An Assessment of Equilibrium-line Altitudes in the Haraz Valley during the Last Glacial Maximum
Pages 305-314
https://doi.org/10.22034/irqua.2017.701948
Mojtaba Yamani, Hamzeh Zamani
Abstract Of all glaciers used as indicators of climate change, cirque glaciers are probably the optimal ones to use. Due to their small size and volume, their response time to positive or negative changes in mass balance is rapidly manifested, often within a couple of years. Singh (2011: 144) suggested that this implies that a sustained negative mass balance, lasting no less than a decade, will rapidly lead to a reduction in size and vice versa. In the quaternary period, glacial and interglacial conditions have occurred in turn in the earth`s history and laid out by geomorphological evidences are undeniable that can be used to determine for snowline borders and equilibrium line altitudes and so on; for studying climate change in that period. It is possible that the reason for external processes of changing the Earth could not have completely cleared away the glacial landforms that remained from of quaternary glaciation.
Material and methods
This research is a basic research; thus the main goal of it is the extension of the quaternary glaciation theory by data analyzing and finding relationship between mountain direction and elevation; and creation of glacier landforms. This research wants to find an answer for these questions: 1) is there correlation between glacial geomorphologic evidences in Haraz valley from altitude and distribution? 2) Is quaternary glacial border in Haraz valley in the last glacial maximum located in different altitude or not? If the answer is yes what are the causes of these differences? 3) What is the relation between volume and distribution of glacial cirques and topography and relieves direction? This research's hypotheses are: 1) Extent, volume and frequency of glacial cirques are more in the northern slopes than southern slopes this issue first of all depends on the precipitation volume. 2) The average of glacial cirques altitude and glacial terminus in northern slopes of Haraz valley is lower than southern slopes. Methods or models which are used to answer this issue can be classified in two groups: first, methods and models which are used in the main part of report, containing contour line methods, this is used to restoring the continental and hydrologic data. In the second part which is used for analyzing data, among the methods that Porter suggested, cirque- floor altitude method is selected for this research. When a glacier just fills a cirque, its steady-state equilibrium line altitudes (ELA) typically lies not far above the average altitude of the cirque floor and cirque floor altitude has sometimes been used as a convenient proxy for former ELAs. This research has been based on the comparison between cirques elevation and determination of the extension of glacial toes in the equator-faced slopes and the pole-faced ones. All data and analyses have been shown with use of ArcGIS and SPSS softwares that illustrated on the different thematic maps.
Results and Discussion
The analysis of foundation of glacial cirques in dissimilar altitudes has initiated with reconnoiter of those cirques that are located in 100-meter contour lines, and then they have analyzed with the statistical methods to obtain permanent snowline in last glacial maximum in octagonal aspects in the Haraz valley. To compare the mean altitude of glacial cirques and the altitude that there is the most frequency of the cirques, it has calculated arithmetic mean and “mode”. The results of this study showed that there is a significant difference between the observed frequencies and the expected frequency and distribution of these cirques was promoted by the mountain aspects; i.e. poleward slopes that receive relatively less energy than equatorward slopes are more appropriate location to formation of cirques and other glaciers features.
Conclusion
According to the calculated equations, temporary snowline is estimated 4938 m in the equator-faced slopes and 5605 m for the pole-faced ones. Based on the synthetic of statistical analysis and cirque floor altitude method, the former ELA has been 2799 m in the study area and modal value is 2706 m. The modal value in the pole-faced ones is 2874 m and in the equator-faced slopes is 2941 m.
The evaporite minerals of Kerman Province, with special reference to spectral and mineralogical properties, and remote sensing
Pages 315-336
https://doi.org/10.22034/irqua.2017.701958
Azam Soltani Nejad, Hojato allah Ranjbar, Sara Dargahi, Mahdi Honarmand
Abstract 1-Introduction
In the world economy, the study of playas is of great importance because many valuable minerals, including sulfate, sodium and potassium carbonate, gypsum, halite, nitrates, borates, as well as a number of rare and valuable metals such as lithium, rubidium, cesium and even uranium and some other rare metals are formed or accumulated in these environments. Iran has a large number of playas, brines, domes and salt pans (about 60 salt pans), and the importance of exploring and studying of the reserves and evaporates mineral potentials is not covered by anyone.
2-Materials and methods
In this study, an ASD Field Spec3® Spectrophotometer was used in Laboratory of Graduate University of Advanced Technology to measure the spectra of samples. This spectrophotometer is capable to record spectra in the range of 350-2500 nm and contains 2151 bands in this range. The satellite data which was used in this study is ASTER images at 1T level of the summer season. These images were geometrically corrected and only atmospheric correction was performed on them, and the Internal Average Reflectance (IAR) method was applied for atmospheric correction. To understand the spectral behavior of evaporite minerals within the ASTER bands, these spectra were resampled based on the wavelengths of ASTER. Constrained Energy Minimization (CEM) method was used for mapping the evaporate minerals in six evaporate areas in Kerman province including Sirjan Playa, Khatoonabad Pan, evaporitic areas of Ravar, three of all Rayen craters, Koshkoieh Pan and Shahdad area. CEM algorithm highlights the known target signature by suppressing background signals and it constrains a specified target signature and minimizes other unknown signatures when the target spectra are provided as user end members. In order to validate the accuracy of the results of this method, the maps were compared with the ground data. In order to assess the mineralogy of the samples, after preparation, 36 samples from all samples taken for XRD analysis and were sent to the Mineral Processing Research Center of Iran. Based on XRD results all samples were categorized to four groups as Halite, Gypsum, Calcite and Thenardite.
3-Results and discussion
Spectral investigations of samples that are not pure are complicated, but what is apparent in the samples of this study is the occurrences of strong adsorptions related to the presence of water, whether in the composition of minerals such as gypsum, bassanite or as adsorptions on minerals such as halite. Since evaporite minerals, especially halite, have a high tendency to adsorb water, this adsorption features were observed in almost all samples near wavelengths of 1400 and 1900 nm. Spectral curves of halite-dominant samples showed that in most of these samples absorption feature occurred within the band 6 of ASTER, but in the case of a pure halite sample, for example, sample ush5 which was taken from the center of Sirjan salt pan, and the sample Rn1, which was taken from crater No.1 of Rayen area, this absorption is occurred within the band 5 of ASTER. It can be deduced that by purifying the halite sample, the absorption feature position on the resampled electromagnetic spectrum tends towards the band with less wavelengths. Gypsum-dominated samples indicate that these samples have the absorption feature within band 6 of ASTER in the resampled spectra to the ASTER. The absorption of 2214 nm in sulfate minerals is due to the sulfate vibration.
CEM algorithm by maximizing the response of the known end members and suppressing the response of the composite unknown background, enhances the contrast between target spectra and the background. The ability of this technique has the advantage of being a straightforward technique that can be used for mapping with fewer field data (Gabr et al., 2010). Based on the results of XRD analyses of studied areas, four groups of endmembers including: halite, gypsum, calcite and thenardite were applied for this method. The maps showed that this method of classification has good results for detecting evaporate minerals.
4- Conclusion
1- According to the results of XRD analysis in the studied evaporatic areas in Kerman province, the main evaporite minerals in each of the areas were identified. Halite is the most dominant evaporate mineral in Sirjan, and the minerals of gypsum, calcite and thenardite are respectively in the next level of frequency. In Khatoonabad, halite is not the main mineral and gypsum and calcite are the most abundant ones; besides, in Khatoonabad area, rare boron-bearing minerals such as inyoite, borcarite, aristarainite along with ulexite were observed. In Ravar, the most dominant evaporite minerals are gypsum and calcite, and halite in abundance is after these minerals. In this area, bassanite and boracite were observed that were not seen in the other areas.
2- The spectral features of evaporite samples of the study areas have been presented in Table 1.
3- In all studied evaporite minerals, absorption is observed in the range of about 1400 and 1900 nm. Absorptions in these wavelengths is due to the presence of water. In the investigated samples, even in minerals that do not have water in their structural composition, these two absorptions are also observed. In the case of minerals that do not have water in their composition, water is adsorbed by these minerals.
4- Evaporite minerals often show the absorption features in band 6 of ASTER, but the present study shows that this issue is different for halite. In the other hand, when the purity of halite sample increases, the absorption tends to be occurred within the band 5 of ASTER. In other words, by purifying the composition of the sample, the absorption band of resampled spectrum on ASTER tends to be in a lower wavelength.
5- Spectral features Studies of thenardite-dominant samples clarified that these samples exhibit a greater absorption width in the spectral range of water absorption rather than halite and gypsum.
6- Evaporite minerals have a high reflection. In the study of the reflection of the four major evaporite minerals of the study areas, it was found that halite and gypsum have the highest spectral reflection and thenardite has the least reflection.
7- According to the results of CEM method on ASTER images of evaporite areas of Kerman province, it was determined that this method is a suitable way for detection of the evaporite minerals.
Pedological stratigraphy and effect of carbontes removing on particle size distribution in loess-Palaeosol sequences in southwest Sari
Pages 337-351
https://doi.org/10.22034/irqua.2017.701959
Hamed Najafi Kersami, Alireza Karimi, Farhad Khormali, Gholam Hossein Hagh Niya
Abstract Abstract
Introduction: Loess deposits are the silt dominated aeolian deposits. Loess-paleosol sequences have been frequently used to determine and reconstruct paleoclimate and paleoenvironment of quaternary. The first step for this purpose, is to identify the sequence of loess and paleosols and describe their pedological, physical and chemical characteristics. Particle size distribution is the most important characteristics of loess deposits. This characteristic is a function of distance from source and pedological processes. Carbonates are the main constituents of the loess deposits which can act as a cement and affect the particle size distribution. Main loess areas in Iran are located in the north of country, especially in Golestan province. However, there are loess deposits in Sari which there is little information about their pedological and morphological properties. The objectives of this study were to 1) identify the loess - palaeosol sequences and 2) determine the effect of carbonates on particle size distribution of two loess-paleosol sequence in southern Sari.
Materials and Methods: There is a loess containing area in southern Sari. During field surveying, two loess-paleosol sections were explored and the loess layers and paleosols (horizons and pedogenic features) were described. The sections were sampled from 10 cm intervals. Calcium carbonate equivalent (CCE), soil organic carbon, pH and particle size distribution of the samples were measured. Particle size distribution was determined using pipette method. The fractions of sand, coarse silt, medium silt, fine silt and clay fractions were measured. To determine the effect of carbonate on particle size distribution, sand, silt (coarse silt, medium silt and fine silt) and clay contents of the samples were measured before and after carbonate removing. Diluted HCl was used to remove the carbonates.
Results and discussion: The thickness of the sections were 408 and 627 cm and were morphologically similar. Both sections contained a modern soil (MS) and three palaeosol which separated by loess layers. This indicated periodic alternation of soil formation and loess accumulation. In the studied sections, the modern soils composed of cambic (Bw) and calcic (Bk) horizons. Paleosols 1 (PS1) and paleosols 2 contained argillic-calcic (Btk) horizons. Paleosols 3 (PS3) indicated vertic properties (Bsskg). In contrast to modern soil in loess in humid regions of Golestan province which contained argillic horizon, the modern soil in the studied sections were not highly developed. Slickenside and wedge shape were the two main vertic properties which observed in PS3. Seasonal saturation in PS3 due to low permeability of Bsskg horizon produced stagnic properties. Accumulation of Mn oxides and to some extent Fe oxides revealed the intermediate reduction states.
Carbonate calcium equivalent (CCE) in the sections ranged from 2 to 48.75 %. High amount of secondary carbonates were found in loess layers and was higher than overlying paleosol. This indicated that in humid periods of soil formation the carbonates translocated from the paleosols. Particle size distribution results indicated that sand fraction mostly composed of hard carbonate nodules and consequently the amount of sand fraction reached to 42 % which is unusual in loess deposits. The amount of sand, silt and clay in the sections were 2 to 48.75 %, 36.2 to 78.2 % and 16.6 to 43.8 % which after removing the carbonates changed to 0.3 to 3.8 %, 47.1 to 81.5 % and 17.6 to 50.3 % respectively. Particle size distribution firstly indicated the distance from the origin. Dominance of medium silt showed that the sediments have been originated from relatively large distance. Weathering and translocation of fine particles during humid periods increase the clay content in the paleosols. The highest amount of clay content and the lowest amount of CCE occurred in PS2 palesols which indicate suitable weathering conditions during PS2 formation. Furthermore, the thick Btk horizons in PS2 paleosols of both sections is another evidence of suitable conditions for soil formation.
Conclusion: Results of the present study indicated that the studied sections are suitable for future paleoclimate and paleoenvironment studies. The sequences of loess-paleosols in southern Sarin was similar to those in humid areas of Gorgan which indicated they experienced similar sequences of climate variations. On the other hand, secondary carbonates accumulated as hard nodules increase d the amount of sand content which may cause misleading interpretation. Therefore, it is suggested removing the carbonates of loess sections in humid areas of northern Iran.
البرز میانی، زمینریختشناسی، قزوین، کارستزایی
Pages 353-366
https://doi.org/10.22034/irqua.2017.701965
Parviz Ghazanfari, Mahdi Bakhtiari, Mahdi TajAbadi
Abstract Identification of geomorphological phenomena that were created by the dissolution can help to identify the karst systems. Hence, karst geomorphology is usually the first step of study. Processes of Karstification on the one hand cause problems in carrying out civil projects, and on the other hand it can help in the exploitation of water resources from hard formations and development of the geotourism industry. Karst develops in many types of rock, including limestone, dolostone, gypsum, salt, quartzite, and some others. These rocks, subjected to different climates, assume many morphologies and landforms. Limestone purity (%CaCO2) is one of the most important controls on karst development. Karst landforms develop best on pure, dense and thick limestones and marbles. In karstification processes three parameters of lithology, climate and fracture are more important than others such as pedology, vegetation cover and topography. Among sedimentary rocks, salt rock has maximum dissolution rate. After that sulphate rocks such as gypsum, shows 10 times more Chemical Denudation than limestone. Limestone also has more dissolution rate compare it to dolostone. Bedding planes and fractures (joints and faults) are of the greatest importance because they host and guide almost all parts of the underground solution conduit networks that distinguish the karst system from all others. The availability of water is the key climatic factor in karst development. It is certainly the principal variable controlling total denudation by dissolution. Alamut Valley is located in north of Qazvin provenance and Central Alborz structural zone. The area of Alamut is 1866 Km2. Average rainfall in this area is more than 300 mm and average of temperature is under 14 OC. Carbonate rocks of Alamut are under highly dissolution because of climate condition and also high density of fractures. Rock units in this area include formations of Paleozoic, Mesozoic and Cenozoic Era. These formations consist of various clastic, carbonate and evaporite sedimentary rocks, as well as a variety of igneous rocks. The most important of carbonate formations of Alamut are Soltanieh (Cambrian), Rute (Permian), Elika (Triassic), Lar (Jurassic) and Tizkuh (cretaceous). In this research, potential of Karstification evaluated after field studies and sampling of carbonate rock units and compare them from the point of view of development of karst landforms formations. After sampling Carbonate rocks and preparing thin sections and also staining using Alizarin Red S for identification dolostone with calcite, they were studied under petrographic microscope. Investigation of remote sensing was performed by satellite images Landsat using ILWIS software to achieve separation and calculation of area of carbonate formations, as well as digital elevation model. The region is located in an area with tow climatic regimes of Mediterranean rainfall (semihumid) and Siberian high pressure (cold-ultracold). Water is the main factor of karst development. The most important of karstic landforms in the area are Karren, dissolution pit, vug, cave and karstic springs. Varieties of Karrens are microkarren, karren, runnel Karren, rill Karren, grike, rain pit. The caves of Alamut mostly identified in Ruteh Formation, for example: Sefidab cave in north of Sefidab village and Vali cave in near Gashnehrud. Angul cave in north of Dinak village also was formed in Elika Formation. The most important parameters casual Karstification of carbonate rocks in Alamut area are: purity, thickness, outcrop area and time of exposure of rock units, also rainfall, temperature and fracture intensity. Because of more rainfall and lower temperature, the north of Alamut valley shows more intensity of Karstification compare to south part of area. Based on combination of all field work and remote sensing data, the intensity of karstification in the area of Alamut in order from high to low are: Rute, Elika, Tizkuh, Lar and Soltanieh formations. Lar Formation shows maximum intensity of karstification in east of central Alborz zone, but in west of Alborz zone (Alamut) it doesn't have less intensity of karstification among all carbonate rock units. This difference is because of less thickness and outcrop of Lar Formation in study area. Based on geomorphic classification, Alamut can be classified as merokarst.
Provenance determination of dissolved load of Khar-Rud River water (S Qazvin Province) using statistical parameters
Pages 367-378
https://doi.org/10.22034/irqua.2017.701966
Saeed Khoda bakhsh, Behrouz Rafiei, Mina Afshar Nia, Shima Kabiri, Reza Ekhlas mand
Abstract River systems are considered as dynamic sediment transport and deposition agents during Quaternary period; they carry dissolved and sediment loads which are produced by weathering of outcrops of geological formations to sedimentary basins. The aim of this study is to investigate geological parameters which affect on the hydrogeochemical properties of Khar-Rud River water, using chemical experiments and statistical methods. The river basin is located in Central Iran structural zone. 35 river water samples (taken from 40 km of the western sector of this river during wet and dry season of 2013-2014 hydrological year) were analyzed. The obtained data were analyzed by some statistical methods (correlation coefficient, cluster analysis and box plot) using SPSS software. The statistical results indicate calcium sulfate and sodium chloride (originated mainly from Miocene evaporite deposits) have the highest effect on the salt content of the river water. The role of carbonate rocks with this regard were not significant.
Introduction
Quality of water resources are controlled by solubility and lithology of drainage basins; rivers are important as fresh-water resources and as an agent of ground-water recharge. The river-water quality is changed by chemical properties of the water of its tributaries. Carbonate and evaporate minerals are more important with this regard.
The drainage basin of Khar-Rud river is a part of Namak-lake basin in Cntral Iran. The aim of this research is to find the origin of the salt content of this river. Therefore, the focus of the research was on the effect of the basin lithology on the river water quality.
Materials and Method
In order to recognize the sources of the dissolved content of Khar-Rud river water, lithology of the outcrops in the river basin were studied; the emphasis was on layers with evaporate origin. 35 river water samples (taken from 40 km of the western sector of this river during wet and dry season of 2013-2014 hydrological year) were analyzed. Physiochemical analysis were performed on these samples. Water samples were taken from 10 cm depth of the water surface (Fig. 1). The physiochemical analysis include: temperature, pH, electrical conductivity, the main anion contents (Cl-, SO42-, CO32- and HCO3-), the main cation contents (Na+, K+, Ca2+ and Mg2+) and total-dissolved solids (TDS, tables 1 and 2). The obtained data were also analyzed by some statistical methods (correlation coefficient, cluster analysis, CA, and box plot) using SPSS software (version 16 for Windows) and Excel software (2007) (Table 3; figs. 4 and 5).
Results and discussion
Khar-Rud river flows westward along the Khar-Rud fault; the river basin is located in the west part of the Central_Iran Structural Zone, adjacent to the Sanandaj-Sirjan Structural Zone. The outcrops on the west (north) bank include Mesozoic formations (Lar, Shemshak, Delichay formations and Cretaceous limestone) and Qom Formation (Cenosoic). The outcrops on the east bank mainly consists of the Upper-Red Formation (Miocene), most evaporite minerals (halite and gypsum) are found in this formation (Figs. 2 and 3).
The Khar-Rud river has six tributaries (Fig. 1) each of which has a distinct effect on the chemical composition of the river water (Fig. 4). Based on the chemical composition of the waters, these tributaries are classified in three types: 1- sodium-chloride type (i.e, Shur, Dashatak, Qare-Mohammad and Hesar-Valiasr), 2- calcium-sulfate type (Qare-Mohammad and Shur) and 3- calcium-carbonate type (Nalbandan). According to the Pearson's correlation coefficients results, TDS has a positive significant relation with SO4+2, Ca+2, Cl-, Na+ and a shows significantly negative relationship with HCO3-2 and K+; a negative correlation is also observed between TDS and HCO3-. This indicates that gypsum and halite are the main dissolved components in the Khar-Rud River water; carbonate minerals are not significant with this regard.
The cluster analysis of data suggests that there are two distinct groups of components, which allows for a tentative assignment of geological sources. The first cluster contains TDS, SO4-2, Cl-, Ca+2, Mg+2, Na+, electrical conductivity (EC) which might be derived from the evaporate minerals of the Upper Red Fm.). The second cluster containing HCO3-2 and K+; they might be originated from other geological sources.
Conclusion
This research was done in order to investigate geological parameters which affect on the hydrogeochemical properties of Khar-Rud River (S. Qazvin Province) water. Results show that gypsum and halite are the main dissolved components of the River water. They are mainly originated from the Upper-Red Formation (Miocene).
The Quaternary Evolution of Kurdistan Qorveh Mountain Mass
Pages 379-391
https://doi.org/10.22034/irqua.2017.701971
Gholam Hassan Jafari, Mina Avaji
Abstract Quaternary glacial and interglacial conditions were alternately and they left geomorphological evidence overwhelming that it can be used to determine the extent of glacier and snow-borders and the study of climate change last period. It is possible due to the fact that external processes such as weathering, water erosion current and range motion could not eliminate the debris of Quaternary glacial erosion completely. Form cirque is a reflection of the topography and geology, the type and duration of glaciers. Structure stone, cracks and gaps is an important factor in a cirque cliffs and deep of cirque basins. When in the mountain, peaks height exceeds a little limit permanent snow, glaciers often in cirques. The study area lies on the political sphere three provinces of Kurdistan, Kermanshah and Hamadan between 34.752 to 35.223 latitude and between latitudes 47.411 to 47.416.
Initially north-eastern and south-western slopes of the Qorveh mountainous region was divided to Wright method. Altitude, which was 60% of cirque higher than, was considered as the permanent snowline altitude after identifying and counting cirque area of the curved lines form and sort them in descending. The position, height and geomorphological features around the cirque were identified. Snow line was estimated height of 2,200 meters on the total area of this method, and it was not much different on the northern and southern slopes. The altitude of more than 60% of cirque were the height of 2200 meters in both slope.
Materials and methods
The method is based on the present conditions Hydro-geomorphology state of minimum temperature during the Quaternary through the legacies of morphological climate changes in the Quaternary in the mountainous region Qorveh. Although the place is cold and semi-arid regions of the country due to the current temperature and precipitation conditions, but experienced cold and frost likely transition phase to warm phase cold during the Quaternary. Accordingly, is used primarily method documents the library has and field.
Results and discussion
Permanent snowline altitude was estimated of 2200 meters due to the dispersion cirque and Wright method. Analysis of the current isotherm map shows the annual average temperature this height of 8.8 ° C. This is the height of a lower temperature than the average temperature of current regional during the Quaternary. Average Quaternary temperature has been -0.12° C. But in this area there is an obvious difference in quaternary permanent snowline in the North East and South West and this is in contrast to research results that suggest the snowline altitude difference in such domains.
Conclusion, Keywords
The land surface of the slope aspect influence is undeniable on the durability snow and feeding more glaciers in mountainous regions temperate areas of the Earth's, but this effect certainly cannot be justified only with snow border. Mountain sinuosity altitude difference, the slope of the lower areas of the mountain sinuosity, extent and dimensions of the cirque and who to cirque associated with low levels of around two domains are factors that should be considered in this impact. Morphology and dominant lithology Qorveh cirque on topographic and geological maps show both sides of the Qorveh Mountain their primary form of crater-like and holes with the same height, conducive to the accumulation of snow, this has affected the ice and snow on the same quaternary snow line in two domains. In fact, early topographic conditions that follow the form tectonics, the formation of more than 60% of the cirque at a height that is known today as the permanent snowline altitude (2200 m).
Lithofacies and depositional environment of Kahrizak Formation in the east of Tehran
Pages 393-403
https://doi.org/10.22034/irqua.2017.701980
Peyman Rezaei, Parvaneh Faridi, Hengameh Najafi
Abstract The Quaternary system contains many events despite of the time constraints, which characterized from all systems of geologic. These distinctions include structural conditions, landform, climate conditions, glaciers, melting ice, development of life especially in relation to human life. In Iran, two-thirds of outcrops belong to the Quaternary deposits. Iran has noticeable geologically dynamic during the Quaternary. Neotectonic motions have been observed in the forms: new activity faulting, folding, volcanic, high extreme weathering and erosion of the oldest deposits. These activities are led to form a wide range of water and wind deposits in the Quaternary of Iran. After deposition Hezar- Dare Formation and its folding with Pasadenian phase, the youngest of Late Alpine orogenic phase, Kahrizak Formation has been settled on Hezar- Dare Formation by unconformity and under the alluvial deposits of Tehran. After Formation of thousands of valleys and folds it with Pasadenian phase, the youngest Late Alpine orogenic phase Formation unconformity on thousands of valley just Kahrizak and Tehran has been under alluvial deposits. Conglomerate of Formation Kahrizak exposed in northern Tehran unconsolidated conglomerate and in southern Tehran showed fine grain with clay composition.
Methodology
Study area based on the UTM system is located between 35°44′ to 35°45′ north latitudes and 51°42′ to 58°48′ east longitudes in the South foot of central Alborz and a distance of about 10 km from the city Tehran. In the study area geological structures such as folding and fractures are E- W. In this study, in order to identify lithofacies and depositional environment of Kahrizak Formation in the east of Tehran were studied four sequences. Stratigraphic column of these sequences were drawn based on vertical distribution facies. In order to identify the nature of the components of Kahrizak Formation, sedimentary deposits were studied from the point of view macroscopic and microscopic and were classified based on folk (1974). For study of fine-grain sediments and clay minerals 4 samples (one example from each section) were sent to the laboratory of the Geological Survey and Mineral Explorations for XRD analysis. Lithofacies has been named by Miall (2006) and according to the architectural element obtained depositional model were interpreted for Kahrizak Formation.
Results and Discussion
According to the Folk classification (1974) identify three major deposits of gravel, sand and clay and according to the architectural element of Miall (2006) identify 4 gravelly lithofacies (Gmg, Gcm, Gh and Gci), 2 sandy lithofacies (Sh, Sm) and 2 fine- grained lithofacies (Fl and Fm) that makes 3 architectural elements CH, SG and FF. XRD results showed that clay minerals, including montmorillonite, illite and chlorite are the main constituent and calcite, quartz and small percentages of sanidine, orthoclase and albite are non-clay components. Petrographical studies also showed that pyroclastic rocks, volcanoes, limestone and shale in Kahrizak Formation have originated directly Karaj Formation (Middle Eocene) or indirectly (erosion of Hezar- Dare Formation). Lithofacies are field data includes texture and structure characteristic which one of the most important tools in the interpretation of clastic sedimentary environments. According to field study and structures for example normal graded bedding, inverse graded bedding, horizontally bedded and massive, clastic deposits of massive structure and finning grain upward, Kahrizak Formation may have been deposited in gravel bed braided river with sediment- gravity flow deposits located on an alluvial fan.
Conclusion
The Quaternary system is the most important systems in Earth's history. Kahrizak Formation is deposits of this system. Due to the position of Kahrizak Formation among Hezar- Dare Formation and alluvial, this Formation can be age the middle- late Pleistocene. Identification 8 lithofacies of gravelly, sandy and fine-grained and 3 architectural elements CH, SG and FF in clastic deposits of Kahrizak Formation indicated these sediments have been settled in gravel bed braided river with sediment- gravity flow deposits located on an alluvial fan, under the effects of low rainfall and high rainfall. Finning grain upward and studied structures supported this interpretation. Petrographical studies show sediments derived from erosion of Karaj Formation and include tuff, limestone, basalt, sandstone and shale.
