Sedimentology
Mahmoud sharafi; Arsalan Zeinalzadeh; Aram Bayet-Goll; Bijan Biranvand; Mehran Moradpour; Farid Taati
Abstract
Miocene siliciclastic sediments with 338m thick are studied in the southern Neka of Northern Alborz flank. Detailed sedimentology study allows recognition four facies associations consist of delta plain, distributary channel, delta front and pro-delta. Delta plain and tidal flat include heterolithic ...
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Miocene siliciclastic sediments with 338m thick are studied in the southern Neka of Northern Alborz flank. Detailed sedimentology study allows recognition four facies associations consist of delta plain, distributary channel, delta front and pro-delta. Delta plain and tidal flat include heterolithic shale-silt-sand and limestone with fenestral fabric. Distributary channel and delta front associations consist of thin to thick channel shape sandstone, which display coarsening-thickening upward cycles with pro-delta/offshore association. Scares Ophiomorpha nodosa and Thalassinoides in these sandstones indicate a stressful condition such as sandy mobile substrate, turbidity and highly salinity fluctuation in the sedimentary environment. Shale-silty sediments of the pro-delta association with abundant framboidal and chamber filling pyrite and organic material display anoxic condition of the sedimentary substrate. Introducing Miocene hydrocarbon sediments in the neighboring region like Turkmenistan and Russia and sedimentary characteristics of the pro-delta/offshore shale of the studied succession allow us to introduce those as high potential candidate for hydrocarbon source.
M Khademi; F Ghaemi; S.K Hosseini; F Ghaemi
Abstract
In this paper, the feedback or interaction between tectonic and surface processes in the Binaloud Mountains and Neyshabour plain has been investigated. To achieve this, we have used topographic data, recorded earthquake data provided by the Geophysical Institute of Tehran University (Mashhad center) ...
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In this paper, the feedback or interaction between tectonic and surface processes in the Binaloud Mountains and Neyshabour plain has been investigated. To achieve this, we have used topographic data, recorded earthquake data provided by the Geophysical Institute of Tehran University (Mashhad center) and field surveying results. Surface processes affect the propagation of tectonic thrust wedges in orogenic belts. In regions where tectonic processes have led to an increase in the surface slopes due to development of mountain highs, surface processes will justify the uplifted areas by smoothing the slopes, eventually shedding off a massive load of clastic sediments into the foreland basin. Because of their huge weight and volume, these sediments prevent the forward propagation of the wedge and therefore increase the accumulation rate of stress in the orogenic wedge. Also the increase of fault-plane dips in the orogenic wedge will make the slip along the fault planes hard or even impossible. Formation of out-of-sequence faults and back-rotation of preexisting thrust faults may be considered as results of these accumulated stresses. North Neyshaboor thrust fault is a later or secondary structure and can be considered as an out-of-sequence thrust because it cuts other thrust sheets and limbs of folds. Our research shows that the high volume of Paleogene/Neogen sediments in the Neyshabour foreland basin has prevented the forwards (southwestward) propagation of the Binaloud mountain range as the orogenic wedge. Releasing of the accumulated forces has therefore led to the development of the North Neyshaboor out-of-sequence fault and back-rotation of former thrust faults.
D Iranbodi; M Zare
Abstract
The south of Tehran lies in vicinity of the active faults such as Pishva, Kahrizak and Eyvan-E Key and in the case of re-rupturing of these faults a serious disaster, perhaps financial and life losses may be occurred. In IBC (International Building Code) formula (Darlene & Batatian, 2002) dip, displacement ...
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The south of Tehran lies in vicinity of the active faults such as Pishva, Kahrizak and Eyvan-E Key and in the case of re-rupturing of these faults a serious disaster, perhaps financial and life losses may be occurred. In IBC (International Building Code) formula (Darlene & Batatian, 2002) dip, displacement and footing of building and criticality of building code have been considered as important factors for setback zone. In up thrown side we must: S=U (2D+F.tan-1θ) . In down thrown side we must: S=U(2D) . There is gap of world standard setback zone in Pishva. The Iranian setback zone code does not respect the IBC formula and is based on the field observations. the formula of IBC consider slip rate of the fault, the displacement factor, the type of structure, foundation of the building and the sensitivity of structure, while in Iran the zoning of the Berberian et al. (1364), which is based on the fault type and field observations has been continuously used. Thus, with combination of these two methods and with regard to the geotechnical issues, construction can be designed more carefully.
A. Rastbood; B. Vosooghi
Abstract
In this research, fracture mechanic concepts and dislocation modeling is used to examine the velocity field of GPS observables on the oblique collision zone of Arabia-Eurasia plates. For this purpose, the significant active faults in the study area were selected and proper boundary conditions applied. ...
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In this research, fracture mechanic concepts and dislocation modeling is used to examine the velocity field of GPS observables on the oblique collision zone of Arabia-Eurasia plates. For this purpose, the significant active faults in the study area were selected and proper boundary conditions applied. Numerical boundary element method with green functions obtained from Okada analytical solution were used to distribute strike slip rates among selected active faults. Velocity field obtained from the model was compared with GPS velocity field of Iranian campaign global geodynamic network and by changing boundary conditions using try and error a better coincidence were generated between model and GPS velocity field. At the final stage the difference of most of GPS observations from model results were inside of 95% confidence ellipse. Regarding accordance among model and geological slip rates, in continue of estimates we tried to get better accommodation between model and GPS velocity fields. For this purpose we tried to get better accordance between deduced slip rates by two methods with changing of boundary conditions and introducing some of geological slip rates as boundary conditions. Slip rates of other faults obtained by initial modeling were considered as boundary conditions for final modeling. These boundary conditions were changed by try and error to get close and close to geological slip rates such that the accommodation of model with GPS velocity field were retained and even get better too. Modeling results show that most of faults modeled slip rates are consistent with slip rates obtained by geological methods. The numerical results also show that most of strike slip faults in Iran are dextral. Regarding that final modeled slip rate for North Tabriz fault (6.4 mm/yr) is more than modeled slip rate for Main Recent Fault (2.2 mm/yr), the model shows that North Tabriz Fault is continuation of North Anatolian Fault in Iran.
B. Zamani Gharechamani
Abstract
Iranian Azerbaijan is a region in Northwest of Iran where has large active deformation and seismicity. It is located between two orogeny, Zagros in the south and Lesser Caucasus in the north. In this research geological structures and tectonic stress state of area are studied to search connection the ...
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Iranian Azerbaijan is a region in Northwest of Iran where has large active deformation and seismicity. It is located between two orogeny, Zagros in the south and Lesser Caucasus in the north. In this research geological structures and tectonic stress state of area are studied to search connection the tectonic and neotectonic of Azerbaijan. In this study the analytical method of Angelir, 2002, is used to analising the stress tensors. Also his methods, 1984 and 2004, are used to separation of stresses. Firstly it is collected seismic and field data of faults and analyzing their stress states. Then 2nd order stress field of Azarbaijan microplate is reconstructed by stress separation analysis. Also remote sensing methods helps to study of imbricate structures in the northern and southern parts of Azarbaijan microplate. The stress analysis results in this study (by analytical method, for seismic and field data) shown there are two compressional stresses (NE-SW and NW-SE directions). First stress system by NE-SW directions cause developing of three tectonic grains as Arasbaran, Ahar (Goshe Dagh) and Bozkosh fold thrust belts. But the second one (NE-SE direction stress system) cause developing of thrusts in N-S direction. Reconstruction of first order stress in relation with the tectonic grains, and structures, reduced the tectonic model of Azerbaijan plateau. In this model the (East) Azerbaijan plateau is in collision with Lesser Caucasus in north, South Caspian basin in east, and Central Iranian block in south and west. In this way reconstructed compression induced the conter-clock wise rotation to the Azerbaijan plateau.
B. Vosooghi; A. Rastbood
Abstract
In this research, the role of various existing tectonic plate and faulting motions in the middle-east region has been investigated on the geodetic data and its purpose is to estimate the contribution of these motions in the GPS velocity field of campaign global geodynamic network in the region of Iran ...
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In this research, the role of various existing tectonic plate and faulting motions in the middle-east region has been investigated on the geodetic data and its purpose is to estimate the contribution of these motions in the GPS velocity field of campaign global geodynamic network in the region of Iran using fracture mechanics concepts and dislocation modeling. For modeling the faulting data in the Middle-East region were decomposed to various categories by considering the tectonics of the region and were included in the model and the induced velocity field due to them were modeled and compared with GPS velocity field. Obtained results show that the contribution of Arabian plate in observational GPS velocity field is more than the contribution of Anatolian plateau faultings and inside faultings of Iran create an internal north-south compression component and a counterclockwise rotation component in the modeled velocity field. According to modeling results about 30% of GPS velocity field components are produced by Iranian inside faults, 60% by Arabian plate and 10% by Anatolian plate.
M. Fatemi Aghda; M. Rahbar; M. Mojezi; G. R. Asadollahfardi
Abstract
Every year, all over the world, landslides cause considerable damage to life and property. In order to prevent the danger and destruction brought about by landslides, it is important to identify the reasons for the occurrence of this phenomenon. This can only be achieved by conducting a thorough investigation ...
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Every year, all over the world, landslides cause considerable damage to life and property. In order to prevent the danger and destruction brought about by landslides, it is important to identify the reasons for the occurrence of this phenomenon. This can only be achieved by conducting a thorough investigation into the geological conditions of the region and a study of the local and global landslides that have occurred in the past across the years. In this research, the reasons for occurrence of landslides in the region have been studied, in addition to the identification of lithological, geological, morphological and tectonical characteristics of the region around the dam. In abutments, landslides occur due to weak lithologies, discontinuities and a high topographic gradient. Landslides around the reservoir occur due to an increase in pore water pressure and changes in water level of the reservoir, in addition to the reasons mentioned above. Finally, the importance and the role of this phenomenon regarding dams and the region have been studied and explained in this research.