S. Khederzadeh; A. Bahrodi
Abstract
Sand box models are in order to investigation of circumstance of deformation create in orogenic event. Progressive rigid indenter is as non-plastic continental crust that moves from one side to ward sand hanging wall that is indication plastic crust. The sand primery thickness and angle of rigid indenter ...
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Sand box models are in order to investigation of circumstance of deformation create in orogenic event. Progressive rigid indenter is as non-plastic continental crust that moves from one side to ward sand hanging wall that is indication plastic crust. The sand primery thickness and angle of rigid indenter are changeable. In the all of models, rises sand in the two side of plan of indenter between fore-slop and back-slop, in the top of indenter progressive edge. The formation rate of anticlinorium folds is related to thickness of sand hanging wall, form of progressive and rate of falling's back-slop plan. Change of primery thickness of sand hanging wall is controler of distance and rate of anticlinorium folds formation. The aim of this experimental work is investigation of thrust belts, progressive indenter, and research of effect's slope in the collision zones and fold-thrusts creation, also comparison of experimental model to natural model.
A. Lashkari; M. R. Ghassemi; M. Qorashi
Abstract
The Caspian (Khazar) fault is the boundary between the Caspian plain and AlborzMountain. As a major tectonic feature, this fault may be considered as the northern mountain front fault of the AlborzRange. Subsidence of the Caspian Sea in north, uplift of the Alborz Mountain, and its over thrusting on ...
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The Caspian (Khazar) fault is the boundary between the Caspian plain and AlborzMountain. As a major tectonic feature, this fault may be considered as the northern mountain front fault of the AlborzRange. Subsidence of the Caspian Sea in north, uplift of the Alborz Mountain, and its over thrusting on southern part of South Caspian basin has occurred along the Caspian fault. In this paper, a segment at the fault which is located between longitudes 52° 30׳ and 53° 00׳ - in the northern part of geological map of Qaemshahr - is considered as a segment that does not outcrop. This paper introduces the general structural and morphotectonic characteristics of this zone and describes the characteristics of the active anticlines (growing folds) and morphotectonic effects in this zone such as effects on rivers.
M. Arjomandi; A. Saremi; A. P. Sarraf; H. Sedghi; M. Roustaei
Abstract
Groundwater modeling, land subsidence hazards and proper management of groundwater resources of the alluvial aquifer in the district 19 of Tehran, south of Tehran Plain need precise estimation of aquifer hydraulic parameters. Besides, traditional techniques and usual graphical methods have been approximate, ...
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Groundwater modeling, land subsidence hazards and proper management of groundwater resources of the alluvial aquifer in the district 19 of Tehran, south of Tehran Plain need precise estimation of aquifer hydraulic parameters. Besides, traditional techniques and usual graphical methods have been approximate, expensive and time-consuming. In this paper, ten sets of aquifer test data were selected; moreover, these data were recorded in a well located in district 19 of Tehran, southwest of Tehran Plain during five years (2008 to 2012). For solving the previous methods’ problems, three computer codes have been developed to optimize aquifer parameters using three optimization approaches on the other hand, two kinds of genetic algorithms and a multi-elitist particle swarm optimization (MEPSO) which avoid getting stuck in local optima and save time. The efficacy and efficiency of the developed codes have been examined using ten sets of aquifer test data of a confined aquifer, and then their results have been compared with the results obtained by the graphical approach using AquiferTest software. Based on the fitness function, i.e. sum of square errors, the MEPSO and the GAs in descending order are more reliable for estimating the parameters contrast with the graphical method. Furthermore, the sensitivity analysis of the parameters during the performance of the optimization approaches has authenticated that the results obtained are enough precise and reliable. Then an equation has been presented according to the amounts of hydraulic conductivity which have been obtained using MEPSO during the years and the amounts of land subsidence rates which have been obtained using geodetic measurement methods to predict the amounts of land subsidence rates through the time when the amount of hydraulic conductivity will reach to Ultimately, based on the equation, after 30 years the amount of hydraulic conductivity will reach to and the total amount of land subsidence will be 0.5213 m from 2008 to 2038 . Moreover, land subsidence rates’ data obtained from interferometry synthetic aperture radar (InSAR) have confirmed the accuracy of the equations.
Economic Geology
H Tajeddin; Ebrahim Rastad; Abdolmajid Yaghoubpour; Mohammad Mohajjel; Richard Goldfarb
Abstract
Barika gold (and silver)-rich volcanogenic massive sulfide deposit is located 18 km east of Sardasht city in the northwestern of Sanandaj–Sirjan metamorphic Zone. The rocks in the vicinity of the Barika deposit predominantly consist of Cretaceous volcanosedimentary sequences of phyllite, slate, ...
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Barika gold (and silver)-rich volcanogenic massive sulfide deposit is located 18 km east of Sardasht city in the northwestern of Sanandaj–Sirjan metamorphic Zone. The rocks in the vicinity of the Barika deposit predominantly consist of Cretaceous volcanosedimentary sequences of phyllite, slate, andesite and tuffite, metamorphosed under greenschist facies grade. Barika deposit is composed of stratiform ore and stringer zone that both are hosted in an altered and sheared metaandesite unit. Fluid inclusion studies indicated that quartz (stringer zone) and barite (stratiform ore) samples homogenized between 132° and 283°C. Salinities of the fluids inclusions show a range from 1.4 to 9.6% wt NaCl equivalent that are close to that of normal seawater. The study indicates the colling occurred in the initial ore fluids, as a result of mixing with sea water, is an important process in the formation of Barika deposit. The δ34S values of sulfide minerals (pyrite, sphalerite and galena) from stockwork mineralization in the Barika deposit range from -0.8 to +5.6 per mil and fall within the range of values observed for volcanogenic massive sulfide deposits. The narrow range of measured δ34S values from the sulfide minerals suggests that similar to almost of Kuroko VMS deposits, the ore-forming sulfur derived from the leaching of igneous sulfur from the underlying andesitic rocks. Calculated sulfur isotope temperatures for twelve coexisting galena-sphalerite and galena-pyrite pairs range from 146-293 ْ C that is consistent with temperatures estimated from fluid inclusion studies.
M. Asadi sarshar; A. Bahroudi; M. Qorashi; M. R. Ghassemi
Abstract
Estimate of moment rate is comparatively reckoned as a new method for dealing with tectonic activities rate in different regions and it prepares the way for putting together different methods. In fact, moment rate states rate of energy which exists in deformation system. There are three different approaches ...
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Estimate of moment rate is comparatively reckoned as a new method for dealing with tectonic activities rate in different regions and it prepares the way for putting together different methods. In fact, moment rate states rate of energy which exists in deformation system. There are three different approaches to state moment rate that each one express tectonic motion and movement of a region from a particular view. These three approaches consist of: geodetic (surveying), seismic and geology methods. Geodetic method which is determined on the basis of gained strain rate tensor from geodetic data, shows deformation rate (including seismic and aseismic) that is happening in the region at this moment in time. Moment rate which has gained on the basis of historical and instrumental catalogues, shows the total released seismic energy during quake events which are available in earthquake of region and geologic moment rate which gained with geometric parameters of faults, reveals potential of the faults in releasing stored elastic energy in. Geodetic moment rate, seismic moment rate (on the basis of historical and instrumental earthquake data) and geologic moment rate are estimated for Central Alborz region. The most moment rate in the study area belongs to geodetic approach (8.83×1019 Nm/yr) and then geologic moment rate (0.12×1019 Nm/yr) and finally the least quantity belongs to seismic moment rate (0.022×1019- 0.046×1019 Nm/yr). Considering, distribution of earthquake epicenters, the most seismic energy is released in the south parts of Central Alborz and considering high geodetic and geologic moment rates in north parts, it seems, north parts of Central Alborz have higher seismic potential.
S. Salehi Rad; S. Sherkati; F. Taati Qoaryem; M. H. Noroozi
Abstract
The Paleozoic sediments are noteworthy for many of petroleum geologists to research within Arabian Plate during last decades. Significant values of oil and gas was generated from the Silurian source rock in this area. This source rock has been modeled by commercial software's (PetroMod and Genex) in ...
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The Paleozoic sediments are noteworthy for many of petroleum geologists to research within Arabian Plate during last decades. Significant values of oil and gas was generated from the Silurian source rock in this area. This source rock has been modeled by commercial software's (PetroMod and Genex) in Saudi Arabia and its maturity proportion determined in various locations. Maturity proportion of this source rock was not characterized truly in Persian Gulf and Zagros foreland basin. Here used geological well data of three drilled wells that one's was penetrated to the Silurian shale (Sarchahan Formation) in Persian Gulf to model and used PetroMod-1D software. These well modeling results and the Saudi Arabia results show that the rate of maturity trend for Silurian shale has increased from Saudi Arabia to Iran, so that the shale is in the recognized gas window in Persian Gulf and over-mature in some part of ZagrosBasin. In Arabian Plate basemental lowlands and highlands exist at the Pre-Cambrian time, therefore cause the maturity of this shale in older highlands than the lowlands area.
H. Azizi; A. Akbarpour
Abstract
Volcanic rocks with mainly andesite composition and lenzoid form outcropped in the Eocene sedimentary host rocks in the east of Sanandaj. Field studies confirm that they are intercalation with the sedimentary host rocks. In thin section, those have porphyritic, glomoroporphyric microlithic and microlithic ...
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Volcanic rocks with mainly andesite composition and lenzoid form outcropped in the Eocene sedimentary host rocks in the east of Sanandaj. Field studies confirm that they are intercalation with the sedimentary host rocks. In thin section, those have porphyritic, glomoroporphyric microlithic and microlithic porphyric textures. Some texture evidences such as glassy inclusion in the center of plagioclase phenocrysts, displacement of plagioclase and mafic phenocrysts with mafic hydrate minerals imply amalgamation of volcanic activity with soft sediments in shallow water; also cracking of plagioclase phenocrysts confirms this subject. Geochemical study shows that these rocks are enriched in incompatible elements such as U, Th, Pb and depleted in Nb, and Ti elements compared with chondrites, primitive mantle and NMORB. If crustal contamination can be responsible for these changes, but as usual these anomalies imply the primary magma generated above the subduction zone. This volcanic rock may have a unique origin the same as Urumieh-Dokhtar volcanic belt.
Sedimentology
Hadi Amin-Rasouli; N. Haghighat jou; Mehdi Moradi
Abstract
Karaftu Cave is located in the 67 km northwest of Divandareh, Kurdistan province. It includes four floors, which the bottom of the second floor, in the bat’s hall, is covered by thick guano deposits. In this study, the distribution of trace elements plus rare earth elements, as well as age determination, ...
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Karaftu Cave is located in the 67 km northwest of Divandareh, Kurdistan province. It includes four floors, which the bottom of the second floor, in the bat’s hall, is covered by thick guano deposits. In this study, the distribution of trace elements plus rare earth elements, as well as age determination, based on 14C, of guano was investigated. Fresh guano decays through bacterial and fungal metabolism and can release organic and inorganic acids. Interactions between these acidic solutions with guano were caused by leaching and changing the distribution and ratios of elements. The rate of leaching is determined by changes in the patterns of distribution of elements and the ratios of Th/U and LREEs/HREEs. The Eu/Eu* and Ce/Ce* ratios are applied to obtain information about the paleoredox conditions of guano deposition. Based on this study, three different climatic conditions, including dry, wet, and dry terms, have been recognized. Geochemical data of guano samples on the La/Th-Hf and Th-Sc diagrams represent intermediate-mafic source rocks. Plot the samples on the Th-Sc-Zr/10 and La/Th-Sc/Ni diagrams, suggesting that their source rocks evolved in a continental island arc tectonic setting. Based on 14C dating, the onset of guano production is about 14260 ± 50 BP after the Last Glacial Maximum recorded worldwide and close to the study area in Zaribar Lake, Zagros Mountains, and Alpine Mountains. The average accumulation rate of guano deposits has been 3.7 mm/year in Karaftu Cave.
M. Saadat; S. A. Alavi; A. Saeedi
Abstract
To analyze the paleostress in Sorkheh Hessar – Khodjir area, different shear – fault planes and the associated slickenside lineations are measured. The stress tensor and the variation of the stress direction in the upper Triassic to Oligocene formations are discussed. Numerous shear data ...
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To analyze the paleostress in Sorkheh Hessar – Khodjir area, different shear – fault planes and the associated slickenside lineations are measured. The stress tensor and the variation of the stress direction in the upper Triassic to Oligocene formations are discussed. Numerous shear data are determined from different locations in the study area and categorized into 16 sites according to the stratigraphic age. The main criteria used to identify the sense of slip are accretionary mineral steps, tectonic tool marks, polished and rough facets, and riedel shears. According to the inversion method which includes determination of the mean stress tensor orientation and sense of slip on numerous faults ,all data are classified based on tectonic events and the principal stress axes and corresponding compressional and extensional directions are calculated.
Based on the derived results from the diagrams, it is suggested that a prominent NE- SW compressional stress direction, which is obvious in Mesozoic and the younger Cenozoic formations, caused the deformation of the Mesozoic strata after Mesozoic and was continuous in Tertiary (Oligocene). It seems that a younger N-S stress direction exists and has had effects on both older and younger formations. It is believed that it would be related to one of the last Alpine orogenic phases.
R. Hassanzadeh; A. Abbasnejad; A. Alavi; E. Sharifi Teshnizi
Abstract
In this article we examine the siesmicity of Kerman city. This city is located in a compressional graben which is bordered by several active faults, some of them are able to trigger an earthquake even stronger than Ms=7.0. Numerous historical earthquakes had occurred around the city which caused minor ...
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In this article we examine the siesmicity of Kerman city. This city is located in a compressional graben which is bordered by several active faults, some of them are able to trigger an earthquake even stronger than Ms=7.0. Numerous historical earthquakes had occurred around the city which caused minor damage to the building. For seismic evaluation of Kerman city both probabilistic and deterministic methods have been taken into consideration. Accordingly, peak ground acceleration due to 15 fault segments can exceed greater than 0.2g. The intensity scale resulting from earthquakes by Kerman – Zangiabad, North Kerman and Ekhteiarabad faults would be around IXMMI in the city. In order to assess the site effect, semi detailed micro zoning was carried out by combining micro tremor and sediment facies maps using GIS. The thick young sediments would amplify the intensity to X+ MMI. Based on the resulting map, the intensity scale would increase in central, western as well as some localities of the southern part of Kerman and many buildings would be damaged by such intensity scale.
A. R. Salehipour Milani; K. Nezhadafzali; F. Bayatani
Abstract
The Gunu storm, due to its severe intensity, caused substantial damages to the coasts of Sistan and Baluchestan and Hormozgan provinces. Tropical storms develop in the form of enormous hurricanes which suck the surrounding air towards them. We feel such rapid movement of air as strong winds; In satellite ...
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The Gunu storm, due to its severe intensity, caused substantial damages to the coasts of Sistan and Baluchestan and Hormozgan provinces. Tropical storms develop in the form of enormous hurricanes which suck the surrounding air towards them. We feel such rapid movement of air as strong winds; In satellite images, it is seen as the movement of clouds (water vapor) towards the core or the eye of the storm. With a velocity of 150 km/h and rain reaching 160 mm, the storm had made considerable gemorphologic changes in the coast of Oman Gulf as well as damages. Such geomorphologic changes were studied using ETM, TM and LISS III satellite data and were compared before and after the Guno storm. Also the early results taken from satellite images were coordinated with field study after the storm. These inquiries show that acute changes have been made in the opening of important estuaries such as Shur, Sargan, Kahir, Bir and Bandini. Also change stream course, due to migration channel on river meander and area of flooded area on coastal plain was determined. Cooperation of satellite data shows, discharge of sediment to the bays such as Pozm, Chabahar that it can be a serious problem for navigation and coastal structures in this area.
M. Asgharian rostami; E. Ghasemi-Nejad; M. Shafiee ardestani; B. Balmaki
Abstract
In order to studying salinity and biostratigraphy in Central Alborz basin, two sections Jorband and Ziarat-kola are sampled and studied Planktonic foraminifera and Echinoids fossil. Studying of foraminifera In Ziarat-Kola section determining three biozone by planktonic foraminifera. 1: Racemiguembelina ...
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In order to studying salinity and biostratigraphy in Central Alborz basin, two sections Jorband and Ziarat-kola are sampled and studied Planktonic foraminifera and Echinoids fossil. Studying of foraminifera In Ziarat-Kola section determining three biozone by planktonic foraminifera. 1: Racemiguembelina fructicosa Interval zone 2:Pseudoguembelina hariaensis Interval zone 3: Pseudoguembelina palpebra Interval zone.that showing late maastrichtian. As well, at Jorband section assigning three biozone by Planktonic foraminifera 1: Contusotruncana contusa Interval zone, 2: Planoglobulina brazoensis Partial range zone, 3- Racemiguembelina fructicosa Interval zone. That showing maastrichtian. Likewise, in order to determining Paleosalinity select two sections at Jorband and Ziarat-Kola. Main object assigning Paleosalinity confirm sensitive Rugoglobigerina to changes of salinity. At former section used from excessive changes of Echinocorys and in later one used from ratio of kinds Foraminifera tests (Porcelaneous, Agglutinate and Hyaline). In middle parts of Ziarat-Kola section, percentage of porcelaneous tests was more than basal and upper ones. In middle parts of Jorband section salinity was less than basal and upper ones that examined by abundancy of the genus of Echinocorys. Physiological changes of body in this echinoderm also justify salinity changes throughout Jorband section. According to Whitenella is ancestor of Rugoglobigerina and also sensitive to salinity, it is possible that Rugoglobigerina show characteristic of its ancestor that justify by studying of salinity changes in two section of Central Alborz.
Z.K. Mossadegh; M.H. Adabi; A. Sadeghi
Abstract
We studied the geochemistry of the Asmari Formation in two outcrop sections: Tang-e-Sapou a 260 m section near Dehdasht City (Kohgiluyeh va Bouyer Ahmad Province) and Tang-e-Ban a 214 m section near Behbahan City (Khozestan Province). Sampling included the complete Asmari Formation and the top of the ...
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We studied the geochemistry of the Asmari Formation in two outcrop sections: Tang-e-Sapou a 260 m section near Dehdasht City (Kohgiluyeh va Bouyer Ahmad Province) and Tang-e-Ban a 214 m section near Behbahan City (Khozestan Province). Sampling included the complete Asmari Formation and the top of the Pabdeh Formation. The Late Oligocene to Early Miocene Asmari Formation lies above the Pabdeh Formation and is overlain by the Gachsaran Formation. Elemental geochemistry (Fe, Mg, Na, Sr, Mn, Ca), and Oxygen and Carbon isotope analyses indicate that meteoric diagenesis affected carbonates of the Asmari Formation. The δ18O/δ13C data plots in an inverted J-trend suggesting that meteoric diagensis occurred in a closed to semi-closed system. The geochemistry also suggests that the original mineralogy was Aragonite. The boundary between the Pabdeh and Asmari Formations can be recognized by changes in the δ 18O and δ 13C. In the Pabdeh Formation the δ 18O and δ 13C values are mostly negative, but in the Asmari Formation values range from positive to negative. Strontium is much higher in the Pabdeh Formation than in the Asmari Formation. Changes in isotope and elemental geochemistry clearly show the Chattian-Aquitanian and Aquitanian-Burgidalian boundaries.
M. Tatar; A. M. Farahbod
Abstract
A moderate earthquake (Ms=6.3) struck the coastal region of north of Iran and the central Alborz on 28 May, 2004 was responsible of several damages and about 35 casualties. The mainshock was followed by a large number of aftershocks, the largest ...
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A moderate earthquake (Ms=6.3) struck the coastal region of north of Iran and the central Alborz on 28 May, 2004 was responsible of several damages and about 35 casualties. The mainshock was followed by a large number of aftershocks, the largest one reaching Ml=4.8, based on the analysis of local waveforms. We study the mainshock, first major aftershock, and about 240 aftershocks recorded by Iranian National Seismic Network (INSN), Tehran Telemetry Seismic Network (Institute of Geophysics, Tehran University), and our temporary local seismological stations, which were installed on 30 May, around the epicentral area of this earthquake. Using waveforms of all permanent stations, the coordinates of the mainshock was determined as 36.30 °N for latitude and 51.60 °E for longitude. The analysis of aftershocks indicates that the seismic activity migrate from east where the mainshock occurred toward west close to the location of the largest aftershock (36.36 ° N, 51.45 ° E). 140 selected aftershocks recorded at a minimum of 6 stations, having rms less than 0.15 sec and uncertainties less than 2 km, were used to infer a precise geometry of the fault region. The aftershocks distribution has 30 km long and trends NW-SE parallel to the North Alborz and Khazar faults. The focal depths comprised between 10 and 28 km, unusually deep for Iran. Distribution of aftershocks cluster on cross-section defines a fault plane which dips at 40-50 degree south-westward. Its upward continuation can be related to either North Alborz or Khazar faults. Most of the focal mechanisms are consistent with reverse faulting on NW-SE trending faults, parallel to the main active structures of the region. Well constraint focal mechanisms which dip gently at a rate of 25-40ْ indicate the activity of the second mentioned faults during the Firozabad-Kojour earthquake. Existence of focal depths up to 28 km indicates an unusual brittle lower crystalline crust in this part of central Alborz.
V. Khaki; Z. Purabrishami; A. Zavarehee; Kh. Khosrotehrani
Abstract
Vertebrate fossil fauna of Late Miocene age in Maragheh contains various mammals preserved in pyroclastic deposits of southern Sahand volcano. This study has been conducted on Gazella capricornis (a perfect skull). Since no other sample with such a good perfectness was found before at other localities ...
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Vertebrate fossil fauna of Late Miocene age in Maragheh contains various mammals preserved in pyroclastic deposits of southern Sahand volcano. This study has been conducted on Gazella capricornis (a perfect skull). Since no other sample with such a good perfectness was found before at other localities (previous ones were isolated horns or tooth rows), it can be proposed as a complemental to the samples type. Gazella capricornis was found not only in Maragheh but also in Samos and Pikermi (Greece), Akkaşdaği (Turkey), Bulgaria, … (east of Europe and west of Asia); which indicates similarities in Late Miocene-Early Pliocene fossil fauna, paleogeography, relative ages, sediments and paleoecology between these regions.
A. Maleki
Abstract
The Large numbers of provinces in country use Karst's water Sources as a main Source of securing water for using in different ground of drinking-agriculture and industry. Kermanshah province with an area about 24953,286 square kilometers is located in the middle of western side of the country which its ...
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The Large numbers of provinces in country use Karst's water Sources as a main Source of securing water for using in different ground of drinking-agriculture and industry. Kermanshah province with an area about 24953,286 square kilometers is located in the middle of western side of the country which its main part is in the zones of nappe and foliated Zagross and its heights are often formed of the hard carbonated formations. The Karsti zonations of Kermanshah province play an important role in the providing and feeding of aquiferouses; for this reason to recognize these zonations and the rate of their modification , the zonation of the modification of the karst is done in this research and its map has been drawn too . For the purpose of acquiring of the aims of the research , first the closed superficial holes as the index of the modification of the karst were recognized by using the topographic maps 1 / 50000 and the recognizing pictures 5 meters irs (BW) , their maps were drawn and after examining statistically and confirm the relationship the maps with the subject , with the help of the Kay square and the rotary operation , seven factors of height , lithologic , geomorphology , temperature , rainfall , vaporization and slope as the effective factors in the modification of the karst have been selected . After digitalization of all of the respective data for evaluation ( giving weight ) the classes of the maps of aquired from the statistics ways , analysis of the hierarchic ( expertizing judgement ) , condensation of the surface , the informational value , the variables weight and the experimental way were used . Then in the environment of gis the maps of the factor of overlapping and the maps of the zonation the modification of the karast has been aquired with the 5 ways mentioned .Among the ways used for zonation , the way of the informational value has the most adaption with the selected index (the closed holes) in the zone being studied .The aquired maps of zanation, beside the determinination of the zones with different degrees of modification of the karst's from in the province, It also has detemined the feeding Limitations of underground waters (Karst) and the favourable areas for Pollution of these Sources in the surface of earth.Which should use Suitable Policy for protecting these areas, Other wise many gangers will threat the feeding places.
Geophysics
Mojtaba Naghavi; Habib Rahimi; Ali Moradi
Abstract
In this study, we have used recorded local earthquakes by 17 permanet seismic stations to separate intrinsic and scattering attenuation in North-West of Iranian pleateau. Intrinsic and scattering attenuation can be applied as useful tools to study the geodynamic and tectonic characteristics of a region. ...
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In this study, we have used recorded local earthquakes by 17 permanet seismic stations to separate intrinsic and scattering attenuation in North-West of Iranian pleateau. Intrinsic and scattering attenuation can be applied as useful tools to study the geodynamic and tectonic characteristics of a region. They also represent thermal, compositional and deformational characteristics of the crust and upper mantle. The wave attenuation has strong correlation with seismicity and heterogeneity of medium and is regularly used in the study of tectonically active regions of the world. Single backscattering and coda normalized methods are used to estimate the coda Q (Qc) and Qs respectively, using 14,969 earthquakes which are recorded by the stations. The results show this region is very active region tectonically and seismically. Due to low values of Quality factor and thus high attenuation values of body and shear waves in North West part of Iran, amplitude of the propagated waves are decreased severely in the interested area.The intrinsic attenuation and the Coda wave attenuations curves around the North Tabriz fault are closer in comparison with entire northwestern Iran region and Tabriz city, indicating a strong attenuation of the earthquake waves around this fault system. Similarly, these curves are closer in Tabriz city than those calculated for the northwestern region of Iran which expresses the overriding intrinsic attenuation from the effect of dispersion. The attenuation effect of seismic waves reduces the damages caused by earthquakes at appropriate distances of faults at the time of earthquake occurrence.
S. M. Hashemi; M. Emami; M. Vossoughi Abedini; M. Pourmoafi; M. Ghorbani
Abstract
In southeastern Tabas there is a 400 square kilometer area of Quaternary basalts, which is geologically located in Lut zone. According to petrographic studies and EMPA analysis, the textures of these rocks are generally porphyric and some times aphyric. The phenocrysts of these basalts are generally ...
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In southeastern Tabas there is a 400 square kilometer area of Quaternary basalts, which is geologically located in Lut zone. According to petrographic studies and EMPA analysis, the textures of these rocks are generally porphyric and some times aphyric. The phenocrysts of these basalts are generally chrisolite, augite, and plagioclase (andesine to labradorite), which are embedded in a texture of plagioclase microlites and small blades of pyroxene. According to the diagrams of accumulative amount of alkaline against the amount of SiO2, the nature of the magma is alkaline to sub-alkaline. The reason for the sub-alkaline character of some of these rocks is that the alkaline magma has been contaminated with crust materials. One of the most important reasons for this is the reduction of niobium in rocks enriched with SiO2. The alkaline samples have normative nepheline and the sub-alkaline samples normative quartz. The studies of Nd and Sr isotopes have confirmed the crust contamination and also the source for early magma of basalts is the upper parts of mantle. Based on the field studies and tectono- magmatic diagrams, these basalts are of intercontinental type because of the activities of great fault of Nayband in Quaternary and separation in their cross point reaching the earth's surface.
L. Bakhshandeh; A. Aghanabati; T. Mohtat
Abstract
The first studied Abtalkh Formation with Campanian – Maastrichtian age is well exposed in Kopeh Dagh area (Mozduran section). This formation conformably underlain carbonates of Abderaz Formation and overlain by Neyzar sandeston Formation, both formations have a gradual contact.
The second studied ...
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The first studied Abtalkh Formation with Campanian – Maastrichtian age is well exposed in Kopeh Dagh area (Mozduran section). This formation conformably underlain carbonates of Abderaz Formation and overlain by Neyzar sandeston Formation, both formations have a gradual contact.
The second studied formation so called Echinid marl formation of Santonian –Late Campanian age is exposed in Baharestan section, Central Iran, Esfehan area.
Based on 100 studied samples, there are litological and paleontological similarities between Abtalkh and Echinid marl formations. These evidences support strongly paleoecological and environmental similarities.
This ascertainment shows the close relation between the Kopeh Dagh and Central Iranbasins.
The fossil evidences found in both sections are as follow:
Globotruncana ventricosa (White), Globotruncanita elevata (Brotzen)
Globotruncana arca (Cushman), Globotruncanita stuartiformis (Dalbiez)
Globotruncana bulloides Volger, Globotruncana lapparenti Brotzen
Globotruncanita calcarata (Cushman), Globotruncana linneiana (d' Orbigny)
M. Asgharian Rostami; E. Ghasemi-Nejad; M. Shafiee Ardestani
Abstract
At this research are studied late cretaceous sediments at Ziarat-kola section, Central Alborz, in order to Palaeobathymetry and sea level change. These sediments are with about 200m thickness consist of monotonous Marl and limy marl. Based on Planktonic foraminifera gain Upper Maastrichtian stage (Abathomphalus ...
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At this research are studied late cretaceous sediments at Ziarat-kola section, Central Alborz, in order to Palaeobathymetry and sea level change. These sediments are with about 200m thickness consist of monotonous Marl and limy marl. Based on Planktonic foraminifera gain Upper Maastrichtian stage (Abathomphalus mayaroensis zone). In order toPalaeobathymetry and sea level change used to three methods common consisting of morphotype Planktonic foraminifera, ratio Planktonic foraminifera to benthic foraminifera and assigning genus and benthic foraminifera species. With morphotype analysis was indicated that third morphotype which are more deep index increase at the initial part and first morphotype that are shallow index increasing at middle section. In this manner, depth change was examinated to use two genus, Globotruncana (deep dweller) and Pseudoguembelina (Mixed layer dweller). In orther to assign paleodepth at this area used to Planktonic foraminifera to total foraminifera minus infaunal Benthic foraminifera and the regression equation [Depth = e (3. 58718 + (0. 03534 × %*p)].examination genus and Benthic foraminifera species depth index and such results gain at above method were indicating that this sediments in upper bathyal and middle bathyal. Thus, results indicate that beginning and end of are deeper from middle section.
H Vafaei; M Peyravi
Abstract
The Kish gas-field is one of the world’s largest gas-fields, and consists of two reservoir rocks of Kangan (Lower Triassic) and Dalan (Late Permian) formations in the Zagros sedimentary basin. In this study, the Kangan formation has been examined. In this research, in addition to the use of raw ...
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The Kish gas-field is one of the world’s largest gas-fields, and consists of two reservoir rocks of Kangan (Lower Triassic) and Dalan (Late Permian) formations in the Zagros sedimentary basin. In this study, the Kangan formation has been examined. In this research, in addition to the use of raw data obtained from logging of a drilled well from the whole extent of the field, probabilistic petrophysics evaluation method was used to assess the petrophysical properties (shale volume, lithology, porosity and water saturation) of the Kangan formation. A method based on statistics and possibilities was also utilized to interpret the graphs (logs) with the help of multi-mineral model, a module of Multimin Software. Based on the results of this assessment and the use of lithology-determining cross-plots, as well as standard charts of Schlumberger, the dominant lithology of the Kangan formation in the studied well was recognized as calcite, dolomite, some anhydrite and small amounts of shale. The ultimate aim of the petrophysical evaluation in hydrocarbon studies of the Kish gas-field is to provide proper inputs to the reservoir static model. In order to make a more detailed study, this formation was divided into two parts, K1 and K2. As a whole, the calculated volume shale in the Kangan formation in this well is low and in K2 part is less. This could be considered as a reason for the equal effective porosity in most of the points along the well.
Mohammad Reza Sheikholeslami
Abstract
Evidence of at least ten different tectonic- controlled sedimentary basins can be recognized in the central part of the Alborz Mountains in the Middle part of the Alpine-Himalayan belt. They formed from Neoprotrozoic to recent time as the results of the relative plate motion in southwest of Asia in Tethyan ...
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Evidence of at least ten different tectonic- controlled sedimentary basins can be recognized in the central part of the Alborz Mountains in the Middle part of the Alpine-Himalayan belt. They formed from Neoprotrozoic to recent time as the results of the relative plate motion in southwest of Asia in Tethyan realm. The basins include: (1) Prototethys Late Neo-Proterozoic to Early Ordovician epi-continental/platform basin; (2 Paleotethys Middle Ordovician to Devonian rift basin; (3) Devonian to Middle Triassic continental shelf basin; (4) Upper Triassic to Lower Jurassic foreland basin; (5) Shemshak back arc rift basin; (6) South Caspian carbonate platform basin; (7) Paleocene clastic sedimentary basin; (8) Karaj back arc basin; (9) Oligo-Miocene foreland basin; (10) Pliocene-Pleistocene intramontane basin. Each basin has its own unique history connected to the different stages of the birth, development and destruction of the Prototethys, Paleotethys and Neothethys Oceans in the Middle East region in the southwest of Asia.
Stratigraphy and Palaeontology
Narges Ghader; Ali Asghar Ciabeghodsi; Mir Amir Salahi; Mohammad sadegh Zangeneh
Abstract
In the present study, In order to study of the planktonic foraminiferal biostratigraphy of Qom Formation in north of Khoy city, West Azarbayjan province (Sanandaj-Sirjan fore-arc basin), stratigraphic section of Sagatlu was selected and sampled. Thickness of Sagatlu section 216 meters was measured. Lithology ...
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In the present study, In order to study of the planktonic foraminiferal biostratigraphy of Qom Formation in north of Khoy city, West Azarbayjan province (Sanandaj-Sirjan fore-arc basin), stratigraphic section of Sagatlu was selected and sampled. Thickness of Sagatlu section 216 meters was measured. Lithology of this section contain shale, siltstone, conglomerate and sandstone. The lower boundary of these deposits is alluvium, and its upper boundary is hard limestone deposits of Qom Formation. Study of the planktonic foraminifera communities found in the mentioned section to identify 16 genera and 37 species of planktonic foraminifers. In this research, 4 biozone are included, Subbotina linaperta assemblage Zone, Paragloborotalia opima Highest-occurrence Zone, Ciperoella ciperoensis Partial-Range Zone, Globigerinoides italicus assemblage Zone were identified as being age equivalent to Priabonian-Burdigalian and comparable to world standard biozones..
Petrology
Ismail KhanChuban; Behzad Haj alilou; Mohsen Moayyed; Mohamadreza Hosseinzadeh; Morovat Faridazad
Abstract
In the Gezeldash_daghi region, there is a significant outcrop of Miocene volcanic activity with andesitic composition associated with pyroclastic deposits including tuff, breccia and agglomerate. These rocks have porphyry to microporphyry texture with coarse crsytals of pagioclase, and matrix includes ...
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In the Gezeldash_daghi region, there is a significant outcrop of Miocene volcanic activity with andesitic composition associated with pyroclastic deposits including tuff, breccia and agglomerate. These rocks have porphyry to microporphyry texture with coarse crsytals of pagioclase, and matrix includes plagioclase, hornblende and minor biotite. Zoning, sieve texture in the coarse crystals of these lavas is an indicative of unstable conditions during magma solidification. These lavas have calc-alkaline nature. The geochemical characteristics of Gezeldash_daghi lavas such as LREE enrichment than HREE as well as enrichment of LILE elements with negative Nb, Ti and P anomalies indicate their affilliation to subduction setting. These rocks contain high amounts of SiO2, Sr, Sr / Y and La / Yb, and lower values of Y, MgO, and Yb than classic calc-alkaline volcanic rocks, and may indicate lava adakitic features. Based on the geochemical data, these lavas had formed partial melting of subducted oceanic crust. The depletion of rare earth elements indicates a residue containing garnet and hornblende in the source area.
H. Asilian Mahabadi; Y. Lasemi
Abstract
The Kazhdomi and Sarvak Formations (Bangestan Group) are mainly composed of carbonate rocks. In order to study facies, depositional environments and sequence stratigrphy of these formations in the northwest of FarsProvince, 4 stratigraphic sections including Namak Kangan, Khartang, Khormonj (Coastal ...
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The Kazhdomi and Sarvak Formations (Bangestan Group) are mainly composed of carbonate rocks. In order to study facies, depositional environments and sequence stratigrphy of these formations in the northwest of FarsProvince, 4 stratigraphic sections including Namak Kangan, Khartang, Khormonj (Coastal Fars) and Shah neshin (Sub-coastal Fars) have been studied.
Carbonate rocks of the Kazhdomi and Sarvak Formations have been deposited in tidal flat (A), lagoon (B), barrier (C) and open marine (D) facies belts. The sandstone facies of the Kazhdomi Formation (Sandstone tongues equivalent to Burgan Sandstone) are quartzarenite, which were probably deposited in a beach environment. Facies analysis and comparison with modern and ancient environments indicate that the Kazhdomi and Sarvak Formations were deposited in a ramp platform.
Sequence stratigraphy of the Bangestan Group in the study area indicate that the Kazhdomi Formation (except for Namak Kangan, which consists of one depositional sequence) include two depositional sequences (sequences 1 and 2) of early to late Albian age. The Sarvak Formation consists of one depositional sequence in Namak Kangan (sequence 3) and four sequences (sequences 3 to 6) of late Albian to Turonian age in other sections.The lower contact of sequence 1, the lower contact of sequence 2 in Namak Kangan and the lower and upper contacts of sequence 6 are type 1 unconformity (SB1) but the contact of other sequences are type 2 unconformity (SB2).
