Original Research Paper
Petrology
saeid samarbakhsh; mohamad hashem emami; Seyed mojtaba Mortazavi; mansor vosoghi abedini
Abstract
The study area, situated 50 km north of Ghaemshahr, structurally belongs to the Central Alborz tectonic zone. The volcanic rocks of the area, including basalt, andesite, trachyandesite, and dolerite are the products of fractional crystallization and some contamination processes. Clinopyroxene, olivine, ...
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The study area, situated 50 km north of Ghaemshahr, structurally belongs to the Central Alborz tectonic zone. The volcanic rocks of the area, including basalt, andesite, trachyandesite, and dolerite are the products of fractional crystallization and some contamination processes. Clinopyroxene, olivine, and plagioclase are the main minerals of these rocks. Porphyritic to mega-porphyritic texture with microlithic, glomeroporphyritic, and amygdaloidal matrix are observed in these rocks. Plagioclase, hornblende, and pyroxene can be considered the main mineral phases of these rocks. The rocks are enriched in LIL and LREE elements and depleted in HFS elements. The ratios of trace elements and rare earth elements in the studied region indicate that the basalts were formed by melting a garnet bearing peridotite at great depths and pressures. Negative Ce anomaly, Nb negative anomaly, Pb positive anomaly the role of continental lithosphere in contaminating the magmatic sources of volcanic rock in the study area. The Pb/Ce ratio similar to ocean island basalt (OIB) sources, induces OIB sources, the asthenospheric mantle, in the initial formation of basaltic magma. it can be concluded that the volcanic rocks of the area have formed in an intra-plate environment in an extensional regime.
Original Research Paper
Economic Geology
Shayan Akrami; Mohammad Ali Aliabadi; Mohammadreza Hezaree; Abbas Asgari; Tayebeh Ramezani
Abstract
The Nineh deposit is a Pb-Zn deposit located in the Malayer-Esfahan metallogenic belt (MEMB) as stratabound and epigenetic mineralization hosted by middle-Jurassic limestone. The replacement and vein mineralization of galena, sphalerite with a minor amount of pyrite occurred in the foreland basin within ...
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The Nineh deposit is a Pb-Zn deposit located in the Malayer-Esfahan metallogenic belt (MEMB) as stratabound and epigenetic mineralization hosted by middle-Jurassic limestone. The replacement and vein mineralization of galena, sphalerite with a minor amount of pyrite occurred in the foreland basin within the Orumieh-Dokhtar zone. The microthermometery results of fluid inclusions trapped in calcite and barite, respectively, show homogenization temperature peak of 107 to 137°C and 150 to 170°C , and a salinity mode of 12.9 to 14.9wt.% NaCl equiv. and 4 to 6wt.% NaCl equiv.. The salinity vs. homogenization temperature diagram attests to cooling and mixing as the main mineralization mechanisms. The δ34S values of sphalerite and galena are within the range of 9.5 to 21.5‰ and 7.5 to 19.5‰, respectively and is about 43.7‰ for barite, the wide range of the sulfur isotope values is consistent with originating from different sources. Additionally, the δ13C (0.1 to 0.5 ‰) and δ18O (-9.5 to -11.5‰) values of calcite samples are in accordance with marine carbonate source and a high interaction of the ore fluids with different sources. Accordingly, the deposit could be classified as Mississippi Valley type (MVT) deposit which undergone more W/R interaction due to multiple orogenic
Original Research Paper
Tectonics
Mohammad Reza Ghassemi; Seyed Ali Aghanabati; Abdollah Saidi
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 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 Alvandi 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.
Review Article
Petroleum geology
Hanie Ghayeni; Mohamad Hosein Mahmudy Gharaie
Abstract
Investigating the hydrocarbon generation potential of the Kazhdumi Formation, which is one of the most important source rocks of the Zagros sedimentary basin, is very important and necessary, Because the tectonic movement of the main faults of Zagros, both during the deposition of Kazhdumi and after, ...
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Investigating the hydrocarbon generation potential of the Kazhdumi Formation, which is one of the most important source rocks of the Zagros sedimentary basin, is very important and necessary, Because the tectonic movement of the main faults of Zagros, both during the deposition of Kazhdumi and after, caused differences in the depth and sedimentation conditions of the different zones of this basin, and changes such as diversity in the way of sedimentation, biological facies and It has resulted in the preservation rate of organic matter. Therefore, 30 samples of this formation were selected and evaluated from different areas of Izeh zone (Perchestan ) and Dezful Embayment (Tang-E Magher , Nowrouz , Soroush , Azadegan and Binak). In this study, in addition to comparing the data of Kazhdumi Formation in different zones of Zagros, it has been tried to study the conditions of sedimentation and sedimentation environment. The recorded values for total organic carbon range from 1.2 to 6.9% and the examination of the thermal maturity of the samples shows a wide range from the immature range to the middle of the oil window,
Original Research Paper
Economic Geology
Shaghayegh Sadat Hashempour; Sajjad Maghfouri; Ebrahim Rastad
Abstract
The Goft and Mohammadabad manganese deposits are located in the southwestern part of Sabzevar, whitin the Late Cretaceous volcano-sedimentary sequences. This sequence is located inside a 100 km long folded structure with northeast-southwest trend. Mohammadabad manganese deposit located in the southeastern ...
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The Goft and Mohammadabad manganese deposits are located in the southwestern part of Sabzevar, whitin the Late Cretaceous volcano-sedimentary sequences. This sequence is located inside a 100 km long folded structure with northeast-southwest trend. Mohammadabad manganese deposit located in the southeastern edge of the southern anticline in the unit 4 of regional stratigraphic column and Goft manganese deposit is occurred in the southeastern edge of the northern anticline in the first unit of the regional stratigraphic column. respectively. According to geochemical studies, tectonic environment of manganese deposits in the southwest of Sabzevar is a rifting environment that has been formed in the Sabzevar back-arc basin. The rocks of the region have a wide range of basalt, rhyolite, dacite, olivine-basalt, andesite-basalt and trachy-andesite, which formed aligned with pyroclastic sediment and Late Cretaceous sedimentary units. Dacite rocks are the thickest felsic rock unit in the area. The values of major oxides, the pattern of rare earth elements (REE), and the changes in trace elements in spider diagrams indicate the bimodal and tholeiitic nature of the volcanic rocks of the region, which are deposited in extension environment with a mixed range from basalt to rhyolite.
Original Research Paper
Stratigraphy and Palaeontology
Ali Jalali; Hamed Yarahmadzahi; Mehran Arian; Abdollah Saidi; Seyed Mohsen Aleali
Abstract
the Shishtou section is located in the north of Tabas . Ghezelin and Asselian sequences of Zaladou Formation with 60 m thickness are divided into five units, includes sandstone, limestone, shale, sandy limestone and limestone. The lower boundary of the Gzhelian deposits with disconformity on top of the ...
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the Shishtou section is located in the north of Tabas . Ghezelin and Asselian sequences of Zaladou Formation with 60 m thickness are divided into five units, includes sandstone, limestone, shale, sandy limestone and limestone. The lower boundary of the Gzhelian deposits with disconformity on top of the Moscovian deposits of the Abshani Formation. The upper boundary of these deposits with the Tighe-Madanou Formation is continuous. Assembelage of fusulinids in the Shishtou section such as Ruzhenzevites-Rauserites-Triticites are identified in the upper part of Gzhalian previously reported from equal deposits in Darvaz, Fergana, Southern Urals, Donetsk and Carnic of Alps, as well as, Central Iran , Central Alborz and Sanandaj-Sirjan zones. Also, different species of Sphaeroschwagerina, Pseudoschwagerina and Likharevites, which illustrate the Asselian age, represent the Carboniferous-Permian boundary in the studied section and allow for comparability with other structural-sedimentary zones of Iran, including Central Iran , Central Alborz (Doroud Group) and Sanandaj-Sirjan zone.This equivalence expresses the transgressive of sea level in different parts of Iran in the late Carboniferous and early Permian periods.In Shishto section 15 genera ,35 species and 2 subspecies of Fusulins have been identified, some of which are reported for the first time from Iran.
Original Research Paper
Economic Geology
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.
Original Research Paper
Petrology
zeinab rahmanian; gholamreza ghadami; hamid Ahmadipour; Mohammad Poosti
Abstract
Dalfard granitoids are located in the south-east of Kerman province and in the margins mainly include quartz diorite. Quartz diorites contain main minerals plagioclase, amphibole and biotite and this work reveals that the rocks in this area are I type granitoides and they belong to calc-alkaline magmatic ...
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Dalfard granitoids are located in the south-east of Kerman province and in the margins mainly include quartz diorite. Quartz diorites contain main minerals plagioclase, amphibole and biotite and this work reveals that the rocks in this area are I type granitoides and they belong to calc-alkaline magmatic series. The enrichment of LREE relative to HREE, high contents of LILE relative to HFSE and anomalies of Nb and Ti in spider diagrams show that the Dalfard quartzdiorites are formed in an arc setting environment. The CaO/(MgO+FeOt) and Al2O3/(MgO+FeOt) ratios (0.55 and 1.36 respectively) show that the parent magmas were formed by the partial melting of basaltic rocks of the lower crust and mantle fluids/melts also participated in their formation. Based on geochemical data such as La/Yb(N) and Th/Yb(N) ratios (4.4 and 6.5 respectively), these magmas are related to pre-plate collision environment and formed in the mature Volcanic arc setting at a depth of about 40 km at the supra subduction zone of the Neothetys oceanic lithosphere and then, they ascent to the higher levels of the crust and passed fractional crystallization.
Original Research Paper
Sedimentology
AFSHIN KARIMKHAMI BAHADOR; SADAT FEIZNIA; Mohsen Aleali; Mehran Arian
Abstract
To prepare sedimentological data, 98 surface sampling stations have been designed from the seabed in the continental shelf in the southern part of the Caspian Sea and along the coast of Iran. Indicators such as the type and amount of sediment load transported to the sedimentation environment, the energy ...
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To prepare sedimentological data, 98 surface sampling stations have been designed from the seabed in the continental shelf in the southern part of the Caspian Sea and along the coast of Iran. Indicators such as the type and amount of sediment load transported to the sedimentation environment, the energy of waves and sea currents, as well as how the slope of the seabed changes, play a role in the production and diversity of the sedimentary facies. 9 sedimentary facies are the most abundant in the surface deposits of this area and on average, in the sediments of the continental shelf, there are 1% by weight of coarse-grained particles, 25% by weight of medium-grained particles and 74% by weight of fine-grained particles. The composition of sedimentary facies in this area is controlled by indicators such as the size of sedimentary particles, the amount of sedimentary load carried to the environment, the energy of waves and sea currents, and how the slope of the seabed changes. In the marine environment of the study area, sub-sedimentary environments, Backshore, Foreshore, Shoreface, Offshore transition zone and Offshore can be identified. The two facies of slightly gravelly Mud and Mud are more abundant than other facies.
Original Research Paper
Tectonics
Fereshteh Jafari Hajati; Maryam Agh-Atabai; Majid Nemati; Ali Biglari Fadafan
Abstract
In this research, to understand the present-day tectonic situation of Gorgan-Plain in the east of the South Caspian basin, the tectonic stress regime of this area and its adjacent areas was estimated using the inversion of the data of the earthquake focal mechanisms. For this aim, in addition to analyzing ...
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In this research, to understand the present-day tectonic situation of Gorgan-Plain in the east of the South Caspian basin, the tectonic stress regime of this area and its adjacent areas was estimated using the inversion of the data of the earthquake focal mechanisms. For this aim, in addition to analyzing focal mechanisms solved by different sources, the focal mechanisms were solved for several earthquakes with appropriate and sufficient information. The results indicate the presence of various mechanisms, including thrust, normal, and strike-slip, and as a result, various orientations of kinematic P and T axes, which can indicate the complexity of the region. By analyzing the earthquakes with a minimum magnitude of 4 in the Gorgan-plain, the Kopeh-Dagh in the east of the plain, and the entire eastern region of the South Caspian, a compression regime with a NNW-SSE trend was obtained. But by analyzing all of the earthquakes (smaller and larger earthquakes) in the Gorgan-Plain, a strike-slip regime was obtained, in which the trend of the P and T axes were calculated NE-SW and NW-SE, respectively. The results indicate that there is a local strike-slip regime in addition to the regional compressional regime in the region.
Original Research Paper
Sedimentology
Enayat Allah Haghfarshi; Payman Rezaee; Seyed Reza Moosavi Harami; Mohamad Faridi
Abstract
Lignite Beds of Tabriz are among of the Neogene formations in the northwestern area of the Iran, which is spread in the eastern suburbs of Tabriz. Its sedimentary facies includes facies groups of fine grains clastics, sandstones, limestones and facies of lignite, tuff and microfacies and petrofacies ...
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Lignite Beds of Tabriz are among of the Neogene formations in the northwestern area of the Iran, which is spread in the eastern suburbs of Tabriz. Its sedimentary facies includes facies groups of fine grains clastics, sandstones, limestones and facies of lignite, tuff and microfacies and petrofacies under them. In this study, two stratigraphic sections of these sediments in the eastern part of Tabriz were collected and studied. 171 samples and 42 thin sections were studied. XRD analysis for mineralogy and SEM electron microscopy for 3-dimensional studies were used to identify microfossils. Identified fossils include the genera and species of gastropods, Pelecypods, ostracods, fish, diatoms, charophyte algae, and foraminifera. The studied fossil assemblages includes species from freshwater to euryhaline and marine. The identified sedimentary environments include the lake basin environment, the shallow coastal environment and the marshy lake environment. Studied in sedimentary strata, strong fossil evidence and sedimentological evidence of the marine environment are not observed, at least during its lifetime. Therefore, it is concluded that the marine taxis in these deposits remain and are adapted from a former marine environment.
Original Research Paper
Geological Environment and Engineering
Abbas Zolfaghari; Mashalah Khamehchiyan; Mohammad Reza Nikudel; Abdollah Sohrabi-Bidar
Abstract
The combined effect of the number of joints, opening, type and thickness of filling on the amount of vibration caused by the propagation of waves in four identical dry limestone blocks with dimensions of 10*10*50 cm was studied. The maximum vibration of particles in intact and jointed rock blocks in ...
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The combined effect of the number of joints, opening, type and thickness of filling on the amount of vibration caused by the propagation of waves in four identical dry limestone blocks with dimensions of 10*10*50 cm was studied. The maximum vibration of particles in intact and jointed rock blocks in three perpendicular directions was recorded by a three-component geophone. In block number 1 with a joint in the middle of the block, the amount of joint opening was changed from 3-6-9-12-15-18-21 mm and the measurements were made for each amount of opening in two series. In the first series, the joint filled with clay was tested, and in the second series, the joint filled with sandy soil was tested. This series of tests were also performed on blocks No. 2 with two joints, Block No. 3 with three joints, and Block No. 4 with four joints. The results of the tests showed that the presence of joints in rock blocks reduced the maximum vibration of particles in all three directions with different proportions. The relationship between the increase in the joint index and the decrease in the maximum vibration of the particles is nonlinear.
Original Research Paper
Tectonics
Khatoun Pirdadi; Maryam Agh-Atabai; Attieh Eshaghi
Abstract
The 2017 Ezgeleh earthquake (Mw: 7.3), which occurred northwest of the Zagros, was followed by many aftershocks. The histogram of the monthly rate of aftershocks shows that, except for the first few months, the aftershock sequence did not follow the Omori law. Therefore, it is necessary to use more complex ...
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The 2017 Ezgeleh earthquake (Mw: 7.3), which occurred northwest of the Zagros, was followed by many aftershocks. The histogram of the monthly rate of aftershocks shows that, except for the first few months, the aftershock sequence did not follow the Omori law. Therefore, it is necessary to use more complex methods to investigate the aftershock sequence. In this research, the temporal multifractal method was used. The results obtained show that the temporal pattern of aftershocks has two short and long-scaling ranges. It seems that short and long ranges are related to the distribution of aftershocks within smaller clusters and the pattern of clusters in the aftershock sequence, respectively. These result showed that the pattern in the longer range is more heterogeneous than the shorter one. On the other hand, by removing the smaller aftershocks, the heterogeneity increases. It seems that the occurrence of several more significant aftershocks with a magnitude of more than 5 has caused an increase in the heterogeneity of the temporal pattern of the aftershock sequence. The results also show that the degree of inhomogeneity of the occurrence time of aftershocks is related to the spatial distribution pattern of aftershocks.
Original Research Paper
Petrology
Niloofar Nayebi; Dariush Esmaeily; Sourosh Modabberi; Ryuichi Shinjo
Abstract
Anomaly 21A, as a part of Bafq iron-apatite ore metallogenic district, is located in Central Iran, and encompasses wide spectrume of igneous, sedimentary and metamorphic rocks. The igneous rocks, and show narrow geochemical variations and dominantly plot in the monzonite to monzodiorite fields which ...
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Anomaly 21A, as a part of Bafq iron-apatite ore metallogenic district, is located in Central Iran, and encompasses wide spectrume of igneous, sedimentary and metamorphic rocks. The igneous rocks, and show narrow geochemical variations and dominantly plot in the monzonite to monzodiorite fields which are plotted in the calc-alkaline and high-K calc-alkaline affinities. Geochemical data are characterized by enrichment LILE and LREE as compare to HFSE and HREE, respectively, and depletions in Nb-Ta-Ti imply the mantle-derived melts modified by subduction components. The isotopic signatures of Anomaly 21A samples, e.g., (87Sr/86Sr)i, εNd(t), imply the dominant mantle signature. Their initial Pb isotopic composition of study rocks are 18.87 to 20.32 for (206Pb/204Pb), 15.72 to 15.84 for (207Pb/204Pb), and 40.74 to 42.32 for (208Pb/204Pb). The isotopic modellings show less than 4% incorporation of melt-derived subducted sediment into the mantle wedge or variable degrees of contamination by upper continental crust. We suggest partial melting of a sub-arc mantle melt that has been metasomatized by slab-derived sediments and interacted with continental crust en-route the shallower surface as the premise of the geodynamic of Central Iran.
Review Article
Geophysics
Asghar Rastbood; Mohsen Sahebi Ilkhchi
Abstract
Very Long Baseline Interferometry (VLBI) is one of the essential approaches in geodesy. Significant capabilities of this technique are creation of International Celestial Reference Frame (ICRF), determination of Earth orientation parameters (EOPs), coordinates of station with high accuracy and light ...
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Very Long Baseline Interferometry (VLBI) is one of the essential approaches in geodesy. Significant capabilities of this technique are creation of International Celestial Reference Frame (ICRF), determination of Earth orientation parameters (EOPs), coordinates of station with high accuracy and light deflection. Many attempts could be done to increase accuracy of VLBI data, including technical improvement of equipment, physical models improvement, using optimal data processing methods and increasing number of stations. In this study, in order to reduce the error of EOPs in CONT17 campaign, the appropriate position for a VLBI station in the Middle East is investigated. The results showed that mean error of EOPs in the Legacy-1and Legacy-2 reduced approximately 6.64% and 13.86% by adding two stations in Oman and Egypt countries, respectively.
Original Research Paper
Economic Geology
Hanieh Kiaee; Ahmad Kazemi Mehrnia; Hamid Samari; Peyman Afzal; Nazanin Zaheri-Abdehvand
Abstract
The Fatehabad Cu deposit is located in the KhorasanRazavi province,35kmSE of theTorbatHeydariyeh and in the Khaf-Kashmar-Bardaskan metal belt.The vein and veinlet mineralization consist ofchalcopyrite, pyrite,magnetite,chalcocite,bornite,covellite,malachite and iron oxides associated with siliceous-sericite,argillite ...
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The Fatehabad Cu deposit is located in the KhorasanRazavi province,35kmSE of theTorbatHeydariyeh and in the Khaf-Kashmar-Bardaskan metal belt.The vein and veinlet mineralization consist ofchalcopyrite, pyrite,magnetite,chalcocite,bornite,covellite,malachite and iron oxides associated with siliceous-sericite,argillite and propyliticalteration in the volcanic rocks formed parallel to the sub-faults that branchoff from theDorouneh fault.The similar pattern ofREEand trace elements in the mineralized veins and associated volcanicrocks suggests an magmatichydrothermal origin of theore elements.In the vein system of Fathabad district, quartz, pyrite,chalcopyrite, and magnetite veins with propylitic alteration in the early stage of mineralization,quartz,pyrite,chalcopyrite and magnetite veins with sericite alteration in the main stage of mineralization and quartz, pyrite and chalcopyrite veins were identified along withargillic and ironoxide alterations.Calciteveins along with sericite and ironoxide alterations were also identified in the late stage of mineralization.The enrichment of trace,LREEs/HREEs ratio positive Euanomalyand negative Ce anomaly,indicate reducing conditions and a highpH of the mineralized fluids.Fluid inclusion studies with low salinity(13.9to4.74wt%NaCleqv.)and low temperature(111to 192oC)indicate dilution and mixing of the sulfur- and element-rich magmatic-hydrothermal fluid with meteoric water, leading leaching and precipitation of trace,rare and copper elements.Theδ34Sisotopes values(-1.58 to -2.86‰)in the chalcopyrite minerals indicate the magmatic origin of sulfur.The geology,geochemistry,and fluid inclusions evidences indicate that the FathabadCu deposit is belong to epithermal systems.
Original Research Paper
Petrology
Leila Maleki; Nematollah Rashidnejad Omran; Abdolrahim Houshmandzadeh; John Cottle
Abstract
In this article, metabasic and gneissic rocks of Gelmandeh and Zamanabad mountain (Boneh-Shurow complex, Saghand region ) have been used for U-Pb dating. Analyses of zircon crystals yielded concordant U–Pb ages with weighted mean 206Pb/238U ages of 545.4 ±3.6 Ma (MSDW=1.7) for garnet amphibolite, ...
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In this article, metabasic and gneissic rocks of Gelmandeh and Zamanabad mountain (Boneh-Shurow complex, Saghand region ) have been used for U-Pb dating. Analyses of zircon crystals yielded concordant U–Pb ages with weighted mean 206Pb/238U ages of 545.4 ±3.6 Ma (MSDW=1.7) for garnet amphibolite, 541.2 ± 4.4 Ma (MSDW=1.8) for metagabbro, 541.3 ±3.5 Ma (MSDW=0.26) for quartz-feldspatic gneiss and 549.2 ± 2.6 Ma (MSDW=0.28) for amphibole- biotite gneiss. The studied zircon crystals has continental, crustal nature and show a strong affinity to magmatic zircons in Chondrite-normalized patterns. The ages that approximately ranges between 541-549 Ma are interpreted as the Crystalline age of the garnet amphibolite and gneissic parental magma. These ages previously assumed as the timing of peak-metamorphism of the Boneh-Shurow garnet-amphibolite and emplacement ages for the granitic precursor of gneissic rocks.
Original Research Paper
Geological Environment and Engineering
Sayyed Naeim Emami; saleh yousefi
Abstract
Mass movements are among the most dangerous natural hazards in mountainous regions. The present study employs machine learning (ML) models for mass movement susceptibility mapping (MMSM) in Iran based on a comprehensive dataset of 864 mass movements which include debris flow, landslide, and rockfall ...
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Mass movements are among the most dangerous natural hazards in mountainous regions. The present study employs machine learning (ML) models for mass movement susceptibility mapping (MMSM) in Iran based on a comprehensive dataset of 864 mass movements which include debris flow, landslide, and rockfall during the last 42 years (1977–2019) as well as 12 conditional factors. The results of validation stage show that RF (random forest) is the most viable model for mass movement susceptibility maps. In addition, MARS (multivariate adaptive regression splines), MDA (mixture discriminant additive), and BRT (boosted regression trees) models also provide relatively accurate results. Results of the AUC for validation of produced maps were 0.968, 0.845, 0.828, and 0.765 for RF, MARS, MDA, and BRT, respectively. Based on MMSM generated by RF model, 32% of study area is identified to be under high and very high susceptibility classes. Most of the endangered areas for mass movement are in the west and central parts of the Chaharmahal and Bakhtiari Province. In addition, our findings indicate that elevation, slope angle, distance from roads, and distance from faults are critical factors for mass movement. Our results provide a perspective view for decision makers to mitigate natural hazards.
Original Research Paper
Petrology
abdolhamid ansari
Abstract
The Chargonbad batholite is located close to Sirjan and southeast of Urumieh-Dokhtar magmatic zone. This batholite is acidic to intermediate is composition and intruded into the Eocene volcanic rocks, The main volume of these rocks consisted of Granodiorite and Monzogranite, . This mass contains numerous ...
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The Chargonbad batholite is located close to Sirjan and southeast of Urumieh-Dokhtar magmatic zone. This batholite is acidic to intermediate is composition and intruded into the Eocene volcanic rocks, The main volume of these rocks consisted of Granodiorite and Monzogranite, . This mass contains numerous mafic microgranular enclaves with a combination of diorite and monzodior. Also, microgranular dykes have cut the mafic mass. Existence of field evidence such as. Mafic microgranular enclaves with spherical to oval shapes, bells and rods, the presence of Syniplutonic mafic dykes, as well as evidence textural disequilibrium indicate the absence of plagioclase with oscillatary 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. 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 study area located in the arc island setting due to subduction and show the characteristic of active continental margin setting.
Original Research Paper
Sedimentology
Mahmoud sharafi; Mahdi Jafarzadeh; Aram Bayet-Goll; Razieh Lak
Abstract
The Urmia Lake, which is a tectonic depression in the northwest of Iran, has received a lot of eroded sediments of the geological records of the lake watershed. Because of the constant drought in the recent years sediments have been subjected to the wind erosion and thus are an important source for local ...
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The Urmia Lake, which is a tectonic depression in the northwest of Iran, has received a lot of eroded sediments of the geological records of the lake watershed. Because of the constant drought in the recent years sediments have been subjected to the wind erosion and thus are an important source for local and regional emission during dust storms. In this research the south and west sediments of the Urmia playa lake have studied on the parent rock issue. Bivariate plots such as Th/Co versus La/Sc and TiO2 versus Al2O3 and comparison proportion of the trace elements such as La/Sc, Th/Sc, La/Co, Th/Co and Cr/Th display mainly the felsic and partly basic rocks source for the studied sediments. Major and trace spider plots of the studied sediments display their depletion with respect to Sc, V, Cr, Ni and enrichment with respect to Th and Sr, confirm mainly a felsic and partly mafic and ultramafic source rocks. Geochemistry of the major elements shows the dry climatic conditions during deposition of Urmia Lake sediments, suggested by bivariate plots of SiO2 against the sum of Al2O3, K2O and Na2O as well as the amount of chemical index of weathering.
Original Research Paper
Stratigraphy and Palaeontology
Abdolvahab Kazemi; Nasrollah Abbassi
Abstract
Agha Jari Formation (Miocene-Pliocene, 788 m) comprises alternations of sandstone, siltstone, and marl in red to brown color layers in the east Gotvand, north Khuzestan Province, southeast Iran. Numerous vertebrate footprints have been found in the middle part of the formation, which includes footprints ...
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Agha Jari Formation (Miocene-Pliocene, 788 m) comprises alternations of sandstone, siltstone, and marl in red to brown color layers in the east Gotvand, north Khuzestan Province, southeast Iran. Numerous vertebrate footprints have been found in the middle part of the formation, which includes footprints of wetland small bird (Aviadactyla media, Gruipeda dominguensis), artiodactyls (Lamaichnum alfi, Lamaichnum isp., Pecoripeda satyri, Pecoripeda isp.), canids (Canipeda isp.) and large reptiles (Hatcherichnus sanjuanensis). Frequency of artiodactyl imprints are high than the other footprints. These footprints proof the living of camels and crocodiles in the Zagros basin for the first time. The ichnotaxa diversity of the footprints in the studied section is higher than the other reports of Agha Jari formation in Iran and its stratigraphic equivalent in the adjacent countries.
Original Research Paper
Geological Environment and Engineering
Ahmad Abbasnejad
Abstract
The purpose of this study is; to determine the geomorphological setting; to assess earthquake, flood, and subsidence hazards, as well as to evaluate the landscape of Iranian urban areas, based on geomorphological criteria. For this purpose, 210 cities, each one having more than 50,000 population, were ...
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The purpose of this study is; to determine the geomorphological setting; to assess earthquake, flood, and subsidence hazards, as well as to evaluate the landscape of Iranian urban areas, based on geomorphological criteria. For this purpose, 210 cities, each one having more than 50,000 population, were investigated. In this study, Google Earth and satellite pictures, aerial photographs, and geological and geomorphological maps were used and, if needed, field investigations were undertaken. This study showed that the number of urban areas totally or partly lying on alluvial fans, flat surfaces, terraces, synclines, piedmonts, anticlines, and deltas are 103, 34, 26, 39, 27, 8, and 9 cases, respectively. The numbers on volcanic cones, cliffs, and wetlands are only 2, 1, and 1 cases, respectively. Also, 158 cases lie only on one landform and the remaining 52 cases predominately lie on two kinds of landforms.There are 158 and 90 cities at the high threat of earthquake and flood and the numbr of cities at the threat of surficial and qanat subsidence are 60 and 47 cases, respectively. The urban areas with uniform and good landscapes are 71 and 52 cases, respectively.
Original Research Paper
Petrology
Seyed Mohsen Kashfi; Saeid alirezaei; Mohammad reza Hosseini; iraj rasa
Abstract
The Zaghdareh area in the Esfandagheh-Faryab ophiolitic complex, southern Sanandaj-Sirjan belt, embraces extensive outcrops of mafic-intermediate lava flows and a felsic intrusive body. The volcanic rocks are calc-alkaline to tholeiitic and metaluminous, and distinguished by depletions in light rare ...
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The Zaghdareh area in the Esfandagheh-Faryab ophiolitic complex, southern Sanandaj-Sirjan belt, embraces extensive outcrops of mafic-intermediate lava flows and a felsic intrusive body. The volcanic rocks are calc-alkaline to tholeiitic and metaluminous, and distinguished by depletions in light rare earth elements and relatively flat patterns for heavy rare earth elements in chondrite-normalized diagram; the (La/Yb)N ratio is lower than unity for most samples. The mineralogy and chemical attributes for the Zaghdareh volcanic rocks are similar to volcanic rocks developed in suprasubduction zones. The Zaghdareh intrusive body is distinguished by abundant plagioclase and quartz, and subordinate hornblende, phenocrysts in quartz-feldspar rich matrix. Representative samples from the intrusion plot in the trondhjemite-tonalite fields in the normative An-Ab-Or diagram. The intrusion is calc-alkaline to tholeiitic, peraluminous, and characterized by enrichments in Na2O and CaO and depletions in K2O, Rb, and other LILEs, as well as low K2O/ Na2O ratios, very low Rb/Sr ratio, and distinct depletions in light rare earth elements, which are typical of the oceanic plagiogranites.
Original Research Paper
Stratigraphy and Palaeontology
Parisa Mohammadi; Abbas Ghaderi; Ali Reza Ashouri
Abstract
The Julfa region in East Azerbaijan Province exhibits one of the best continuous marine sedimentary successions across the Permian to Triassic boundary. The present study is focused on the brachiopod contents of the Julfa beds in Qareh-Goz section (41.5 m thickness) in the south of Julfa. This study ...
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The Julfa region in East Azerbaijan Province exhibits one of the best continuous marine sedimentary successions across the Permian to Triassic boundary. The present study is focused on the brachiopod contents of the Julfa beds in Qareh-Goz section (41.5 m thickness) in the south of Julfa. This study is led to the determination of 11 genera and 21 species of the orders Athyridida, Orthotetida, Orthida, Productida, Spiriferida, and Terebratulida, all representing the Cathaysian bioprovince for this area in the Western Paleotethys. Accordingly, four Wuchiapingian biozones, including Araxilevis intermedius Zone, Araxilevis intermedius-Permophricodothyris ovata Interval zone, Permophricodothyris ovata Zone, and Transcaucasathyris araxensis Zone, have been detected. These biozones correlate well through the other stratigraphic sections of the Julfa area in the Ali Bashi and Zal Mountains, Dorasham section in the Transcaucasia, Hembast Formation in the Abadeh area, and Nesen Formation in the central Alborz, approving the potential of these brachiopods in biocorrelation at a regional scale in the Late Permian.
