Original Research Paper
Volume 23, Issue 92 , September 2014, Pages 1-1
Original Research Paper
Volume 23, Issue 92 , September 2014, Pages 2-2
Original Research Paper
Volume 23, Issue 92 , September 2014, Pages 3-3
Original Research Paper
E Eshaghi; A Kamkar-Rouhani; A Arab-Amiri
Abstract
Every geophysical method has its own advantages and disadvantages. The integration of the results obtained from surveys using various geophysical methods causes the weaknesses of a particular geophysical method to be covered by the other geophysical methods. For this, different exploration, engineering, ...
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Every geophysical method has its own advantages and disadvantages. The integration of the results obtained from surveys using various geophysical methods causes the weaknesses of a particular geophysical method to be covered by the other geophysical methods. For this, different exploration, engineering, environmental and other investigations using various geophysical methods usually provide more reliable results. In this research work, it is attempted to integrate the results of electrical resistivity tomography (ERT) and ground-penetrating radar (GPR)surveys in order to examine the advantages and weaknesses of each of the two methods, and finally, to present more accurate and more reliable interpretation as a result of this integration. The ERT method that is, in fact, one of optimal resistivity survey methods, renders acceptable results in complex geology areas. The GPR method as a high resolution non-destructive geophysical method, which is based on transmission of electromagnetic waves in the ground and recording the reflected waves from the interfaces of the subsurface layers, is used for shallow subsurface investigations. In this research work, a water qanat was selected as a suitable target for detection by these two geophysical methods, and the, ERT and GPR surveys were carried out in an area enclosing the target. The results obtained from processing, modeling and interpretation of the acquired data indicated that the GPR method, compared to the ERT method, had higher resolution than the ERT method. However, the ERT method, compared to the GPR method, had higher depth of penetration. The results of both methods were mainly in good agreement with each other in depicting features such as subsurface cavities, variation of the grain sizes of the subsurface sediments and water percolation from the qanat to its surroundings. Furthermore, following the integration of the results of these two methods, it was found that the accuracy and reliability of the interpretation were considerably enhanced.
Original Research Paper
B Rahimzadeh; F Masoudi; Sh Ranjbar
Abstract
Scoria is one of the main pyroclastic units in Damavand volcano, which its main crystals are plagioclase, olivine and pyroxene. In this study, characterization of bubbles and their formation during the eruption considered using Bubble Size Distribution (BSD) method including study of volume, 3D modeling, ...
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Scoria is one of the main pyroclastic units in Damavand volcano, which its main crystals are plagioclase, olivine and pyroxene. In this study, characterization of bubbles and their formation during the eruption considered using Bubble Size Distribution (BSD) method including study of volume, 3D modeling, nucleation and bubble growth. For selected sample, thebubbles investigated in 3 perpendicular dimensions (X-Y-Z) and in total 16830 bubbles (X=7357, Y=5385, Z=4088) were measured and drawn. The Bubbles volumes calculated in 3 dimensions are X=47.21, Y=40.27, Z=40.01 percent. The Bubbles axes were calculated: X=1:1:4, Y=Z=1:1:3.4 and the 3D schematic shape is ellipsoid which the longest axis (L) is about 4 times longer than the other two axes (I, S). The L axis is parallel to the lowest pressure dictated on magma and the bubbles could be grown 4 times more in that direction. The bubbles shape of Damavand scoria is an ellipsoid with an average of 1:1:3.7 for its axes. The presence of 3 peaks in frequency distribution versus bubble size diagram, suggesting polymodal events of bubbles generation and in the Damavand volcano the bubbles nucleation occurred in 3 events(F1, F2, and F3). The nucleation density increased from F1 to F3 but the bubbles growth reduced in the same direction. The first group of bubbles formed in the magma chamber and the second group formed during the magma ascent. The third group of bubbles could form either in the space between earlier groups or in the last stage of magma eruption.
Original Research Paper
M Abdi; M.H Karimpour; M.H Zarinkoob
Abstract
The main purpose of this study is processing of raw data by factor analysis method and having interpretation and integration them by geological, alteration and mineralization data. The distinctiveness of third factor of factor analysis for Au, Mo and W and the coincidence of third factor anomalies by ...
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The main purpose of this study is processing of raw data by factor analysis method and having interpretation and integration them by geological, alteration and mineralization data. The distinctiveness of third factor of factor analysis for Au, Mo and W and the coincidence of third factor anomalies by gold, high primary sulfide bearing area, secondary iron oxide and sericitic and silicic alterationrevealed that the third factor of factor analysis is the agent of mineralization in the study area. The suitable tectonic setting, shallow depth intrusiveswithintermediate composition, calc-alkalineand oxidant magmatism, anomaly of gold and disseminated mineralization in thehost rock and sulfide veinlet accompanied byabundant secondary iron oxide providedproperconditions for porphyry and epithermal type gold mineralization in the study area.
Original Research Paper
R Shabanian; N Ghanizadeh
Abstract
The Illanqareh Formation consists of sandstone, shale, dolomite, extrusive igneous rocks, and limestone. This Formation is about 400 m thick and crops out in the west of Illanlu village, south of the Aras dam, north of the West Azarbaijan province. The clastic deposits of the Illanqareh formation attributed ...
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The Illanqareh Formation consists of sandstone, shale, dolomite, extrusive igneous rocks, and limestone. This Formation is about 400 m thick and crops out in the west of Illanlu village, south of the Aras dam, north of the West Azarbaijan province. The clastic deposits of the Illanqareh formation attributed to the late Devonian and the upper carbonate division belongs to the early Carboniferous. The study of prepared thin sections resulted in recognizing 15 species related to 9 genera of 8 foraminifera families. The comparison of identified foraminifera' assemblage in the studied stratigraphical section with those from other Carboniferous formations of Iran and the world indicated a Tournasian- Visean age for the marine deposits of this formation. The Illanqarah formation in the Illanlu section overlies the early Devonian Muli formation and underlies the early Permian Doroud formation both disconformably.
Original Research Paper
Z Khosravi; S.M Hosseini-Nezhad
Abstract
The carbonate and terrigenous sedimentary sequence of the Padeha and Bahram formations (late Givetian- late Frasnian) with a total thickness of 126 m have a gradational and conformable contact at Baghin region of W Kerman in Central Iran. The terrigenous facies are mainly consisting of sandstone and ...
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The carbonate and terrigenous sedimentary sequence of the Padeha and Bahram formations (late Givetian- late Frasnian) with a total thickness of 126 m have a gradational and conformable contact at Baghin region of W Kerman in Central Iran. The terrigenous facies are mainly consisting of sandstone and shale deposited in the beach environment. The carbonate rocks including dolomite and limestone have tidal flat, lagoon and barrier (shoal) facies. Based on the index conodonts and brachiopods the late Givetian- late Frasnian age is suggested for this studied section. The conclusions of petrographical studies indicated a shallow carbonate platform of ramp type for these sediments. The stratigraphical study of the Bahram formation at the studied area resulted in identifying 3 sedimentary sequences of the third order, which according to the microfacies and conodonts consist of the following items. The first sequence begins with transgression at the base of the Lower falsiovalis – Upper falsiovalis zone (TST), with continuation of transgression, it reaches the maximum flooding level (mfs) indicated by the coral bindstone facies in a shoal environment and then is followed by the relevant HST parasequences. The second sequence begins at transitans – punctata zone, and finally the TST parasequences with ooid grainstone in a shoal environment reaches the maximum flooding level (mfs) at the Lower rhenana zone and ceases, and then is followed by the HST parasequences. The third sedimentary sequence begins at the base of Upper rhenana-? linguiformis zone, its maximum flooding surface (mfs) is in the middle of the Upper rhenana -?linguiformis zone and is identified by the spiculate wackestone facies in an open sea environment, and it is followed by the HST parasequences. These sequences are limited by the sequential boundaries of SB1 and SB2 types.
Original Research Paper
R Behbahani; R Lak; N Chanani; G Hosseinyar
Abstract
In order to study of organic geochemistry of bed sediments in Khowr-e-Mussa and its adjacent marine areas, 61 surface sediment samples were collected. Based on granulometric analysis of the sediments, 4 major sedimentary types comprising mud, sandy mud, muddy sand, and slightly gravelly muddy sand were ...
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In order to study of organic geochemistry of bed sediments in Khowr-e-Mussa and its adjacent marine areas, 61 surface sediment samples were collected. Based on granulometric analysis of the sediments, 4 major sedimentary types comprising mud, sandy mud, muddy sand, and slightly gravelly muddy sand were determined. The bed sediments are mainly composed of terrigenous (quartz, feldespar, rock fragments, carbonate lithics and clay minerals) and chemical – biochemical (bivalve, gastropod, foraminifera, ostracod and bryozoa) particles. Based on the organic geochemistry studies, the total organic carbon (TOC) varies from 0.11 to 0.70 %wt, which increases in the muddy sediments. The studied kerogens (based on S2/TOC diagram) indicate that the kerogen types III (%33) and mixture of III-II (%55) are the most abundant. In addition, the hydrogen index versus Tmax diagram, revealed the similar results. The studied kerogens indicated that this part of the Persian Gulf affected by the transportation of terrestrial (fluvial, III type) rather than the marine organic matter (II type).
Original Research Paper
P Rezaee; R Zarezadeh
Abstract
Qeshm is the largest island of the Persian Gulf and is located at the southern end of the folded Zagros zone. The stratigraphic units of the QeshmIsland include the Hormoz series, Mishan formation, Aghajari formation and the Quaternary deposits. The Quaternary calcareous marine terraces are an important ...
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Qeshm is the largest island of the Persian Gulf and is located at the southern end of the folded Zagros zone. The stratigraphic units of the QeshmIsland include the Hormoz series, Mishan formation, Aghajari formation and the Quaternary deposits. The Quaternary calcareous marine terraces are an important part of the deposits and an relief index of sea level changes of the Quaternary period in the QeshmIsland. These terraces overly unconformably the older deposits, specially the Aghajari formation. The field and laboratories studies show that these sediments were developed mostly in different parts of an inner ramp comprising of supra-intra tidal, lagoon, and barrier. Application of the radiocarbonical method in different levels of these terraces revealed a Holocene-Pleistocene age. According to this age, an uplift rate of 0.22 mm/y can be estimated for this island, while the throw rate of the Persian Gulf level during the Quaternary is -0.125 mm/y.
Original Research Paper
L Bakhshandeh; T Mohtat; H Bakhshandeh; S Senmari
Abstract
The Ilam Formation, cropping out in the ZagrosMountain, consists of 195m of cream-colored limestones in the type section, south of Ilam city. This formation has conformable and continuous contacts with the lower Surgah and the upper Gurpi formations. In the present study, 35 foraminifera planktonic species ...
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The Ilam Formation, cropping out in the ZagrosMountain, consists of 195m of cream-colored limestones in the type section, south of Ilam city. This formation has conformable and continuous contacts with the lower Surgah and the upper Gurpi formations. In the present study, 35 foraminifera planktonic species of 17 genus have been identified. The Ilam formation was divided into 4 cosmopolitan biozones on the basis of the planktonic foraminifera which, consist of: Biozone 1-Marginotruncana sigali -Dicarinella primitiva Partial Zone, Biozone 2- Dicarinella concavata Interval Zone, Biozone 3- Dicarinella asymetrica Total -range zone, and Biozone 4- Globotruncanita elevata Partial- range zone. According to these biozones, the Ilam formation was deposited from the late middle Turonian to the early Campanian.
Original Research Paper
R Emami; R Rezaei; M Rezapour
Abstract
The availability of a large amount of seismic waveform data recorded by the Tabriz seismic network during the recent years has motivated this study to develop relations for the Empirical Distance Attenuation and the Local-Magnitude Scale with Joint Hypocentral Determination (JHD) technique for the northwest ...
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The availability of a large amount of seismic waveform data recorded by the Tabriz seismic network during the recent years has motivated this study to develop relations for the Empirical Distance Attenuation and the Local-Magnitude Scale with Joint Hypocentral Determination (JHD) technique for the northwest of Iran from digital horizontal components of the seismic waveform data records. ML is a very useful scale for engineering. Many structures have natural periods close to that of a Wood-Anderson instrument (0.8 s), and the extent of earthquake damage is closely related to ML. Therefore, any comprehensive seismic hazard analysis one needs a calibrated magnitude relationship as well as an earthquake catalog for the study region. It is a well-known fact that regional geology has a great influence on the magnitude relations. We considered a large data set of waveforms (68978 recordings for the horizontal components and 34489 for the vertical) to calibrate a local magnitude scale valid for northwestern Iran. The data refer to 6518 events occurring in the period from 1996 to 2009 in the area between 34 and 41 N and 43 and 52 E. We calculated the associated synthesized Wood Anderson seismogram for each SS-1 waveform, which is a velocity instrument. The procedure of calculating coefficients is based on the arithmetic mean of Horizontal component amplitudes. Current techniques for the development of a local magnitude scale involve the simultaneous determination of the following: the magnitudes of a number of earthquakes, site-specific correction terms for each of the recording stations, and the two constants in the equation engaged to represent the variation of amplitude as a function of distance. Therefore, we used the JHD technique for inversion. The resulting distance-correction function can be expressed as –log A0=1.4050 log (r/100) + 0.0019 (r-100) +3.0, with amplitude A0 in millimeters and hypocentral distance r in kilometers, showing a strong attenuation with distance. The distance-correction function can be expressed as –log A0=1.4050 log (r/100) +0.0019 (r-100) +3.0, with amplitude A0 in millimeters and hypocentral distance r in kilometers, showing a strong attenuation with distance. The Nuttli`s MN magnitude for each event was determined and compared with ML. ML is related to MN by MN=0.9177ML +0.6159 for earthquakes with 1≤ML≤6.2 in this region. This equation indicates that ML=MN is a reasonable inference in a wide magnitude range of 3.5≤ML≤6 in the northwest of Iran.
Original Research Paper
S Parham; M.R Kamali
Abstract
The Dalan Upper member (Permian) with carbonates and evaporite interlayer is one of the most important gas reservoirs in the folded Zagros area and Persian Gulf. In this investigation porosity types, their genesis and controlling factors have been studied at Surmeh surface section and a subsurface section ...
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The Dalan Upper member (Permian) with carbonates and evaporite interlayer is one of the most important gas reservoirs in the folded Zagros area and Persian Gulf. In this investigation porosity types, their genesis and controlling factors have been studied at Surmeh surface section and a subsurface section in Persian Gulf. Based on the new genetic classification of Ahr (2008) for carbonate porosity, porosity is created or altered by hybrids of depositional processes, diagenetic processes and mechanical fracturing in the studied intervals. In subsurface samples, porosity is hybrid of depositional and diagenetic types. In grain-supported microfacies, like ooidgrainstone related to the shoal environment, interparticle porosity is created which is a type of depositional porosity. Moldic, vuggy and intercrystallineporosity, which are diagenetic types of porosity,were formed in the later stages of diagenesis. Therefore, porosity in this microfacies is facies-selective and facies map can be used as a proxy for porosity distribution map. In surface section, besides depositional and diagenetic porosity, fracturing and brecciation are also significant. Brecciationoccured as a result of dissolution of anhydrite of Nar Member and formed the solution collapse breccias. Active tectonic in the folded Zagros belt and folding are another possible sources of fracturing in the surface samples. The properm data of routine analysis shows that the reservoir characteristic of the studied interval is heterogeneous.So, it has been compartmentalized into six zones with different reservoir qualities from poor to very good.
Original Research Paper
H Gholamalian; S Ghoreishi Maremy; M Parvaneh Nezhad Shirazi
Abstract
The Bahram Formation equivalent sequence in the Gerik section (eastern Zarand) displays middle Frasnian to early Famennian age on the basis of conodont investigation. Twenty-eight species and subspecies were identified. Seven biozones were recognized on the basis of vertical distribution of these taxa ...
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The Bahram Formation equivalent sequence in the Gerik section (eastern Zarand) displays middle Frasnian to early Famennian age on the basis of conodont investigation. Twenty-eight species and subspecies were identified. Seven biozones were recognized on the basis of vertical distribution of these taxa along the stratigraphic column; older than Upper hassi Zone, Upper hassi – jamieae zones, ?Lower rhenana Zone, Upper rhenana – linguiformis zones, Lower triangularis, Middle triangularis - Lower crepida zones, Middle – Upper crepida zones. Index conodont species those are recovered from the biostrome horizon in the lower part of section proved the middle Frasnian age (Upper hassi – jamieae zones). From view of conodont fauna, lithostatigraphy and age; the Gerik section is comparable with other successions of the Bahram Formation in Kerman, Tabas and Esfahan areas and shows a shallow sedimentary environment.
Original Research Paper
A Shafiei Bafti; M Pourkermani; M Arian; M ghorashi
Abstract
One of the most important tools of recognition for uplifting Movements in an area is study of rivers. The Davaran Mountain Range, which situated between Zarand and Rafsanjan cities, is limited by the Jorjafk fault in the north face. This fault is 160 km long and divided into two northern and southern ...
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One of the most important tools of recognition for uplifting Movements in an area is study of rivers. The Davaran Mountain Range, which situated between Zarand and Rafsanjan cities, is limited by the Jorjafk fault in the north face. This fault is 160 km long and divided into two northern and southern parts. The north part is in the northern margin of Davaran Mountain Range and 100 km long. The southern part is an intra-mountain fault and 60 km long. In the northern part, thrust faulting of the pre-Neogene rock units over the Neogene-quaternary sediments shows the recent activity movements of this fault, although there is no record of historical and instrumental seismicity of the Jorjafk fault. For investigation of uplifting movements caused by this fault, we studied the morphotectonics of rivers limited to this fault. According to our studies, the sinuosity rates for 21 rivers calculated and gave mean ratio of 1.11. The mean ratio of SL index for 15 major rivers is 165.6. The V index shows less than 1 value for 7 rivers. The long profiles of 7 rivers prepared and all show the concave profiles with the minor dome in their long. The minor dome caused by the lithological variations in floor of the rivers. The greatest concaving belongs to river no 5. Our studies show the moderate uplifting values in central part of the Jorjafk fault, near the Hosen village. The uplifting movements show a reduction from the central to the end point of this fault.
Original Research Paper
M Agh-Atabai
Abstract
The Golestan province lies on one of the seismically active zones of the world. The occurrence of numerous historical and instrumental earthquakes in this area indicates its high seismic activity. Therefore, it is necessary to study its seismicity using different methods. In this research, the mono and ...
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The Golestan province lies on one of the seismically active zones of the world. The occurrence of numerous historical and instrumental earthquakes in this area indicates its high seismic activity. Therefore, it is necessary to study its seismicity using different methods. In this research, the mono and multifractal analyses have been applied for quantification of earthquakes pattern in the GolestanProvince. For this aim, the correlation dimension, generalized multifractal dimensions and singularity spectrum f (αq) have been calculated using the correlation integral and fix-mass methods. The epicentral analyses of earthquakes showed that their distribution has two scaling ranges with two different patterns and mechanisms controlling the earthquake pattern in these scales. It seems that the movements of small faults and fractures, which caused increasing the correlation dimension (1.84) and heterogeneity of multifractal structure, controlled the small scale. However, at large scale, the distribution of earthquakes is mostly controlled by the main structural trends, which in turn results in becoming almost linear their correlation dimension and also more homogeneous multifractal structure.
Original Research Paper
M. Sadeghian; M. Sheibi; S. Badallo
Abstract
The Gol-e-Zard granitoidic pluton with an age of ~ 165±5 Ma is located in the north of Aligoudarz city, Lorestan province, in the Sanandaj-Sirjan structural zone. The pluton intruded into the late Triassic-early Jurassic slates, phyllites and micaschists. The granodiorites, dominant rock types ...
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The Gol-e-Zard granitoidic pluton with an age of ~ 165±5 Ma is located in the north of Aligoudarz city, Lorestan province, in the Sanandaj-Sirjan structural zone. The pluton intruded into the late Triassic-early Jurassic slates, phyllites and micaschists. The granodiorites, dominant rock types of the pluton, are cut by the leucogranites, aplitic veins, pegmatites and gabbro-dioritic dykes. The S-type nature of the Gol-e-Zard granite is evidenced by the presence of metaplitic enclaves (surmicaceous and andalusite-sillimanite hornfels), silica enclaves, andalusite and garnet xenocrysts and silica veins relicts. The anisotropy of magnetic susceptibility (AMS) method was used to investigate the mode of emplacement. The total numbers of 868 oriented core samples were analyzed for magnetic susceptibility. The obtained mean susceptibility (Km) in µЅІ was 227, 57 and 585 for granodiorites, leucogranites and gabbrodiorite dykes, respectively. The low Km values (
Original Research Paper
A Shaker Ardakani; M Arvin; B Oberhänsli
Abstract
The Lower Paleocene felsic plutonic rocks in the N- NE of Ghaleh-Ganj, are located on the western side of the Makran accretionary prism and the Jazmurian Depression and the east side of the Jiroft fault. They are parts of the intrusives in the Ganj complex, which itself is a part of the Jazmurian ophiolitic ...
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The Lower Paleocene felsic plutonic rocks in the N- NE of Ghaleh-Ganj, are located on the western side of the Makran accretionary prism and the Jazmurian Depression and the east side of the Jiroft fault. They are parts of the intrusives in the Ganj complex, which itself is a part of the Jazmurian ophiolitic belt or Inner Makran. Petrographically, the intrusives are quartz diorite, plagiogranite, tonalite, granodiorite, monzogranite and albite granite in composition with mainly equigranular to inequigranular textures and subordinate textures such as micrographic, granophyric, poikilitic and zoning. Mineralogically, the plutonic rocks consist of plagioclase, quartz, orthoclase, microcline, amphibole, biotite and opaques. The plagioclases show normal, reverse and oscillatory zoning and based on their mineral chemistry studies, are mainly albite to oligoclase in composition. Amphiboles are calcic type and magnesiohornblende in composition with affinity to actinolite. The geochemical studies show that the felsic plutonic rocks are trondhjemite to tonalite in composition and belonging to a sub-alkaline magmatic series with calc-alkaline nature, and have characteristics of peraluminous granitoids. Using trace element discrimination diagrams and ocean ridge granites-normalized multi-elements diagram clearly show that the Ganj felsic plutonic massifs are plotted in arc-related granites field with affinity towards ocean ridge granites field. These characteristics along with Nb-Ta negative anomalies are known as evidences for formation of Ganj felsic plutonic rocks in a supra-subduction zone environment.
Original Research Paper
A Ghahramani Zakaria; H Nazari; M Pourkermani
Abstract
This research has been achieved with the purpose of morphotectonic studies of the Sufian-Shabestar fault zone in the West Alborz-Azerbaijan (NW Iran). The fault zone cuts the Neogene and Quaternary units in south of the MishoMountains. The maximum of horizontal and vertical displacements along the Sufian-Shabestar ...
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This research has been achieved with the purpose of morphotectonic studies of the Sufian-Shabestar fault zone in the West Alborz-Azerbaijan (NW Iran). The fault zone cuts the Neogene and Quaternary units in south of the MishoMountains. The maximum of horizontal and vertical displacements along the Sufian-Shabestar fault zone are H=2500±200 m in Meshnaq river and V=66±4 m in fan east of Benis village, respectively. The minimum of horizontal and vertical displacements along this fault are H=9±0/5 m in offset stream of N Sharafkhaneh city and V=6±4 m in river NW of Kozehkanan city, respectively, all estimated based on combining data of Digital Elevation Model in scale of 1/25000, aerial photographs in scale of 1/20000, LANDSAT ETM satellite imagery and field studies. The estimated rate of horizontal and vertical displacements are H=135±20 m V=19±4 m in NW of Sharafkhaneh city, respectively and all allow us to estimate the rake of fault by geometry calculations. Based on estimate, the rake of the Shabestar fault segment is 11±4W. The Sufian-Shabestar fault zone is a right lateral-reverse strike slip fault with strike N81E and rake range of between 04, 11 with westwards dip, all estimated based on the rake of fault plane and morphotectonic data. Therefore, the Sufian-Shabestar fault zone (including faults segments of Sufian, Shabestar, F1, Sharafkhaneh (F2) and F3) is neotectonically an active zone.
Original Research Paper
F Kangarani Farahani; A.A Calagari; A Abedini
Abstract
The Shahbolaghi laterite deposit is located in ~40 km southeast of Damavand, Tehran province. This deposit was developed as stratiform horizons within the shales and sandstones of Shemshak formation (Jurassic). Mineralogical investigations show that the major minerals in this deposit include hematite, ...
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The Shahbolaghi laterite deposit is located in ~40 km southeast of Damavand, Tehran province. This deposit was developed as stratiform horizons within the shales and sandstones of Shemshak formation (Jurassic). Mineralogical investigations show that the major minerals in this deposit include hematite, boehmite, and anatase accompanied by lesser amounts of goethite, magnetite, chamosite, kaolinite, quartz, calcite, diaspore, zircon, pyrite, and rutile. The microscopic evidences such as development of spastoidic textures within the ores suggest a high energy water-saturated sedimentary environment during the lateritization processes. By considering the mineral assemblage and textural characteristics, deposition and diagenesis of this horizon occurred in an oxidizing and almost near surface environment. Based on the obtained data from the field observations, geochemistry of major, trace, and rare earth elements the lateritic horizon at Shahbolaghiwas developed probably byalteration of parent rocks with basaltic composition. The bauxitization process was occurredintrends of kaolinization, destruction of kaolinite, and deferrugenization. The geochemical investigations indicated that the distribution of trace elements in this horizon was controlled by clays and minor mineral phases.
Original Research Paper
Sh Shafiei; M Ghiyasi
Abstract
Chahmesi vein type deposit in the Kerman porphyry copper belt is located in the southwest of the Miduk porphyry copper deposit. The complex of Eocene volcanic rocks outcropped in this area. Analysis of structural data in outside of Chahmesi deposit and comparison of structures in outside border with ...
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Chahmesi vein type deposit in the Kerman porphyry copper belt is located in the southwest of the Miduk porphyry copper deposit. The complex of Eocene volcanic rocks outcropped in this area. Analysis of structural data in outside of Chahmesi deposit and comparison of structures in outside border with structures within this deposits reveals that the emplacement of main vein of this deposit has occurred in relationship to the extensional faults and the minor veins have located in related to the extensional-shear faults after the phase of main faulting.The extensional-shear faults had no effect on the emplacement of main vein and just caused a displacement of previously fractures. In the other hand these faults are faulted joints. The structures such as, pinch& swell structure , cohesive and incohesive fault rocks in crash zone and in addition the related symptoms with kinematic components shows the role of normal faulting in the emplacement of Chahmesi deposit. The map of specific resistivity shows that the emplacement of this deposit has occurred in a fault zone. The result of this study emphasizes. that the exploratory drilling should be designed based on structural analysis.
Original Research Paper
L Izadi kian; M Mohajjel; S.A Alavi
Abstract
Hamedan area is in the NW of the Sanandaj-Sirjan Zone. Different types of plutonic rocks are outcropped in this area which in turn, surrounded by the various metamorphic rocks (regional and contact metamorphism). Four ductile deformation stages were recognized. Each of them is accompanied with formation ...
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Hamedan area is in the NW of the Sanandaj-Sirjan Zone. Different types of plutonic rocks are outcropped in this area which in turn, surrounded by the various metamorphic rocks (regional and contact metamorphism). Four ductile deformation stages were recognized. Each of them is accompanied with formation of fold, foliation and lineation. The first generation foliation (S1) and folds (F1) formed at the first stage of deformation (D1). The second deformation defined by refolding of the first axial surface and forming of the second foliation (S2) and folds (F2). This stage is the strongest deformation and formed main foliation in this area. Axis of these folds changes from horizontal to vertical. The direction of this fold axis follows the Alvand pluton form. The second foliation shows wide dispersal in orientation and their trends follows the Alvand pluton form. The third deformation (D3) defined by close to open, mostly upright with curved hinges folds (F3) and the axial-plane foliation (S3). This foliation (S3) is predominant in areas east of the Alvand pluton and is crenulation cleavage to fracture foliation. The most axis of F3 show N165 plunging. Because of the interference pattern between the first, second and third folding at the regional and contact metamorphic rocks, these stages of deformation are coaxial deformation. D4 is characterized by a crenulation cleavage (S4) and a mineral lineation (L4(. L4 have a NE-SW plunging. This lineation does not exist at the contact metamorphic rocks. The rotation of axis of F2 and the second foliation is obvious around the Alvand pluton. This rotation shows that the final strain field is followed the pluton forms and probably the main granitic Alvand pluton intruded during the second deformation in this area.
Original Research Paper
M.R Omidvar Ashkalack; A Khakzad; N Nezafati; M.A.A Mokhtari; B Borna; S Rozbeh Kargar
Abstract
The studied area is located in the western part of the Central Alborz structural zone and contains a bauxitic- lateritic horizon between the Elika and Shemshak formations. This horizon belongs to the middle Triassic, and croups out with E-W trend in the four regions (trends) including Zard Kuh- Loriteh, ...
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The studied area is located in the western part of the Central Alborz structural zone and contains a bauxitic- lateritic horizon between the Elika and Shemshak formations. This horizon belongs to the middle Triassic, and croups out with E-W trend in the four regions (trends) including Zard Kuh- Loriteh, Shagol- Sangrood, Abasak- Hir, and Arsheh Kuh- Zakabar. The complete cross section of bauxitic- lateritic horizon contain dark grey pisolites in the lower part, yellowish red laterite in the middle part, and an upper part with light grey color. Kaolinite and quartz are the main mineral components of this horizon. The minerals such as diaspore, bohemite, anatase, hematite and goethite present as minor phase. The grey- colored upper and lower parts contain high grade of Al2O3 and low grade of Fe2O3 while in the middle part, high grade of Fe2O3 and low grade of Al2O3. The average grades of Al2O3, Fe2O3, SiO2 and TiO2 in the samples are in turn 35%, 14%, 35% and 5%. The maximum grades of Al2O3 in the mentioned four trends are 51%, 61%, 48% and 48%. There is a distinctive negative correlation between Al2O3 and Fe2O3, between Fe2O3 and SiO2, and between Fe2O3 and TiO2. Furthermore, there is a positive correlation between Al2O3 and TiO2. The results of laboratory investigations indicated that the best bauxitic- lateritic horizon in the studied area considering grades of major oxides is the Abasak- Hir trend.
Original Research Paper
H Amini; M Fattahi; M.R Ghassemi
Abstract
The Doruneh fault is the second longest fault systems in Iran. This fault is 700 km long and extended from the Afghanistan-Iran border to the central Iran desert. Despite of its length, and position in the convergence zone between the Arabian and Eurasian plates and its seismic potential, only one historical ...
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The Doruneh fault is the second longest fault systems in Iran. This fault is 700 km long and extended from the Afghanistan-Iran border to the central Iran desert. Despite of its length, and position in the convergence zone between the Arabian and Eurasian plates and its seismic potential, only one historical earthquake (M>7) and two instrumental (M>6) earthquakes are recorded on this fault. Therefore, study of this fault is very important for evaluation of its seismic hazard. In our study, we used the Landsat images, aerial photographs, topography maps, geological maps and field work data to identify and estimate the amount of displacements of rivers, rock units, and some alluvial fans along this fault. Three branches of the Doruneh fault investigated in this study, named as the north, middle and south branches according to their geographical locations. This study demonstrates that both of the maximum and minimum fault displacements have occurred on the southern branch. Furthermore, the amount of displacements of the rivers, which have cut the alluvial fans during the Quaternary period, suggests that this branch, particularly between 57˚00΄ and 58˚50΄E, is more active than the other branches. Although, several slip rates were previously determined using different methods for some parts of this fault by the authors and other researchers, we suggest further dating and geodetic methods in the same regions and other part of the fault to estimate and compare the slip rate of different branches of this important fault.
Original Research Paper
S Azadbakht; M.R Majidifard; S.A Babazadeh
Abstract
In this study, the Surgah formation is identified and introduced for the first time in the east of Khoram-Abad. This formation in the east of Khoram-Abad consists of up to 260 meters light grey, thin to thick –bedded limestone with intercalation of shaly-limestone and a Turonian to Santonian age. ...
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In this study, the Surgah formation is identified and introduced for the first time in the east of Khoram-Abad. This formation in the east of Khoram-Abad consists of up to 260 meters light grey, thin to thick –bedded limestone with intercalation of shaly-limestone and a Turonian to Santonian age. In this section, the Surgah formation has continuous and conformable contacts with the lower Sarvak formation and the upper Ilam formation. In this study, 13 genera, 33 species and 3 biozones of the planktonic foraminifera have been recognized: Biozon I, Helvetoglobotruncanahelvetica-Clavihedbergella –Hedbergella Assemblage Zone indicating Turonian age, Biozon II, Marginotruncana sigali- Marginotruncana schneegansi Assemblage Zone indicating Coniacian age, and Biozone III, Globotruncana ventircosa -Dicarinella concavata Assemblage Zone showing Santonian age.
