Original Research Paper
Sedimentology
Mahdi Ghaderi; Mohsen Moayyed; Nasir Amel; Monire Mojarrad
Abstract
The Saray volcano is located on the East of the Urmia Lake. This extinct stratovolcano mainly consists of Leucitite lavas and related pyroclasts. Dykes with composition of Leucite phonolite, Lamprophyre, Trachyte and microsyenite intruded into leucitite. Field evidences indicate that minette and trachytic ...
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The Saray volcano is located on the East of the Urmia Lake. This extinct stratovolcano mainly consists of Leucitite lavas and related pyroclasts. Dykes with composition of Leucite phonolite, Lamprophyre, Trachyte and microsyenite intruded into leucitite. Field evidences indicate that minette and trachytic dykes intruded into each other. A microsyenitic stock and dykes outcrops in the central valley of this volcano. The trachytic pyroclasts eruption is the last activity of the Saray volcano and probably caused the destruction of volcanoe’s caldera and formed its current shape. Leucitites maimly consist of leucite and clinopyroxene phonocrysts, minettes consist of biotite and clinopyroxene phenocrysts and trachytes consist of biotite, sanidine and clinopyroxene phenocrysts. The Saray magmatism has potassic to ultrapotassic nature and its geochemical features indicate that this magma should be originated from a micaceous garnet clinopyroxenite mantle. The coexistance of leucitite, lamprophyre and trachyte, could not be explained only by the function of fractional crystallization in leucitite magma. Sanidine is the most abundant feldspar in the Saray volcano. Sanidine megacrysts crystalize in a medium size magma chamber with continuing temperature cycling, so that the magma temperature remains close to the liquidus temperature of the K-feldspar for a long time.
Original Research Paper
Economic Geology
Meysam Nikfarjam; Ardeshir Hezarkhani
Abstract
In this research, we have used different integration methods for creating the geochemical evidential map that is one of the most important layers in mineral potential mapping. The Study area (Varzaghan 1:100,000 sheet) is located in East Azarbaijan province and Ahar-Arasbaran metallogenic zone. This ...
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In this research, we have used different integration methods for creating the geochemical evidential map that is one of the most important layers in mineral potential mapping. The Study area (Varzaghan 1:100,000 sheet) is located in East Azarbaijan province and Ahar-Arasbaran metallogenic zone. This region, because of its geological situation and presence of several porphyry copper deposits like Sungun porphyry-skarn deposit, is considered as an important metallogenic province in the northwest of Iran. In this study, we have used 1067 stream sediment samples as primary data that picked up by Geological Survey & Mineral Explorations organization of Iran. By selecting indicator elements of porphyry copper deposit, like Cu, Mo, Au, Ag, Pb, Zn, Au and As, the evidential map of each element have generated by the continuous fuzzy method. In the next step, by using Union Score (US) method, fuzzy OR operation, and geometric average, the individual geochemical maps have integrated. Finally, Prediction-Area plots have drawn to validate the evidential maps. This plot showing that geochemical evidential map that produced by US method, can predict 76 percent of known mineral occurrences and it can consider as a proper method for creating the geochemical evidential map for porphyry copper deposits.
Original Research Paper
Petrology
haleh ghorbani; robab hajialioghli; mohsen moazzen
Abstract
The Ghareh naz migmatites were formed as a result of partial melting of amphibolites under granulite facies conditions. Structeral, textural, mineralogical and geochemical evidence in the migmatites migmatites indicates their formation via partial melting during partial melting. The studied migmatites ...
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The Ghareh naz migmatites were formed as a result of partial melting of amphibolites under granulite facies conditions. Structeral, textural, mineralogical and geochemical evidence in the migmatites migmatites indicates their formation via partial melting during partial melting. The studied migmatites have a variety of structures including patchy, scholen, ophthalmitic, stromatic, diktyonitic, ptygmatic, phlebetic, schliren, pegmatitoid and nebulitic. The presence of striated plagioclases and amorphous quartzes along with granular texture, myrmecite and peritite in the locosome parts as well as the presence of zoning, polysynthetic twin in the plagioclases indicate a partial melting role in the formation of migmatites. Based on mass balance calculations in the ghareh naz migmatites, the parts of the migmatite components of the locosome, melanosome, and mesosome are aligned in a straight line, indicating a partial melting source of the studied migmatites.The percentage of partial melting for the studied megmatites was calculated to be about 36.5% and 43.6%,respectively. The difference in partial melting percentages may depend on the relationship between the rate and melt outflow and to a small extent on the amount of melt in the region. The formation temperature of these migmatites is determinated about 850-850 ° C and the pressure is about 6-7 kbar.
Original Research Paper
Economic Geology
Elnaz Zahmatkesh; Seyed Mehran Heidari
Abstract
Zavarian gold occurrence formed within andesitic volcanic units in northwestern Iran. The volcanic complex is in fact a part of magmatism related to Urumieh-Dokhtar magmatic belt crosscutting northwestern rim of Central-Iran zone. This system is a part of the volcanic-sedimentary sequence of the Qom ...
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Zavarian gold occurrence formed within andesitic volcanic units in northwestern Iran. The volcanic complex is in fact a part of magmatism related to Urumieh-Dokhtar magmatic belt crosscutting northwestern rim of Central-Iran zone. This system is a part of the volcanic-sedimentary sequence of the Qom Basin that is formed as an intercontinental stratovolcane in a tension environment. Gold has the highest correlation with Mo, Bi, As, Sb, Ag, Cd and Cu which indicates relationship mineralization with magmatic fluids and role of bi-sulfide complexes in gold transport. Hydrothermal alteration in this area is most in the vicinity and within intrusions, and along fractures with NE-SE trending and have more intense around siliceous zones. The activity of hydrothermal system starts by alterations related to the subvolcanic intrusive, and creates the first mineralization phase by oxid-silicic alteration along the fractures. This mineralization phase continued by hydrothermal breccia with tourmaline and copper sulfide, and finally finished with high sulfide mineralization and deposition of gold mineralization in the cavities and fractures. Therefore, Characteristics of this mineralization indicate that it is most similar to epithermal related to subvolcanic deposits.
Original Research Paper
Petrology
Mahboobeh Jamshidibadr; Narges Sadat Faramarzi
Abstract
Hormuz Island, a salt diapir in southern Iran, mostly composed from evaporite-carbonate sediments of Neoproterozoic. So far, no significant studies have been done belong to the petrography and geochemistry of the Hormuz evaporite-carbonate sediments. Moreover, Salt movements made it difficult to distinguish ...
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Hormuz Island, a salt diapir in southern Iran, mostly composed from evaporite-carbonate sediments of Neoproterozoic. So far, no significant studies have been done belong to the petrography and geochemistry of the Hormuz evaporite-carbonate sediments. Moreover, Salt movements made it difficult to distinguish rocks relationship only based on field observations. In the recent study, with the understanding of field evidences (e.g. the salt thickness, type and amounts of enclaves, as well as field relationship between evaporite unit and volcanic rocks), mineralogical studies (such as studying fluid inclusions within evaporite unit, studying enclaves from evaporite-carbonate unit as well as the mineralogy of dolomite, pyrite and rhyolitic tuffs) and doing geochemical analysis (e.g. Inductively coupled plasma- mass spectrometry and Scanning Electron Microscope), not only the evaporite-carbonate sediments, but also the reconstruction of the events occurring in the Hormuz sedimentary basin, have been investigated. The existence of evaporites with different thicknesses, enclaves and interlayers indicate that deposition of evaporites occurred in two separate stages. The island’s rhyolitic volcanism happened in the gap between sedimentation of lower and upper evaporite units. The volcanoclastic rocks are coexistence with deposition of upper evaporite unit. The deposition of both evaporite units occurred during the upper Ediacaran.
Original Research Paper
Remote Sensing
mohammad sharifikia; jalal karami; Ehsan Falahati
Abstract
Optical Remote Sensing is a low-cost and efficient method to alteration zone detection. However in the area that have been covered by vegetation or alluvial, the identification of these areas is not very accurate with optical images. In this study fusion and integrating of ALOS-PALSAR L-band and ASTER ...
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Optical Remote Sensing is a low-cost and efficient method to alteration zone detection. However in the area that have been covered by vegetation or alluvial, the identification of these areas is not very accurate with optical images. In this study fusion and integrating of ALOS-PALSAR L-band and ASTER data by HSV, HSL, Maximum Likelihood and Artificial Neural Network has been done to discover and enhance the Argilic and Propylitic Alteration zones over the west part of Qazvin province in IRAN. For this purpose, Argilic and Propylitic alterations were primary identified unseeing ASTER image. Then based on geological data and field study, some areas with alterations covered by quaternary sediments, not detectable by ASTER images, were identified. In the following, the integration of the ALOS PALSAR L-band data and the ASTER SWIR bands with HSV, HLS, Maximum Likelihood and Artificial Neural Network were performed. The results of this study showed that the radar and optics data fusion, using HSV and HLS methods, increases the enhancement of visible argillic alteration zones in the study area. Also, the integration of radar and optics data with the Maximum Likelihood and the Artificial Neural Network methods,
Original Research Paper
Petrology
Mohammad reza Ghasempour; Nahid Shabanian; alireza Davoudian; hasamaldin moeinzadeh
Abstract
The Horjand area is located in northeast of Kerman in the Central Iran zone and the Kashmar-Kerman tectonic belt. In this area, gabbroic rocks and doleritic dykes are intruded into the sedimentary rocks of Desu Series with Infra-Cambrian age. The gabbros and doleritic dykes have relatively same composition. ...
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The Horjand area is located in northeast of Kerman in the Central Iran zone and the Kashmar-Kerman tectonic belt. In this area, gabbroic rocks and doleritic dykes are intruded into the sedimentary rocks of Desu Series with Infra-Cambrian age. The gabbros and doleritic dykes have relatively same composition. The main minerals are plagioclase and clinopyroxene. Their texture is medium to fine granular and ophitic to sub-ophitic. The plagioclase minerals of the rocks have labradorite composition (An53-67), but as a result of saussuritization in gabbros and doleritic dykes, the plagioclase changed to oligoclase and albite composition, respectively. The mineral chemistry of clinopyroxenes display Mg-Ca-Fe type which are diopside and augite. The distribution of aluminum in clinopyroxenes structure show that the minerals were crystallized from a magma with water vapor pressure less than 10 percent. On the basis of the chemical charaterstions of the clinopyroxenes, the magma source has predominantly had tholeiitic to minor alkaline affinities with a tectonic setting related to within plate environments. Geothermobarometry evaluations of the clinopyroxenes reveal that the mafic rocks were formed at temperatures of 1127-1200 ˚C and pressure less than 6 Kbar.
Original Research Paper
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.
Original Research Paper
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.
Original Research Paper
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.
Original Research Paper
Petrology
Morteza Khalatbari Jafari; Narmin Banehee; Mohamad Faridi; Mehdi Moradi
Abstract
The Neogene volcanic rocks are exposed in south Arab abad, Lut block. The studied volcanic rocks covered Eocene and Oligocene volcanic lavas and Neogene evaporitic deposits. The base of the Neogene volcanic sequence made of breccia and tuff gradually covered by andesite, trachyandesite and dacitic lavas. ...
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The Neogene volcanic rocks are exposed in south Arab abad, Lut block. The studied volcanic rocks covered Eocene and Oligocene volcanic lavas and Neogene evaporitic deposits. The base of the Neogene volcanic sequence made of breccia and tuff gradually covered by andesite, trachyandesite and dacitic lavas. These lavas have aphyric-phyric textures and microlitic to hyalomicrolitice in matrix. These lavas show calck alkaline magmatic trend. REE patterns and spider diagrams display enrichement in LREE and LILE relative to HREE and depletion in HFSE which like as subduction zone magmatism. In the tectonomagmatic diagrams they plot of subduction and post-collisions fields. Interpretation of the geochemical data indicates that the studied lavas probably produced from partial melting of lithospheric mantle which had previously enriched by subduction components (fluids and melt). Partial melting of crust, probably involved in generation of acidic lavas. It seems that in the Neogene period, lithosphere thinning induced partial melting of heterogeneous Sub Continental Lithospheric Mantle (SCLM). These processes consequently occurred by lithospheric delamination and asthenospheric upwelling.
Original Research Paper
Economic Geology
Susan Ebrahimi; Alireza Arabamiri; Hadi Ghanbari
Abstract
The Sharifabad-Bardeskan copper mineralization is located in northeast of Bardeskan and south section of Sabzevar Zone. Mineralization occurs as vein in the pyroxene andesite, tuff, sandstone and conglomerate of Eocene age, which bearing local sericite - carbonate and silicic alterations and regional ...
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The Sharifabad-Bardeskan copper mineralization is located in northeast of Bardeskan and south section of Sabzevar Zone. Mineralization occurs as vein in the pyroxene andesite, tuff, sandstone and conglomerate of Eocene age, which bearing local sericite - carbonate and silicic alterations and regional propylitic alteration. Mineralization occurs as open space filling, disseminated, veinlets and consists of chalcocite pyrite, chalcopyrite, malachite, azurite with calcite and quartz as gangue minerals. Fluid inclusion studies in calcite show the evidence of mixing trend during the ore formation occurred at a wide range of temperature 200to 437 °C and varying salinity between 0.1 to 9.2 wt.% NaCl equivalent. The stable isotope composition of δ34S fall in a range of -23 to -24.3‰ could be considered as biogenetic sulfur from bacterial sulfate reduction. The δ13C values of calcite vary between -3.4 to -24.5‰ suggest a major contribution of marine carbonates associated igneous carbonates. Copper and sulfide rich hydrothermal fluid has flowed upward through the local faults and permeable interbeds within the Eocene volcanic sequence and formed the mineralized veins. Based on the mineralization, alteration, fluid inclusion and stable isotopes, Sharifabad mineralization is similar to those manto type deposits in Chile.
Original Research Paper
Sedimentology
keyvan ahzan; Nader Kohansal Ghadimvand; Seyed Mohsen Aleali; Davood Jahani
Abstract
The Jahrum Formation (Paleocene-Mid Eocene) is one of the most important reservoir units in the Zagros basin and the Persian Gulf. The thickness of this formation in Binaloud oil field in Persian Gulf, which mainly consists of limestones and Dolomites, is about 660 meters. In this research, depositional ...
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The Jahrum Formation (Paleocene-Mid Eocene) is one of the most important reservoir units in the Zagros basin and the Persian Gulf. The thickness of this formation in Binaloud oil field in Persian Gulf, which mainly consists of limestones and Dolomites, is about 660 meters. In this research, depositional environment, sequence stratigraphy and effective diagenesis processes on Reservoir quality of the Jahrum Formation were investigated in Binaloud oil field. The Jahrum succession, which consists of crystalline limestones and dolomites, is overlain by the Asmari Formation and is underlian by the Tarbur Formation unconformably. According to study of cutting samples, eleven microfacies that were deposited in four facies belts, have determined . The most important diagenetic process that was observed in this formation as follows: bioturbation, cementation, dolomitization, dissolution, porosity generation and fracture systems wich is worthy to mation bioturbation and anhydrite cement causes the reduce of reservoir quality and dolomitization , dissolution and secondary porosity causes the reservoir quality. improvement most of facies jahrum formation are mud supported and have very low primary porosity. According to sequence stratigraphy studies, a third order sedimentary sequence with type SB1 boundary was identified in Jahrum subsurface succession.
Original Research Paper
Geophysics
Ata Eshaghzadeh; Alireza Hajian; Roghayeh Alsadat kalantari
Abstract
Potential field data is the assembled of effects of all underground sources. Computing regional-residual anomaly is a critical step in modeling and inversion in the gravity method. Existence quantitative noise in corrected gravity data is unavoidable. In this paper, we present a novel separation method ...
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Potential field data is the assembled of effects of all underground sources. Computing regional-residual anomaly is a critical step in modeling and inversion in the gravity method. Existence quantitative noise in corrected gravity data is unavoidable. In this paper, we present a novel separation method based on a Singular Value Decomposition (SVD) analysis of gravity dataset. With the SVD, a matrix of bouguer gravity data can be decomposed to a series of eigenimages. The number of required eigenimages or threshold for the reconstruction of the regional and residual (local) anomalies maps and noise distribution map from bouguer anomaly is determined based on the derived singular values by SVD. To reconstruct the data set by eigenimages may lose negligible information. We have considered which this value is equivalent with the mean of the variance of the resulted matrixes by eigenimages. The efficiency of the Singular Value Decomposition method was tested with the noisy synthetic gravity data of a hybrid model of the sphere as a local anomaly and deep-seated sloping plane as a regional anomaly. The separation results are satisfactory. The proposed method was applied on gravity field dataset of the Qom area, Iran.
Original Research Paper
Stratigraphy and Palaeontology
Manizhe Famarini Bozchalouei; Nasrollah Abbassi; Armin Salsani; Afshin Zohdi
Abstract
Soltanieh Formation comprises seven informal submembers as alternation of dolomites and shales, more than 1110 meters in thickness, was surveyed in the Seyedkandi section, 32 km southwest of Zanjan, northwest Iran. These submembers were subdivided as lower dolomite, lower shale, second dolomite, second ...
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Soltanieh Formation comprises seven informal submembers as alternation of dolomites and shales, more than 1110 meters in thickness, was surveyed in the Seyedkandi section, 32 km southwest of Zanjan, northwest Iran. These submembers were subdivided as lower dolomite, lower shale, second dolomite, second shale, third dolomite, upper shale and upper dolomite, respectively. Based on ichnological data from 109 specimens, 23 ichnogenera and 42 ichnospecies have been recognised. The abundance of trace fossils is very high in the second shale submember, so that 99 specimens were collected from this rock unit. Ichnofossil data from the studied section showsthat the Neoproterozoic-Cambrian boundary is located in the 8 m above the base of second dolomite submember in the studied section, where the first occurrence of Treptichnus pedum was been recorded.
Original Research Paper
Petrology
Gholamreza Tajbakhsh
Abstract
Mafic dyke swarms of the Zarigan granitoid in the north of Bafq have intruded the Lower Cambrian volcanic-sedimentary sequence of central Iran. These dykes are lithologically classified as gabbro-diorite and alkali gabbro. The alkaline gabbros are younger and penetrate higher horizons. Geochemically, ...
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Mafic dyke swarms of the Zarigan granitoid in the north of Bafq have intruded the Lower Cambrian volcanic-sedimentary sequence of central Iran. These dykes are lithologically classified as gabbro-diorite and alkali gabbro. The alkaline gabbros are younger and penetrate higher horizons. Geochemically, gabbro-diorites have a tholeiitic to transitional nature with enrichment of LILE, HREE and depletion of Nb and Ta elements. By contrast, alkali gabbros have the sodic alkaline nature, exhibiting Nb-Ta enrichment and high LREE/HREE ratio. Gabbro-diorite magmas are derived from partial melting of sub-continental lithospheric mantle affected by subduction components in equilibrium with spinel lherzolite. On the other hand, the alkali gabbros originate from greater depth and lower partial melting of enriched asthenospheric mantle in equilibrium with garnet lherzolite. These dykes are formed in an intra-arc extension setting associated with subduction of the continental margin. Geometry and mechanism of motion of Posht-e-Badam and Kuh Banan basement faults caused an anticlockwise rotation, crustal fracturing, lithospheric thinning, and stenosphere upwelling of these two faults bounded block.
Original Research Paper
Tectonics
Amir Shafiei bafti
Abstract
Radon is a radioactive noble gas . The best places for accumulation of radon in groundwater would be geodynamic active areas,deep basement faults and fractures. This paper aims to investigate the relationship between the radon gas concentrations with the behaviors of active tectonic faults. Jorjafk fault ...
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Radon is a radioactive noble gas . The best places for accumulation of radon in groundwater would be geodynamic active areas,deep basement faults and fractures. This paper aims to investigate the relationship between the radon gas concentrations with the behaviors of active tectonic faults. Jorjafk fault with a length of nearly 160 km from North-West to South-East in southern central Iran. This fault shows active tectonics aspects, The distribution of Davaran Mountain seismic centers shows low Seismicity for the region. In addition, the few focus of the events in the south of the mountain and unequal distribution and lack of clear trend is among its seismic properties. For the measurement of radon concentration in water resources leading to the Jorjafk fault,, 35 sampling stations were identified as suitable, and on two occasions the samplings were performed. The highest and lowest concentrations measured in the first stage were 53, 183, and 138 Becquerel's respectively for the stations of 13, 3 and 8, and in the second stage, the highest and lowest concentration were measured with values of 56, 233, and 169 Becquerel's respectively for the stations of 29 and 25. By comparing the obtained concentrations for each station and its compliance with seismic activity in the region, it was observed that in places where seismic activity is higher, the concentration of radon gas is also higher. Therefore, it can be said that the areas with high concentrations of radon gas, have more potential and are more likely to earthquake events
Original Research Paper
Sedimentology
Javad Anjerdi; Mahdi Jafarzadeh; Adel Najafzadeh; Rahim Mahari
Abstract
In this research, a combination of petrography, geochemistry and heavy minerals analysis methods are implemented for investigating the provenance of quartzarenitic and subarkosic sandstones of Ilanqareh Formation with Late Devonian age in Azerbaijan, south of Jolfa. Investigation of the quartz types ...
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In this research, a combination of petrography, geochemistry and heavy minerals analysis methods are implemented for investigating the provenance of quartzarenitic and subarkosic sandstones of Ilanqareh Formation with Late Devonian age in Azerbaijan, south of Jolfa. Investigation of the quartz types in the studied sandstones, geochemical characteristics of sandstones and shales of Ilanqareh Formation including Al2O3/TiO2 ratio and La/Sc against Co/Th ratios, illustrates that the dominant parent rocks of most of these deposits are granitic igneous ones. The presence of granitic parent rock along with the presence of euhedral zircon and tourmaline among the well-rounded indicate the erosion of uplifted blocks of Iranian basement in the rifted basin of Paleotethys as effective factor in providing sediments. However, geochemistry and heavy mineral assemblages confirm the recycling of sediments from older formations as another source of sediment. The petrography, geochemistry and heavy minerals also indicate the craton provenance and passive margin tectonic setting at the deposition time of the Ilanqareh sediments. According to the present study, one can consider a combination of uplifted source rock (Cadomian basement) and sedimentary recycling of older formations as main sources and Arabian craton as a subsidiary source in the supply of detritus sanstones of Ilanqareh Formation.
Original Research Paper
Economic Geology
Morteza Delavari; Amir Ali Tabakh Shabani; Samaneh Ghanbari
Abstract
The Oligocene dacitic volcanic rocks display widespread exposures in south of Julfa (eastern Azerbaijan). They generally show porphyritic to hyalo-porphyritic textures with major minerals of plagioclase, amphibole, quartz and biotite. Electron probe micro analyzer (EPMA) data indicates oscillatory zoning ...
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The Oligocene dacitic volcanic rocks display widespread exposures in south of Julfa (eastern Azerbaijan). They generally show porphyritic to hyalo-porphyritic textures with major minerals of plagioclase, amphibole, quartz and biotite. Electron probe micro analyzer (EPMA) data indicates oscillatory zoning and chemical variation of amphiboles (pargasite and edenite). The plagioclase crystals are, chemically, andesine (An= 29-51%) which mostly display oscillatory zoning. Based on geobarometric calculations, plagioclase displays pressures of 5 to 8 kb and amphiboles demonstrate different pressure ranges of 1.5 to 3 and 5 to 9 kb. Moreover, geothermometric calculations of plagioclase and amphibole provide temperatures of 1020-1050 and 850-900 °C, respectively. On the basis of geobarometric results, crystallization and growth of the minerals took place in magmatic chambers of different levels. Some of the amphiboles nucleated in lower continental crust and subsequently grown during magma ascent in middle crust whereas some others crystallized in the upper continental crust. Therefore, existence of minerals of different levels inside the studied rocks could be related to magma mixing in shallow magma chambers.
Original Research Paper
Exploration and Mining
Mojtaba mohammadi; Seyed Mahmoud Fatemi Aghda; Mehdi talkhablou; َAkbar Cheshomi
Abstract
Description and Understanding the sedimentary environment helps a lot in the initial estimation of the engineering properties of materials and planning of geotechnical studies. Most of the quaternary sediments (coarse and fine grained) of the Isfahan city were deposited by the Zayandehrood river. Understanding ...
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Description and Understanding the sedimentary environment helps a lot in the initial estimation of the engineering properties of materials and planning of geotechnical studies. Most of the quaternary sediments (coarse and fine grained) of the Isfahan city were deposited by the Zayandehrood river. Understanding the geotechnical characteristics and subsurface development of these sediments are essential in the old sedimentary environment for a couple of reasons. Firstly, it is difficult to determine the geotechnical characteristics of coarse-grained sediments and there is uncertainty in the subsurface development of these sediments at distant locations from the Zayandehrood river. Secondly, it is development of construction and the necessity of digging underground spaces Therefore, in this study, using the geotechnical data of 384 boreholes, maps of the approximate range of coarse-grained sediments of the Zayandehrood River were prepared at depths of 5, 10, 20 and 30 m and their geotechnical characteristics were statistical analyzed by the results of laboratory and in situ tests. The results show that the geotechnical characteristics of coarse-grained sediments do not change significantly with the change of depth and the approximate range of subsurface expansion of this river has been in the past in places other than the present river route.
Original Research Paper
Tectonics
Mohammad Ali Ghanbarian; Ali Yassaghi
Abstract
This research has presented the results of the structural and microstructural analyses of the Faryadoun region which is located in the NE of the Fars province. In this research, a new NW-striking belt has been introduced in the central part of Zagros hinterland and NE of the Sanandaj-Sirjan metamorphic ...
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This research has presented the results of the structural and microstructural analyses of the Faryadoun region which is located in the NE of the Fars province. In this research, a new NW-striking belt has been introduced in the central part of Zagros hinterland and NE of the Sanandaj-Sirjan metamorphic belt. The mean attitudes of the foliation and lineation in this new belt are 315˚, 57˚ NE and 23˚, 116˚, respectively. The study of kinematic indicators revealed the occurrence of a sinistral top-to-the NW shear in this new belt which is different with the known dextral deformation in the central region of the Sanandaj-Sirjan metamorphic belt.
Original Research Paper
Sedimentology
Somayeh Parham; Alireza Piryaei; Mansur Ghorbani; Seyyed Reza Moosavi Harami
Abstract
Late Cretaceous in Zagros encompasses regional tectonics and caused foreland basin to form in northeast of the Arabian Plate. Salt tectonics is also locally affected this area. One of the time periods that can better picture this tectono-sedimentary evolution is Maastrichtian. In order to investigate ...
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Late Cretaceous in Zagros encompasses regional tectonics and caused foreland basin to form in northeast of the Arabian Plate. Salt tectonics is also locally affected this area. One of the time periods that can better picture this tectono-sedimentary evolution is Maastrichtian. In order to investigate this evolution in the Maastrichtian time, a regional cross-section was made inthe Fars outcrops and wells. A sedimentological study and sequence stratigraphy have been accomplished along this transect. Maastrichtian deposits consist of the upper part of the Gurpi and the Tarbur formations in the studied transect. Based onsedimentological investigation, 14microfacies have been identified. This microfacies were deposited in 4microfacies belt including tidal flat, restricted and open lagoon, reef and open marine in a shelf carbonate platform. Based on sequence stratigraphic studies, 3 sedimentary sequences were identified in the studied interval. Correlation along the transect revealed that the Maastrichtian deposits occurred on the forebulge of Zagros foreland basin. It is also concluded that the fore-buldge shows a nearly smooth topography and thus accommodation space is homogeneous. Hence the thickness of the Maastrichtian deposits does not vary so much along this transect. Thickness anomaly in Namak-dehkuyeh occurs as a result of salt structure which decreased accommodation space.
Original Research Paper
Economic Geology
nasrin khajehmohammadlou; Ali Asghar Calagari; Kamal Siahcheshm; Ali Abedini
Abstract
The Aghbolagh iron-copper skarn is located in ~21 km north of Oshnavieh, southwest of West-Azarbaidjan province. The intrusion of Cretaceous granitic body into the Cambrian Barut, Zagun, and Lalun Formations (carbonate, shale, and sandstone) was accompanied by development of calcic-type skarn, hornfels, ...
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The Aghbolagh iron-copper skarn is located in ~21 km north of Oshnavieh, southwest of West-Azarbaidjan province. The intrusion of Cretaceous granitic body into the Cambrian Barut, Zagun, and Lalun Formations (carbonate, shale, and sandstone) was accompanied by development of calcic-type skarn, hornfels, and marble in the study area. The garnets of the Aghbolagh skarn belong to solid solution series of grossularite-andradite in which andradite is the dominant phase (>80%). These garnets are isotropic and lack zonation. The pattern of REE distribution in these garnets shows the enrichment of LREE relative to HREE and also the occurrence of negative anomalies of Eu/Eu* and Ce/Ce*. The comparison of the distribution pattern of REE in garnets with those in igneous (granite and monzonite) and sedimentary (carbonates and sandstones) rocks demonstrates that the REE in garnets were derived mainly from the igneous rocks rather than the sedimentary units. The increase in Pr/Yb ratios in parallel with increase in the ƩREE is indicative of the magmatic origin of the ore-forming fluids in the Aghbolagh skarn. However, the lack of sensible variations between Ce/CE* and ƩREE values indicate that the meteoric waters might have also played a part in skarn-forming fluids at Aghbolagh.
Original Research Paper
Economic Geology
Mohammad Jafar Kupayi; Ebrahim Rastad; Saeed Madanipour; Sajjad Maghfouri
Abstract
Cretaceous sedimentary sequence in the Yazdan area is consisting of four rock units as, from the old to the new, clastic-carbonate (Kc), carbonate (Kl), Shale and marl (Km) sequences, and Sandy limestone and sandstone (Kls). The Kls unit is host of ore mineralization in the study area and formed from ...
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Cretaceous sedimentary sequence in the Yazdan area is consisting of four rock units as, from the old to the new, clastic-carbonate (Kc), carbonate (Kl), Shale and marl (Km) sequences, and Sandy limestone and sandstone (Kls). The Kls unit is host of ore mineralization in the study area and formed from four members. Ore mineralization in the Yazdan Deposit has occurred as a stratiform horizon in the sandstone units of the third member. Texture and structures studies, shown three ore facies with elemental zonation in the Yazdan Deposit. These ore facies includes, stringer zone, massive ore facies and the bedded ore facies. This ore facies formed from laminated and layered sulfide and sulfate minerals. Fluid inclusions studies represents 255-136 ° C of homogeneity temperature with an average temperature of 189 ° C. Also, the salinity of fluid inclusions was calculated to be between 14.6-6% NaCl (on average, 9.5% NaCl). Geological evidence, host rocks type, texture and structures, existence of ore facies with elemental zoning as well as fluid inclusion investigations indicate the Yazdan Deposit has most similarity with Sedex-type deposit.
Original Research Paper
Stratigraphy and Palaeontology
maryam naderiyan; elahe zarei; khadijeh Mohammad-khani
Abstract
The Dalichai Formation in Darjazin section in NE Semnan with a thickness of 631 meters consisting of an alternation of bulish-gray was studied. This formation overlies the Shemshak formation disconformity with conglomerate bed and it has gradually been covered by the thick-beded limestones of the Lar ...
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The Dalichai Formation in Darjazin section in NE Semnan with a thickness of 631 meters consisting of an alternation of bulish-gray was studied. This formation overlies the Shemshak formation disconformity with conglomerate bed and it has gradually been covered by the thick-beded limestones of the Lar formation. In order to study paleoenviroment of the Dalichai Formation the authors examined many different factors including Microfacies and palynological data (abundance and diversity of Dinocyst, proximate to chorat Dinocyst, palynofacies analysis and "selective preservation of organic matter"). A high percentage of brown wood and sporomorphs and the dominance of cavate and proximate dinocysts such as Nannoceratopsis gracilis, and pareodinia ceratophora and fluorescent amorphous organic matter, as well as Miliolid benthic foraminifera are evidence of suboxic to anoxic condition, which favored accumulation and preservation of organic matter in open marine lagoon, in the lower part of Dalichai Formation. A decrease in the brown wood and abundance and species richness of marine palynomorph (mainly chorate dinocysts) reflects more offshore settings in the upper part of Dalichai Formation. On the other hand, Appearance and increase of planktonic foraminifera and Radiolar and posidonia indicate development of strong marine transgression and deposition in an open marine environment.
Original Research Paper
Petrology
manijeh Asadpour; Soraya Heuss
Abstract
Acidic patches with alkali-granite nature have been intruded within the mafic rocks of the Qushchi complex (70 Km north of Urmia city). This area is northwestern part of the SSz zone with Precambrian basement. These granits have high amounts of K2O and SiO2 (over 70 wt%). Dating by U-Pb age of zircon ...
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Acidic patches with alkali-granite nature have been intruded within the mafic rocks of the Qushchi complex (70 Km north of Urmia city). This area is northwestern part of the SSz zone with Precambrian basement. These granits have high amounts of K2O and SiO2 (over 70 wt%). Dating by U-Pb age of zircon grains show 303.4 ± 2.2 Ma, indicating late Carboniferous - early Permian magma activity. The presence of older cores in some of zircon grains with age between 400 to 600 Ma, indicate presence of older rocks in the study area. The whole-rock isotopic analysis show negative initial Nd (t) = -1.3 with TDM = 1.61. These data provide evidence for partial melting of crust (with Neoproterozoic- Cambrian age) in early Permian. The 87Sr/86Sr = 0.752348 and εNd = -1.4 of whole rock and Th/U (>0.5) values in zircons show the involvement of more crustal and less mantle components, during the opening of Neo-Tethys Ocean. Due to the same mineralogical and geochemical composition and homogeneity with Qushchi granite, it is inferred that these patches are genetically related to Qushchi granite and are A type granite.
