Z. Mardani; M. Ghorashi; M. Arian; Kh. Khosrotehrani
Abstract
Geomorphic indices of active tectonics are useful tools to analyze the influence of active tectonics.These indices have the advantage of being calculate from ArcGIS and remote sensing packages over large area as a reconnaissance tool to identify geomorphic anomalies possibly related to active tectonics.This ...
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Geomorphic indices of active tectonics are useful tools to analyze the influence of active tectonics.These indices have the advantage of being calculate from ArcGIS and remote sensing packages over large area as a reconnaissance tool to identify geomorphic anomalies possibly related to active tectonics.This is particulary valuable in west-central Alborz where relatively little work on active tectonics based on this method was done,so this method is new and useful. Based upon values of the stream length-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), ratio of valley-floor width to valley height (Vf), index of drainage basin shape (Bs), and index of mountain front sinuosity (Smf),we used an overall index(Iat) that is a combination of the other indices that divides the landscape into four classes of relative tectonic activity. The moderat class of Iat is mainly in the south of Manjel dam,while the rest of the study area has high active tectonics (shahrud drainage basin and sefidrud drainage basin),and high to very high(Taleghan and Alamut drainage basin). The stream network asymmetry (T)was also studied using morphometric measures of Tranverse Topographic Symmetry.Analysis of the drainage basins and subbasins in the study area results in a field of T-vectors that defines anomalous zone of the basin asymmetry.Acomparsion of T index clearly coincide with the values and classes of active tectonics indices and the overall Iat index.
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.
M. Mohamadi Vizheh; A. Kamkar Rouhani
Abstract
Ground water, cavities, and isolate buried structures embedded at shallow depths are well detectable by resistivity and GPR methods because of distinct contrast in their electric and electromagnetic properties in comparison with their surrounding media. In this research work, 3 different profiles on ...
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Ground water, cavities, and isolate buried structures embedded at shallow depths are well detectable by resistivity and GPR methods because of distinct contrast in their electric and electromagnetic properties in comparison with their surrounding media. In this research work, 3 different profiles on such targets have been chosen, and their responses have been investigated. Using both resistivity and GPR methods together, it has also been possible to investigate capabilities and limitations of the methods in practice. The results obtained from this research work indicate that the GPR method, in addition to its speed and simplicity in data acquisition, is very successful in detection of interfaces or boundaries between different media in which electromagnetic properties at the boundaries change rapidly. The resistivity surveys, which have been carried out using Wenner array in this study, indicate low resistivity of the media under investigation. The low resistivity of the subsurface media caused the depth of penetration of the GPR method to be low, and as a result, made it impossible to investigate the targets buried at depths greater than 2 meters. Unlike the GPR method, the resistivity method has not been very successful in detection of multiple targets with high resistivity contrasts. Lower resolution of the resistivity method in comparison with GPR method has caused this problem. In this study, considerable information has been obtained by selecting two different processing algorithms and applying them on a series of raw GPR dataset. The obtained information from the resistivities of the subsurface structures as a result of the resistivity surveys has made it possible to choose and apply these processing algorithms. This research work well indicates that high conductive areas in resistivity sections coincide with the areas in the GPR sections having intensive attenuation. This characteristic can be used well in the interpretation of the GPR sections. Finally the resistivity method can be introduced as a suitable supplementary geophysical method to the GPR method.
H. R. Nankali; B. Vosoughi; F. Soboutie; K. Hessami; M. Talebian
Abstract
A three-dimensional lithosphere model with horizontal dimensions of 1500 km×600 km and a depth extent of 70 km for the Zagros is constructed from available geophysical data to find out strength of the outermost layers in this area. The structural boundaries of the model are based on the results ...
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A three-dimensional lithosphere model with horizontal dimensions of 1500 km×600 km and a depth extent of 70 km for the Zagros is constructed from available geophysical data to find out strength of the outermost layers in this area. The structural boundaries of the model are based on the results from the deep seismic sounding profiles. First the finite element model for the temperature is solved in order to obtain initial temperature and the geotherm, after that structural viscoelastic problem is solved using the same mesh as in the thermal initial condition. Preliminary results for wet and dry rheology indicate that the depth of the BDT is about 8 km and 11 km for hot geotherm and 10.5 km to14 km for cold geotherm. The results are in good agreement with focal depth in the Zagros that most earthquakes occur in 8 to 15 km depth (Tatar et al., 2004 and Jackson et al., 2008), that the long-term strength of the continental lithosphere resided only in its upper part, which was contained wholly within the crust.
M Nouredini; M Yazdi; A Ashouri; S Rahmati
Abstract
The Lower Carboniferous deposits (Shishtu II Formation) is exposed in the Banarizeh section, Southeastern Isfahan, Central Iran. The Shishtu II Formation is characterized by continental to shallow marine deposits, where it unconformably overlies the Alluvial deposits and is unconformably overlain by ...
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The Lower Carboniferous deposits (Shishtu II Formation) is exposed in the Banarizeh section, Southeastern Isfahan, Central Iran. The Shishtu II Formation is characterized by continental to shallow marine deposits, where it unconformably overlies the Alluvial deposits and is unconformably overlain by the Sardar Formation. The thickness of Shishtu II Formation reach to 195m and contain moderate diversity, high richness Holothurian sclerites assemblages and other skeletal particles of scatter Crinoids, Brachiopods and Corals. The systematic studies and taxonomic investigation carried out on the collected samples from studies area led to recognition of 8 species belonging mainly to 4 families (Calclamnidae, Achistridae, Palaeocaudinidae, Theelidae). The Holothurian sclerites in Shishtu II Formation are dominantly as: Eocaudina subhexagona, Eocaudina ovalis, Microantyx permiana, Mercedescaudina langeri, Protocaudina hexagonaria, Achistrum monochordata, Thalattocanthus Consonus. Based on sratigraphical distribution of the Holothurian sclerites, Tournaisian- Visean age is suggested for Shishtu II Formation.
S Hojati; H Khademi
Abstract
There is no information about the occurrence and characteristics of sepiolite deposits in Iran. Thus, to identify and characterize the physicochemical and mineralogical properties of Eliyato deposits in northeastern Iran, 10 samples from different locations were taken and studied by powder X-ray diffraction, ...
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There is no information about the occurrence and characteristics of sepiolite deposits in Iran. Thus, to identify and characterize the physicochemical and mineralogical properties of Eliyato deposits in northeastern Iran, 10 samples from different locations were taken and studied by powder X-ray diffraction, scanning and transmission electron microscopy, X-ray fluorescence, thermal analysis, infrared spectroscopy, specific surface area and cation exchange capacity. The results indicated that these deposits consist of well-crystallized sepiolite (70–80%), with minor amounts of quartz (10–20%) and dolomite (5–10%). The electron micrographs of the samples showed sepiolite as a long interwoven fibrous mat, pore-filling and coating material. This textural evidence suggests direct chemical precipitation of sepiolite from an Mg-rich solution and/or after the precipitation of dolomite. The chemical composition, determined by X-ray fluorescence, indicated a Mg-rich mineral with the structural formula (Si11.97Al0.03) (Mg7.20Al0.11Fe0.15) O30 (OH)4 (H2O)4.8H2O. This suggests low isomorphic substitutions of Al for Si and Mg in the tetrahedral and octahedral sheets of the mineral, respectively. In addition, thermal analysis indicated four endothermic reactions at 134, 336, 546 and 818 °C which are associated with the gradual elimination of adsorbed and zeolitic water from the mineral structure. The associated weight losses are 8.69, 3.31, 2.65 and 10.19%, respectively. The high surface area of the material, compared to that of the Vallecas sepiolite deposit in Spain, suggests its suitability for industrial applications.
Rahimzadeh Bahman; F. Masoudi; S. M. Fatemi Aghda; T. Parhizkar; A. Pour Khorshidi
Abstract
In the north of Abyek - Qazvinmain road, various volcanic units contain olivine basalt, basalt, andesitic basalt, dacite, andesite and their associated tuffs with Eocene to Quaternary age are exposed. In order to examine geochemical and petrographic features effect on pozzolan activity, five samples ...
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In the north of Abyek - Qazvinmain road, various volcanic units contain olivine basalt, basalt, andesitic basalt, dacite, andesite and their associated tuffs with Eocene to Quaternary age are exposed. In order to examine geochemical and petrographic features effect on pozzolan activity, five samples of different rocks in the area crushed and analysed by thermogravimetric method in Housing and BuildingResearchCenter. Unweathered glassy tuff s with 26.83% pozzolanic activity ranked as good quality pozzolan. Relatively weathered tuffs and dacite present pozzolanic activities in the range of 21 to 24 % and are medium quality pozzolan. Lithic tuffs with 19.70% pozzolanic activity are in the weak quality pozzolan category. Generally, tuffs and dacits with no alteration and glass in their matrix are suitable alternatives to use as pozzolane in mix cement and lithic bearing tuffs with weathering are poor in pozzolanic features and are not recommended to be used in cement composition.
M Baghernejhad; M.R Ghassemi; B Oveisi
Abstract
There is a close relationship between resistance to slip along decollement surfaces and presence of deep and shallow decollement levels in thin-skinned fold and thrust wedges. Decollement units in lower (Upper Red Formation) stratigraphic levels in Mianeh-Mahneshan fold belt have an effective role onthe ...
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There is a close relationship between resistance to slip along decollement surfaces and presence of deep and shallow decollement levels in thin-skinned fold and thrust wedges. Decollement units in lower (Upper Red Formation) stratigraphic levels in Mianeh-Mahneshan fold belt have an effective role onthe geometry and kinematics of deformation of the area. In order to understand the fold geometry and folding mechanisms, and to exploredepth-to-the-decollement surface, we carried out data collection and field study in an area between Mianeh and Mahneshan cities. Folded structures in the study area are different from other structures within the area, as well as from the structures in the neighboring Alborz Mountains.The rise of salt domes along with the plasticity of marls in the Upper Red Formation have resulted in extreme complexities in folding pattern. In order to analyze syn-sedimentary structural features and interpret the geological evolution of the area, we used detailed structural measurements, sedimentological and sedimentary environment features, sedimentary rock studies, and paleogeography.One of the results of this study was the interpretation of syn-sedimentary growth structures in the Mianeh-Mahneshan area, which helped us to construct six structural cross-sections (AA’, BB’, CC’, DD’, EE’ and FF’)across the folded structures. Measured shortening along two Sections AA’ and DD’is 46.65% and 38.05%, respectively, with an average of 42.3%. These values are different from those estimated forthe neighboring Alborz and Zagros Orogens, where shortening ranges between 16-30%. We attribute this difference to local intense shortening in the study area caused by several factors such as basin slope, deep faults and weak beds along decollement surfaces. This study indicates that dominant folding mechanisms in the study area are detachment folding, and fault-propagation or fault-bend folding. The presence of evaporitic material (gypsum and salt) within the succession has played a major role in the kinematics of folding.
A. Kaveh Firouz; H. Nazari; M. Arian; A. Shafei; T. Majidi; M. Shokri
Abstract
The North Tehran Fault with a length of about 110 km in North of Tehran and soutern of central Alborz with W-E trend (N25˚E) and dipping (30˚NE) is located in western of Mosha Fault.The branch of Chitgar such as Milad and Vardavard Fault in the form of propagation fault is increased toward south. Previous ...
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The North Tehran Fault with a length of about 110 km in North of Tehran and soutern of central Alborz with W-E trend (N25˚E) and dipping (30˚NE) is located in western of Mosha Fault.The branch of Chitgar such as Milad and Vardavard Fault in the form of propagation fault is increased toward south. Previous morphotectonical investigation along the North Tehran Fault show that shear of quaternary sedimentation and pressure mechanism with left-lateral component. Determination of seismic parameter and seismic action that result of this fault movement, need to doing paleoseismological investigation. In this text with using stratigraphy correlation method, estimated of subsidence rate is 0.16 mm/yr and logging with ratio and ortho photography method, 3-6 event is determined with 6.4-7.4 magnitude and recurrence
J Ghalamghash; R Chaharlang
Abstract
The Late Miocene- Quaternary volcanoes including Sahand, Ararat, Nemrut, Suphan, Tendurek and Lesser Caucasus volcanoes in the Arabia-Eurasia collision zone, are studied in this paper. The volcanoes have been erupted pyroclastic materials and lava flows with basaltic to rhyolitic composition, in several ...
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The Late Miocene- Quaternary volcanoes including Sahand, Ararat, Nemrut, Suphan, Tendurek and Lesser Caucasus volcanoes in the Arabia-Eurasia collision zone, are studied in this paper. The volcanoes have been erupted pyroclastic materials and lava flows with basaltic to rhyolitic composition, in several times. These volcanic rocks have calk-Alkaline (Sahand) to Alkaline nature (Tendurek). The Nb, Ta, Ti and Y depletions in accompanied with Rb, Ba, K, Sr and Th enrichments are the common geochemical features of these volcanic rocks in primitive mantle normalized multi element diagrams. In addition, enrichment of LREE relative to HREE in chondrite–normalized REE patterns is visible in all volcanic rocks of the regions. The enrichment of LREE and depletion of HREE in Sahand and Lesser Caucasus volcanic rocks is implying that their magma is derived from fraction melting of garnet-lherzolite of mantle source. In contrast, the volcanoes of eastern Anatolia melted from spinel-lherzolite rocks of mantle. The negative Nb, Ta anomalies in primitive mantle normalized multi element diagrams of volcanic rocks indicate geochemical features of Pre-collision subduction component in parental magma of studied volcanoes. High contents of La, Th, Ce and Rb indicate magma contamination during parental magma emplacement in crust accompanied with assimilation, fractional crystallization process.
A Abedini
Abstract
The Basir-Abad area (northeast of Ahar, East-Azarbaidjan province) is a part of the Cenozoic Ahar-Arasbaran magmatic belt in northwest of Iran. Intrusion of granitic and granodioritic igneous rocks of Oligocene age into the Eocene volcanic rocks (andesite, trachy-andesite, andesi-basalt and basalt) resulted ...
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The Basir-Abad area (northeast of Ahar, East-Azarbaidjan province) is a part of the Cenozoic Ahar-Arasbaran magmatic belt in northwest of Iran. Intrusion of granitic and granodioritic igneous rocks of Oligocene age into the Eocene volcanic rocks (andesite, trachy-andesite, andesi-basalt and basalt) resulted in occurrence of metallic mineralization along with development of widespread alteration zones in this area. Mineralogical studies indicate that these alteration zones include silicic (quartz), intermediate and advanced argillic (kaolinite, smectite, quartz and alunite), and propylitic (chlorite, epidote, albite and calcite). Hypogene ores within veins and veinlets of silicic alteration zone contain pyrite, chalcopyrite and galena accompanied by covellite, copper-carbonate minerals (malachite and azurite) and iron-oxides and- hydroxides (goethite, limonite and hematite) of supergene origin. The distribution patterns of REEs normalized to chondrite display differentiation and enrichment of LREEs relative to HREEs and occurrence of variant negative Eu anomalies in all alteration zones. Mass balance calculations of elements, using isocon method, indicate that during development and evolution of the silicic and the intermediate argillic alteration zones, REEs experienced enrichment in the former and depletion in the latter. Furthermore, development of advanced argillic and propylitic alteration zones was accompanied by enrichment of LREEs and selective depletion of HREEs. Further investigation revealed that occurrence of negative Eu anomaly (0.20-0.23) in silicic alteration zone is related to abundance of chloride ions, increase of oxygen fugacity of hydrothermal system and highly acidic nature of the fluid. The results obtained from geochemical studies (mass balance calculations, changes in values of Eu and Ce anomalies and ratios of REEs) suggest that changes of pH, temperature, oxygen fugacity, difference in abundance and type of complexing ions in solution, fluid/rock ratio, and presence of minerals such as kaolinite, goethite, smectite, hematite and alunite played important role in differentiation, mobilization and distribution of lanthanides in the studied alteration system.
S Soleymani; M.H Mahmudy Gharaie2; F Ghasemzadeh; A Sayyareh
Abstract
Water quality assessment is very important in the area where water resources are used as drinking water. Monitoring of polluted waters and its distribution are applied in water management planning. It requires information on the location, the amount and distribution of chemical parameters on the samples ...
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Water quality assessment is very important in the area where water resources are used as drinking water. Monitoring of polluted waters and its distribution are applied in water management planning. It requires information on the location, the amount and distribution of chemical parameters on the samples from studied area. Identification of contaminant type, the sites, and also optimum use of water for different purposes are helpful. Thus, for these purpose six chemical parameters of TDS، SO42-، Cl-، Na+، Mg2+، Ca2+, which are referred by WHO standard were examined to apply for GQI method by GIS. The GQI method of groundwater quality evaluated and prepared a groundwater quality map in west region of kooh-sorkh. Values of GQI index vary between 82.9% to 94.8%, which indicate the groundwater quality placed in suitable to acceptable class of quality. Groundwater quality map indicate that GQI index values reduced from lateral sides to the center of studied region. It may be affected by geological factors such as lithology, current direction and also hydrothermal system in the area.
Arman Heravi; H. Nazari; A. Shahidi; M. Talebian
Abstract
The Garmsar Fault with a length of about 75 km and E-W trend is located in Garmsar.This Fault observed in north of Garmsar and eastern part of central Alborz with slop toward north, continus east of Eyvanakey Fault. Base of the morphotectonical investigation, along the Garmsar Fault this ...
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The Garmsar Fault with a length of about 75 km and E-W trend is located in Garmsar.This Fault observed in north of Garmsar and eastern part of central Alborz with slop toward north, continus east of Eyvanakey Fault. Base of the morphotectonical investigation, along the Garmsar Fault this fault is devided to 5 segments from east (Dehnamak village) to the west (Eyvanakey), with attention to this segmentation we could consider the branch of kuh-e-sorkh Fault at west of Garmsar in kuh-e-sorkh anticline such as separated fault with slop toward north and pressure mechanism with small left-lateral strike slip component. Base on observations and Paleostress measurment along the Garmsar Fault in Bon-e-kuh station and eastern segment of this fault, we could consider that Paleostress direction around Neogen Time, is N-S with pressure component. However, base of data, is gain from morphotectonical investigations, young and overcome mechanism in eastern segment (Fault segment 1) left-lateral with pressure component, on the other side, in kuh-e-sorkh anticline at western part of research area, considered stress direction at quaternary period E-W under the effect of Thrust fault with left-lateral component. Base of this study from geometry point of view, the Garmsar Fault is a fault with slop toward north which is able to devide in to 5 segments that is strike and geometry of each fault segment mechanism is from left-lateral with pressure component until Tension and the Garmsar Fault is considered as an active fault in quaternary period. Maximum and minimum on the left horizontal displacement measured on the fault equal to 220 meters and 4 meters of a fault on the part of the fault system and third segment on the drainages of Garmsar displaced is visible.
H. Khalilzadeh; A. A. Calagari; A. Abedini; H. Rahimpour-Bonab
Abstract
Boket residual horizon is located in ~15 km northeast of Ajabshir, East-Azarbaijan province. This horizon was developed as stratiform lenses along the contact of Ruteh (middle-upper Permian) and Elika (Triassic) carbonate formations. The ores within this horizon display pelitomorphic, micro-granular, ...
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Boket residual horizon is located in ~15 km northeast of Ajabshir, East-Azarbaijan province. This horizon was developed as stratiform lenses along the contact of Ruteh (middle-upper Permian) and Elika (Triassic) carbonate formations. The ores within this horizon display pelitomorphic, micro-granular, micro-ooidic, pseudo-porphyritic, ooidic, pisoidic, pseudo-breccia, and nodular textures. Based on geochemical data, the ores within this horizon are divided into five types, (1) ferritic laterite, (2) bauxitic laterite, (3) kaolinitic laterite, (4) ferritic kaolinite, and (5) laterite. Comparison of distribution patterns of elements across a selected profile indicates the effective role of Al and Ti in distributing and concentrating of Zr, Ga, Nb, Th, V, and HREEs within the ores. Incorporation of data obtained from petrographical and geochemical studies shows that the ores have authigenic origin. Furthermore, factors such as chemical variations of weathering solutions, fixation in neomorphic phases, existing in resistant minerals, heterogeneity of protolith, differences in the degree of weathering intensity, and adsorption processes coupled with weak drainage, diagenesis, dynamic pressures, and fluctuation of underground water table played crucial roles in distribution and development of ores within this horizon. The most notable geochemical characteristics of the ores (except in kaolinitic laterite) is the greater mobility of LREEs relative to HREEs during weathering processes. This abnormal behavior within the horizon could be related to factors such as differences in stability of primary minerals containing REEs, the pH variation (from 6.7 to 7.8) of weathering solutions, and moderate degree of evolution of the profile.
M.A Rajabzadeh; Z Ghorbani; M Jalalifard; M Mohammadzadeh
Abstract
Parvadeh coalfield with an area of 1200 km2 is one of the largest coalfields in East-Central Iran. The coal-bearing clastic rocks of the coalfield belong to Ghadir Member of the Upper Triassic Naiband Formation and could be classified as bituminous coal, containing low volatile, high ash and medium to ...
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Parvadeh coalfield with an area of 1200 km2 is one of the largest coalfields in East-Central Iran. The coal-bearing clastic rocks of the coalfield belong to Ghadir Member of the Upper Triassic Naiband Formation and could be classified as bituminous coal, containing low volatile, high ash and medium to high sulfur. Pyritic sulfur is the main form of sulfur in the Parvadeh coals. Quartz, illite, kaolinite, pyrite, and calcite/dolomite are the principal mineral phases. Enrichment in major elements and depletion in minor elements were observed in studied samples when compared with those of the earth crust. The element contents of coal-bearing layers are similar to those of the US and world coals except for Cd, Li, As and Zn. Based on the calculated enrichment factor, the elements As, Co and Cd are the most pollutants in Parvadeh area. Strong correlations among ash contents and Si, K and Al values indicate that the coal ash is mainly composed of aluminosilicates. Meanwhile, Cd, Co, As, Fe, and S show that Cd, Co, As participated in pyrite lattice. These results were confirmed by factor and cluster analyses. The calculated recovery index shows that Li, Mo, Pb and Cu are bounded to maceral and organic matter thus are enriched in the cleaned coals. The other minor metals, however, are present in mineral part of the coal and enriched in ash.
Masoumeh Nabilou; Mehran Arian; Peyman Afzal; Ahmad Adib; Ahmad Kazemi Mehrnia
Abstract
The multifractal modelling is an effective approach for separation of geological and mineralized zones from the background. Following cases are addressed in this study; Concentration-Distance to Major Fault structures (C-DMF) fractal model and distribution of the known Fe indices/mines in the Bafgh ...
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The multifractal modelling is an effective approach for separation of geological and mineralized zones from the background. Following cases are addressed in this study; Concentration-Distance to Major Fault structures (C-DMF) fractal model and distribution of the known Fe indices/mines in the Bafgh area to distinguish the Fe mineralization based on their distance to basement faults, surface faults and master joints, using remote sensing information, airborne geophysics information and field surveys. Application of the C-DMF model for the classification of Fe mineralization in the Esfordi and Behabad 1: 100,000 sheets reveals that the main Fe mineralizations have a strong correlation with their distance to the major and basement faults. Accordingly, the distances of Fe mineralization that has the grades upper than 55% in this area )43%≤S≤60%), are lower than 1 km related to basement faults, while such distance for this threshold is 2344<DMJ≤1778 meter for the master joint and also for the faults of 1:100,000 Behabad and Esfordi geology sheets in 43%S≤60% threshold (for the graides) the distances are 3162<DGF≤4365 meter to the faults. This indicates a positive correlation between Fe mineralization and distance to the basement faults. On the other words, the proximity evidence for the Precambrian high grades Fe deposits related to basement faults indicates syn-rifting tectonic events. This C-DMF fractal model can be used in exploration of the magmatic and hydrothermal ore deposits.
M. E. Moslempour; M. Khalatbari-Jafari; T. Morishita; M. Ghaderi
Abstract
Mantle sequences exposed in west of Fannuj-Maskutan area comprise of lherzolite and porphyroclastic cpx-bearing harzburgite in the lower part and recrystallized fine-grained lherzolite with chromitite lenses in the upper parts of the sequence. Petrography studies and microprobe data show evidence ...
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Mantle sequences exposed in west of Fannuj-Maskutan area comprise of lherzolite and porphyroclastic cpx-bearing harzburgite in the lower part and recrystallized fine-grained lherzolite with chromitite lenses in the upper parts of the sequence. Petrography studies and microprobe data show evidence of melt/peridotite interactions, post-melting processes and subsolidus interactions associated with the appearance of two generations of deformed primary pyroxene-olivine and fine-grained pyroxene-olivine-amphibole neoblasts. Second generation of minerals formed as inclusion, interstitial and fine-grained. These two groups of minerals have different geochemical characteristics, i.e., the first group are comparable with abyssal peridotites and the second group are comparable to suprasubduction peridotites. Therefore, the chemical compositions of different generations of minerals show different petrogenesis for ultramafic rocks of the Fannuj-Maskutan ophiolitie complex. Interpretation of whole rock chemical data indicate that these rocks have a depleted MORB mantle source which underwent 5-15% partial melting. Rare earth element patterns normalized with chondrite standard values and compared with patterns of depleted MORB mantle (DMM), indicate enrichment in LREE/MREE ration and show U-shape patterns. Thus, the peridotites of the Fannuj-Maskutan ophiolitie have experienced multistage evolution and show characteristics of abyssal environment to suprasubduction zone. It might be said that transition from abyssal environment to suprasubduction has been affected by fluids derived from the subducted slab.
S. Rajabi; M. Eliassi; A. Saidi; A. Shahidi
Abstract
In this research, heterogeneous fault slip data are used as the main data for doing paleostress analysis in North-Tehran tectonic wedge, which is restricted between Mosha and North-Tehran faults. Using these data and paleostress methods, the studied area is divided into 15 smaller stable stress regions ...
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In this research, heterogeneous fault slip data are used as the main data for doing paleostress analysis in North-Tehran tectonic wedge, which is restricted between Mosha and North-Tehran faults. Using these data and paleostress methods, the studied area is divided into 15 smaller stable stress regions and the mean stress tensor related to each region is determined. Then, stress events are separated using Multiple Inverse Method. Based on mean stress tensors -obtained from stress regions- and rotation of fault data orientation -based on Anderson’s theory in compressional tectonic regimes-, the stress trajectory map is sketched for mean stress tensors acting in the regions during geological time. Configurations of trajectories show that they seem to obey the overall tectonic regime in Iran. This result refutes that the North-Tehran tectonic wedge could be a dynamic wedge.
A. Haddad; E. Khorasani
Abstract
Semnan plain is located on the northern edge of Iran's central desert and has a semi-arid climate. In recent decades, rapid population growth, increasing Industrial areas and water demand has led to excessive extraction of groundwater resources. As a result, the crisis of the severity of the decline ...
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Semnan plain is located on the northern edge of Iran's central desert and has a semi-arid climate. In recent decades, rapid population growth, increasing Industrial areas and water demand has led to excessive extraction of groundwater resources. As a result, the crisis of the severity of the decline in groundwater levels and ground subsidence in Semnan plain was reported. Satellite imagery interferometry (InSAR) monitoring in the specific period of 2003 to 2004 shows that maximum of 133 mm of ground subsidence in Semnan city has been occurred. The factors affecting the ground subsidence of Semnan plain were investigated by drawing hydrographic charts of groundwater level using the results of 15 observational wells. Continuous drawdown of groundwater levels can be seen during the water period of 2003 to 2009. Minimum rate of decline in groundwater level equal to 22 centimeters per year was reported. Merging the results of ground subsidence and decline of groundwater level illuminated the exploitation of groundwater resources over the aquifer recharge rate which increases the effective stress in soil layers and thus sediments high consolidation. This was the key factor for subsidence in Semnan plain with respect to the geotechnical properties of the aquifer. Therefore, water resources management was recommended for sustainable development of agriculture and industry.
R Lak; M Taghizadeh
Abstract
The Persian Gulf has an area about 240000 km2, considered as the northern part of the counterclockwise movement of Arabian Plate and as a recent example of Holocene carbonated sedimentary environment in dry (arid) climate. The basin volume, regarding to its average depth (36m), is estimated about 87,000km3. ...
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The Persian Gulf has an area about 240000 km2, considered as the northern part of the counterclockwise movement of Arabian Plate and as a recent example of Holocene carbonated sedimentary environment in dry (arid) climate. The basin volume, regarding to its average depth (36m), is estimated about 87,000km3. The present study was done in order to examine the sea level changes and determine the rate of sedimentation of Holocene deposits in the northeast of Persian Gulf. A complete and undisturbed core from the Holocene deposits (1070 cm length) located in the south of Rajaee port in theHormozgan province was prepared. Following the exact description of this core, based on the objective observations, 52 samples were taken according to the facies divisions and they were sedimentologically and geochemically tested. The granulometric analysis, mineralogy by XRD method, abundance percentage of elements by ICP-OEC device and polarograph, percentage of organic matter by the Rock Eval device, percentage determination of carbonates by automatic calcimeter device were done for all samples and 10 samples were dated by 14C AMS method. The granulometric results indicated that most of the deposits are mud containing sand and gravel. The gravels are mainly related to shell fragments. The amount of carbonates varies from 17 to 84 percent. The silisiclastic deposits include quartz, feldspar, muscovite, pyroxene and clay minerals such as kaolinite, chlorite, montmoryonite, illite and paligorskite. The chemical and biochemical sediments are mainly calcite, dolomite and aragonite. The percentage of organic matter contained in the sediments varies from 0.02 to 0.13. The variation curve of calcium and strontium, which indicates intrabasinal sediments, is correlated to sea level changes in combination with objective evidences such as grain size, sediment type, and amount of organic matter, texture and structure of sediments. The abundance of most elements especially Al, Mg, Mn, Cr, Ba with continental origin, revealed a reversed relation with the sea level variations. In addition, two significant phases of rapid transgression have occurred from 6800 to 3700 and from 9300 to 7900 years ago. The dating results showed that the average rate of sedimentation in the study area is about 1mmper year(966mm/ka).
Stratigraphy and Palaeontology
Mohammad Hassan Shokri; Fatemeh Hadavi; Lida Khodadadi; M. Notghi Moghaddam; Hossein KAMYABI SHADAN
Abstract
Economically the Surgah Formation is the most significant in the Zagros sedimentary basin. In this study, the calcareous nannofossils have been investigated of the Surgah Formation from the Shah-nakhjir section. The thickness of the Surgah Formation is about 147 meters and composed of marly limestone ...
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Economically the Surgah Formation is the most significant in the Zagros sedimentary basin. In this study, the calcareous nannofossils have been investigated of the Surgah Formation from the Shah-nakhjir section. The thickness of the Surgah Formation is about 147 meters and composed of marly limestone deposits with diversity and well-preservation of calcareous nannofossil assemblages. In total, 41species belong to 22 genera were determinate and ultimately have compared with nannofossil standard zones. According to identified nannofossils, the age of the Middle Cenomanian- Middle Santonian corresponding to CC10- CC17 (Sissingh, 1977) includes Microrhabdulus decoratusZone (CC10), Quadrum gartneri Zone (CC11), Lucianorhabdus maleformis Zone (CC12), Marthasterites furcatus Zone (CC13), Micula decussataZone (CC14), Reinhardtites anthophorus Zone (CC15), Lucianorhabdus cayeuxii Zone (CC16), Calculites obscurus Zone (CC17) were suggested for the Surgah Formation in the studied section. Palaeoecological interpretations based on the identified species show warm climate and low depth conditions in low latitudes for deposits of the Surgah Formation in southwest of Ilam city (Shah-nakhjir section).
Economic Geology
Hossein Abasnia; M. H. Karimpour; Azadeh Malekzadeh Shafaroudi
Abstract
Damanghor area is located northern Bardaskan, Khorasan Razavi province, and structurally, it is a part of Taknar zone. Geology of the area includes of Taknar metamorphosed sedimentary rocks and metarhyolite, which is intruded by diabasic rocks as stoke and dyke. The texture of metarhyolies is porphyry ...
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Damanghor area is located northern Bardaskan, Khorasan Razavi province, and structurally, it is a part of Taknar zone. Geology of the area includes of Taknar metamorphosed sedimentary rocks and metarhyolite, which is intruded by diabasic rocks as stoke and dyke. The texture of metarhyolies is porphyry and contains of quartz and feldspar, whereas diabas has ophitic texture and contain plagioclas, pyroxene, and hornblend. Age of metarhyolite and diabas determined 550 Ma (Neoprotrozoic) and 8.8 Ma (Miocene), respectively, using zircon U-Pb method. Metarhyolites have peraluminous nature and were formed at intracontinental rift. Low enrichment in LREE relative to HREE and Eu negative anomaly indicates the magma is formed at plagioclase stability depth. (87Sr/86Sr)i (0.700712), (143Nd/144Nd)i (0.511852), and εNdi (–1.51) values show source of magma was mantel or lower crust. Diabases have toleitic to metaaluminous nature and were formed at subduction zone. (87Sr/86Sr)i (0.710527), (143Nd/144Nd)i (0.512716), and εNdi (+1.7) values indicate magma is drived from partial melting of metasomatized mantle wedge by released fluid of subducted slab, which is assimilated with continental crust. Taknar formation acidic Neoprotrozoic magmatism, which is formed at rift setting, associated with Miocene basic magmatism, which is formed at subduction zone, reveals an insight of tectonomagmatic conditions of Taknar zone in different times.
M Mohammadi; H Amiri Bakhtiar; F Amraee
Abstract
This study aimed to compare Asmari Formation in two sections in Maleh-Kuh and Amiran anticlines based on benthonic foraminifera. In this study, 26 species and 16 genera of benthonic foraminifera from the Maleh-Kuh section yielded 2 biozones of Elphidiumsp. 14 – Peneroplis, farsenensisandBorelismelocurdica ...
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This study aimed to compare Asmari Formation in two sections in Maleh-Kuh and Amiran anticlines based on benthonic foraminifera. In this study, 26 species and 16 genera of benthonic foraminifera from the Maleh-Kuh section yielded 2 biozones of Elphidiumsp. 14 – Peneroplis, farsenensisandBorelismelocurdica – Borelismelomeloweresuggesting an age of Aquitanian – Burdigalian for the formation. In Amiran anticline based on 27 species and 20 genera only the biozone of Borelismelocurdica – Borelismelomelo (Burdigalian)was recorded.Based on this study, the Asmari sequence in Maleh-kuh Section (with a thicknessof 310m) deposited earlier In Aquitanian. But in Amiran section (with a thickness 162m) deposition started in Burdigalian and ended synchronously in both sections. In both sections the Asmari Formation overlain Shahbazan Formation disconformably and is in turn under lain by Ghachsaran Formation concordantly-transitionally in Maleh-Kuh and by a sharp contact in Amiran Section.
Exploration and Mining
Ali Aalianvari; Saeed Soltani-Mohammadi; Maryam Miri
Abstract
The main objective of this paper is to estimate water seepage from the Azad dam foundation, based on the combined geotechnical investigations and multivariate geostatistical methods. Geological filed investigations and records at the 38 exploratory boreholes have been considered as the main source for ...
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The main objective of this paper is to estimate water seepage from the Azad dam foundation, based on the combined geotechnical investigations and multivariate geostatistical methods. Geological filed investigations and records at the 38 exploratory boreholes have been considered as the main source for seepage calculations. Due to expansion of reservoir and a few boreholes and limitation of geological investigations, distribution of permeability and permeability changes in the reservoir area is not an indicator for reservoir. In this research using geostatistical method (Kriging), Lugeon values have been estimated for abutments and foundation of the reservoir. Afterward, seepage was estimated for reservoir by using numerical method (FEM).results show that around 450 lit/min water was seepage from the dam. That is very close to the observed seepage from dam foundation. Based on the results, the total seepage estimated is around 450 lit/min that is relatively closed to the observed and measurements flow (350lit/min).
