M Emami Jafari; M Mehrpartou; A Akbarpoor; B Shamsi
Abstract
BLEGmethod is one ofmodern methodsusedfor goldgeochemicalexplorationstudies.Themethod has helped to locate many low grade gold deposits. The significant change of the method compared to common geochemical exploration methods is to use of large volumes ofsamples regardless of their sizeandlow densityof ...
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BLEGmethod is one ofmodern methodsusedfor goldgeochemicalexplorationstudies.Themethod has helped to locate many low grade gold deposits. The significant change of the method compared to common geochemical exploration methods is to use of large volumes ofsamples regardless of their sizeandlow densityof sampling.In order to evaluate the efficiency of the BLEG geochemical method with stream sediment method, 1:100000 SiahRud sheet was chosen in geological region of Azarbaijan in a district that geological map and geochemical exploration has already been carried out.The study area is 1850 km2, located in a mountainous area of northwest Iran in the Eastern-Azarbaijan province (NW of Ahar city).The rock units of the area consist mainly of the Upper Cretaceous limestone and flysch complex, Oligocene intrusive bodies and Eocene volcanic-sedimentary rocks. The Oligocene intrusive bodies are the most important igneous unit in the area.In this project, 168 BLEG samples and 103 stream sediment samples (silt samples) were prepared and studied. The range gold values in BLEG samples are from 0.1 to20 ppb, and in the stream sediment samples from 3 to459 ppb.The results ofsampling and analysis present four districts with high anomalous degrees: 1) Anigh-GharehChilar district, 2) Namnegh district, 3) Eshtobin district, and 4) Andrian or MiveRud district. Analysis ofthe stream sedimentsamplesrepresentshigh value of Cu andAu. Correlation of the elements in stream sediments taken from the Anigh-GharehChilar district represents high correlation of gold with arsenic, copper and leads elements. Copper also shows a high correlation with molybdenum, which is in accordance with mineralization of this area.
S.H Moeinzadeh
Abstract
In calculation the region’s faulting there are various factors that can be considered. Photolineament factor is a function of length, number and cross of faults per unit area and considered as Suitable method for the quantification of structural data. Naturally most alterations are relevant with ...
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In calculation the region’s faulting there are various factors that can be considered. Photolineament factor is a function of length, number and cross of faults per unit area and considered as Suitable method for the quantification of structural data. Naturally most alterations are relevant with faults and fractures which facilitate the penetration of hydrothermal liquids. Comparing the situation of areas with the highest concentration of lineaments in volcanic regions in calderas of Mosahim and Bidkhan and studying alteration faces in central of calderas indicates the association of supergene alteration with regional lineaments, while phyllic alteration that mostly has endogenous origin has a weaker relation with lineaments. Argillic alteration can have endogenous or exogenous source. In Mosahim caldera the origin of clay minerals is mostly sinking water and kaolin is its major mineral. According to the results of XRD experiments, minerals such as Pyrophylit and Dikyt cannot be seen in most parts of Mosahim caldera. So most of the alterations of Mosahim volcano are argillic with exogenous origin; while in Bidkhan caldera in spite of the majority of argillic alteration and phyllic alteration with mostly endogenous origin has a notable covering. Drawing the matching matrix alteration and upper bound of photolinieament factor in Mosahim and Bidkhan show the respectively matching coefficients of 37.8% and 29% for argillic alteration and coefficients of 1.1 % and 10.7 % for phyllic alteration in the above mentioned region. Positive relationship between argillic alteration and photolinieament factor and weaker association of phyllic alteration with this factor in the center of Mosahim and Bidkhan calderas along with closer relative of overall alteration regime (mostly exogenous) of the Mosahim region with photolinieament factor indicate severe faults effect in the supergene than hypogene processes in these areas.
M. Hosseini-Barzi; R. Alinejad-Kurdi; H. Ghalavand
Abstract
The calcimeteric analysis of samples from Pabdeh Formation, in type section (north of Dezful embayment subzone), represent a marl and shaly marl lithology. SEM images from these samples represent chlorite flakes with diagenetic origin (transformation of illite to chlorite) and imply the possible existence ...
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The calcimeteric analysis of samples from Pabdeh Formation, in type section (north of Dezful embayment subzone), represent a marl and shaly marl lithology. SEM images from these samples represent chlorite flakes with diagenetic origin (transformation of illite to chlorite) and imply the possible existence of other detrital clay minerals (include chlorite). However, XRD analysis of selected samples indicates the existence of montmorillonite, illite and chlorite showing a descending trend for clay percent and montmorillonite and ascending one for illite and chlorite from bottom to top of these deposits. Based on these evidences, we introduced the possibility for cooling in climate condition and shoaling in depth of deposition, from bottom to top of the Pabdeh Formation.
Study of Th, K & Th/K peaks of NGS log represents the existence of montmorillonite and illite, as common clay mineral. Calculating clay mineral percent, shale percent and uranium trend imply an anomaly at the uppermost part of the Pabdeh Formation which could be related to fault activity in Central Dezful embayment subzone and sediment supply probably due to Pyrrenean orogeny.
Therefore, investigation of clay mineral represent difference in sedimentary framework between northern Dezful embayment subzone and central Dezful embayment subzone and their different response to change in geological condition.
N. Sarbaz; A. Mahboubi; R. Moussavi-Harami; M. Khanehbad
Abstract
The Koppeh- Dagh Basin in the northeast Iran formed after closure of the Paleotethys in the south of Turan plate. Kashafrud Formation in the Navia Section (west of Bojnourd) with a thickness of 749 m is composed of silici-clastic rocks (conglomerate, sandstone and shale). In order to interpret provenance ...
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The Koppeh- Dagh Basin in the northeast Iran formed after closure of the Paleotethys in the south of Turan plate. Kashafrud Formation in the Navia Section (west of Bojnourd) with a thickness of 749 m is composed of silici-clastic rocks (conglomerate, sandstone and shale). In order to interpret provenance of this formation in the study section, 12 shale samples have been geochemically analyzed. The samples are rich in quartz and clay minerals, with respect to (UCC) depletion in Na2O, CaO, MgO, Cu, Nb and Sr and enrichment in Ni, Co, V, Y and U. Plotting TiO2 versus Al2O3, Zr versus TiO2, as well as ternary diagram (SiO2/20), (k2O+ Na2O), (MgO+ TiO2+ FeO) and diagram Al2O3, (Cao+ Na2O+ K2O), (FeO + MgO) suggest that the original source of this formation was probably from intermediate igneous rocks. Calculated PIA and CIA indicate high chemical weathering and semi- humid climatic condition in the source area. Prepared discrimation diagram using the major oxides (SiO2 versus K2O/Na2O and ternary diagrams SiO2/20, Na2O+ K2O, TiO2+ MgO+ Fe2O3), shows that the shales of this formation were plotted in the passive continental margin. Paleogeographic reconstruction for this formation, during the Middle Jurassic shows that sedimentation of this formation is mainly controlled by intracontinental subsiding basin and the source of these sediments was from the southeast of the Kopph-Dagh Basin.
Economic Geology
maryam sadat lajouei kalaki; Afshin Akbarpour; Alexandre Tarantola; Shohreh Hassanpour; Behzad Mohammadi; Monireh Poshtkoohi
Abstract
The Gheshlaghe mil deposit is located in the Urumieh-Dokhtar magmatic belt. Vein- type mineralization is concordance within the rhyodacitic and rhyolite meta-tuff with Eocene age. Alteration zones of sericite, silica, argillic and iron oxides are observed in the investigated area. Primary sulfide minerals ...
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The Gheshlaghe mil deposit is located in the Urumieh-Dokhtar magmatic belt. Vein- type mineralization is concordance within the rhyodacitic and rhyolite meta-tuff with Eocene age. Alteration zones of sericite, silica, argillic and iron oxides are observed in the investigated area. Primary sulfide minerals of pyrite, fine-grained chalcopyrite and Oxidized specularite and Secondary minerals goethite, limonite, malachite and quartz in Microscopic and field studies have been identified. Based on X-ray diffraction analysis studies minerals such as chlorite, illite, kaolinite, hematite, quartz, mica group and calcite have been observed in the bearing gold veins. According litho-geochemical studies, the gold element has a positive correlation with iron, molybdenum, nickel and lead. A number of 157 fluid inclusion studies in the Gheshlaghe Mil ore mineralization area has been showed mineralization temperature of 99 to 299 °C, rate of salinity ore deposit 1.81 and 12.30 equivalent to the Nacl weight percent. Using Raman laser studies (13 points), the presence of gaseous phases (CO2, N2, H2O) in the fluid inclusions have been demonstrated. Regarding to studies have been done in this area, the Gheshlaghe Mil ore mineralization can to know to a vein type- hydrothermal bearing gold-copper ore deposit.
Economic Geology
A. Baharvandi; M. Lotfi; M. Ghaderi; M. R. Jafari; H. A. Tajeddin
Abstract
Shekarbeig barite deposit is located 46 km southwest of Mahabad in northwestern part of the Sanandaj-Sirjan zone. The outcropped rock units in the area are Late Protrozoic metamorphosed volcano-sedimentary rocks, equivalent to Kahar Formation. The main ore mineral occurs as stratiform barite lenses in ...
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Shekarbeig barite deposit is located 46 km southwest of Mahabad in northwestern part of the Sanandaj-Sirjan zone. The outcropped rock units in the area are Late Protrozoic metamorphosed volcano-sedimentary rocks, equivalent to Kahar Formation. The main ore mineral occurs as stratiform barite lenses in three horizons accompanied by sulfide minerals as massive and/or parallel bands within metamorphosed rhyolitic tuffs (metatuff). The deposit footwall is composed of phyllite and slate crosscut by silicic and sulfide-bearing barite veins and veinlets (stringer zone). Primary minerals in the ore are mainly barite, pyrite, marcasite, chalcopyrite and bornite and secondary minerals are chalcocite, covellite, malachite, siderite, goethite, hematite and other iron hydroxides. Gangue minerals include quartz, sericite, calcite, dolomite, feldspar and chlorite. In terms of metallic ores, the Shekarbeig deposit does not vary much having only pyrite and chalcopyrite. Types of fluid inclusions in the Shekarbeig deposit are two-phase liquid-vapour (LV), mono-phase vapour and mono-phase liquid; two-phase liquid-vapour being the dominant type in both stringer and stratiform parts. Sulfur isotope data indicate that seawater was the main mineralizing fluid for Shekarbeig mineralization. These data suggest that complete reduction of recent seawater sulfate and the rate of mixing of hydrothermal solution with cold waters in deep parts of the basin may result in precipitation of large amount of sulfides in the stringer and stratifrom zones. On the other hand, partial reduction of recent seawater sulfates provided required sulfur for the deposition of barite. Geological evidence, evaluation, lithostratigraphy, mineralization geometry and the results of fluid inclusion and sulfur isotope studies for samples from the Shekarbeig deposit indicate derivation of the hydrothermal fluids of low salinity and moderate temperature from seawater and circulation and upward movement by a heating source (probably subvolcanic intrusions) and finally cooling and deposition of the fluids as sulfate and sulfide on the sea floor due to mixing with seawater, similar to massive sulfide Kuroko-type deposits.
R. Gholipour; A. Solgi; Y. Sattarzadeh-Ghadim; A. Sorbi
Abstract
Geomorphic indices of active tectonics are useful tools to analyze of the active tectonics in a large area. These indices have the advantage of being calculate from the software and remote sensing packages over large area as a reconnaissance tool to identify geomorphic anomalies possibly related to active ...
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Geomorphic indices of active tectonics are useful tools to analyze of the active tectonics in a large area. These indices have the advantage of being calculate from the software 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 Ajichai basins where relatively little work on active tectonics based on this method was done, so this method is new and useful. Based upon valuable of the stream length-gradient index(SL), drainage basins asymmetry(Af), hypsometric integral (Hi), ratio of valley-floor width to valley height (Vf), drainage basins index shape (Bs), and index of mauntain 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 moderate class of Iat is mainly in the class 2 (high), with 1045.46 Km2 ,11.26 percent, class 3 (moderate), with 2940.67 Km2 ,31.67 percent and with 5297.30 Km2 ,57.06 percent occupying of all zone. The stream network asymmetry (T) was also studied using morphometric measures of Transverse Topographic Symmetry. Analysis of the drainage basins and sub-basins in the study area results in a field of T-vectors that defines anomalous zone of the basins asymmetry. A comparison of T index clearly consist with the values and classes of active tectonics indices and the overall Iat index.
S Angornai; H Memarian; M Shariat Panahi; M.J Bolourchi
Abstract
Land subsidence is an environmental phenomenon that involves gradual or sudden settlement of the land surface because of compaction of underground material. Groundwater withdrawal, which occurs due to excessive use of water resources, is among the most important reasons for this phenomenon. Therefore, ...
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Land subsidence is an environmental phenomenon that involves gradual or sudden settlement of the land surface because of compaction of underground material. Groundwater withdrawal, which occurs due to excessive use of water resources, is among the most important reasons for this phenomenon. Therefore, land subsidence can lead to destructive results in residential, industrial and agricultural areas. As a result, subsidence caused by excessive use of groundwater resources has occurred in many countries in the world. Tehran metropolitan plain in Iran is one of the most obvious examples, where land subsidence is happening. Although the relationship between land subsidence, groundwater level decline and changes in the physical properties of subsurface material is broadly understood, a comprehensive and precise model to predict land subsidence remains unconstrained. Land subsidence modeling is a complicated matter in geological engineering but can help to better understand subsidence and possibly prevent damages. The commonly used numerical methods for modeling land subsidence are generally based on simple assumptions, which make the model results to be associated with some errors. In this study, artificial intelligent methods such as Artificial Neural Networks (ANN) were used to propose a new method to predict land subsidence. The efficiency of this method was then tested in the South Tehran plain as a case study. We have used hydrological, geotechnical, remote sensing and ambient vibrations for site effect investigations. First, the collected data was studied statistically. Then, the delay between groundwater withdrawal and subsidence was computed by genetic algorithms using available hydrographs and GPS data in a period of 27 months. Model input parameters include changes in groundwater level, natural frequency of soil, alluvial thickness, defined geographic coordinates and time. The model output was an estimated subsidence measured by radar interferometry method. The model was built in 15 time steps using a set of data having 4 months of time difference with the data used to create the model. The comparison between the predicted (modeled) and real (measured by remote sensing) subsidence shows a good correlation, which makes the proposed model reliable.
Petrology
Hamid Ahmadipour; Hamideh Salehinejad; Seyed Hesam-Aldin Moeinzadeh; Abbas Moradian
Abstract
Shan Abad–Raviz basic intrusions from the West of Rafsanjan (Kerman province), represent a part of Dehaj-Sarduyieh belt and intruded into the Eocene volcano-sedimentary rocks as dykes and apophyses. Thicknesses of the dikes and the diameters of the patches reach up to 4 and 10 meters respectively. ...
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Shan Abad–Raviz basic intrusions from the West of Rafsanjan (Kerman province), represent a part of Dehaj-Sarduyieh belt and intruded into the Eocene volcano-sedimentary rocks as dykes and apophyses. Thicknesses of the dikes and the diameters of the patches reach up to 4 and 10 meters respectively. In the field, they appear as dark intrusions contain sporadic euhedral pyroxene crystals with up to 5 mm in size. They are gabbro and diorite and their main minerals are plagioclase and pyroxenes set in a fine-grained matrix and show intergranular and porphyroid textures. These rocks have low-K calc-alkaline affinities and their geochemical characteristics tend to the subduction zone settings. In these rocks, 87Sr/86Sr and 143Nd/144Nd ratios vary between 0.70403 to 0.70409 and 0.5128 to 0.5129 respectively and εNd(i) values change between 3.52 to 6.6. These evidences along with the special textures show that their parent magmas affected by fractionation, assimilation and magma mixing processes. Considering that these rocks have intruded into the Eocene volcanics, we suggest that they represent the last stages of Eocene magmatism in the Cenozoic Kerman magmatic belt and intruded into the crust after the intiation of Neo-Tethys subduction beneath to Central Iranian block, probably in a continental margin tectonic setting.
N Mohammadi Akbari; M.R Kamali
Abstract
Sarvak Formation (with the age span of Cretaceous) is considered as one of the most prominent oil reservoirs in the south of Iran and a significant volume of oil accumulation in the Persian Gulf basin is attributed to this formation. In the present research plan, in order to evaluate the hydrocarbon ...
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Sarvak Formation (with the age span of Cretaceous) is considered as one of the most prominent oil reservoirs in the south of Iran and a significant volume of oil accumulation in the Persian Gulf basin is attributed to this formation. In the present research plan, in order to evaluate the hydrocarbon generation capacity of this formation, cores, cuttings and oil samples collected from fields’ wells located in block D underwent some investigations which were in the Iranian sector of the Persian Gulf. Correlation is defined as the geochemical comparison between hydrocarbons themselves, or also hydrocarbons with source rocks, and furthermore defining the quality of the genetic relation between them. In order to achieve this goal a variety of gadgets and parameters are used, some of them being biomarkers and stable isotopes.
The results obtained from geochemical analyses including primary analyses (pyrolysis rock-eval), bitumen extraction and separation, complementary analyses (gas chromatography), gas chromatography-mass spectrometry and stable isotope studies on samples indicate that kerogen of studied samples is a combination of types II and III and it implies that most organic matter generating hydrocarbon were formed in a marine environment along with a little entering from land. The hydrocarbons existing in Sarvak Formation were generated from a semi carbonated clastic source rock and were sedimented under a reduced or semi-reduced environment. The saturate sections of the Chromatograms samples indicate the lack of environmental biodegradation in the studied samples. The Oil and inter bed shaly-marl samples of the Sarvak Formation show a fair to good hydrocarbon potential. The set of under study samples are located in the beginning of the oil generation window (late diagenesis) and early catagenesis in terms of their maturity degree. Furthermore, hydrocarbons show a paraffinic-naphthenic characteristic. It seems the shaly-marl layers existing in some parts of the Sarvak Formation (Ahmadi member), in Block D, in the Persian Gulf, have been the cause for the generation of hydrocarbons available in the Sarvak reservoir.
M Daryapeyma Hormozi; H Biabangard; S Bagheri; M.R Bakhshi Mohebi
Abstract
Dasht Kuh volcanic complex is located to ~75 km to the north of Iranshahr. It consists of two parts: A (main body) and B (the isolated part in the northern Dasht Kuh). Based on the geological maps of the area, the volcanic bodies intruded the flysch type rocks of the East Iran in Cretaceous; the rocks ...
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Dasht Kuh volcanic complex is located to ~75 km to the north of Iranshahr. It consists of two parts: A (main body) and B (the isolated part in the northern Dasht Kuh). Based on the geological maps of the area, the volcanic bodies intruded the flysch type rocks of the East Iran in Cretaceous; the rocks are separated from Eocene conglomerate across a fault zone. The Dasht Kuh volcanic complex essentially consists of basalt, andesite, basaltic andesite and trachybasalt. The main rock-forming minerals are plagioclase, pyroxene, hornblende, and sanidine with dominant porphyritic texture. Minor pyroclastic materials occur in the lower parts of the complex.Samples rocks from of Dasht Kuh in the rare earth elements diagram relative to abundance of these elements in the Chondrite, shows a significant negative slope observed that the samples are enriched in light rare earth elements (LREE) and depletion of heavy earth elements (HREE). Different chemical composition, Tectono-magmatic and origin digrams shows that rocks in these bodies have alkaline nature of mantle origin and were formed in continental volcanic arc. It seems Dasht Kuh volcanic comlex are part of island arc that wide arc from northern Pakistan to Iran that have been separated from their origin by younger tectonic events.
Petroleum geology
Nasim Maleki Sadeghi; Ahmad Ahmadi-khalaji; Reza Zarei Sahamieh; Zahra Tahmasbi
Abstract
The study area is a part of Zagros Folded zone and located in the Lorestan sedimentary basin. In this regard, three areas with high bitumen potential were selected, which include the northern area of Kuhdasht, northeast of Poldokhtar and southeast of Sepiddasht. In the study areas, bitumens are exposed ...
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The study area is a part of Zagros Folded zone and located in the Lorestan sedimentary basin. In this regard, three areas with high bitumen potential were selected, which include the northern area of Kuhdasht, northeast of Poldokhtar and southeast of Sepiddasht. In the study areas, bitumens are exposed as veins between the fractures and as interlayers with host rock that the thickness of these veins is between 10 cm to more than 1.5 meters. Field studies showed that the studied bitumens have developed in the shales of Amiran Formation. Based on the results of organic geochemistry, 80.10 to 93.60% of the extractable saturated compounds are in the category of asphalts and have a very good quality in terms of thermal maturity (maturity of organic matter). The studied samples are formed in a reducing to slightly reducing sedimentary environment. Drawing the diagram of C34/C35 Homohopane vs. C29/C30 Hopane for the studied bitumens showed that the generating rocks of the studied samples are carbonate and detrital in nature. This can be explained by the lithology of bituminous formations such as Ilam and Gurpi formations in the study areas. The triangular diagram of regular streams (m/z = 217) for the studied bitumens showed that the source of organic compounds of the studied bitumens is mostly marine with a small amount of entry from dry environments. Severe depletion of the carbon isotope (average -28.83 per mill) indicates organic origin and biomass in these samples. On the other hand, sulfur compounds with depletion (-12.16 per mill) indicate formation in a reduced to semi-regenerated sedimentary environment and oxygen isotope data (+15.03 per mill) indicate the formation of organic matter of sedimentary origin.
M. Sadeghian; H. Ghasemi; Z. Farsi
Abstract
Chah Salar granitoidic pluton is located in the N of Chah-Salar village, SW of Neishabour, in the northern margin of structural Central Iran zone. This pluton intruded in Sabzevar ophiolitic Zone and based on the field observations, petrographical and geochemical classification diagrams, its lithological ...
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Chah Salar granitoidic pluton is located in the N of Chah-Salar village, SW of Neishabour, in the northern margin of structural Central Iran zone. This pluton intruded in Sabzevar ophiolitic Zone and based on the field observations, petrographical and geochemical classification diagrams, its lithological composition composed of diorite, quartzdiorite, granodiorite and alkali feldspar granite. Alkali feldspar granites as a much fractionated end-members of this rock association are intruded in this pluton in the form of dikes or apophyse shapes. Granitic pegmatites and their associated quartzolites are the most differentiated end-member of this rock association. Their subvolcanic equivalents such as pyroxene-bearing andesite, andesite, trachyandesite and dacite cut this pluton in the forms of dikes or domes. The studied rocks show variety of textures including granular, myrmekitic, graphic, porphyritic, microlitic porphyry and pilotaxitic. Except alkali feldspar granites which are highly fractionated, the other lithological compositions, on the variations diagrams of major, trace and rare earth elements versus SiO2 or differentiation index show continuous compositional variations. This pluton has calc-alkaline and metaluminous nature and belongs to I-type granitoids. Also tectonic setting discrimination diagrams indicate that the Chah Salar granitoidic pluton belongs to volcanic arc granitoids (VAG) and continental arc granitoids (CAG). Detailed investigations of field geology, petrography and geochemical characteristics indicate that magma-forming of this pluton is resulted from partial melting of subducted oceanic slab (metabasite) or metasomatized mantle wedge and then evolved by fractional crystallization, magma contamination or magma mixing.
A.R. Arab-Amiri; A. Moradzadeh; D. Rajabi; N. Fathianpour; B. Siemon
Abstract
Today Helicopter-borne electromagnetic (HEM) data survey play important role for high resolution and fast 3D mapping of resistivity structures within the vast area. The standard method of interpretation of these data is to inverse them frequently. As surveying system is not fixed during the survey, hence ...
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Today Helicopter-borne electromagnetic (HEM) data survey play important role for high resolution and fast 3D mapping of resistivity structures within the vast area. The standard method of interpretation of these data is to inverse them frequently. As surveying system is not fixed during the survey, hence noise is accompanying the measured data. To process the measured noisy data they are fed into the several filters to get better data to be used for modeling. During the filtering stage some of signals are also lost. Therefore, it is required to choose modeling techniques that has minimum error and provide accurate subsurface model. In this paper, first the response of the three synthetic layered earth models were calculated by using three different Hankel transform forward modeling methods. Then with adding different percents of random noise to the synthetic data, they were modeled inversely by different methods. The obtained results indicate that the so-called improved Guptasarma-Singh inverse modeling method could provide better responses for all three synthetic models.
A Sarhangi; S Modabberi; S.R Mousavi Harami; M Zibayi
Abstract
The anthropogenic and natural contaminants are considered as the main factors threatening water resources and they are in direct connection to the public health and also threaten the development of water resources. The Latyan Dam reservoir is the main source of drinking water of Tehran metropolitan ...
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The anthropogenic and natural contaminants are considered as the main factors threatening water resources and they are in direct connection to the public health and also threaten the development of water resources. The Latyan Dam reservoir is the main source of drinking water of Tehran metropolitan area. In this paper, the environmental geochemistry of water and sediments have been studied. Eight sampling stations were selected in the lake and water samples were taken for measurement of trace elements in dissolved and particulate phases. In addition, sediment samples were taken at the same points by using a grab. The geochemical analysis performed by ICP-OES method showed that the concentration of potentially toxic metals were measured below the detection limit of the instrument and fall in the ranges of safe drinking water guidelines. The sediment samples showed concentrations within the quality guideline values except for As and Pb. The enrichment factor and Igeo were calculated for the sediment samples indicating that the sediments are not contaminated. Metal enrichment in sediments is however very strong compared to water samples and it is suggested that the adsorption processes have important role in sorption of metal contaminants onto the surface of sediment particles and it could be regarded as a potential for contamination if they return to water column in case of change in sediment physicochemical conditions.
M.E Hekmatian; V Ebrahimzadeh Ardestani; M.A Riahi; A Memar Koucheh Bagh; J Amini
Abstract
Pattern recognition algorithms especially neural network in geophysical interpretations and other Earth sciences have been used since some years ago. In neural network and other pattern recognition algorithms like support vector classifier (SVC) that the latter method is used in this research, by using ...
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Pattern recognition algorithms especially neural network in geophysical interpretations and other Earth sciences have been used since some years ago. In neural network and other pattern recognition algorithms like support vector classifier (SVC) that the latter method is used in this research, by using the values of the features, which has been extracted from the objects (in our work gravity profiles are objects), classification of the objects can be done. Usually the features are selected subjectively. In this paper, we have presented a homemade software that can select proper features objectively. By using SVC and the mentioned features selection (FS) software, depth estimations of anticlines have been done in this research. We have shown the difference of using proper features and improper ones in the mentioned depth estimation (a kind of classification). In this paper, twenty synthetic gravity profiles with anticline shape sources are created for training SVC and the same amount of synthetic profiles are created for testing. It has shown that depth estimation with proper features is more precise than depth estimation with improper features. Also it should be emphasized that FS is important not only in depth estimation of anticlines, but also in all kinds of classifications in Earth sciences and the mentioned homemade software code is applicable in all of them.
M Sheban; F Ghaemy; A Abbasnejad; F Ghaemy
Abstract
Neotectonics that is a major factor of landform development in tectonically active regions has significantly affected fluvial systems and mountain-front landscapes in the Behabad area of the Central Iran Zone. To assess tectonic activities in the area, we analyzed geomorphic indices including the mountain-front ...
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Neotectonics that is a major factor of landform development in tectonically active regions has significantly affected fluvial systems and mountain-front landscapes in the Behabad area of the Central Iran Zone. To assess tectonic activities in the area, we analyzed geomorphic indices including the mountain-front sinuosity (Smf), stream-gradient index (SL), valley floor width–valley height ratio (Vf), drainage basin shape (Bs) and drainage basin asymmetry (Af). These indices were combined to yield the relative active tectonics indices (Iat). Based on Iat values, the study area was divided into four parts: Class 1 (very high relative tectonic activity, 1.52% in area), Class 2 (high, 68.58%), Class 3 (moderate, 20%), and Class 4 (low, 9.9%). The results are consistent with field observations on landforms and geology. The active tectonics indices and geomorphological evidences indicate that the tectonic activity rate in the studied area is predominantly moderate to high.
M. H. Mir Yaghoobzadeh; M. R. Ghanbarpour
Abstract
Snow cover was one of important parameter in snow melt runoff model. Because snow telemetry in mountainous basin is difficult, remote sensing image is an alternative object in snow cover mapping. Snow cover maps derived in remote sensing imagery is one of the important data entries in snow melt runoff ...
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Snow cover was one of important parameter in snow melt runoff model. Because snow telemetry in mountainous basin is difficult, remote sensing image is an alternative object in snow cover mapping. Snow cover maps derived in remote sensing imagery is one of the important data entries in snow melt runoff models. MODIS imagery was selected for deriving snow cover maps in this study. In order to investigate the difference in reflectance bands, vertical profile in each image was generated. Capability of NDSI in MODIS imagery was confirmed. Finally snow melt runoff simulation in Karaj Dam basin was carried out as the fundamental remote sensing data capabilities. Result showed that the NDSI using threshold on band 2 and band 4 demonstrates an efficient relation in snow cover maps. Moreover simulation of snow melt in 2001-2000 with the coefficient of R2=0.4678 and ∆v=0.1292 m3/s indicated. The high accuracy of snow cover maps derived from remote sensing data.
M. H. Davoudi; M. Fatemi Aqda
Abstract
Stabilization of potentially sliding terraces and natural slopes are of great importance from view point of resident security, environment protection, river engineering and water and soil conversation. Soil reinforcement using tree toots is one of methods being studied by many researchers. Most of them ...
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Stabilization of potentially sliding terraces and natural slopes are of great importance from view point of resident security, environment protection, river engineering and water and soil conversation. Soil reinforcement using tree toots is one of methods being studied by many researchers. Most of them have worked on the effect of root density and few of them on the root diameter leading to contradicting results. In this paper the combined effect of root diameter and density on the shear resistance of soil is investigated by series of in-situ direct shear tests. Eighteen tests were carried out on soil having Willow roots and the results were compared with those of non rooted soil as reference. To explain the observations, a new parameter referred to as root diameter-density index (RDDI) was defined. The results reveal that an increase in RDDI causes a significant increase in the apparent cohesion of rooted soil, but a little decrease in the internal friction angle. In both cases the rate of variation decreases with increasing RDDI and tends to a little value; however the extreme values of 212% and -15% were observed respectively. As general conclusion for rooted soils, the dominance of variation of apparent cohesion with respect to that of internal friction angle results the shear resistance ameliorates within a range of RDDI, and for further values it tends to a stabilized value. Also, for practical purposes, a relation was developed to be used by designer engineers.
M. Talebian; S. H. Tabatabaei; M. Fattahi; M. Ghorashi; A. Beitollahi; A. Ghalandarzadeh; M.A. Riahi
Abstract
The Iranian plateau lies between the Arabian and Eurasian plates and accommodates approximately 22 mm/yr of N-S shortening. About 9 mm/y of this shortening is taken up by folding and thrusting in the Zagros while the remaining 13 mm/yr is taken up in the Alborz and Kopeh-Dagh. The Central Iran ...
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The Iranian plateau lies between the Arabian and Eurasian plates and accommodates approximately 22 mm/yr of N-S shortening. About 9 mm/y of this shortening is taken up by folding and thrusting in the Zagros while the remaining 13 mm/yr is taken up in the Alborz and Kopeh-Dagh. The Central Iran block is relatively stable and thus moves to the north with an average velocity of about 13 mm/y. As the stable Afghanistan block lies to the east, the northward motion of Central Iran produces a right-lateral shear in eastern Iran, which is distributed mainly over a few major faults to the west (~5 mm/yr) and east (~ 8 mm/yr) of the Lut desert. Limited information is available about the slip rates of individual faults in eastern Iran; therefore in this study we try to combine all geological, geodetic and available Quaternary dating results to estimate the fault slip rates and distribution of active deformation in eastern Iran. Finally, we report the results from OSL dating of samples taken from uplifted plain deposits near the south end of the Bam-Baravat fault. These results show that this fault is growing in the vertical direction with at a rate of ~ 0.5 mmy-1. Considering geometric relation between the Bam-Baravat and the south Bam earthquake fault, we estimate a slip rate of about 2 mm/y for the south Bam earthquake fault.
H. Gholamalian; S. M. Hosseini-Nezhad; Z. Khosravi; I. Turkzadeh Mahani
Abstract
Bahram Formation equivalent sequence in the Baghin area spans late Givetian to late Frasnian age. Thirty-two species and subspecies are identified. Ancyrodella alata, An. pristina, Polygnathus aspelundi, P. aequalis, P. subincompletus,P. politus, Icriodus alternatus alternatus, I. iowaensis iowaensis ...
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Bahram Formation equivalent sequence in the Baghin area spans late Givetian to late Frasnian age. Thirty-two species and subspecies are identified. Ancyrodella alata, An. pristina, Polygnathus aspelundi, P. aequalis, P. subincompletus,P. politus, Icriodus alternatus alternatus, I. iowaensis iowaensis are of important species. The presence of An. pristina and An. alata in the lower part of Bahram Formation in this section shows the late Givetian marine transgression. Five conodont biozones are recognized on the basis of stratigraphic ranges of species: Lower to Upper falsiovalis zones; transitans to punctata zones; Lower hassi to jamieae zones; Lower rhenana Zone; and Upper rhenana to ?linguiformis zones.
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.
H. Shafaii Moghadam; M. Rahgoshay; H. Whitechurch; I. Monsef; A. Soltan Mohamadi
Abstract
Basalts, gabbros, tuffs, diabasic dikes, agglomerates and breccias and the rock fragments of breccias are the main mafic constituents of the Balvard-Baft ophiolites. Geochemical signatures of these rocks reveal depletion in HFSE and enrichment in LILE and simultaneous occurrence of island-arc tholeiitic ...
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Basalts, gabbros, tuffs, diabasic dikes, agglomerates and breccias and the rock fragments of breccias are the main mafic constituents of the Balvard-Baft ophiolites. Geochemical signatures of these rocks reveal depletion in HFSE and enrichment in LILE and simultaneous occurrence of island-arc tholeiitic and calc-alkalic volcanisms. These geochemical behaviors are the evidences suggesting that these mafic rocks are of supra-subduction zone affinity. These special signatures associated with the position of the Nain-Baft ophiolitic belt behind the Mesozoic magmatic arc of the Sanandaj-Sirjan zone, suggest back-arc spreading (in the active margin of the Central Iranian block), during middle Cretaceous due to the oblique subduction of Neo-Tethys beneath the Central Iranian block.
S.J Yousefi; A Aftabi
Abstract
The investigation on toxic elements in sediments around the Chahar Gonbad copper-gold mine indicates sediments with various sources of pollution. In order to investigate the source and chemical fractionation of toxic elements 38 sediment samples were collected from 0 to 5 cm depth of river, alluvium ...
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The investigation on toxic elements in sediments around the Chahar Gonbad copper-gold mine indicates sediments with various sources of pollution. In order to investigate the source and chemical fractionation of toxic elements 38 sediment samples were collected from 0 to 5 cm depth of river, alluvium and dam sediments randomly. The average values of elements in sediments are: 0.09 ppm Ag, 17.82 ppm As, 0.48 ppm Bi, 0.22 ppm Cd, 17.58 ppm Co, 91.49 ppm Cu, 43161.33 ppm Fe, 1152.83 ppm Mn, 0.97 ppm Mo, 41.5 ppm Ni, 10.82 ppm Pb, 484 ppm S, 1.3 ppm Sb, 0.13 ppm Se, 1.05 ppm Sn, 3067.67 ppm Ti, 0.35 ppm Tl, 126.5 ppm V and 90.82 ppm Zn, respectively. The average values for waste dam sediments include 0.22 ppm Ag, 28.37 ppm As, 13.14 ppm Bi, 0.26 ppm Cd, 51.88 ppm Co, 1981.4 ppm Cu, 81677.33 ppm Fe, 2165.13 ppm Mn, 72.86 ppm Mo, 80.67 ppm Ni, 191.38 ppm Pb, 5593.17 ppm S, 47.75 ppm Sb, 0.66 ppm Se, 1.77 ppm Sn, 2136.83 ppm Ti, 0.43 ppm Tl, 80.75 ppm V and 989.94 ppm Zn. The obtained results were evaluated by using of multivariation statistical method including correlation coefficient, principal component analysis (PCA), and cluster analysis (CA). By using a multivariation statistical method it becomes obvious that the sediments can be divided into four different categories. The first category of these sediments are derived from mining activity, which in the first component of the PCA analysis are related to Ag, As, Cd, Co, Cu, Fe, Mo, Pb, Sb, Se, Sn, Tl and Zn. The second category of sediments are not affected by mineralization and in the second component of PCA analysis are indicated by Al, Sc, Sr, V, Ta, Ti. The third category is of natural sediments, on which, rock source and mineralization had an influence, thus include the third component of PCA analysis and are indicated by Bi, Mn, and S. The forth category of sediments include toxic elements such as Cr and Ni that either are derived from weathering of sulfides or probably from ophiolitic rocks.
S. H. Hejazi; M. H. Adabi; S. R. Moussavi Harami
Abstract
The Givetian-Frasnian sandstones in the Kuh-e-Tizi section (25 km NE Kerman), unconformably overlie the Upper Cambrian Kuhbanan and underlie the Lower Carboniferous Hutk Formations respectively, in southeastern Central Iran. Petrographical data show that these sandstones are well-sorted, sub-angular ...
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The Givetian-Frasnian sandstones in the Kuh-e-Tizi section (25 km NE Kerman), unconformably overlie the Upper Cambrian Kuhbanan and underlie the Lower Carboniferous Hutk Formations respectively, in southeastern Central Iran. Petrographical data show that these sandstones are well-sorted, sub-angular to rounded quartzarenite. Diagenetic features include physical and chemical compactions (straight, concavo-convex, sutured grain contacts and pressure solution of quartz grain), reduction of the pore space through rearrangements and cementation (mostly silica, as quartz overgrowth). The provenance and tectonic setting of these sandstones have been interpreted using integrated petrographic and geochemical data. Petrographic analysis using standard methods revealed that mono and poly-crystalline quartz grains have been derived from plutonic rocks of an interior cratonic setting. Trace element analyses and their ratios used for provenance studies (Th/Sc and La/Sc) are similar to sediments derived from weathering of mostly felsic rocks. Values representing chemical index of alteration (CIA) and the plagioclase index of alteration (PIA) range from 44.24 to 83.43, with an average of 69.96, and from 42.98 to 92.56, with an average of 75.8, respectively. However, most samples have values greater than 60, suggesting moderate to high weathering in the source area or during transportation prior to find deposition. Major and trace element concentrations indicated a depositional setting in a passive continental margin.
