE) and depletion of heavy earth elements (HREE). Different chemical composition, Tectono-magmatic and origin digrams shows that rocks in these bodies have alkaline nature of mantle origin and were formed in continental volcanic arc. It seems Dasht Kuh volcanic comlex are part of island arc that wide arc from northern Pakistan to Iran that have been separated from their origin by younger tectonic events.
Original Research Paper
H Ghasemi; M Rostami Hossuri; M Sadeghian; F Kadkhodaye Arab
Abstract
Subduction of the Neo–Tethyan oceanic lithosphere beneath the southern edge of the Central Iran caused development of extensional back-arc basins behind the Urumieh–Dokhtar magmatic belt during Mesozoic and Cenozoic. Some researchers have noted formation of the oceanic back-arc basins in ...
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Subduction of the Neo–Tethyan oceanic lithosphere beneath the southern edge of the Central Iran caused development of extensional back-arc basins behind the Urumieh–Dokhtar magmatic belt during Mesozoic and Cenozoic. Some researchers have noted formation of the oceanic back-arc basins in Nain, Sabzevar and Sistan in Central Iran during Mesozoic, but little is known about generation of such basins in Cenozoic. The depressed extensional back-arc basin of Central Iran contains sedimentary successions of intracontinental extensional environments associated with alkaline basic magmatic rocks. These magmatic rocks are outcropped in the Oligo-Miocene gypsiferous red marls (red formations), as both intrusive (gabbro) and extrusive (basalt) forms. The present study has focused on the basaltic lava flows in the Oligo-Miocene siliciclastic-evaporitic sedimentary succession extending for about 300 kilometers from Sabzevar to Shahroud along the northern edge of Central Iran. These lava flows are observed as interbedded with the Oligo-Miocene sedimentary units. In the Kalate-Sadat area, located SW of Sabzevar, there are at least five intermittent basaltic lava flows in the red marls. These basaltic rocks (with a composition of olivine-basalt to basalt) show porphyritic, glomeroporphyritic and trachytic textures and are composed of olivine, clinopyroxene and plagioclase phenocrysts in a glassy to microlitic ground mass. On the basis of geochemical data, the parent magma of these rocks had a sodic-alkaline affinity, enriched in LILEs and LREEs and depleted in HREEs, without negative anomalies in HFSEs. The basalts show the geochemical characteristics of the basaltic magmas originated from partial melting of adjusted enriched garnet lherzolite mantle source beneath the continental areas of extensional back-arc basins.
Original Research Paper
B Mostafavi; F Hadavi; M Allameh; M Notghi Moghaddam
Abstract
The Abtalkh Formation is one of the Cretaceous sedimentary units of Kopeh-Dagh sedimentary basin that consist shale and marl. This formation is rich in ostracods. This study lead to recognition of 18 genera and 48 species. The recognized assemblages of ostracods is compared with those reported from Iran ...
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The Abtalkh Formation is one of the Cretaceous sedimentary units of Kopeh-Dagh sedimentary basin that consist shale and marl. This formation is rich in ostracods. This study lead to recognition of 18 genera and 48 species. The recognized assemblages of ostracods is compared with those reported from Iran and other adjacent regions. Based on the identified species three biozones (Cytherelloidea sp1, Veenia sp2, Limburgina sp.) have been determined in this section. According to the established ostracod biozones and correlation with biozones provided based on nannofossil, the age of the Abtalkh Formation in the studied section is Late Campanian- Early Maastrichtian- Late Maastrichtian.
Original Research Paper
SH Safari; A Asghari Moghaddam; A Nadiri; K Siahcheshm
Abstract
Arsenic is one of the most toxic and dangerous soluble substances in natural water. It has long-term ill effects on human health. Arsenic-contaminated water resources have been reported from many parts of the world and Iran, particularly from the Kurdistan province in the west of the country. The aim ...
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Arsenic is one of the most toxic and dangerous soluble substances in natural water. It has long-term ill effects on human health. Arsenic-contaminated water resources have been reported from many parts of the world and Iran, particularly from the Kurdistan province in the west of the country. The aim of this study is to identify the source of arsenic and mechanisms of its release into groundwater resources of the Chahardoli plain aquifers. Groundwater resources in this plain supply much of the water needs for drinking, agriculture and industry. Therefore, 31 water samples were collected from the plain aquifer and chemically analyzed for major and minor ions in the Hydrology Laboratory of Earth Sciences Department of the Tabriz University. Also, the trace elements were analyzed in the Kurdistan Waste Water Organization Laboratory. The results show high arsenic concentrations in the groundwater of the area. The highest arsenic concentration (270 µg/L) is related to a well located in the northwest part of the area which supplies water for agricultural purposes of Delbaran sector. According to the results obtained from multi-variable and graphical methods, there is a meaningful correlation between arsenic and major ions such as Na and K as well as silica, indicating that the source of arsenic is from volcanic rocks. It is therefore a geogenic rather than an anthropogenic phenomenon. The mechanism of arsenic releases into the water can be related to competitive adsorption of dissolved SiO2 in adsorption sites such as oxides of iron, aluminium and manganese.
Original Research Paper
T Rabani; N Taghipour; R Aharipour
Abstract
Gheshlagh district contains coal deposits in a large syncline in Shemshak group sediments in East Alborz. To determine the palaeoenvironmental setting of the coal deposits based on organic and mineral components, eleven samples from coal seams from four active mines are collected. Minerals such as quartz, ...
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Gheshlagh district contains coal deposits in a large syncline in Shemshak group sediments in East Alborz. To determine the palaeoenvironmental setting of the coal deposits based on organic and mineral components, eleven samples from coal seams from four active mines are collected. Minerals such as quartz, kaolinite, pyrite, siderite, biotite, montmorillonite and dolomite are identified in Gheshlagh coal mines. The Ground Water Index (GWI) suggests ombrotrophic hydrological conditions for coal layers in Gheshlagh coal region. K13 and k11 layers have much higher GWI among others due to its higher mineral content than other layers. Vegetation index (VI) of the Gheshlagh coals is less than 3, which could indicative of the dominance of aquatic/herbaceous plants in the formation of coal seams. Petrographic data on organic and inorganic matter with facies diagram suggest evidences of anaerobic to low oxygen, alkaline conditions and variations in water level with relative proximity to the marine environment.
Original Research Paper
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.
Original Research Paper
E Farshid; B Hamdi; V Hairapetian; S.A Aghanabati
Original Research Paper
Z Tashakkori; M Ghorashi; M Pourkermani
Abstract
The Kopet Dagh zone has been an area interest for geologists due to its sedimentary and structural similarities to the Zagros zone. In this study, the Jozek-Ghetlish main fault is introduced using the results of field studies, remote sensing, stratigraphic changes and seismic activities. The studies ...
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The Kopet Dagh zone has been an area interest for geologists due to its sedimentary and structural similarities to the Zagros zone. In this study, the Jozek-Ghetlish main fault is introduced using the results of field studies, remote sensing, stratigraphic changes and seismic activities. The studies show that in terms of seismicity, the earthquakes of August 1943 (Ms 7.6) and February 1976 (Ms 4.3) are the most important events recorded on this fault. From stratigraphy point of view, the facies changes from Shoorijeh formation to Zard formation from east to west is the most obvious stratigraphic change across the fault. Thickness variation (Isopach) maps of the Shoorijeh formation also show that its sickness decreases westward to zero adjacent to the fault, where the Zard formation thickens in the same direction. Deflected and offset stream channels across the southern part of the fault indicate a sinistral displacement along it. The streams draining the Yemendagh mountains in south of Ashkhane are deflected westward across the fault, and some of them show offsets of about 60 to 130 meters. In addition, in the northern part near the reservoir of Shirin Dareh dam, the axis of the syncline supporting the dam reservoir represents a sinistral displacement in the Aytamir sandstones. Further to NE, also, fold axis displacements in the Amirabad syncline, the Miyansoo anticline and even the Gifan syncline are other indications of the left-lateral motion along the fault. According to the NE-SW trend of the fault, its sinistral mechanism, and its effect on the tectonic zonation of this region, the Jozek-Ghetlish fault can be considered as the structural boundary between the eastern and western Kopet Dagh. Also, based upon stratigraphic thickness and facies variations across the fault (Zard and Shoorijeh formation), it can be a key to understand the Kopet Dagh oil reservoirs.
