Editor-in-Chief Lecture
Volume 22, Issue 86 , December 2012, Pages 1-1
Reviewers
Volume 22, Issue 86 , December 2012, Pages 2-2
Original Research Paper
A. Fathian Baneh; S. Solaymani Azad; H. Nazari; M. Ghorashi; M. Talebian
Abstract
Tabriz city, the most highly population city of NW Iran, is located close to the North Tabriz Fault (NTF). This 150 km right-lateral strike-slip fault consists of two major fault segments arranged in right-stepping pattern. A pull-apart basin has been formed within the overlap zone of these fault segments ...
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Tabriz city, the most highly population city of NW Iran, is located close to the North Tabriz Fault (NTF). This 150 km right-lateral strike-slip fault consists of two major fault segments arranged in right-stepping pattern. A pull-apart basin has been formed within the overlap zone of these fault segments due to the recent right-lateral motion. The basin margins mark by fault branches and fault splays, which connect these two major segments of NTF. High level historical earthquakes occurrence shows seismic activity of NTF. Among which, NTF is responsible of at least two destructive earthquakes occurred in 1721 A.D. (Ms 7.3) and 1780 A.D. (Ms 7.4). This fault has not experienced any strong seismic events since 1780 A.D. Within past decades, it has been tried to recognize large number of old earthquakes utilizing paleoseismological investigation. Previous paleoseismological studies have been focused on the NW and SE segments of the fault. In the present study, to complete the data sets necessary to assess the seismic hazard related to Tabriz city, we focus on overlap zone of the two main fault segments. Using aerial photos, satellite images and field investigations, a potential site has been recognized within the zone (6 km NW of Tabriz City) to perform paleoseismological studies. Trench opened perpendicular to fault scarp strike and focused paleoseismological investigations in that, show evidences of at least two macroseismic events.
Original Research Paper
H. Pashaei; B. Hamdi; S. A. Aghanabati
Abstract
The studied section (Ruteh) is situated in central alborz, 31km north of Tehran.The thikness of measured section is 312m. The Elika Fm in Ruteh section is located 1 km far from the north of Ruteh village and 3 km far from the north of Fasham city. Lowermost strata seems to be parallel to ...
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The studied section (Ruteh) is situated in central alborz, 31km north of Tehran.The thikness of measured section is 312m. The Elika Fm in Ruteh section is located 1 km far from the north of Ruteh village and 3 km far from the north of Fasham city. Lowermost strata seems to be parallel to rocks of the units which attribiuted to the Nessen Formation.and the upper boundary with Shemshak Fm. is obviously indicate disconformity. The Elika Fm. is subdivided to 9 lithological subunits.the lower part is consisting of thin-medium-bedded limestone. The upper part is mainly consisting of thick-bedded dolomite with intercalations of thin-bedded limestones. The Nessen Fm in this section subdivided to 2 lithological subunits. The lower part is consisting of 8 m bauxite-laterite and the upper part is mainly consisting of thin-medium-bedded limestones. Base of micropaleontology studies, 26 genus, 47 species and 1 subspecies of Foraminifers and conodont element have been recognized illustrating 1 Foraminifer biozone and 4 Conodont biozones. This Conodont biozones in Elika Fm consist of: Hindeodus parvus zone Pachycladina – Hadrodontina zone, Neospathodus cristagalli zone, Parachirognathus – Furnishius zone. According to Conodont data, carboniferous sequences in Ruteh Section were deposited from lower Griesbachian to Anisian-Ladinian in age. Also 8 genus and 14 species of Foraminifers have been described for the first time in uppermost of the bauxite – laterite ,so 1 Assemblage zones have been reported: Paraglobivalvulina mira – Pachyphloia iranica Assemblage zone. Comparision of color index Alteration (CAI) or postmortal facies Conodont elements with standard table presented by Epstein et al. (1977), show that CAI is 4 that indicate temporal interval of 190 – 300 with notation to this degree of temperature absence Oil and Gas in area.
Original Research Paper
A. Naeimi; Gh. Heidarzadeh; M. R. Sheikholeslami
Abstract
The ~100km-long NE-SW Cheshmeh nay fault zone is located in Alborz-Allah Dagh Mountains. This fault zone is composed of several faults with dips between 40 to 85° toward NW or SE. The Cheshmeh nay fault zone belongs to the Shahrud fault system and has a left-lateral motion. Geomorphic evidence such ...
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The ~100km-long NE-SW Cheshmeh nay fault zone is located in Alborz-Allah Dagh Mountains. This fault zone is composed of several faults with dips between 40 to 85° toward NW or SE. The Cheshmeh nay fault zone belongs to the Shahrud fault system and has a left-lateral motion. Geomorphic evidence such as deflected streams, bisected alluvial fans and cut Quaternary deposits shows that this fault zone has been active during Quaternary. Exposure of Paleozoic and Mesozoic formations over or in contact with younger units as well as abundant thrust fault planes present in the fault zone indicate that there seems to have been a thrust faulting along the fault zone sometime during its evolution. In addition, the Cheshmeh nay fault zone coincides with the F-431 aeromagnetic lineament, indicating that the fault zone is supposed to be an old basement fault. Making part of the boundary between the Alborz and Kopeh Dagh basins, this fault zone was a basin-bounding normal fault zone which changed the kinematics into a thrust fault zone. This kinematics change resulted likely from the Iran Block moving toward the Turan and Kopeh Dagh regions and/or in Late Cretaceous. Following the regional reorganization in the Arabia-Eurasia collision zone between 3-7 Ma and/or in Quaternary, the Cheshmeh nay fault zone became a fault zone with a dominant left-lateral movement.
Original Research Paper
B. Oskooi; G.A. Fanaee-Kheirabad
Abstract
Geothermal energy is playing a large role as an alternative energy source for both electricity generation and space heating. Sabalan is a high temperature geothermal region in Ardabil province northwestern of Iran. In this study the conductivity structure of the top crust (depth lower than 2 kilometers) ...
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Geothermal energy is playing a large role as an alternative energy source for both electricity generation and space heating. Sabalan is a high temperature geothermal region in Ardabil province northwestern of Iran. In this study the conductivity structure of the top crust (depth lower than 2 kilometers) is examined using data from collected 212 magnetotelluric (MT) and time-domain electromagnetic (TDEM) soundings across the Sabalan volcano in 1998. The MT data collected between 1-8192 Hz is of useful quality and provides good control on the surface layers in majority of sites. The MT data were corrected for static shift effect using TDEM data. The TDEM data and MT data were jointly inverted to yield 1D and 2D models. In practice for geothermal investigation, measured MT data are never entirely 1D and diagonal elements of the impedance tensor are always non-zero. However, in many cases the Earth response is dominated by an overall 2D structure, permitting data analysis within these lower dimensions. In this study, in order to have the best possible interpretation we used two modes MT data in 2D inversion. Static shift correction and inversion approach accomplished by using WinGlink software. We choose three intersect profiles with 54 MT sites along with, to show resistivity distribution around Sabalan and try to predict the main intrusive magma chamber position as the heat source of the system. MT resistivity images confirmed the findings of previous surveys and the reported geological features in the Sabalan field. To have a better view about resistivity distribution, we combine the 2D models at the intersection points to obtain a 2.5D view about the resistivity in the area. The resulting models reveal the extension of the high conductivity anomalies in the western and southwestern parts of the area that most probably is related to the main heat source of the geothermal system at shallow depths.
Original Research Paper
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.
Original Research Paper
V. Alizadeh; M. Momenzadeh; M. H. Emami
Abstract
Based on Qayen 1:100000 geological map, the copper mineralization of Vorezg in volcanic rocks is attributed to Paleocene-Lower Eocene. Submarine volcanic rocks of the study area are found in two forms of lava and pyroclastics. Based on field and laboratory investigations, the outcropped rocks in Vorezg ...
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Based on Qayen 1:100000 geological map, the copper mineralization of Vorezg in volcanic rocks is attributed to Paleocene-Lower Eocene. Submarine volcanic rocks of the study area are found in two forms of lava and pyroclastics. Based on field and laboratory investigations, the outcropped rocks in Vorezg deposit are andesite, andesite – basalt, basalt and several small exposures of pyroclastic rocks such as tuff. Alkaline volcanic rocks of the area show within plate characteristics. Texture of mineralization is vein-veinlet, disseminated and open space filling amygdales. According to the mineralography studies, main minerals of copper are chalcocite, β-chalcocite, bornite, covellite, digenite and rare native copper. Chalcocite is the most abundant mineral. Intergrowth among copper ores is observed in most cases. Silver was detected as accessory phase (copper element paragenesis) in this ore deposit. Whereas silver has not founded an independent crystalline phase, therefore in the crystal of chalcocite, copper was replaced by Ag. Fluid inclusion studies on trapped fluids in quartz show homogenization temperature average is 230-250 ºC and salinity degree of fluids is 5-6%wt NaCl. On the basis of recognized characteristics, Vorezg ore deposit is comparable with Manto and Volcanic redbed type copper deposits. Recently, these two types of deposits are considered as synonyms.
Original Research Paper
M. Maghsoudi; F. Rafia; M. Ghorashi
Abstract
Classification of discontinuities and fractures in rock plays an important role in study and problem solving in geosciences fields, especially in Engineering Geology and Rock Mechanics. Nowadays, joints are classified on the basis of two geometrical parameters of dip and dip direction, presented on stereonets. ...
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Classification of discontinuities and fractures in rock plays an important role in study and problem solving in geosciences fields, especially in Engineering Geology and Rock Mechanics. Nowadays, joints are classified on the basis of two geometrical parameters of dip and dip direction, presented on stereonets. It is clear that the behavior of discontinuities cannot be thoroughly presented by these parameters in solving such related problems, as stability of geotechnical structures like rock slopes and tunnels. The present paper deals with the results of a research within which a new method of joint classification by 3 parameters has developed. This is done in 3D environment software, utilizing Matlab and SPSS softwares as supporting programs. Two employed parameters are conventional dip and dip direction, while the third parameter can be one of other joint characteristics such as infilling, length, aperture and so on. In order to check the validity of the method, it was applied in one of the Neyriz Marble quarries, where rock mass contains well defined and clear joints. In this research, the type of infilling of joints has been taken into account as the third parameter, and the results were compared to the traditional 2-parameters classification. This revealed that one joint system defined on stereonets, in new 3-parameter classification, is distinguished as two separate joint systems regarding their type of infilling, namely, iron oxides and non-filling. Field investigation shows the joint system with no infilling is contributing in instability of rock walls and also occurrence of spalling phenomenon in toes of some benches. Utilizing SPSS software, a regression analysis has been performed for each set of joint data, and it is shown that a better correlation factor exists between the values in the new 3D classification. It also shows that the more non-filling joints extend northward, their dips tends to 90°, and this can be a key in slope stability studies, as well as in mining design and planning.
Original Research Paper
M. Azizi; S. Senemari
Abstract
Using calcareous nannofossils is a powerful way for biozonation in sub-stage level, especially in the Late Cretaceous and Cenozoic, because they are planktonic, cosmopolitan, abundant and have very short age. Considering lack of any precise paleontological studies about the Gurpi Formation in the NW ...
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Using calcareous nannofossils is a powerful way for biozonation in sub-stage level, especially in the Late Cretaceous and Cenozoic, because they are planktonic, cosmopolitan, abundant and have very short age. Considering lack of any precise paleontological studies about the Gurpi Formation in the NW of shiraz (Bavan), nannofossils chose to investigate. This Formation consists of shale, marl and limestone. In this study, 23 genera and 46 species of nannofossils were identified. According to the identified marker species, 14 biozones were diagnosed that classified as CC14-CC26 and NP1(Base of the Pabdeh Formation). According to these biozones, it has been suggested that this section is aged of the Gurpi Formation from Early Santonian to Danian. The existence of CC26-NP1 zonal marker species of the K/T boundary has been considered which indicates continuous sedimentation from the Late Cretaceous to Early Paleocene.
Original Research Paper
M. Khalatbari Jafari; M. Ghani
Abstract
The extrusive sequence exposed in the vicinity of Gez village located in the NW Sabzevar, comprises a diversity of rocks which could be divided in three main parts. The lower part contains abundance hyaloclastic breccia and tuff, and the middle part comprises vesicular pillow lava and the upper part ...
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The extrusive sequence exposed in the vicinity of Gez village located in the NW Sabzevar, comprises a diversity of rocks which could be divided in three main parts. The lower part contains abundance hyaloclastic breccia and tuff, and the middle part comprises vesicular pillow lava and the upper part has an alternation of sheet flow and volcanic-sedimentary rocks. The intercalations of pelagic limestone have Late Cretaceous microfouna. The abundant of hyaloclastic breccia-tuff, sheet flow and aphyric vesicular pillow lava versus phyric pillow lava indicate the formation of this sequence in the fast spreading rate. The supra-ophiolite volcanic-sedimentary rocks located in the Afchang area contain an alternation of turbidites with lava flow, phyric-aphyric lava, chert-radiolarite and pelagic limestone. The paleonthology studies of those revealed Late Cretaceous age, which suffer this idea that the supra-ophiolite serie formed in a trough juxtapose the Sabsevar oceanic crust at Late Cretaceous. Based an geochemical data, the sheet flow of lower part and the pillow lava of the middle part show OIB characters but the lava flows of the upper part of extrusive sequence and the phyric, aphyric and lava flow of supra-ophiolite serie are depleted in Nb and slightly depleted in Zr could be comparable with subduction volcanism. Study of the tectonomagmatic diagrams verifies the OIB and island arc tendency and seems that the generation of the magma of the lower and middle parts influenced by mantle plumes. The magmatic source of the upper part of extrusive sequence and supraophiolite lavas is depleted which have different enrichement from the subduction components (fluids-melt) released from subducted slab. The tectonomagmatic setting of extrusive sequence and supra-ophiolite series can be justified with the senario of general subduction of oceanic slab beneath the centeral Iran microcontinent during Upper Crtaceous, towards in a back-arc basin.
Original Research Paper
M. Nemati; D. Hatzfeld; M. R. Gheitanchi; M. Talebian; N. Mirzaei; A. Sadidkhouy
Abstract
The Shahroud fault system plays important role in seismotectonic of the eastern Alborz. In this paper we have surveyed the seismicity of the middle-eastern Alborz and its southern area. At this investigation, the data of the Geological Survey of Iran local seismological networks, the seismological networks ...
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The Shahroud fault system plays important role in seismotectonic of the eastern Alborz. In this paper we have surveyed the seismicity of the middle-eastern Alborz and its southern area. At this investigation, the data of the Geological Survey of Iran local seismological networks, the seismological networks of the Institute of Geophysics of the University of Tehran and the International Institute of Earthquake Engineering and Seismology of Iran were used for processing the focal mechanism of micro-earthquakes and the south of Damghan earthquake and its greatest aftershock. Distribution of the micro-earthquakes and the south of Damghan events epicenters indicate intense activity of the Shahroud fault system and the Toroud fault. Focal mechanisms of them shows near vertical dipping of the faults and left lateral mechanism of the western segments of the fault system and the Toroud fault. The focal mechanisms suggest the Astaneh, Chashm and Firouzkuh faults from the system fault behave in a same manner with no deference between them at depth and have seismic potential proportion to their total length. Also due to left lateral mechanism of the south of Damghan earthquakes, Toroud fault treats like of the eastern Alborz seismotectonically and this area could cover Toroud fault.
Original Research Paper
E. Ghasemi-Nejad; M., Asadi; M. Shahmoradi; A. Aghanabati; T. Mohtat
Abstract
The Nayband Formation was sampled at Chal-Sefid and Zard mountains in central Iran, for palynology and palynostratigraphy in order to take the advantage of dinoflagellate cysts to locate the Triassic and so called Jurassic boundary. The Chal-Sefid section is located about 45 km southwest of Kashan city ...
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The Nayband Formation was sampled at Chal-Sefid and Zard mountains in central Iran, for palynology and palynostratigraphy in order to take the advantage of dinoflagellate cysts to locate the Triassic and so called Jurassic boundary. The Chal-Sefid section is located about 45 km southwest of Kashan city and Zard Mountain some 70 km northeast of Esfahan. The studied strata attain a thickness of 1750 meters in Chal-Sefid and 1820 meters in Zard Mountain. They consists sandstone and shale beds. Totally 75 samples from Chal-Sefid and 22 samples from Zard Mountain were collected and treated in the Palynology laboratory of the Geological Survey of Iran. The recorded dinoflagellate cyst species were differentiated in four palynozones in Chal-Sefid and two palynozones in Zard Mountain as follows: Chal-Sefid section: Palynozone 1: Rhaetogonyaulax wigginsii, encompasses 160 meters of the section, suggesting an early to middle Norian age. Palynozone 2: Suessia listeri with a thickness of 140 meters, suggesting a middle Norian age. Palynozone 3: Hebecysta balmei encompasses 550 meters of the section, suggesting middle to late Norian age. Palynozone 4: Rhaetogonyaulax rhaetica with a thickneses of 900 meters suggests an early to middle Rhaetian age. Zard Mountain section: Palynozone 1: Hebecysta balmei, encompasses 442 meters of the section, suggesting a middle to late Norian age. Palynozone 2: Raetogonyaulax rhaetica, encompasses 491 meters of the section, suggesting an early to middle Rhaetian age. It is revealed that all the rock units investigated here are of late Triassic age and no evidence of Jurassic ages was identified.
Original Research Paper
H. R. Nassery; F. Alijani; M. Nakhaei
Abstract
To determine the ground water potential of the karst aquifers, in the southwest of Izeh, three profiles and 62 vertical electrical sounding (VES) conducted by Schlumberger array, eight profiles were performed using dipole-dipole configuration, and 3-D configuration applied in two sites. However, Schlumberger ...
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To determine the ground water potential of the karst aquifers, in the southwest of Izeh, three profiles and 62 vertical electrical sounding (VES) conducted by Schlumberger array, eight profiles were performed using dipole-dipole configuration, and 3-D configuration applied in two sites. However, Schlumberger tomography with high investigation depth (about 180 m) may be shows the different zone of karst aquifer but because of 50-100 m of VES spacing has not the detectability of cavities with lower than 50 m diameter. The results show that Ilam-Sarvak limestone is similar to hard rocks while Asmari formation has been identified as developed karst with high matrix porosity. The results in the 2-D geoelectrical tomography using a dipole-dipole configuration, shows that, compared to an electrode spacing of 5 m, an electrode spacing of 1 or 2 m has a higher ability to delineate karst voids. Because of the higher depth of the investigation, however, the longer electrode spacing allowed obtaining a comprehensive insight of different parts of karst regions. The high resolution 3-D electrical tomography has a good ability to detection of geological features and karst voids. The geoelectric results and interpretation of tomograms have been asserted by drilling success of four wells with high yield at Asmari formation and two wells with moderate yield at Ilam-Sarvak formation.
Original Research Paper
K. Mohammadiha; M. Sabzehie; M. Ghahraei pour; A. Kosari Torbehbar
Abstract
Located in the NW Iran, in Sanadaj-Sirjan metamorphic belt, the studied area mainly comprises of metamorphic and varied acidic-basic igneous originated rocks. Basic metamorphic rocks have been chemically controlled by two main metamorphic processes including metasomatism and dynamic deformation. Amphibole ...
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Located in the NW Iran, in Sanadaj-Sirjan metamorphic belt, the studied area mainly comprises of metamorphic and varied acidic-basic igneous originated rocks. Basic metamorphic rocks have been chemically controlled by two main metamorphic processes including metasomatism and dynamic deformation. Amphibole and plagioclase are of the most significant minerals occurring in the rocks. Here we represent the chemical variations of those metamorphic minerals in relation to their host rocks and prograde metamorphism. Mineral chemistry analyses of amphibole minerals reveal an increase in Al2O3, TiO2 and a decrease in MgO, MnO during mylonitization of gabbroic rocks. Affected by metasomatism, the Al2O3 and Na2O contents of amphiboles have been also increased. CaO content of plagioclase has declined; in contrast, Al2O3 and Na2O have raised during mylonitization and metasomatism processes. These variations are overally ruled by chemical composition of the intruded pluton, pressure-temperature condition, oxygen fugacity and occurrence of equilibrant phases. Increasing Al and Na brings about tschermakite substitution in the deformed amphiboles and edinite substitution in the metasomatized rocks respectively.
Original Research Paper
F. Rostami; V. Ahmadi
Abstract
In this research two stratigraphic sections of Lower Cretaceouse to Upper Jurassic sedimentary (Surmeh and Fahliyan Formation in Folded-Zagros Zone) have been selected. Based on microfacies studies (in 400 thin-sections) three species of Ichnofossils microcoprolites from Crustaceans related as the Follow: ...
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In this research two stratigraphic sections of Lower Cretaceouse to Upper Jurassic sedimentary (Surmeh and Fahliyan Formation in Folded-Zagros Zone) have been selected. Based on microfacies studies (in 400 thin-sections) three species of Ichnofossils microcoprolites from Crustaceans related as the Follow: Palaxius decaochetarius, Helicerina siciliana, Palaxius tetraochetarius, palaxius isp. In general, considering Ichnotaxons studies, two assemblage-zones were identified for microcoprolites Crustaceans. Assemblage-zone (No:1) of Tithonian to Berriasian and assemblage-zone (No:2) whichis lated of Valanginian, taxons Helicerina isp. Assemblage-zone (No:2) which is related.
Original Research Paper
Kh. Hashemi; B. Oveisi; A. Saeedi
Abstract
Young deformations and folds are one of the impressive characteristics of Zagros simple folded belt. The studied structure is Hormud fault-related fold which is situated in the coastal Fars and the southward of Lar town. In order to illustrate the geometry of the studied structure and its kinematic relationship ...
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Young deformations and folds are one of the impressive characteristics of Zagros simple folded belt. The studied structure is Hormud fault-related fold which is situated in the coastal Fars and the southward of Lar town. In order to illustrate the geometry of the studied structure and its kinematic relationship with north and south structures, a structural cross section with ~27 km length from NE to SW was prepared. This study showed that Hormud anticline has been formed in the footwall of Lar fault, synchronous with kinematic reorganization in the core of Lar anticline and increasing horizontal stresses. Interpretation of crustal young deformations in the vicinity of the footwall of Lar fault indicates that Hormud anticline is growing in the form of a constant limb length detachment fold. Estimation of relative shortening rate (0.9± 0.2) for south limb of Hormud anticline is showing its fast growth in the form of a rocket fold which was associated by fast propagation of Hormud fault toward the surface. As a consequence of this process, kinematic model of Hormud anticline changes from a constant limb length detachment fold to a shear fault bend fold. Estimations predict 0.7 ± 0.1 mm/yr relative uplift rate for young Hormud anticline in its crest.
Original Research Paper
B. Shafiei; S. Lali faz; Gh. H. Shamanian; H. Taghizadeh; M. Hossaini; R. Mathur
Abstract
In present study, Re concentration determined in 30 hexagonal (2H) and trigonal (3R) molybdenite samples belong to veinlets of different stages of hypogene mineralization from 7 porphyry Cu and Mo deposits from Kerman region. Re concentration in molybdenites of these ore deposits varied from 49 ...
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In present study, Re concentration determined in 30 hexagonal (2H) and trigonal (3R) molybdenite samples belong to veinlets of different stages of hypogene mineralization from 7 porphyry Cu and Mo deposits from Kerman region. Re concentration in molybdenites of these ore deposits varied from 49 g/t to 1449 g/t which are in Re concentration range of other porphyry Cu and Mo deposits around the world. In general, 3R molybdenites show the higher Re concentration (average ~ 563 g/t) than those of 2H molybdenites (average ~ 479 g/t). Variations of Re concentration in molybdenite types deposited during different stages of hypogene mineralization indicate more concentration of Re in molybdenites precipitated with transitional (B-type veins) and late (D-type veins) stages of mineralization than those of early stage veinlets (A-type veins). This distribution suggest that Re with more acidic and cooler hydrothermal fluids at the transitional and the late stages of porphyry system evolution is more concentrated with silicification, sericitization, and argillization alterations. Present study indicated that molybdenites with high Re content are associated with porphyry copper deposits which are characterized by low average grade of Mo, limited contents of molybdenite, and also their productive intrusive is resulted from significant contribution of mantle-derived magmas respect to crustal materials.In addition to abovementioned signatures, frequency of 3R poly-type of molybdenite in ore deposits, less fractionated and more calcic composition of productive intrusive of ore deposits with their less radiogenic of Sr and Pb isotope ratios, as well as occurrence of late stages of acidic and low temperature hydrothermal alteration and mineralization processes in formation and evolution history of ore deposits are signatures of porphyry copper and molybdenum deposits with high Re contents.
Original Research Paper
P. Rajabi; I. M. Moghadam; F. Gharib
Abstract
In this study, the Sediments of Taleh-Zang Formation was investigated in South West of Khoramabad. The thickness of Taleh-Zang Formation in Qalebi section measured 200m. In this section the sediment of Taleh-Zang Formation is isoclines between Amiran Formation at the base, and Kashkan Formation at the ...
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In this study, the Sediments of Taleh-Zang Formation was investigated in South West of Khoramabad. The thickness of Taleh-Zang Formation in Qalebi section measured 200m. In this section the sediment of Taleh-Zang Formation is isoclines between Amiran Formation at the base, and Kashkan Formation at the top. This Formation composed of gray limestone with chert nodules and Sandy Limestone. The study of samples taken from the studied section led to identification 28 genera and 4 species of benthonic Foraminifera and 6 genera and 2 species of green algae. The benthonic Foraminifera of the measured section were used to recognized the age of Succession and justify their correlation Based on the recognized Foraminifera such as Miscellanea miscella. The Qalebi section is Comparable to biozonation introduced by Wynd (1965). It is analogous to Miscellanea – Kathina assemblage zone (No# 43). According to distribution of the index Foraminifera, the age of the Sediments in Qalebi Section is Thanetian.
Original Research Paper
A. N. Fazlnia
Abstract
A barrovian-type metamorphism occurred in the mafic rocks from the Qori complex (South Sanandaj - Sirjan zone), because of a regional arc-related metamorphism with a peak metamorphic condition of 700 °C and 8.5 kbar at 147 million years ago. As a result of the process, the rocks changed to migmatite. ...
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A barrovian-type metamorphism occurred in the mafic rocks from the Qori complex (South Sanandaj - Sirjan zone), because of a regional arc-related metamorphism with a peak metamorphic condition of 700 °C and 8.5 kbar at 147 million years ago. As a result of the process, the rocks changed to migmatite. Trondhjemitic granitoids were formed as the dike form because parts of the melts can be extracted from the migmatites. Decreasing and increasing trace and rare earth elements in the amphibolites and trondhjemites were resulted of stability or instability in the metamorphic minerals during peak of the metamorphism, which caused migmatization and also formation of trondhjemite. Based on the partition coefficients of elements in different minerals, light rare earth elements (LREE) were mostly controlled by hornblende and garnet and apatite (but not a lot) during the partial melting of the amphibolites. Related to the LREE, heavy rare earth elements (HREE) and Y were controlled by apatite and garnet. Elements with high field strength (HFS), such as Zr, Nb, Ta and Th were controlled and distributed by hornblende and ilmenite. Large ionic lithophile elements (LILE) such as Sr, Ba and Rb showed that plagioclase and biotite were main minerals to control and distribute the elements. The evidence suggests that the Qori trondhjemitic granitoids are similar to the Al-poor trondhjemites, which are the result of partial melting of the garnet-hornblende from the amphibolitic protolith in presence of calcic plagioclase as stable phase.
Original Research Paper
M. R. Nikudel; M. Hashemi; N. Hafezi Moghaddas; M. Khamehchiyan
Abstract
The overview of geological condition of an area is too important for land-use planning. An engineering geological model can provide this overview. In this research, based on carried out studies and investigations, a model is given that shows the general engineering geological conditions of sediments ...
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The overview of geological condition of an area is too important for land-use planning. An engineering geological model can provide this overview. In this research, based on carried out studies and investigations, a model is given that shows the general engineering geological conditions of sediments in western Caspian Sea coast. This research is based on geomorphological, geological, sedimentological, hydrogeological and geotechnical studies. In this model, land units with similar behavior are defined and then the engineering geological characteristics and relevant geological hazards of these units are quantified. This model cannot be used as detail site investigation but serves as useful tool for preliminary investigation. This model helps to better design of field surveys as well as optimal selection of investigation methods for future civil engineering projects.
Original Research Paper
M. Talebian
Abstract
The north east of Iran, extending from central Alborz to Kopeh Dagh Mountains, is one of the most seismically active regions of Iran. Several large and ancient cities are located in this region and thus provide relatively reach documented history of earthquakes. Numerous active faults have been known ...
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The north east of Iran, extending from central Alborz to Kopeh Dagh Mountains, is one of the most seismically active regions of Iran. Several large and ancient cities are located in this region and thus provide relatively reach documented history of earthquakes. Numerous active faults have been known in this area, some of them have already been under geological investigations, yet many needs to be studied. However, recent geodetic measurements provide a general view about rates of strike slip and shortening across the region. This study evaluates potential of implementing geologic and geodetic data in seismic hazard assessment in this part of Iran. To achieve this, the region of study has been divided to 5 structural zones. The moment accumulating rate was then calculated for each zone using both geological and geodetic measurements. This moment has been compared with moment released by earthquakes. Comparison of seismic moment released by instrumental and historical earthquakes with moment accumulating rate along major active faults suggest that geologic and geodetic data can be considered as a reliable source of information in seismic hazard analysis, especially where there is no sufficient record of earthquakes in the catalogs.
Original Research Paper
K. Orang; Mohammad Mohajjel; F. Mousivand; E. Rastad
Abstract
The Chah Gaz Zn-Pb-Cu volcanogenic massive sulfide (VMS) deposit is a polydeformed, polymetamorphosed ore body in southern part of the Sanandaj-Sirjan zone. The ore bodies are comprised predominantly of stratiform, tabular and lenticular massive sulfide lenses and are elongated in 0600-0700 orientation. ...
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The Chah Gaz Zn-Pb-Cu volcanogenic massive sulfide (VMS) deposit is a polydeformed, polymetamorphosed ore body in southern part of the Sanandaj-Sirjan zone. The ore bodies are comprised predominantly of stratiform, tabular and lenticular massive sulfide lenses and are elongated in 0600-0700 orientation. The host rocks and massive sulfides have been complexly deformed during three deformation stages (D1, D2, D3) and two associated episodes of green schist facies metamorphism (M1, M2) that all events occurred after middle Jurassic. The earliest structural elements in the mine area are bedding and continuous foliation (S1) that are preserved in the host rocks; include phyllites, slates and schists. F1 folds have not been identified in the ore bodies, Although they do recognized as shallowly to moderately plunging to NW and isoclinal folds within the Chah Gaz area. Geometry of ore bodies was mainly controlled by D2 structures (include folds and foliations). F2 plunge shallowly to NE or SW. F2 are close to open and their axial planes dip steeply to S and N. Ore bodies are commonly transposed from S0-S1 and show rearrangement parallel to axial planar foliation (AS2) and composite foliation (ST2). ST2 is vertical and strikes NE-SW. Sulfide minerals in the ore bodies have undergone extensive deformation, remobilization and dynamic recrystallisation during D2 tectono-thermal stage. D3 structures are locally controller of ore bodies and include folds and shear zones.
Original Research Paper
S. Parham; M. R. Kamali; F. Fayazi
Abstract
The Dalan Formation (Upper Permian) is mainly composed of limestone and dolostone with minor evaporite interbeds. Upper carbonates of the Dalan Formation constitute one of the main gas reservoirs in the Zagros fold thrust belt especially in the Fars and the Persian Gulf. The upper part of the Dalan Formation ...
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The Dalan Formation (Upper Permian) is mainly composed of limestone and dolostone with minor evaporite interbeds. Upper carbonates of the Dalan Formation constitute one of the main gas reservoirs in the Zagros fold thrust belt especially in the Fars and the Persian Gulf. The upper part of the Dalan Formation consists of oolitic grainstone with high reservoir quality. Based on sedimentological studies in the upper Dalan unit, seven microfacies have been recognized. This microfacies have been deposited in warm, arid intertidal, lagoon and shoal. They deposited in a homoclinal ramp. Different diagenetic process affected this unit are bioturbation, micritization, neomorphism, replacement, dolomitization, anhydritization, mechanical and chemical compaction, cementation, dissolution and fracturing. Based on the evidence like widespread dissolution, formation of moldic and vuggy porosity and precipitation of different types of meteoric cements and based on paragenetic sequences, it can be concluded that the studied interval, have not buried after the deposition, but at least some parts like oolitic shoal exposed subearially and was affected by meteoric diagenesis that was followed by deep burial diagenetic environment.
Original Research Paper
M. A. A. Mokhtari; H. Moinvaziri; M. R. Ghorbani; M. Mehrpartou; G. Hosseinzadeh
Abstract
Kamtal skarn zone is located in the 20km north of Kharvana in the Eastern Azarbaijan. Skarn-type metasomatic alteration is the result of Kamtal monzonitic intrusion into the Upper Cretaceous impure carbonates. Kamtal skarn include exoskarn and endoskarn zones. Exoskarn is the major zone that its thickness ...
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Kamtal skarn zone is located in the 20km north of Kharvana in the Eastern Azarbaijan. Skarn-type metasomatic alteration is the result of Kamtal monzonitic intrusion into the Upper Cretaceous impure carbonates. Kamtal skarn include exoskarn and endoskarn zones. Exoskarn is the major zone that its thickness varies between 100-600m. Field and mineralogical studies demonstrate that exoskarn zone composed of garnet rich sub-zone (garnet skarn), epidote rich sub-zone (epidote skarn) and marble sub-zone. Garnet is the most important calc- silicate mineral within the garnet skarn sub-zone. They are mainly grossularitic in composition (Ad33-35), but along the fractures, andraditic composition (Ad66-73) is predominant. Clinopyroxene is the other dominant mineral within garnet skarn sub-zone that has diopsidic composition (Di82.8-85.7). In the epidote skarn sub-zone, epidote is the predominant mineral while garnet and clinopyroxene present in some places and have low concentration. Petrographic studies indicate that marly limestone was the primary rocks of the garnet skarn sub-zone while clay-bearing marl was the primary rocks of the epidote skarn sub-zone. Skarnification process can be categorized into two discrete stages: 1) prograde and 2) retrograde stages. Prograde stage began immediately after the initial emplacement of the Kamtal monzonitic magma into the enclosing impure carbonate rocks. The effect of heat flow from the intrusion caused the enclosing rocks to become isochemically marmorized in almost homogeneous limestone layers and bimetasomatized (skarnoid–hornfels) in thin interlayers of clay-rich carbonates. Invasion of segregated fluid phase of Kamtal intrusion into the fractures and micro-fractures of the marmorized and skarnoid–hornfelsic rocks incorporate considerable amounts of Fe, Si and Mg into the metasomatic aureole. During retrograde stage, due to relatively low temperature hydrothermal fluids and processes such as hydrolysis, carbonation and sulfidation, considerable amounts of hydrous calc-silicates, sulfides, oxides and carbonates replaced the anhydrous calc-silicates. Garnet and clinopyroxene are the most abundant mineral assemblage in Kamtal skarn zone, which were formed in temperature lower than 550°C. Lack of wollastonite in this mineral assemblage, intergrowth of garnet and clinopyroxene crystals and lack of any reaction rim between these crystals, and lack of emplacement texture indicate that they formed contemporaneously within the temperature and ƒO2 ranges of 430–550ºC and 10-26–10-23, respectively.
Original Research Paper
M. K. Hafizi; H. Ranjy Roodposhti
Abstract
In this paper, the results of recent archaeological studies in Neyshabour, Iran, by the application of Electrical Resistivity (ER) and Induced polarization (IP) methods have been presented. The aim of this study was to verify the effectiveness and suitability of these techniques in detecting of the buried ...
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In this paper, the results of recent archaeological studies in Neyshabour, Iran, by the application of Electrical Resistivity (ER) and Induced polarization (IP) methods have been presented. The aim of this study was to verify the effectiveness and suitability of these techniques in detecting of the buried archaeological structures and remains in Iran and other similar sites that were mostly constructed out of adobe, mud brick. Several geoelectrical profiles were conducted in addition to IP and ER experiments on the samples and the test profile. The test profile was performed over an adobe-made wall outcrop. This work shows that these methods are so effective and useful for investigating of structures like walls, furnaces and pavements which their materials contain a large amount of clay.
Original Research Paper
S. R. Moussavi-Harami; Y. Nasiri; A. Mahboubi; A. Bayetgoll
Abstract
Amiran Formation (Paleocene) in Lorestan, folded Zagros zone, contains a diverse and exceptionally well preserved ichnofauna. A quantitative study of trace fossil in the Paleocene deep-marine clastic systems, this Formation, shows that they are powerful discriminators of submarine fan and related environments. ...
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Amiran Formation (Paleocene) in Lorestan, folded Zagros zone, contains a diverse and exceptionally well preserved ichnofauna. A quantitative study of trace fossil in the Paleocene deep-marine clastic systems, this Formation, shows that they are powerful discriminators of submarine fan and related environments. The host lithologies are conglomerates, sandstones, siltstones and mudstones. These sediments are interpreted to be deposits in upper to lower-fan palaeoenvironment. Channel deposits consist of thick-bedd turbidite and interchannel deposits are interpreted to be deposited by unconfined debris flows and high concentration turbidity currents. The ichnofauna with high diversity is most frequently, and best, preserved within the Tcde interval of turbidities, which are interpreted as interchannel deposits, produced by low concentration turbidity flows. On the basis of trace fossil diversity, ichnotaxonomic composition, ethology, and morphologic complexity, trace fossils assemblage were grouped into pre-depositional or post-depositional forms. The predepositional assemblage is rich in graphoglyptids and grazing trails, and feeding structures. The ichnodiversity, ethology, and morphologic complexity of the predepositional association are indicative of the Nereites ichnofacies. The postdepositional association essentially consists of dwelling and feeding traces. The post-depositional association includes elements of the Skolithos ichnofacies. Overall characteristics of trace fossils suggest that from the proximal to the distal environment of Amiran Formation, proportions of domichnia trace-fossil assemblages decreases while agrichnia, fodinichnia and pascichnia increases.
Original Research Paper
N. A. Rashidnejad Omran; A. A. Fattahi; F. Masoudi
Abstract
The late Eocene post-collisional Khoshoumi- Dar-Anjir intrusive complex consist of two adjacent Khoshoumi granite and Dar Anjir diorite plutons in Saghand area, located in 120 km northeast of Yazd in Central Iran structural zone. This complex intruded within high-grade metamorphic rocks of Chapedony ...
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The late Eocene post-collisional Khoshoumi- Dar-Anjir intrusive complex consist of two adjacent Khoshoumi granite and Dar Anjir diorite plutons in Saghand area, located in 120 km northeast of Yazd in Central Iran structural zone. This complex intruded within high-grade metamorphic rocks of Chapedony Complex. Syenogranite, monzogranite, granodiorite, tonalite and quartzdiorite constitiue its lithologies. Aplitic and micromonzonitic to microdioritic dikes crosscutting the entire body. Hybrid rocks and mafic microgranular enclaves with various shapes and sizes are widely seen in this complex. Geochemical investigations show that these rocks are metaluminous to moderately peraluminous, magnesian and high- K calc- alkaline I- and A-type granitoids. Chonderite- normalized REE patterns of both plutons and related dikes display intra-elemental fractionation (2.72 >(La/Yb)N >41.64) and concentration of LREE and Eu negative anomalies (ave Eu/Eu*= 0.63). Trace elements behavior represent depletion in Nb, Ti, P and enrichment in K, Rb, Ba and Th that could be assigned to mafic magma contamination by crustal materials. Their tectonic setting match with Volcanic Arc Granites (VAG) and Within Plate Granites (WPG). Petrographical, geological and tectonomagmatic characteristics of this intrusive complex are very similar to high- K calc- alkaline granites (KGC) and like most of them, fractional crystallization and mafic – felsic magma mixing play significant role in its evolution and petrogenesis.
Original Research Paper
N. Kharazizadeh; M. Almasian; Sh. Sherkati
Abstract
Geometric style and deformation analysis of folding are two important aims of geological studies in Zagros, which is related to concentration of considerable of hydrocarbon reservoirs in anticlinal traps of the belt. In this study, evolution and geometry of Aghajari subsurface anticline (Dezful embayment) ...
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Geometric style and deformation analysis of folding are two important aims of geological studies in Zagros, which is related to concentration of considerable of hydrocarbon reservoirs in anticlinal traps of the belt. In this study, evolution and geometry of Aghajari subsurface anticline (Dezful embayment) is considered based on 3D seismic data and well information. Based on illustrated structural cross sections, special attention was paid to geometrical variations of folding from fold pericline to central part of this structure. Geometrical complexity along and normal to the fold axis is related to implication of intermediate soft units in sedimentary pile. Fold evolution analysis shows limb rotation and hing migration which are the main mechanism for fold growth and passing from box to chevron style as well. Development of satellite structure around main anticlines in Zagros is promising features for hydrocarbon entrapment, which related to involment of decollement levels in folding.
Original Research Paper
Yahya Djamour; M. M. Hossainali; Y. H. Chavari; P. Vanicek; H. Nazari; M. Amighpey; S. Arabi
Abstract
The technique of precise leveling is certainly the most precise in gathering height difference observations. The main limitation of the mentioned technique is its high cost and low speed characteristics. Hence, for the purpose of repeating the precise leveling measurements (re-leveling), which is necessary ...
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The technique of precise leveling is certainly the most precise in gathering height difference observations. The main limitation of the mentioned technique is its high cost and low speed characteristics. Hence, for the purpose of repeating the precise leveling measurements (re-leveling), which is necessary for vertical geodynamical studies, it is important to gather these observations in an optimum manner. The main purpose of this study is analyzing the characteristic features of the vertical deformation in Iran. This would assist us in concentrating the measurements in the areas that are more prone to vertical deformation as well as the analysis of vertical deformation has a priority in them. For this purpose, various kinds of data from geology, geophysics, seismology, geodesy as well as the population densities have been put together and analyzed. Result of this analysis is a new strategy to make precise re-leveling observations in Iran in a optimum way needed for vertical geodynamical studies, as a solution to the request of National Cartographic Center of Iran.
