Petrology
Tahereh Parsa; Monireh Kheirkhah; Mir Ali asghar Mokhtari
Abstract
Cenozoic acidic volcanic rocks at the south of Qezel Ozan River are located within the Western Alborz-Azarbaijan magmatic zone and northern part of the Iranian-Turkish Plateau. The Oligocene acidic lavas in north part of Zanjan show rhyolitic to dacitic composition. Hyaloporphyritic to hyalomicrolithic ...
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Cenozoic acidic volcanic rocks at the south of Qezel Ozan River are located within the Western Alborz-Azarbaijan magmatic zone and northern part of the Iranian-Turkish Plateau. The Oligocene acidic lavas in north part of Zanjan show rhyolitic to dacitic composition. Hyaloporphyritic to hyalomicrolithic porphyritic textures are the main texture in these rocks. They were erupted along the main faults in this area. Feldspars, biotites and hornblendes are the major phenocrysts which are embedded in a glass matrix or micro phenocrysts of felsic and mafic minerals. By Geochemical studies it is indicated that these rocks have high-K calc-alkaline to shoshonitic nature and classified as meta-aluminous and I-type acidic rocks. In the chondrite normalized rare earth elements diagram, these rocks demonstrate LREE enrichment and high LREE/HREE ratio. Enrichment in LREE and depletion in HREE is characteristic of the calc-alkaline rocks in active continental margins. Furthermore, these rocks show enrichment in LILEs and negative anomalies of HFSEs (Ti, Nb and Ta) which is the feature of magmatic rocks associated with Post-COLG subduction zones. The geochemical evidences suggest that the parental acidic magma is resulted from partial melting of lower crust as a result of pressure reduction during the local tension mechanism.
SH. Shafiei Bafti; S.A. Alavi; M. Mohajjel
Abstract
Faryab area at the southeastern part of the Sanandaj-Sirjan zone, containing the Paleozoic rocks in the internal part of Zagros Orogen, displays two folding episodes through a progressive deformation event. Axial planes of recumbent F1 folds dip moderately to the north and the ...
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Faryab area at the southeastern part of the Sanandaj-Sirjan zone, containing the Paleozoic rocks in the internal part of Zagros Orogen, displays two folding episodes through a progressive deformation event. Axial planes of recumbent F1 folds dip moderately to the north and the axes also plunge moderately to NW - SW. F1 folds were generated in a flexural-flow condition in whole lithological units. Thrust faults were produced along the overturned limbs of the F1 folds. These thrusts are most abundant in the central domain, the north of Zartorosht Au-index. At the southern edge of the central domain, displacement of large slabs of calcschist with interbedded marble were produced by these thrust faults.
Overturned limbs were cut by ductile shear zones of thrusts and development of green-schist facies in these shear zones implying the medium dips for thrusting. F2 folds were developed by co-axially refolding of F1 that are well exposed in Pasefid, Zartorosht and Zehmakan anticlines. Structural data shows the variation of F2 axis between S45W - N80W directions. Interference patterns of Z on S, M on S and S on S indicate coaxial refolding F1 by F2 (Hook Type).
D. Mokhtari; M. R. Nikjoo
Abstract
Tectono-geomorphologic features such as pressure ridges along strike-slip faults provide a reliable way to determine the fault displacement. The E-W trending active and strike-slip northern Mishow Fault is continuation of great Tabriz fault, that its ...
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Tectono-geomorphologic features such as pressure ridges along strike-slip faults provide a reliable way to determine the fault displacement. The E-W trending active and strike-slip northern Mishow Fault is continuation of great Tabriz fault, that its activity has created numerous geomorphologic traces. We document pressure ridges about Baghlar basin as a geomorphic effect of northern Mishow fault, based on tectono-geomorphic interpretation of field geologic and geomorphic observations. our results show that Pressure ridges of study area by the names of Sisdah and Tapah-Bashy, are developed along northern Mishow fault, which resulted from long-term tectono-geomorphic growth in Quaternary, specially. Present pressure ridges development indicate neotectonic movements in the study area. Occurrence of three phenomena of river diversion, river capture and continous go back of elbow of capture in a small segment of Baghlar basin, are the most important effects of high dynamics and durability of slope instabilities in pressure ridges. This case study, thus, provides a good example for understanding the long-term tectono-geomorphological evolution of a major intracontinental strike-slip fault.
G. Barzegari; A. Uromeihy
Abstract
Development of liquefaction in saturated cohesionless deposits is one of the most dramatic causes of damage in civil structures during earthquakes. The potential damage caused by liquefaction includes: 1) loss of bearing capacity, 2) excessive settlement, 3) lateral spreading, 4) flow failure, and 5) ...
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Development of liquefaction in saturated cohesionless deposits is one of the most dramatic causes of damage in civil structures during earthquakes. The potential damage caused by liquefaction includes: 1) loss of bearing capacity, 2) excessive settlement, 3) lateral spreading, 4) flow failure, and 5) ground oscillation.
The liquefaction susceptibility of a specific deposit is affected by many factors for example, wave-induced liquefaction characteristics, soil type, geological history, confining pressure, permeability, relative density, water content, and properties of the soil grain size.
Chapar-Abad Dam is an inhomogeneous earth-fill dam with height and crest length of 44.5 and 427 meters, respectively. The reservoir capacity is 127 million cubic meters. The dam which is under construction is located about 75 km southeast of UromiehCity, in West-Azerbaijan province. The foundation materials include 60 meters of alluvium deposits overlying the bedrock layers of carbonate units. The abutments consist of carbonate and schistose layers of Precambrian age. In this paper the potential of liquefaction of the site is evaluated according to the SPT results form in-situ tests performed in boreholes driven into the depth of alluvial deposits. Furthermore, recently modified relations of correction factors such as stress reduction factor (rd), earthquake magnitude scaling factor for cyclic stress ratios (MSF), overburden correction factor for cyclic stress ratios (Ks), and the overburden normalization factor for penetration resistances (CN) are presented and used in liquefaction assessment of alluvial foundation at Chapar-Abad Dam. The results indicate the possibility of liquefaction and instability of granular soils during earthquake and any types of strong motions.
Remote Sensing
Mina Zamyad; Peyman Afzal; Mohsen Pourkermani; Reza Nouri; Mohammadreza Jafari
Abstract
Tirka area is situated in NE Iran as a part of the TCMB which consists of Paleogene sediments and volcanic rock units with a combination of Eocene intermediate to basic rocks. The research aim is to determine the alteration zones using C-N fractal model based on ASTER satellite images. First, the ASTER ...
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Tirka area is situated in NE Iran as a part of the TCMB which consists of Paleogene sediments and volcanic rock units with a combination of Eocene intermediate to basic rocks. The research aim is to determine the alteration zones using C-N fractal model based on ASTER satellite images. First, the ASTER data was processed using SFF method for determination of iron oxide, propylitic, phyllic, and argillic alteration zones. The C-N fractal model is utilized for the separation of different parts of alteration zones. The results derived via the C-N fractal model showed that the main trend of the alteration zones is in NE-SW direction. Also, based on the C-N log-log plots, there are six geochemical populations for iron oxide alteration, four geochemical populations for argillic and phyllic alterations, and five geochemical populations for propylitic alteration. There is a high intensity of alteration zones commences with 223 for iron oxide, 204 for argillic, 199 for propylitic and phyllic alteration zones. In order to validate the results, field observations and petrographical studies based on thin-polish sections were carried out. These data confirmed the alteration zones obtained by the modeling. the data obtained from the combination methods, were verified by Logratio matrix,
S. S. Mohammadi; M. Vossoughi Abedini; M. Pourmoafi; M. H. Emami; M. M. Khatib
Abstract
Bibi Maryam Granitoid body with 5 km2 exposure area is located in the east Iranian ophiolite mélange belt in Sistan suture zone. This intrusive body consists of tonalite- quartzdiorite and granodiorite. The main mafic minerals are hornblende and biotite in quartzdiorite-tonalite. Existence of ...
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Bibi Maryam Granitoid body with 5 km2 exposure area is located in the east Iranian ophiolite mélange belt in Sistan suture zone. This intrusive body consists of tonalite- quartzdiorite and granodiorite. The main mafic minerals are hornblende and biotite in quartzdiorite-tonalite. Existence of microdioritic enclave in tonalite and its absence in granodiorites is one of the main characteristics of the body. Perthitic and granophyric textures in granodiorites represent low water vapor pressure and relatively fast crystallization, respectively. Geochemical study of rock samples shows that the body is calc-alkaline and metaluminous to peraluminous. Trace element patterns in spider diagrams represent a trough for Nb and enrichment for K, Rb, Ba and Th that indicate contamination by crustal materials. Although Bibi Maryam intrusive body cuts the ultramafic rocks, it lacks petrographic and geochemical characteristics of oceanic plagiogranites. The geochemistry of the body is comparable with I-type granitoids and based on tectonic setting it can be classified as orogenic and VAG type.
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.
M Hajibahrami; N Taghipour; G Ghorbani
Abstract
The Hamyerd iron deposit is located in the northeast of Semnan in the boundary of the southern Alborz and Central Iran structural zones. A sub-volcanic body of monzonite and monzodiorite composition intruded limestone and pyroclastic rocks (equivalent to the middle Eocene Karaj formation). The iron mineralization ...
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The Hamyerd iron deposit is located in the northeast of Semnan in the boundary of the southern Alborz and Central Iran structural zones. A sub-volcanic body of monzonite and monzodiorite composition intruded limestone and pyroclastic rocks (equivalent to the middle Eocene Karaj formation). The iron mineralization occurred at the contact between intrusive bodies and these sedimentary rocks. The extensive hematite content along with minor amounts of magnetite, goetite, limonite, pyrite, dolomite, barite and calcite are important characteristics of the Hamyerd ore deposit. Mineralization occurred as veins and also hematite lenses with minor magnetite content. Fluid inclusion and stable isotope (S, C and O) studies were integrated to explore the Hamyerd iron ore genesis. Petrographic studies display five types of fluid inclusions in quartz and 4 types in barite. Fluid inclusions in quartz include single-phase liquid, single-phase gas, two-phase liquid-rich, two-phase gas-rich, and three-phase (liquid-solid-gas) inclusions. Three-phase liquid-solid-gas inclusions were not detected in barite. Microtermometry studies in two-phase liquid-rich inclusions revealed homogenization temperatures of 200-250 ˚C and 100-200 ˚C, and salinities of 10-20 and 0.5-5 wt% NaCl equivalent for quartz and barite fluid inclusions, respectively. Microthermometry of halite-bearing three-phase fluid inclusions showed homogenization temperature from 200 to 350 ˚C and salinity from 30 to 40 wt% NaCl equivalent. δ34SCDT values of pyrites at Hamyerd iron deposit are in the range of 2.2 to 7.4‰. The isotopic values of barites range from 13.6‰ to 20.2‰ for δ34SCDT and 10.2‰ to 12.1‰ for δ18OVSMOW, respectively. The carbon and oxygen isotopic values of calcite are in the range of -3.4‰ to -4.5‰ and 17.7‰ to 19.1‰, respectively. Microthermometry of fluid inclusions and stable isotopes (S, O, C) at Hamyerd iron deposit suggested mixing of magmatic and meteoric fluids as origin of hydrothermal solutions. Mineralization in the Hamyerd iron deposit is probably similar to Fe-skarn deposits.
Economic Geology
faraj fardoost; Akbar Abdollahi Hydarbaghi; Solmaz Baluchi
Abstract
The Robaei Iron deposit is located in 96km south of Damghan. Host rocks of deposit are Late Cretaceous limestones (part I) and Eocene volcano- sedimentary rocks including sandy tuff (part II.( The alterations include chloritization, epidotization, argillation, silicification, carbonatization and hematitization. ...
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The Robaei Iron deposit is located in 96km south of Damghan. Host rocks of deposit are Late Cretaceous limestones (part I) and Eocene volcano- sedimentary rocks including sandy tuff (part II.( The alterations include chloritization, epidotization, argillation, silicification, carbonatization and hematitization. Minerals forming can be divided into three groups; iron minerals (hematite, magnetite, pyrite, pyrrotite goethite and limonite), copper- minerals (chalcopyrite, chalcocite, covellite and malachite) and gangue minerals (calcite, dolomite, quartz, garnet, epidote and chlorite). The structure and textures of ore minerals are massive, vein- veinlet, open space filling and disseminated. In part I, the metals grade of Fet is about 60%, Cu 0.7 % and Au 2.7 ppm and in the part II, the Fet are variables between 5.88 to 82.91% (average 31.2%), Cu between 275 to 20761 ppm and Au 0.89 ppm. Fluid inclusion studies were carried out on quartz mineral from the part II that homogenization temperature is frequency variables between 200 to 249°C with salinity of 2-4% wt. %NaCl. Based on the results of this investigation, part I has similarities with calcic skarn of low temperature and part II showed more similarities with iron oxide- copper- gold (IOCG) deposits.
S Alipour; B Hosseinzade; Y Rahimsouri
Abstract
Khanik-Gazan titanium potential is located at 82 km northwest of Urmia at the extremity of NW of Sanandaj-Sirjan geological zone. This deposit has formed in the Qazan mafic-ultramafic intrusive complex that intruded into the early Paleozoic sedimentary rocks. It consist ...
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Khanik-Gazan titanium potential is located at 82 km northwest of Urmia at the extremity of NW of Sanandaj-Sirjan geological zone. This deposit has formed in the Qazan mafic-ultramafic intrusive complex that intruded into the early Paleozoic sedimentary rocks. It consist of two general rock units including 1) mafic unit as the main outcrop volume and 2) ultramafic unit in smaller volume. The mafic rock type is gabbro in general formed of medium grained and layered accompanying by anorthosite sill and microgabbro (diabase). Layered mela and meso-gabbro are the main host rocks for titanium mineralisation in the studied area. The main minerals of the host rock included clinopyroxene (mainly augite), and calcic plagioclases. Opaque minerals and rarely olivine and apatite are the minor minerals and tremolite-actinolite, epidote, zoisite, chlorite, albite, sericite and calcite are the secondary minerals. Saussuritization, uralitization, sericitization and chloritization are the main alterations of main silicate minerals. Ilmenite, titanomagnetite, magnetite, and some hematite and pyrrhotite are the main primary opaque ore minerals. Open-space filling textures including granular and exsolution are the major textures of the ore, while, Spherical, martitization, mylonitization are the minor textures. Total abundance of ilmenite, magnetite, titanomagnetite in the studied polished sections ranges between 5 to 12 vol%. Oxide and silicate phases are associated with the host rocks due to the relatively low oxygen fugacity, which don’t occurred in complete separation of the silicate melt from oxide melt. Based on geochemical studies, the primary magma had revealed an alkaline to sub-alkaline (mainly tholeitic trend) series. According to the mineralogical and petrographical evidences and chemical analyses, the Khanik-Qazan ilmenite-titanomagnetite deposit is similar to the low grade apatite- ilmenite–magnetite Kauhajarvi and Lumikangas deposits, in western Finland.
M. Salari Rad; M. Irannejad; M.A. Mohammadi
Abstract
The Tarom Sofla copper ore zone includes several oxidized copper ore deposits, the most famous being Cheeseh, Aghdarreh and Yamaghan deposits. In view of the diversity of reserves and productivity of ore deposits in the area, two production capacities ...
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The Tarom Sofla copper ore zone includes several oxidized copper ore deposits, the most famous being Cheeseh, Aghdarreh and Yamaghan deposits. In view of the diversity of reserves and productivity of ore deposits in the area, two production capacities ( high : 2000 tpd and low : 90 tpd) , two leaching processes and two methods of recovery were considered to compare the economics of cementation vs. solvent extraction for recovering copper from leach solutions of these ores. Taking all the three parameters (production capacity, leaching processes and methods of recovery) into consideration eight alternatives were evaluated. Capital costs were estimated by employing order of magnitude calculations while operating costs were estimated by scaling up lab- scale costs. Economic comparison was made by the NPV method. The results showed that the NPV of the high capacity model was higher than the low capacity model while vat leaching has a lower NPV than agitation leaching. Similarly it was shown that cementation for the low capacity model has a higher NPV than solvent extraction while for the high capacity model the order is reversed. Hence it is concluded that for capacities less than or equal to 90 tpd cementation is the economically preferable method for recovering copper from leach solutions but for capacities greater than or equal to 2000 tpd solvent extraction is the better option.
Exploration and Mining
Keytash Moshtaghian; Seyed Mohammad Abtahi Forooshani; Hooshang Asadi Harooni; Mohammad Hajheidari; Ghazal Janghorban
Abstract
The Dalli porphyry Copper-Gold deposit consists of two northern and southern indexes located on the Urmia-Dokhtar Volcanic Belt in Markazi province. Due to the presence of magnetite beneath the potassic alteration zone in the center of porphyry mineralization, a magnetometric survey was performed ...
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The Dalli porphyry Copper-Gold deposit consists of two northern and southern indexes located on the Urmia-Dokhtar Volcanic Belt in Markazi province. Due to the presence of magnetite beneath the potassic alteration zone in the center of porphyry mineralization, a magnetometric survey was performed in the region. In the current study in the northern index, first, we extracted the local anomaly via removing the regional and aliasing effects from the magnetic data. Then, using three-dimensional inverse modeling of the reducted data illustrates the presence of a body with high magnetic susceptibility, in the depth range of 40 to 640 meters of the study area. A comparison between geochemical analysis of two exploratory core drilling with the depth variational model of the estimated magnetic susceptibility in the study area indicates a spatial correlation between increases in the grades of copper and gold and large variations of the magnetic susceptibility. Also, comparison between the magnetic susceptibility model and resistivity and chargeability models estimated from IP/RS data of three parallel profiles indicates a relation between sulfidic and altered mineralized zones and magnetic susceptibility variations. Therefore, the current study shows a high potential for the copper-gold mineralization in the northern Dalli index.
Petrology
Jalil Ghalamghash; Meysam Akbari; Reza Jamal
Abstract
The Taftan volcano hosts an extensive volcanic activity during Late Miocene to Quaternary where took place over Makran-Chagai subduction zone. Taftan rocks are mainly basaltic andesite, andesite, trachyandesite, and dacite that occur as lavas and pyroclastic rocks. They are characterized by basic-intermediate ...
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The Taftan volcano hosts an extensive volcanic activity during Late Miocene to Quaternary where took place over Makran-Chagai subduction zone. Taftan rocks are mainly basaltic andesite, andesite, trachyandesite, and dacite that occur as lavas and pyroclastic rocks. They are characterized by basic-intermediate inclusions enclosed by acidic groundmass, and disequilibrium textures in plagioclase phenocrysts including sieve texture, zoning, and dissolution margin, which may reflect magma mixing. These rocks record high-K calc-alkaline to calc-alkaline affinity with enrichment in LREE and LILE relative to HREE and HFSE, respectively. These features, coupled with the clear depletion in HFSE (such as Nb, Ta, and Ti) are consistent with typical subduction-related volcanic arcs. Taftan primary melts might have been produced by ~15% partial melting of spinel lherzolite mantle. The normalized multi-element patterns which mimic the upper continental crust values, and enrichment in Pb, Th, U, and Rb agree well with magma evolution by assimilation and fractional crystallization (AFC). The available isotopic geochronology dataset reveal that the youngest volcanoes of the Makran-Chagai magmatic arc are Bazman and Kuh-e-Sultan volcanoes. A geochemical comparison of these volcanoes highlights that magmatism in the Taftan where the crust is thick, underwent a higher degree of crustal assimilation en route to the surface.
M Farnaghi; A Mansourian
Abstract
Accurate and up-to-date spatial data play a crucial role in disaster management. However, currently utilization of spatial data in decision making process before, during and after disasters is limited due to various problems. Automatic composition of geospatial web services can significantly improve ...
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Accurate and up-to-date spatial data play a crucial role in disaster management. However, currently utilization of spatial data in decision making process before, during and after disasters is limited due to various problems. Automatic composition of geospatial web services can significantly improve the decision making process in disaster management. This article is going to represent an approach for utilization of automatic web service composition in disaster management. In this approach, geospatial web services of different organization are syntactically and semantically described and registered in the national geoportal. The services are composed based on user requirement using Artificial Intelligence Planning algorithms. The new composite web services are registered as new geospatial web services. The applicability of the approach is illustrated in a case study for generating a composite web service that can build landslide susceptibility map.
H Gerivani; N Hafezi Moghaddas; E Haghshenas; E Abdollahi Fard
Abstract
Notwithstanding geological and geophysical surveys and studies for hydrocarbon reservoir detection cost very much, those have lots of uncertainties. Then, engineers and scientists try to find and use new methods. Recently, some studies have suggested using ambient noise as a tool for hydrocarbon reservoir ...
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Notwithstanding geological and geophysical surveys and studies for hydrocarbon reservoir detection cost very much, those have lots of uncertainties. Then, engineers and scientists try to find and use new methods. Recently, some studies have suggested using ambient noise as a tool for hydrocarbon reservoir investigation. This new passive seismic technique, named HyMas, is based on the positive energy anomaly in data spectra between 1 to 6 Hz for microtremor measurements over reservoirs, which are called hydrocarbon microtremors. Despite the acceptable results obtained by the HyMas technique, there are many unknowns, especially concerning the source and generation mechanism of hydrocarbon microtremors and the relations between reservoir characteristics and the attributes of hydrocarbon microtremors. In this study, it has been tried to review the published experiences and studies and conclude the results and findings.
S.A Babazadeh; M Ghavidel-Syooki; H Ghasabi
Abstract
The Asmari Formation is well-exposed at Kuh-e-Mish, locating at Gorg-Darreh area (The Zagros fold-thrust belt). In this area, the true thickness of Asmari Formation is 480m. This formation was studied for its microfacies analysis in Gorg-Darreh area (kuh-e-Mish). In this study, seven microfacies was ...
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The Asmari Formation is well-exposed at Kuh-e-Mish, locating at Gorg-Darreh area (The Zagros fold-thrust belt). In this area, the true thickness of Asmari Formation is 480m. This formation was studied for its microfacies analysis in Gorg-Darreh area (kuh-e-Mish). In this study, seven microfacies was recognized within this formation. These microfacies belong to the tidal flat, restricted lagoon, protected lagoon, patch reef, foreslope, basin sub-environments. A carbonate ramp is suggested for depositional environments of the Asmari Formation. Likewise, distributions of foraminifers of this formation were studied in order to determine the age relationships of the Asmari Formation. In this study, 45 species belonging to 41 genera were identified. In general, three assemblage biozones were recognized in this formation, consisting of Lepidocyclina – Operculina - Ditrupa Assemblage Zone, Peneroplis evolutus - Austrotrillina howchini Assemblage Zone and Borelis melo curdica – Meandropsina iranica Assemblage Zone. Therefore, based on these assemblage biozones, the Asmari Formation is assigned to late Oligocene (Chattian) – early Miocene (Aquitanian- Burdigalian).
F Doulati Ardejani; M Pishdadian; A.R Arab-Amiri; R Kakaei; M Mohammado Khorasani
Abstract
In the aim of petroleum exploration at Qum area, gravity and magnetic measurements incorporating 2059 measuring stations have been conducted in order to detect likely buried oil traps, any volcanic intrusive, faults and subsurface folding related to the Qum formation. Bouguer and total magnetic anomaly ...
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In the aim of petroleum exploration at Qum area, gravity and magnetic measurements incorporating 2059 measuring stations have been conducted in order to detect likely buried oil traps, any volcanic intrusive, faults and subsurface folding related to the Qum formation. Bouguer and total magnetic anomaly maps were produced when the required corrections were made on the gravity and magnet data. The fractal method incorporating intensity-area model was used to produce residual gravity and magnetic maps. These maps were compared with those maps produced by trend surface analytical method and then interpreted. The results obtained by the interpretation show that although the presence of an anticline which was determined using gravity method is important for petroleum exploration; however, the magnetic intensity is very high on a part of this anomaly. Furthermore, it is probably affected by the surrounding faults. The results obtained in this study can be effectively used to decide doing further exploration works in the study are.
A Bayat Gol; N Abbassi
Abstract
A detailed ichnological study on the Geirud Formation (Late Devonian-Early Carboniferous) from the Zaygon area, central Alborz shows a diverse trace fossils, which include 14 ichnogenera represented by 23 ichnospecies. These trace fossils contains various ethological patterns, such as domichnia, fodinichnia, ...
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A detailed ichnological study on the Geirud Formation (Late Devonian-Early Carboniferous) from the Zaygon area, central Alborz shows a diverse trace fossils, which include 14 ichnogenera represented by 23 ichnospecies. These trace fossils contains various ethological patterns, such as domichnia, fodinichnia, grazing, equilibrichnia, and fugichnia. These trace fossils are: Arenicolites, Asterosoma, Chondrites intricate, Chondrites targionii, Diplocraterion parallelum, Arenicolites isp., Asterosoma isp., Chondrites intricate, Chondrites targionii, Chondrites isp., Diplocraterion parallelum, Helminthoidichnites isp., Helminthopsis abeli, Helminthopsis isp., Palaeophycus heberti,Palaeophycus tubularis, Planolites beverleyensis, Planolites isp., Phycodes cf. palmatus, Rhizocorallium jenense, Rhizocorallium irregular, Rosselia soccialis, Taenidium serpentinum, Taenidium satanassi, Talassinoides horizntalis, Thalassinoides suevicus, Thalassinoides paradoxicus, Zoophycos isp. Studied beds consist by alternations of laminated mudstones and siltstones, and thick- to medium-bedded sandstones with wavy lamination. Hummocky, trough and low angle to planar cross-bedding are common in layers. It seems that these beds were deposited in the delta to open marine environments. Determined ichno-assemblage represents characteristic of a moderately shallow-marine environment, which effected occasionally by high-energy conditions. A trace fossil assemblage has been examined from the uppermost dark-colored shale layers of the Geirud Formation in the Devonian/Carboniferous (D-Ca) boundary. This assemblage include Chondrites targionii, Zoophycos isp., which involved by Hangenberg event.
S Afzali; N Nezafati; M Ghaderi
Abstract
The Gazestan magnetite–apatite deposit is located 78 km east of Bafq, in the Bafq-Poshtebadam subzone of the Central Iran structural zone. The rock units in the area belong to the Rizou series and consist of carbonate rocks, shale, tuff, sandstone and volcanic rocks. Intrusive rocks in the form ...
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The Gazestan magnetite–apatite deposit is located 78 km east of Bafq, in the Bafq-Poshtebadam subzone of the Central Iran structural zone. The rock units in the area belong to the Rizou series and consist of carbonate rocks, shale, tuff, sandstone and volcanic rocks. Intrusive rocks in the form of stock and dyke crop out as granodiorite and granite in various places. Trachytic and dacitic rocks in the area are green due to chloritic alteration and host iron and phosphate mineralization. The main alteration types are chloritic and argillic, while sericitic, potassic, and silicic alterations as well as tourmalinization and epidotization are also found in the rock units. Five forms of mineralization are distinguished in the Gazestan deposit, including massive iron ore with minor apatite, apatite-magnetite ore, irregular vein-veinlets (stockwork) in the brecciated green rock and disseminated and monomineralic massive apatite veins. Fluid inclusion studies were conducted on the apatites of two stages. According to these studies, temperature and salinity values in the stage-I apatite are higher than those in stage-II apatite. Lower salinity values in the stage-II apatite could be due to contamination of magmatic fluids with meteoric waters during later stages of mineralization. Oxygen, hydrogen and carbon stable isotope composition of magnetite, quartz, apatite and calcite; and calculation of oxygen isotope composition in the fluid equilibrated with the oxide minerals suggest mixing the magmatic fluids with basin brines in mineralization of the Gazestan deposit.
F. Dabbaghi Sadr; K. Seyed-Emami; M. Majidi Fard
Abstract
Upper Jurassic rocks are well developed at the western part of the Binalud Range (northeast Iran). These consist mainly of limestone, marlstone and marl with few intercalations of sandstone and conglomerate. The thickness of this succession in the study section (Bormahan, northwest of Neyshabour) ...
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Upper Jurassic rocks are well developed at the western part of the Binalud Range (northeast Iran). These consist mainly of limestone, marlstone and marl with few intercalations of sandstone and conglomerate. The thickness of this succession in the study section (Bormahan, northwest of Neyshabour) is 1084 meters and can be subdivided into 6 members. The lower boundary with the dark siliciclasts of ?Kashafrud Formation (Upper Bajocian / Lower4 Bathonian) is sharp. The upper boundary with buff and cliff-forming carbonates of the ?Mozduran Formation (Upper Jurassic) is transitional. Ammonites are the most important and abundant macrofossils.Totally more than 300 specimens have been collected, comprising 21 genera and 36 species.The relative abundances at the family level are: Phylloceratidae (48%), Perisphinctidae (42%), Oppeliidae (6%), Haploceratidae (2%), Aspidoceratidae (1%) Based on the ammonite fauna 15 biozones are recognized which can be fairly good compared with the ammonite biozonation of Sub-Mediterranean Province. According to the ammonite fauna an Early Bathonian to Kimmeridjian age is proposed.The ammonite fauna is closely related to those of the Sub-Mediterranean Province, indicading a permanent faunal exchange.
H. Ghasemi; Mojtaba. Garavand; N. Hafezi Moghddas
Abstract
In this paper, the role of Gorgan metamorphic complex, as a geogenic source of the heavy metals has been investigated in the soils of south Kordkoy and Gorgan areas. For this, some important soil chemical parameters such as pH, EC, CEC, and concentrations of the heavy metals in 14 soil samples and 6 ...
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In this paper, the role of Gorgan metamorphic complex, as a geogenic source of the heavy metals has been investigated in the soils of south Kordkoy and Gorgan areas. For this, some important soil chemical parameters such as pH, EC, CEC, and concentrations of the heavy metals in 14 soil samples and 6 rock samples have been determined and interpreted. The enrichment factor, geo-accumulation index, contamination factor and degree of soil contamination for the elements of As, Cd, Co, Cr, Cu, Mn, Mo, Pb, V and Fe, have been studied. Multivariant Statistical methods including Pearson correlation, cluster analysis and principal component analysis were done to study the correlations and paragenetic relations. The results shown that the average concentration of Fe (80502.86 ppm) is higher than maximum allowable concentration (70000 ppm) and located near the threshold (100000 ppm). Also, average values of V (165.09ppm) is higher than maximum allowable concentration (150 ppm) but is very lower than its threshold (450 ppm). Average values of Cr, Ni, Co and Cu are in the range of the background concentration and those for Pb, As, Mo and Cd are lower than background. Calculation of the enrichment factor indicates the low enrichment of As and Fe in these soils. Iron, with the geo-accumulation index of 0.14, is uncontaminant to slightly contaminant. Also, contamination factors of iron, cobalt and vanadium are low and overaly, in the sense of environmental quality, the soil of this area classified among uncontaminated or very low contaminated areas. The results of the statistical analysis of the heavy metal data indicate the lowest concentrations of these elements in the soils derived from pelitic schists, especially in Tuskestan valley, and the highest values of them in the soils derived from the basic igneous rocks, such as Naharkhoran valley. These results show a natural geogenic origin for the heavy metals and the role of chemical composition of the Gorgan metamorphic complex in the entrance of them in the soils of this area.
A Jamshidi; M.R Nikudel; M Khamehchiyan
Abstract
In cold regions, freeze-thaw cycles are one of the most important agents affecting on the mechanical properties of stones and consequently their durability. Uniaxial compressive strength, Brazilian tensile strength and P-Wave velocity are among important mechanical properties in assessing the durability ...
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In cold regions, freeze-thaw cycles are one of the most important agents affecting on the mechanical properties of stones and consequently their durability. Uniaxial compressive strength, Brazilian tensile strength and P-Wave velocity are among important mechanical properties in assessing the durability of the stones used in cold regions. As regards of determination these properties during the freeze-thaw cycles experiment is very time consuming and cumbersome, statistical relationships can be used to estimate the mechanical properties. In this study, a multivariate statistical model is presented for 15 samples of travertine, which can estimate uniaxial compressive strength, Brazilian tensile strength and P-Wave velocity in each cycle of the freeze-thaw experiment. In this model, mechanical properties after freeze-thaw cycles were considered to be the dependent variable that dependent on the variables of the initial mechanical properties, water absorption and the number of freeze-thaw cycle. The statistical tests results and also data from other researchers show that model presented is reasonably accurate in estimating uniaxial compressive strength, Brazilian tensile strength, P-Wave velocity and consequently their durability of the travertines in each cycle of the freeze-thaw experiment.
Kh Noraei Nezhad; H Amiri Bakhtiar; R Mohammadian; A Azizi
Abstract
Marun Oil Field is located in the southern part of Dezful embayment, in the mid part of the zagros simple folded mountain range and along the Ramin and Aghajari anticlines. In this study, based on the subsurface data and using subsurface analytical methods the folding mechanism and fractures of this ...
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Marun Oil Field is located in the southern part of Dezful embayment, in the mid part of the zagros simple folded mountain range and along the Ramin and Aghajari anticlines. In this study, based on the subsurface data and using subsurface analytical methods the folding mechanism and fractures of this anticline has been studied. In this research, using the primary results of geophysical data, analysis methods, geometric curvature changes, mud loss and reservoir engineering data, geometry of anticline and fractures associated with folding have been analyzed. Folding mechanisms in this anticline is a combination of flexural-sliding folding and folding with neutral surface. In other words, the Marun subsurface anticline is a thrust fault- related fold and also a faulted detachment fold. Seismic profiles showthat the Marun anticline as a concentric fold that from surface to depth space has been decreased. This decrease of space associated with faulting in the southern flank and these faults disappear in the Gachsaran formation. A good conformity among geometric analytical methods, mud loss data, index productivity on bending region in the Marun anticline and presence of fractures in this region exist. The data analysis shows that the highest density of fractures is related to the bending region in the Marun Oil Field. Finally, using these parameters, it is recommended that for further drilling of development and production wells these parameters must be regarded and the northeastern part of the Oil Field as well as southern flank of the anticline must be given full consideration.
M Mirzaei Souzani; A Shahidi; R Ramezani; F Alizadeh Sevari
Abstract
In order to survey the extensional forces dominated in central Alborz since Late Triassic (Norian) to Middle Jurassic (Early-Bajocian), synsedimentary normal and strike-slip fault systems in Balladeh valley which contains significant distribution of Shemshak Group have been studied. Analysis of σ3 ...
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In order to survey the extensional forces dominated in central Alborz since Late Triassic (Norian) to Middle Jurassic (Early-Bajocian), synsedimentary normal and strike-slip fault systems in Balladeh valley which contains significant distribution of Shemshak Group have been studied. Analysis of σ3 orientation for 404 fault planes in 35 normal fault systems, show two major extension directions at NNE (020°) and NE (070°) trends during sedimentation of Shemshak Group. Also, the presence of a minor extension direction trending WNW (300°) which is coincident with extension direction of synsedimentary strike-slip fault systems implies the existence of transtentional basins in the Shemshak basin at that time. The southward movement of southern edge of Eurasia (from latitude of 30° to 15°) and its clockwise rotation for some 40°-50° during Triassic-Jurassic periods led to domination of N-S extension in early times of Shemshak Group sedimentation, and as soon as the Eurasian plate rotated, the extension direction was changed into a NE-SW trend. These separated records of paleostress axis trends are also due to the high sedimentation rates and subsidence in Norian-Rhaetian and Toarcian-Aalenian during Shemshak Group sedimentation. The minor extension trending WNW-ESE (278°-307°) is due to σ2/σ3 permutation between N-S σ3 direction of stress tensor and its σ2 axis. Low values of Φ (less than 0.4) generally correspond to situation characterized by σ2/σ3 permutation; therefor it causes multidirectional extension in extensional stress regimes. About 80 percent of sites which show WNW-ESE paleostress extension trend have low Φ values. This issue explains σ2/σ3 permutation of N-S major extension trend. The areas of mentioned stations and also those ones with strike-slip fault systems σ3 directions of which are directed WNW-ESE had high basin crustal anisotropy.
H Karimian zade; M.R Vaziri; A Lotf abad Arab
Abstract
In order to study the paleoecology of the Aptian gastropods, the Bafgh section with 380 meters thickness, in East of Yazd were studied in detail. In this region, a variety of different fossil groups, including macrofossils (gastropods, ammonites and echinoids) and microfossils (foraminifers and ostracods) ...
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In order to study the paleoecology of the Aptian gastropods, the Bafgh section with 380 meters thickness, in East of Yazd were studied in detail. In this region, a variety of different fossil groups, including macrofossils (gastropods, ammonites and echinoids) and microfossils (foraminifers and ostracods) are present and suggest an Aptian age for this section. 11 genus and species of gastropods are reported for the first time from this section. The microfossils and macrofossils assemblage all show a shallow environment with a suitable conditions for the time of sedimentation in the study area.
