M. H. Ahmadi; G.H Shamanian; H. Azmi
Abstract
The Motrabad vein system is located 30 Km southwest of Bajestan in the northern part of the Lut Block. The vein host rocks consist of intermediate to silicic volcanic rocks. The mineralization occurs as irregular veins, veinlets and hydrothermal breccias. Based on field geology and textural evidences ...
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The Motrabad vein system is located 30 Km southwest of Bajestan in the northern part of the Lut Block. The vein host rocks consist of intermediate to silicic volcanic rocks. The mineralization occurs as irregular veins, veinlets and hydrothermal breccias. Based on field geology and textural evidences four types of quartz veins (A, B, C and D) were identified. Hydrothermal alteration is developed around the veins and tends to be more intense in the vicinity of the veins. Hydrothermal alteration consists of silicic, sericitic, propylitic and argilic assemblages. The plot of the Ishikawa alteration index (AI) Vs. chlorite-carbonate-pyrite index (CCPI), known as alteration box plot, display the main alteration trends. The hydrothermal alteration assemblage of quartz, adularia, chlorite, illite, calcite, and pyrite that envelopes the Motrabad vein system formed from the upwelling of near-neutral to weakly alkaline chloride waters. The mineralogic, alteration and geochemical characteristics of the studied area and their comparison with epithermal ore deposits represent an epithermal system of the low-sulfidation type.
J. Daneshian; D, Baghbani; S.A. Aghanabati; N. Norouzi
Abstract
Oligocene-Lower Miocene sediments at Nareh section, situated in SW Jahrum consists of limestone, argillaceous limestone, marl and evaporatic sediments with a rich association of planktonic and benthonic foraminifera. In lower part of this succession, the Pabdeh sediments with a thickness of 115m is composed ...
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Oligocene-Lower Miocene sediments at Nareh section, situated in SW Jahrum consists of limestone, argillaceous limestone, marl and evaporatic sediments with a rich association of planktonic and benthonic foraminifera. In lower part of this succession, the Pabdeh sediments with a thickness of 115m is composed of shale, marl and intercalations of argillaceous limestone. The mentioned sediments continue through Late Eocene to Oligocene, which are overlain conformably by the Asmari Formation. The Asmari Formation consists of 250 m limestone and argillaceous limestone of which 210 m belongs to the lower Asmari and 40 m to middle Asmari. Argillaceous limestone and evaporatic-marly sediments of the Gachsaran Formation are overlain by the Asmari Formation. The Gachsaran Formation with a thickness of 510m is composed of three members of Chehel, Champeh and Moll. Pure and thick basal limestones of the Mishan Formation (Guri Member) with a thickness of 302 m, is situated above the Gachsaran Formation. Finally, Bakhtyari conglomerate lies uncomformably over the Mishan Formation. Variety of studied rock units in this section has caused different sedimentary environments, different facies and presence of abundant planktonic and benthonic foraminifera. By studying 203 samples including 193 hard and 10 washed samples, 34 genera and 47 species of benthonic foraminifera and 8 genera and 13 species of planktonic foraminifera, algae, briozoa and different macrofossils fragments were identified. Based on foraminiferal assemblages, the age of the lower part of the Pabdeh Formation is Late Eocene (Priabonian) and the upper part is Early Oligocene and the Asmari Formation is Oligocene (Late Rupelian-Chattian) to Early Miocene (Aquitanian). Also, the Gachsaran Formation belongs to Early Miocene (Aquitanian-Burdigalian) and the age of the Mishan Formation (Guri Member) is Late Miocene (Burdigalian) .On the basis of recognized foraminifera association, Nareh stratigraphical section can be correlated with first to fourth Biozones of biozonation of Adams and Bourgeois (1967) and 54,57,59,61,63 and 64 Biozones of Wynd (1965).
Yaser Bageri; Esfandiar Abbas Novinpour; A Nadiri; Keiwan Naderi
Abstract
Most of the country's geographically area is located in dry and semi-dry zone with low rainfall. The growing population, the limitation of water resources and the prevalence of groundwater resources in most parts of the country requirement to accurate prediction of the amount of these resources due to ...
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Most of the country's geographically area is located in dry and semi-dry zone with low rainfall. The growing population, the limitation of water resources and the prevalence of groundwater resources in most parts of the country requirement to accurate prediction of the amount of these resources due to the importance of these resources in optimal planning and management. In this research, in order to estimate the fluctuations of groundwater level in the Baruq aquifer, the artificial intelligence models including fuzzy, support vector machine and neural network models were used by the data of depth from 7 piezometers with long-term data of 14 years, as well as changes in temperature and precipitation in this period. Despite the inherent abilities of each models in predicting groundwater level, the heterogeneity of the study area prevented the high efficiency of these models. Therefore, SOM-AI modeling combined the self-organized maps (SOM) classification method and each model that is increased the efficiency of each composite model in different parts of the aquifer by dividing the study area into homogeneous regions. The results showed that the proposed method can be an effective method in the modeling of heterogeneous and even multi-layered aquifers.
S Jalalat Vakil-Kandi; M Shahpasand-Zadeh; H Ahmadi-pour; M Honarmand
Abstract
Dehsheikh ultramafic-mafic complex is located in the Esfandagheh ophiolitic mélanges belt of Kerman province. The Dehsheikh complex comprises harzburgite, lherzolite, dunite, chromitite, pyroxenite and layered gabbros. The presence of abundant chromite ore deposits has made this complex important. ...
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Dehsheikh ultramafic-mafic complex is located in the Esfandagheh ophiolitic mélanges belt of Kerman province. The Dehsheikh complex comprises harzburgite, lherzolite, dunite, chromitite, pyroxenite and layered gabbros. The presence of abundant chromite ore deposits has made this complex important. The complex constitutes part of the Neotethys oceanic lithosphere deformed during upwelling from the upper mantle and later emplacement in the upper levels of the Sanandaj-Sirjan continental crust. Microstructural analysis of this complex reveals three deformation mechanisms including intracrystal plasticity, diffusive mass transfer and cataclasis. The microstructures of deformation twins, wavy extinctions, kink bands, exsolution lamellas, dynamic recrystallizations, microboudins, pull-apart microfractures, mineral stretching and elongation, mineral lineations and shear band cleavages formed due to the intracrystal plasticity deformation mechanism. The diffusive mass transfer deformation mechanism was associated with development of indenting, truncating and inter-penetrating grain contacts and micro-veins. The cataclasis deformation mechanism was accommodated by development of micro-fractures and micro-faults. This microstructural study also manifested different generations of olivines, pyroxenes and spinels under upper mantle to crustal conditions.
S Tabasi; A KamkarRouhani; M.M Khorasani
Abstract
Archie’s equation, which is the most fundamental equation for water saturation calculation,consists of three factors: Cementation factor (m), saturation exponent (n) and tortuosity (a). Cementation factor is a function of the shape of pores. Hence, the study of pore type is important in determining ...
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Archie’s equation, which is the most fundamental equation for water saturation calculation,consists of three factors: Cementation factor (m), saturation exponent (n) and tortuosity (a). Cementation factor is a function of the shape of pores. Hence, the study of pore type is important in determining the Archie’s coefficients. In order to achieve more precise and reliable results in Archie’s coefficient determination and then water saturation accurately, the rocks must be rated based on texture and porosity type, where the coefficients should be constrained for each class. In this paper, fractal method is used to rate the resistivity log data and calculate Archie’s coefficient in an exploration well of a hydrocarbon reservoir in southwest of Iran. The results show three different zones based on porosity type and texture of the rocks. Then the Genetic algorithm method is used to calculate the Archie’s coefficients in each of the zones separately. The results show that this method is able to consider the complex behavior of each of the coefficients in the calculations.
Tectonics
Golnaz Abbasi; Ali Solgi; Mohsen Pourkermani; Hosein Motamedi; alireza farrokhnia; Keivan Orang
Abstract
We used 2D seismic profiles, field observation and well data to constrain the structural evolution of the Saveh basin during the late-lower Miocene to late Pliocene. During this time period almost 8-9 kilometers of Upper Red Formation (URF) and the Pliocene conglomerates were deposited in the basin depocenter. ...
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We used 2D seismic profiles, field observation and well data to constrain the structural evolution of the Saveh basin during the late-lower Miocene to late Pliocene. During this time period almost 8-9 kilometers of Upper Red Formation (URF) and the Pliocene conglomerates were deposited in the basin depocenter. During the late- lower Miocene (to early- middle Miocene ?), Syn-depositional activity of west-east-northwest-southeast trending high-angle fault zones, with an extensional component, created accommodation space for deposition of lower Upper Red Formation. Since the late- middle Miocene (or late Miocene), initiation of a compressional phase has resulted in regional deformation.The deposition of upper part of the URF and the Pliocene conglomerates was contemporaneous with compressional deformation. During this stage, the middle part of the URF acted as an effective detachment horizon and detachment folds, such as the Saveh and Taraz Naeen anticlines, were formed. The thinning of the Pliocene conglomerates towards the crestal point of these folds indicates late structural growth. According to the top Qom depth map, there are no traps with fault independent closure within the Saveh basin. The top of the Qom Formation is estimated at -4250 m in the Taraz Naeen anticline.
Gh. H. Shamanian; L. Amini; Sh. Shataee; Sh. Shataee
Abstract
Grade control and ore quality determination has always been considered a challenging task for geologists and mining engineers. Ore quality is dependent on various factors such as size and geometry of a deposit, geological disturbances, and texture and ore mineralogical composition. Determination of factors ...
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Grade control and ore quality determination has always been considered a challenging task for geologists and mining engineers. Ore quality is dependent on various factors such as size and geometry of a deposit, geological disturbances, and texture and ore mineralogical composition. Determination of factors which control ore grade and prediction of a suitable area are very important in terms of economics and productivity of mining operations. This study has tried to develop spatial and statistical analyses for evaluating ore quality and recognition of ore grade influencing factors at Jajarm Bauxite Mine. Through incorporating topographic, geologic and geochemical data, the effects of faults, elevation and depth on the ore grade and module (wt% Al2O3/Wt% SiO2 ratio) has been assessed. The results showed that the amounts of Al2O3 and module increased as we get closer to the faults. Furthermore, there was not any effect of faults type and strike on grade and module. A negative correlation between both elevation and depth with the amounts of Al2O3 and module indicates ore quality improvement in lowlands and shallow depths. Thus, the combination of geographic information system (GIS) methods and multivariate statistical analyses might be more efficient in geo-spatial assessments.
M. Husseini Barzi; M. Jafarzadeh
Abstract
Petrofacies analyses of Asmari Formation carried out on thin sections, obtained from oil wells of number 11, 85 and 89 in Ahvaz oil field, show 5 carbonate-evaporate microfacies associations (related to a carbonate ramp) and 2 siliciclastic petrofacies. Point counting data plotted on Qt93.34F4.10Lt2.59 ...
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Petrofacies analyses of Asmari Formation carried out on thin sections, obtained from oil wells of number 11, 85 and 89 in Ahvaz oil field, show 5 carbonate-evaporate microfacies associations (related to a carbonate ramp) and 2 siliciclastic petrofacies. Point counting data plotted on Qt93.34F4.10Lt2.59 and Qm86.75F4.10L9.15 diagrams imply the cratonic and recycled orogen tectonic provenance. Furthermore, these results and the other petrographic evidences indicate a source rock with sedimentary and low to medium degree metamorphic composition for Ahvaz sandstone. Combining the obtaind results with global sea level changes, variation in sediment supply and regional and local tectonic evolution, assisted us to recognize 6 evolutionary stages for Samara basin. In fact, Asmari Formation deposited in a carbonate-evaporate ramp with different amount of sediment influx through the time.
J Rabbani; E Ghasemi-Nejad; A.R Ashouri; M Vahidinia
Abstract
The basal unit of the Pabdeh Formation at Bisheh-Deraz section composes of 47m purple to green to grey shale and marl. These beds gradually change to shale and argillaceous limestone in the top of the section. In order to study paleoecology and paleoenvironment of these beds, palynological evidences ...
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The basal unit of the Pabdeh Formation at Bisheh-Deraz section composes of 47m purple to green to grey shale and marl. These beds gradually change to shale and argillaceous limestone in the top of the section. In order to study paleoecology and paleoenvironment of these beds, palynological evidences including palynofacies, abundance and diversity of dinocysts and environmental index have been investigated. Four Palynofacies types including IV: shelf to basin transition, VII-VIII: distal dysoxic-anoxic shelf, IX: distal suboxic-anoxic basin) have been differentiated that propose a distal suboxic-anoxic basin as depositional setting. According to the microfacies of planktonic foraminiferal Wakestone/Packestone a deep environment is proposed as the depositional basin. Using such parameters as palynofacies evidences, C/PPC ratio, AOM/MP ratio, abundance and diversity of dinocysts and environmental index, three system tracts related to one sequence (3rdorder) with one sequence boundary type 2 and one maximum flooding surface have been determined. In general, the factors all together show a deepening upward trend through this rock unit.
A. Saki; A. A. Baharifar
Abstract
Intrusion of the Alvand complex (intrusions formed during Jurassic) into the host metapelitic rocks (schists) created pelitic hornfelses and anatectic migmatites in the Alvand aureole. Partial melting in the Alvand aureole was restricted to pelitic bulk compositions. Existing of spinel-quartz minerals ...
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Intrusion of the Alvand complex (intrusions formed during Jurassic) into the host metapelitic rocks (schists) created pelitic hornfelses and anatectic migmatites in the Alvand aureole. Partial melting in the Alvand aureole was restricted to pelitic bulk compositions. Existing of spinel-quartz minerals and appearance of orthopyroxene in these rocks marks the transition from amphibolite- to granulite-facies conditions, and is commonly attributed to the process of fluid-absent partial melting. Reactions Sil/And + Bt = Crd + Spl+ Kfs + melt and Bt+Als+Pl+Qtz = Grt+Kfs+melt, are the most reactions for the development of melt in the metapelitic rocks of Alvand aureole. This metamorphism is mainly controlled by conductive heat transter through magmatic intrusions into all levels of the crust. The Hamadan metamorphic rocks have experienced multiple episodes of metamorphism driven by burial and heating during arc construction and collision during subduction of a Neotethyan seaway and subsequent oblique collision of Afro-Arabia (Gondwana) with the Iranian microcontinent in the Jurassic-Cretaceous, and these events are associated with local partial melting at high grades, near the Alvand complex pluton.
Petrology
zahra badrzadeh
Abstract
Abstract The studied Chaltian granitoid is located in the endpoint of the southern Sanandaj–Sirjan Zone. This pluton has Low-Al trondhjemitic composition with tholeiitic to transitional nature. The intrusion has been intruded in the early Mesozoic volcanic and sedimentary rocks. According to U-Pb ...
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Abstract The studied Chaltian granitoid is located in the endpoint of the southern Sanandaj–Sirjan Zone. This pluton has Low-Al trondhjemitic composition with tholeiitic to transitional nature. The intrusion has been intruded in the early Mesozoic volcanic and sedimentary rocks. According to U-Pb SHRIMP age dating of zircon grains, this pluton was intruded at the 187.5 ±3.2Ma ago. Studied pluton has low Al2O3, Sr/Y, (La/Yb)N ratio and less fractionated REE pattern. In the primitive mantle normalized spider diagrams, studied samples show enrichment of LIL elements such as K, Rb, Ba and Th relative to HFS elements and has negative anomaly in Ta, Nb and Ti elements, which are considered characteristic of magmas generated in subduction related settings. In terms of their origin, based on geological and geochemical characteristics, trondhjemitic melt has been generated by low pressure dehydration melting of amphibolitic source in an continental extensional tectonic setting related to subduction environment.
M. Mohammadi; A. Ernst; M. Yazdi
Abstract
Two bryozoan species are described from the Geirud Formation (Upper Devonian) of Central Alborz. The Geirud Formation is a sequence of nearly 340 meters of alternating silisiclastics and limestone and 1-2 andesitic lava units, with extensive exposures in the Central Alborz mountains. ...
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Two bryozoan species are described from the Geirud Formation (Upper Devonian) of Central Alborz. The Geirud Formation is a sequence of nearly 340 meters of alternating silisiclastics and limestone and 1-2 andesitic lava units, with extensive exposures in the Central Alborz mountains. The study comprises the Type Section of the Geirud Formation in the Geirud valley and two sections in Zaigun and Lalun valleys near the Type Section, all in northern Tehran (Fig.1). In some calcareous beds we found bryozoan species from Famennian. Trepostome Schulgina mutabilis Troizkaya, 1975 is known from the Upper Devonian (Famennian) of Central Kazakhstan. The Ascopora .sp. is the earliest known representative of habdomesine genus Ascopora Trautschold, 1876. This is the first study on the bryozoans of the Geirud Formation in Central Alborz.
M Fereidoni; M Lotfi; N Rashid nejad; M Rashidi
Abstract
The Qalikuh area,~35 km southwest of Aliqudarz, contains oil shale deposits in Garue and Sargelu formations(Jurassic-Cretaceous). Some 20 samples across two sections(Charun3-Deh ye Qali3) were selected and analyzed(Rock Eval – ICP – XRD – XRF) to study organic and mineral parameters(to ...
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The Qalikuh area,~35 km southwest of Aliqudarz, contains oil shale deposits in Garue and Sargelu formations(Jurassic-Cretaceous). Some 20 samples across two sections(Charun3-Deh ye Qali3) were selected and analyzed(Rock Eval – ICP – XRD – XRF) to study organic and mineral parameters(to determine type of organic material and kerogen, total organic carbon, thermal evolution, concentration, and classification of elements and minerals) and to model the relations between these parameters. The Qalikuh oil shale has a great potential for oil production with high levels of TOC (13.5 wt%), type 2 kerogen, low thermal maturity. However Qalikuh oil shale has metallic and nonmetallic element anomalies and high concentrations of strategic elements compared to Clark values. Dendritic diagrams suggest variable origins for elements and minerals in the samples. Some are associated with development of organic materials, TOC parameters, Resin and Asphaltene, and some are associated with clastic materials, aluminosilicates and source rock weathering.
H. Javanbakht Jabarabadi; S. A. Alavi
Abstract
The studied area located at the main suture zone of Zagros in the northeastern of Kermanshah. To do structural analysis in this area, six structural sections have been drawn perpendicular to structures direction. Structures and faults with different mechanism show that the studied area has passed two ...
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The studied area located at the main suture zone of Zagros in the northeastern of Kermanshah. To do structural analysis in this area, six structural sections have been drawn perpendicular to structures direction. Structures and faults with different mechanism show that the studied area has passed two tectonic phases from Cretaceous up to present. The first phase which is a Compression phase, started from Cretaceous and lasted until Miocene. The created faults in this phase are thrusts with vast displacements in which the Main Zagros Thrust is the most important one of them. The second tectonic phase which is very young and active acts as a Transpressional system. The main structures created in second phase are dextral faults of Mianrahan and Sahne. These tow faults are part of Main Recent Fault and created some secondary structures such as Dinevar pull apart and flower structure on Sahne fault. Finally structural evolution model of the area has been expressed in six steps according to the relation among the structures and layers with different ages. During these steps, faults with the same dirctions but different mechanism have been created which demonstrates the counterclockwise rotation of stress axis σ1 since Cretaceous.
Tectonics
Zahra Mohammadyasl; Abdollah Saidi; Mehran Arian; Ali Solgi; taher Farhadinejud
Abstract
The Studied area is located in the small part of the structural zone of Urumieh- Dokhtar Magmatic Arc, at 60km far from south of Qom and 12km far from south east of Kahak. In the beginning, 1:25000 map of the area was prepared, because, region is located in two 1:100000 scale map sheet of Kahak and Aran, ...
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The Studied area is located in the small part of the structural zone of Urumieh- Dokhtar Magmatic Arc, at 60km far from south of Qom and 12km far from south east of Kahak. In the beginning, 1:25000 map of the area was prepared, because, region is located in two 1:100000 scale map sheet of Kahak and Aran, and more rock units were separated. In the next step, in a several step of the field observations, 17 samples of regional volcanic rocks were taken for XRF and ICP chemical analysis, and they main Oxides, heavy metals and rare elements were identife. Most of the samples have been located in the Calk- alkaline series, and some in the Tulleit series. In the lithology diagrams, these samples respectively are arranged in the range of Andesite, Dacite, Trachy Andesite and Rhyolite Rocks. Due to the anomalies and the amount of Nb in the samples of the region, they formation can be related to the subduction zone. On the other hand, the depletion of Nb and Ti is special in magmatism in the subduction zone. Because in the subduction regions released fluids from floating lithospheric rich in LILE, increases in the mantle wedge. Since in the study area rocks exhibit calc- alkaline with moderate to high potassium, it can be concluded that the stones are related to active continental margin associated with subduction.
F Jalili; F Hadavi; B Rahimi; A.R Khazaei
Abstract
In this research, biostratigraphy of a stratigraphic section in the east Afzalabad section in Lut Block (part of flyschoid basin in East Iran) were investigated based on calcareous nannofossils. Nineteen genera and 52 species of calcareous nannofossils were identified based on which the studied ...
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In this research, biostratigraphy of a stratigraphic section in the east Afzalabad section in Lut Block (part of flyschoid basin in East Iran) were investigated based on calcareous nannofossils. Nineteen genera and 52 species of calcareous nannofossils were identified based on which the studied sequence confirm with NN8- NN10 biozones of Martini (1971) indicating a middle Miocene to late Miocene age.
R. Jadidi; H. Karimzadegan; N. Badri
Abstract
Tourism is a valuable and quick-impact on economic approach and is raised to land use considerations, and has fewer risks and costs in the field of investment due to the availability of resources compared to other projects. The purpose of land use planning is to balance geographical distribution of economic, ...
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Tourism is a valuable and quick-impact on economic approach and is raised to land use considerations, and has fewer risks and costs in the field of investment due to the availability of resources compared to other projects. The purpose of land use planning is to balance geographical distribution of economic, social and cultural activities in the area toward natural and human resources, and therefore to achieve sustainable development. Tourism as one of the multi-dimensional aspects of spatial development of a region has the potential to be the first in the development planning. In the last decade, “geoparks” as geotourism targets are considered the main approach of development in many advanced countries and those that have limited resources or related industries. National and international introduction and registration of empowerment zones called “geoparks” is the new initiatives in the development of geotourism, and is important strategies in order to achieve goals such as sustainability and environmental protection, rehabilitation and economic stability of local communities (employment, income), creation of social welfare in rural areas and low population centers which are of low interest of industrial, mining and oil budgets. In this paper, with the use of descriptive survey method (review the attractions and potentials of the Lorestan province), using SWOT strategic plan, necessary strategies to establish eoparks have been developed and proposed. Based on IE matrix, the sum of total score of internal factors of geopark role in the province geotourism was obtained to be 3.916, which means strength of the internal factors in the province. Therefore, the province capabilities in the creation of eoparks has overcome the weaknesses. The sum of total score of external factors was obtained 3.674, which means opportunities overcome the threats in the creation of geoparks. So, the creation of geoparks as a preference option in empowerment in Lorestan province was proposed and studied, and aggressive strategy was determined as the prioritized strategy in this regard.
H Hadizadeh1; A.A Calagari; N Nezafati; H Mollaei; H Azmi
Abstract
The Neian epithermal deposit in northwest of the Lut block is located in ~35 km southwest of Bejestan. The studies done on this deposit indicate the development of zonation in altered rocks around the ore-bearing siliceous veins and the existence of silicic (quartz, chalcedony, adularia, calcite, illite, ...
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The Neian epithermal deposit in northwest of the Lut block is located in ~35 km southwest of Bejestan. The studies done on this deposit indicate the development of zonation in altered rocks around the ore-bearing siliceous veins and the existence of silicic (quartz, chalcedony, adularia, calcite, illite, and sericite), silicic-argillic (quartz, adularia, illite, sericite, and pyrite), argillic (illite, quartz, calcite, adularia, sericite, kaolinite, smectite, and chlorite), and propylitic (chlorite, calcite, albite, epidote, quartz, and smectite) alterations as the major alteration zones in this deposit that were formed during the five stages. Th geochemical diagrams, molar elemental ratios, and petrographic consideration illustrate the presence of transitional transformation and mineral conversion arrays during the development of hydrothermal system at Neian. Consideration of these diagrams indicate a wide spread of argillic and silicic and a relatively limited extent propylitic alteration zones in the Neian deposit. These diagrams also show that the mineral arrangements such as plagioclase-illite, plagioclase-adularia, illite-adularia, and plagioclase-smectite were developed during the prograde stages, whereas adularia-illite arrangement was formed during the retrograde (waning) stages of hydrothermal system. Permeability, high water/rock ratio in the host rocks (generated by faulting and the presence of extensive pyroclastic rocks) are the main factors for development of alteration zones and formation of widespread adularia in the area. In addition, considering the mineralogical composition of the deposit, the presence of minerals such as adularia and illite in the central and kaolinite in the peripheral part of the system may suggest that they were formed by the fluids having temperatures > 220 °C and <140 °C, respectively. The presence of mineral assemblage of quartz, adularia, illite, pyrite, chlorite, and calcite may reflect the involvement of upward flowing Chloride-bearing fluids with pH ranging from almost neutral to moderately alkaline. The contemporaneous formation of calcite, smectite, illite, and kaolinite in peripheral parts of the system was resulted by the reaction of CO2-rich fluids (containing hot vapors) with the host rocks. Increasing of temperature and potassium metasomatism in the central parts of the system caused widespread formation of illite at the first stage of alteration and of adularia-illite at the second (maximum K-metasomatism) during the geothermal activity at Neian. Concurrent with the waning stage of hydrothermal alteration and decreasing of K-metasomatism, illite replaced adularia again. The prevalence of conditions (for a long period of time) suitable for stability of illite may account for the greater abundance and extent of this mineral relative to adularia in the host rocks of Neian deposit.
M. V. Valizadeh; H. R. Abdollahi; M. Sadeghian
Abstract
The intrusive bodies of Central Alborz constiute speciale distribution. And they are located near major faults, and also they are accompnied by pyroclastic rocks of the Karaj Formation.Moreover they display lithological diversity and they occur as sill, lopolith, stock ...
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The intrusive bodies of Central Alborz constiute speciale distribution. And they are located near major faults, and also they are accompnied by pyroclastic rocks of the Karaj Formation.Moreover they display lithological diversity and they occur as sill, lopolith, stock and plug.
These intrusive bodies blong to post upper Eocene and they are related to the Pyrenean- equivalent orogenic phase.
Rregarding the geochemical results obtained by other researchers, as well as determining the nomenclature, definiton of granitoid and gabbroic bodies the composition of the above mentioned masses, fall within the calc - alkaline to alcaline range.
However, most specimens are plotted in the field of type I granitoids.From the tectonic viewpoint, all of the intrusive bodies are Considered as syntectonic. Moreover, they are often of continental subduction Zone(CAG)origin , while other may be long to continental collision type(CCG), and a few are located to the island arcs(IAG).
M Nasrabady; F Rossetti; H Moin Vaziri; S.M.H R; M M
Abstract
Some syntectonic tonalitic and trondhjemitic intrusion bodies have been injected into the Soltan Abad (NE Sabzevar) metamorphic complex. The geochemical investigations of these intrusion bodies demonstrated their very obvious adakitic characteristics (very high ratio of Sr/Y and very low contents of ...
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Some syntectonic tonalitic and trondhjemitic intrusion bodies have been injected into the Soltan Abad (NE Sabzevar) metamorphic complex. The geochemical investigations of these intrusion bodies demonstrated their very obvious adakitic characteristics (very high ratio of Sr/Y and very low contents of Y and Yb). According to the field and microscopic evidences and the geochemical characteristics of the whole intrusion bodies, the creation of such adakitic properties originates from the influence of both partial melting and magmatic differentiation processes. The probable scenario is the partial melting of subducted oceanic lithosphere in a hot subduction zone and the generation of adakitic intermediate melt, then amphibole fractionation and enhancing of adakitic indicators of final acidic melt. The resultant residual of partial melting is garnet-hornblenditic blocks that observed adjacent to some intrusion bodies. The primary adakitic intermediate melt accurs as amphibole-rich diorite in the study area. The differentiated cumulate phase and final fractionated melt constitute the hornblenditic dykes and hololococratic tonalitic-trondhjemitic bodies, respectively. The creation of hot thermal regime and partial melting of subducting oceanic lithosphere have been affected by the factors such as subduction velocity variations, mid oceanic ridge subduction or the slab break-off of the subducting oceanic plate and upwelling of the hot asthenosphere.
Tectonics
E. Haji; H. Safari
Abstract
The Saqqez-Baneh area, as a part of the NW Sanandaj-Sirjan zone, is selected for investigation of different deformation stages. In this research, firstly, the lithology of outcropped rock units and visible lineaments were mapped using remote sensing approach. Then, field surveys were carried out for ...
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The Saqqez-Baneh area, as a part of the NW Sanandaj-Sirjan zone, is selected for investigation of different deformation stages. In this research, firstly, the lithology of outcropped rock units and visible lineaments were mapped using remote sensing approach. Then, field surveys were carried out for structural measurements, during which major and minor faults and shear zones (as ductile zones) were measured and mapped. These data were then entered to GIS environment as vector layers (and attributed descriptions), resulting in preparation of a structural map. The results of field surveys along with geometric and kinematic analyses show that the major faults together with their related fault orders formed a curved shape of structures, outcropped rock unit patterns and intrusive localities. Geometric and kinematic analyses demonstrated three stages of movement: with north-south (in ductile environment), northeast-southwest (in ductile to brittle environment) and east-west (in brittle environment). These three stages caused three stages of faulting with trends along N140-150, N70-80 and N10-20 directions, which can be attributed to three orogenic phases in Precambrian and/or late Triassic (Katangai and/or Cimmerian), Cretaceous (Laramide) and Neogene (late Alpine events such as Savian to Pasadenian).
S. Yusefzadeh; A. A. Nadiri
Abstract
Today Ground water is the main source of drinking, agriculture and other uses for humans. The demand for this critical and strategic natural resource increased with population growth and development of society. This increasing has been declining water resources and damage aquifers environment. Therefore, ...
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Today Ground water is the main source of drinking, agriculture and other uses for humans. The demand for this critical and strategic natural resource increased with population growth and development of society. This increasing has been declining water resources and damage aquifers environment. Therefore, we need to manage aquifers and understanding the hydrogeological parameters to deal with the water crisis and prevent the distraction of aquifers. The one of most important parameter is hydraulic conductivity. Although, the ground water system is a complex system and estimation of hydrogeological parameters is associated with inherent uncertainty and also is costly and time consuming that usually done with classical methods such as laboratory tests, slug test, tracing test and pumping tests. So recently use artificial intelligence methods for estimation of hydraulic conductivity, reduced the uncertainty of this parameter and it adds up some accuracy. So that it can overcome on the shortcoming of classical methods. In this study, four artificial intelligence methods; mamdani fuzzy logic(MFL) system, sugeno fuzzy logic(SFL) system, Wavelet-neural network method and Least square support vector machine(LS-SVM) method were used as individual models to estimate the hydraulic conductivity by using of surface geophysical data in Maragheh-Bonab aquifer. Given that each these models based on their inherent properties, they presented good results in some parts of area. Therefore, for concurrent use of performance of all these models the nonlinear combination method as a supervised committee machine artificial intelligence (SCMAI) model were used to estimate the hydraulic conductivity in maragheh-bonab aquifer. The result of this model showed that this new combinational model has high performance than other single models that presented by using different evaluation criteria. Therefore, this model could also be used for estimation hydrogeological parameters in areas with high complexity. The SCMAI model was tested against 15 data. The RMSE and for SCMAI prediction were computed as 0.045 and 0.97, respectively. Comparing the error measure values with dose of individual models above, it is seen that SCMAI outperforms individual AI models with low RMSE and high values. This result implies that SCMAI model shows high performance for estimation the hydraulic conductivity values in the heterogeneous unconfined aquifer in Maragheh-Boanb plain.
H. Mahdizadeh; Y. Djamour
Abstract
Today, with the use of Global Positioning System (GPS), it is possible to determine the geodetic height (relative to a Reference Ellipsoid) in easy mode with less time and cost. Despite of some advantages for leveling with GPS (GPS/Levelling) relative to traditional leveling, there is an important limitation ...
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Today, with the use of Global Positioning System (GPS), it is possible to determine the geodetic height (relative to a Reference Ellipsoid) in easy mode with less time and cost. Despite of some advantages for leveling with GPS (GPS/Levelling) relative to traditional leveling, there is an important limitation which indicates the difference between Ellipsoid (as the reference datum for geodetic height) and Geoid (as the reference datum for orthometric height) named geoidal height. In order to achieve maximum accuracy in height component and then evaluating the quality results, different aspects of GPS/Levelling are considered in this study. In order to study the Feasibility of replacing precise levelling with GPS in Iran, a part of 55 km physical geodesy and geodynamic network in Azerbaijan region as well as the dense geodetic multipurpose network in Qeshm island were used. Based on different distances between each couple of points, this information, consisting of Orthometric and Geodetic heights for each point, is classified in 5 groups. The last Geoid model of Iran (IRGeoid10) with an absolute average accuracy of ±26 cm and a relative average accuracy of ±2.8 ppm are used for geoidal height. Obtained results show the accuracy of leveling height difference with GPS would be reduced by increasing the length of baseline. Index K as a criterion for determining level degree was calculated. This index shows that levelling with GPS in Iran could provide a precision of 4th degree leveling which can serve many engineering applications.
B. Hosseini; A. R. Ahmadi; M. Ghanbari Dolatabadi
Abstract
A suite of dykes at the north of Mashad –Ardehal which intruded into the Eocene volcanic and sedimentary rocks represents part of Tertiary volcanism in middle part of the Urumieh-Dokhtar magmatic belt. The rocks are cogenetic and are mainly basaltic andesite, andesite and trachy andesite ...
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A suite of dykes at the north of Mashad –Ardehal which intruded into the Eocene volcanic and sedimentary rocks represents part of Tertiary volcanism in middle part of the Urumieh-Dokhtar magmatic belt. The rocks are cogenetic and are mainly basaltic andesite, andesite and trachy andesite in composition and belong to tholeiitic and medium-K calc alkaline series. Chondrite-normalized REE patterns exhibit moderate enrichment in LREE relative to MREE. Enrichment in LILE and depletion in HFSE relative to REE on multi-element diagrams is similar to subduction related magmatic rocks. From the geochemical point of view, these rocks demonstrate intermediate characteristics of active continental margins and island arcs settings. Geochemical evidences and also association of the magmatic rocks with green tuffite and other shallow marine sedimentary rocks suggest that the rocks generated in an extensional continental (ensialic) back-arc basin.
H. Baboli-moakher; K. Shirani; A. R. Taghian
Abstract
Catchments are natural systems in which natural phenomena like landslides are considered as natural disasters. As a chaos factor, they have a main role in forming unstable condition, tackling energy, accelerating erosion and generating sediment. So factors causing slope instability are reaction of the ...
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Catchments are natural systems in which natural phenomena like landslides are considered as natural disasters. As a chaos factor, they have a main role in forming unstable condition, tackling energy, accelerating erosion and generating sediment. So factors causing slope instability are reaction of the system to positive feedback. This study aims to employ theory of natural system chaos, in the form of Shannon entropy index, to find the factors causing landslide and its hazard zonation in Fahlian basin. First, input layers including geology, rainfall, slope, aspect, land use, distance to river, distance to fault, and elevation were digitized using GIS techniques. Then occurred landslides were detected using satellite images and field study. Landslide hazard zonation based on defined weights of each parameter was generated. In order to run model and study its accuracy, receiver or relative operating characteristic (ROC), was used with 70 and 30 per cent of data as training and test, respectively. Results show that slope and aspect have the maximum effect on landslide occurrence with ultimate weight of 0.662 and 0.308, respectively. Landslide susceptibility zonation map show that more than half of study area (56.97 percent) have very high to high susceptibility. Disaggregation of areas with SCAI method show the high accuracy of the model in detection of area with average, low and very low susceptibility. Frequency ratio of hazard classes deals with high accordingly, area under curve (AUC) of ROC was estimated 0.87 with 0.026 standard deviation which is known as very good accuracy of model.
