Quaternary Journal of Iran

Abstract 1-Introduction
Environmental changes, such as changes in lake levels and changes alluvial environment and its effects on the settlement pattern of archaeological sites, represent the human dependence on environmental resources. Findings of the Zagros region, suggesting climate change and the environment and creating opportunities and threats to human societies in the past. Archaeological evidence shows that human societies during the Holocene in settlements located in this area have been established. The occurrence of landslides in the river path and formed a dam lake in the alluvial environments such as saymareh basin with water and fertile soil, not only causes the environmental changes but also can lead to displacement, loss, or changes in the settlement’s pattern of archaeological sites within the lake area. In the early Holocene big kabir kuh landslide occurred, causing the formation Saymareh Lake. Kabir-kuh landslide and the formation of Saymareh Lake in four stages have caused some changes in the settlement’s pattern of archaeological sites within the lake. The aim of this study is to investigate different effects of formation of the Saymareh Lake on the settlement’s pattern of archaeological sites in the lake area.
2-Materials and methods
In this study, the basic information of Saymareh basin has been gathered using tools such as the position and cultural period of archaeological sites, topographic and geological maps, satellite imagery, digital elevation models, software, Arc GIS, Global Mapper, and field studies. Using these tools and field studies, the highest level of terraces lake’s sediments using GPS was obtained and the area of the Seymareh Lake and its terraces was determined based on the contour line of 700 meters. Then, the position specific sites on the lake terraces were determined and a polygon characterized by the height of the preparation of terraces was provided, and finally a 3-dimensional model of the lake terraces was drawn. Finally, the archaeological sites were classified based on their periods, overlapped on the terraces and then were analyzed in relation to each of the phases in which the lake has been formed. In the end, overlapping of sites on the terraces has been utilized to estimate the occurrence of landslides and the formation of the lake.
3-Results and discussion
Studies which have been done on Kabir-Kuh landslide and Saymareh Lake, confirm the occurrence of landslides in the early Holocene. However, the lake varve, sediment thickness and the establishment of the archaeological sites during the prehistoric on the lake terrace in the first and second stages, show that landslides occurred in the late Pleistocene and early Holocene. As a result of occurrence of Kabir-Kuh landslides in four stages and the formation of four lakes, lake terraces can be seen as a stairs in 4 different levels. Distribution of more than 300 archaeological sites on the terraces represents human’s establishment from the Neolithic period to the Islamic period in this area. Most sites are located on the first terrace and the lowest density is on the fourth terrace. This represents a decrease in the area of the lake from the first to the fourth stage. Overlapping of the sites on the first terrace represents that Neolithic sites have been formed on the terraces, so the first stage has been the formation of the lake before the Neolithic period. The second phase of the Lake has happened with a time lag after the first stage and its wideness has been smaller rather than the ones of the first phase. The existence of the Neolithic sites on the surface of the terraces also shows the formation of the lake was in the second stage before the Neolithic period. There is a long periods between the third and the fourth stages of the formation of the lake before and lakes also had less vastness than the one’s of earlier. The lack of archaeological sites before Bronze Age on the third and fourth terraces represents lakes of the third and the fourth stages were formed after the Chalcolithic period. Moreover, within all four levels of the lake terraces, the highest density of sites belongs to the Islamic period.
4- Conclusion, Keywords
Based on field studies and the distribution of archaeological sites that have been done on the lake level terraces, phases one and two of the lake were formed before the Neolithic period. Neolithic sites have been established on deposits of lake sediments after drying, because according to studies that has been done after draining the lake, the lake had become a wetland like and then sediment would have been dried. At this point, after a long delay in the settlement area of residence, the first settlement has been formed. Due to the vastness of the lake at the third and fourth phases and distribution of the sites on the surface of sediments, it seems that there have not occurred a lot of changes in the settlement’s pattern of the sites in this process.

Abstract Introduction
Cham-e Souran is located in Ravand basin in the west side of Larini Adjudan village, which is in the east side of Islam Abad, Kermanshah. It includes the wide area and an open site of Paleolithic formed on an exposed ophiolite. Compared to the other open sites of the Paleolithic, this site extended to an outdoor area and has a relatively large dispersion of tools. Since, source routing of cherts have a very important role in reconstructing cultural and communicative networks in prehistoric times. Source routing of the stone tools in this archaeological site, re-examine some issues of the Paleolithic tool-making technology and its relation with access to mines and stone deposits.Accordingly, the elemental composition of sample eight by eight pieces taken from samples of chert stone and natural geological sources to identify their potential and their connections with each other with the method of the Mass Spectroscopy Inductively Coupled Plasma (ICP-MS), sent to the Act labs laboratory in Canada and were analyzed. According to chemical analysis conducted in this study rock samples collected from outcrops Cham-e Souran with the artifacts scattered all over the area, matches the rare elements. This compliance can be seen in river’s cherts as well. The distribution of artifacts in some parts of the riverbank is much more than the exposed terraces
dominated the river. Based on this dispersion pattern, it seems that the easy access and the river stone abundance in this era have priority compared to other deposits of this study.The chemical composition of sediments and fine-grained sedimentary rocks is an important factor in the study of source rocks and sedimentary environment of sedimentary rocks (Taylor & McLennan, 1985).Materials and Methods
Since, the chemical and mineral composition of the used stone as stone tools is similar and comparable to a large extent with sedimentary rocks of the study area, studies the chemical composition of the stone tools along with data from other studies, such as petrography, is very useful for source routing of the used natural materials.In order to study the geological source used for the manufacture of stone tools, small amounts of each sample to less than 74 microns were powdered in Agate mortar. In the next step, soft samples were sent to Act Labs Company’s laboratory in Ontario, Canada. In this laboratory, about 25.0 grams of each sample were solved in multi-acid digestion method at four acids, including hydrochloric acid (HCl), hydrofluoric acid (HF), nitric acid (HNO3) and perchloric acid (HCLO4) and then measured by ICP- MS machine. To investigate the dispersion pattern of elements and compare the chemical data (trace and rare earth elements) with the average composition of the Earth's crust data, according to Taylor and McLennan (1985), and Rudnick and Gao (2003), the obtained data from the analysis of studied sample were normalized. Based on the obtained geochemical evidence, it seems that the stones used in the study of Chame Souran’s stone tools, have been taken from mafic-ultramafic deposits of the studied region in theophiolite territory in the range of Islamabad valleys and Souran’s ophiolite veins of the exposed irregularities and nearby river.Dispersion pattern of artifacts components and stone tools around the river can be seen in thelong journey along the river, indicated human groups in this region during the Middle Paleolithic stone searching for sources of stone used in tools have picked up their most required stones from Chert riverbed pebbles. Most of the river Cherts samples are respectively in a range of brown, darkred and gray colors.Results and DiscussionBased on the chemical analysis conducted in this study, rock samples collected from Cham-eSouran’s outcrops and the artifacts parts scattered in the area were consistent in terms of rare elements as well as the matching elements in samples of river chert pebbles too.The studied artifacts samples in this area in terms of density of chip components were muchmore in some parts of the riverbank rather than the rest, including exposed terraces overlooking the river.According to the dispersion pattern seems that it was in a priority use in this period rather than other deposits in the study area in terms of easy access and abundant river stone resources.Yet, despite the Harold Dibble Theory (1984) about the lack of resources of the MiddlePaleolithic stone in the central Zagros and multiple retouching of tools due to the lack of access to suitable stone resources, it can be said that in fact re-done retouching on Dibble samples in thisperiod were the manifest of special tooling industry in the central Zagros and basically it had nothing to do with the lack of stone resources and afresh retouching of this time tools cannot be connected to the lack of chert stone resources. However, this hypothesis should be studied andtesting other Paleolithic artifacts collections of the area should be consolidated.

Abstract This study provides morphology and field survey data on Ghasr-e-Ghand and Kahorkan thrusts, in the central part of eastern Makran accretionary wedge, in southeast Iran. The N-dipping thrusts with E-W strike, which brought Upper Oligocene turbidites onto Lower-Middle Miocene sediments, are one of the most important structure in this area and separate Inner Makran to the north from Outer Makran in the south. A clear facies changes are recorded in hanging wall of Ghasr-e-Ghand thrust, i.e. from shale in the east to sandstone-dominated to the West.
We combined the field data with geomorphic indices and show how lithology changes along Ghasr-e-Ghand Thrust influenced topography and morphology and so reveal not reliable active tectonic areas in view of geomorphic processing.
2_Materials and Methodes
Morphotectonic indices, Stream Length-Gradient (SL), Mountain Front Sinuosity (Smf) and hypsometric integral (Hi), which are sensitive to uplift and topography changes, are used to determine the tectonic activities along Ghasr-e-Ghand and Kahorkan thrusts. 78 adjacent catchment draining are extracted by ArcGIS 10.1 and Arc hydro software in the study area.
Field survey data were used to determine kinematic and recent activities of the thrusts, based on measurements along the thrusts, lithologic observations and stratigraphic relations across the faults.
The results of morphotectonic and field data as well as geological map and Digital Elevation Model (DEM) are combined in ArcGIS software as different layer to determine relationship between the layers and their effect on morphology of the area.
3_Results and Discussion
The morphotectonic analysis consist of low value (<1.10) of mountain-front sinuosity index (Smf) for all part of the Ghasr-e-Ghand and Kahorkan thrust, which points to high activities along the faults. Hypsometric integral index (Hi) shows high tectonic activities in west and eastern part of the Ghasr-e-Ghand and suggest tectonic activities for all over the Kahorkan thrust, while high SL value in most western part of the Ghasr-e-Ghand indicate a high exhumation for this area.
Fault measurements and related slicken lines indicate same kinematic along the Ghasr-e-Ghand and Kahorkan faults, i.e. N-dipping thrust with hanging wall movements toward south. In other hand, the Ghasr-e-Ghand Thrust cut and bended Holocene conglomerate in the eastern segment clearly. This evidence as well as thick Pliocene-Pleistocene conglomerate, which has dips of about 30º in the foot wall of the eastern part of the thrust indicate high recent activities for this segment. The most western part of the thrust in not clear and reveal an inactive fault. The kahorkan thrust did not influenced the quaternary sediments in front, which points to low tectonic activities along the thrust in the study area.
As we shown, the field survey data in contrast with morphotectonic analysis. Detail investigation on field and geological map reveal different lithology along hanging walls of Ghasr-Ghand and Kahorkan thrust. A facies changes occur from weak shale with thin and fine sandstone in the eastern segment to rhythmic sandstone and shale and some time to thick to massive volcanoclastic coarse sandstone in the western segment of Ghasr-e-Ghand. This lithology changes caused an inhomogeneous strength and so different behavior of erosion along the thrusts. The field data show high recent tectonic activities in eastern segment, although this area show very low topography compare to the western part. In other hand, big difference in strength of lithology across the thrust in the western segment, thick sandstone in hanging wall and weak marl in foot wall, caused higher topography and effected the geomorphic indices. E-W mountains in south of the Ghasr-e-Ghand and Kahorkan with almost straight frontal mountain formed by differences of strength in lithology and erosion, i.e. in base weak marl and on top thick and hard sandstone. Filed observation consist of stratigraphy contact between these lithology and for sure absent of faults. For such stratigraphic contact, Smf and width-valley height ratio (Vf) indices were measured in previous work and show a high tectonic activities for this part.
4_Conclusions
Field survey data indicate a recent tectonic activity for the eastern segment of Ghasr-Ghand thrust, which is in contrast with morphotectonic analysis. We believe facies changes in hanging wall of the thrust, caused different lithology with different strength and so different behavior in erosion along the thrust, which caused lower topography in the eastern segment with outcrops of shale in hanging wall to higher topography in the western segment with outcrops of volcanoclastic sandstone. Some E-W mountain, south of Ghasr-e-Ghand and Kahorkan thusts, make a sharp front without present of faults in the northern flank. Different lithologic strength caused to have such a landscape in the southern part of Makran. 

Abstract Behashtabad Damsite is located in High Zagros Zone, at 6-km distance from the south of Ardal Thrust Fault and 7-km from the north of Dopolan Thrust Fault. The outcropped deposits in the studied area locate in Zagros thrust zone. Paleozoic deposits contain red shales and sands belonging to Cambrian. Mesozoic deposits mostly belong to Cretaceous. The lower part contains limestones and dolomite limestones belonging to Fahlian-Dariyan. The middle part includes limestones, bituminous marly limestones, sandy limestones and thin-bedded chert belonging to Kajhdomi. Finally, the upper part contains thick-bedded limestones, abundant with karstic vugs. Thichness of the bed is 900 m and it is related to Sarvak-Ilam Formation. Goorpy Formation includes marly, silt and shaly limestones, marlstones and siltstones. Cenozoic deposits include Jahrom Formation which is made of dolomite limestones and dolomites belonging to Eocene-Oligocene. Chert nodules and shapeless cherts are seen in some beds. Assemary Formation is made of thick-bedded limestones belonging to Oligo-Miocene. Razak Formation, on the other hand, is made of thin-bedded sandy limestones, light green to gray marlstone and conglomerates. Finally, Bakhtiary Formation includes conglomerate outcrops and red sandstone belonging to Polio- Pleistocene. Quaternary deposits mostly include lacustrine sediments and alluvial fans have covered the rocky units in dam site and reservoir. These young deposits spread in a vast area in vicinity plains.
Materials and Methods:
The Dam site is located in Sheikh Mahmoud valley at southern limb of Sangvil Anticline. The study area is located at about 6 Kms south of Ardal fault and 7 Kms north of Dopolan fault with coordinates of 510 39' 10" E and 300 52' 39" N. The anticline axis is in northwestern-southeastern direction with plunge of 16° toward the southeast. This anticline is made of Jahrom-Assemary limestone and Razak marly formations. This zone is a Seismic one in Zagros Zone. Seismo tectonic activities have caused some mega fault in this zone which are mostly reverse thrust ones. The faults at the dam site are mostly secondary thrust faults, which are due to the activity of the main thrust faults. Such faults are seen in the dam site which will definitely threaten the structure. Accordingly, active faults in the dam site area were studied specifically. These local faults are covered by lacustrine deposits. So, these sediments are evidences of last events. Any movement and activity of faults, affect directly these young deposits. Investigating last movement of these faults is possible by studying lacustrine deposits belonging to quaternary period. In terms of Geomorphology, the major Morphology of study area is concluded from high mountains. They are included from limestone, dolomitic limestone and dolomite. Marlstones are located at lower altitudes. Plains and lowlands areas are covered by lake sediments.
Results and Discussion:
Based on field studies, F4 fault is one of the main local faults crossed by F1 fault. Any movement in F4 fault will be transmitted to F1 fault trace. Regarding study on F1 and F4 faults, a trench on lacustrine deposits was drilled perpendicular to F1 fault trace. There was no evidence on replacement of these young deposits. So, it`s concluded deposits ‘age is showing that the latest movement of these faults is occurred before lacustrine deposits composition. In this study, the OLS method was applied to determine the age of quaternary deposits.
Luminescence Dating Techniques are the ones based on the increase of electric charge in crystal minerals (caused by radioactivity). Such method is applied by geologists and archeologists to determine the time of the last exposure of the minerals. The estimated age in this method actually indicates when the older deposits were covered in 1-700 ka timespan. Luminescence dating was proposed by David Huntley in physic department of University in British Columbia in 1985. Basis of this method is the electrons being emitted by alpha, beta and gamma radiations, which is applicable for the deposits containing quartz and feldspar.
Conclusion:
Thermo-luminescence dating of operation method (OSL) on Quaternary deposits located on faults, a good way to approve or disapprove Late Quaternary faulting at the site is by faults in the area.According to the investigations using OSL method, these deposits belong to 190,000 years ago, and no activity evidences have been seen such as cracking, joints, etc on them. Based on seismotectonic principles, regarding the age of Quaternary Deposits, all of faults around the dam site are denied to be active.  

Abstract 1-Introduction
The Institute of geophysics of Tehran University is establishing a luminescence sample preparation laboratory.  The following investigations and experiments was performed to find the safe light for this lab. This paper is written in Farsi to provide answer to many questions that the first author has been asked locally about which light is suitable for both sample preparation lab and in the field during sampling in dark. To answer those questions we decided to publish our finding. Luminescence methods particularly optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) date the last time that quartz and feldspar has been exposed to light due to a manmade or natural event such as construction of bricks, building, dam, wall, earthquake, volcanic eruption, flood, tsunami and wind. Therefore, samples should not be exposed to natural light during sampling, transport and sample preparation in the lab.  Otherwise, natural light bleach the natural luminescence signal and cause luminescence dating method to underestimate the real age of the event.  Therefore, suitable light has a key role in establishing luminescence lab. In reviewing the excitation spectrometry of stimulated luminescence from quartz and feldspars and the various recommendations about laboratory lighting over the last three decades by different authors including Spooner and Prescott (1986), Smith (1988), Ditlefsen (1991), Galloway and Napier (1991), Bøtter-Jensen et al (1994), Lamothe, M. (1995), Spooner et al (2000), Huntley and Baril (2002), Mauz et al (2002), Berger, G.W., Kratt ,C (2008) it became clear that by changing understanding of the luminescence responses of quartz and feldspars, as well as with changes in the availability of affordable lighting technology, different light has been employed in different laboratories.  However, the reddest visually comfortable illumination is preferred for preparing quartz, and wavelengths in the region ca. 530-630 nm has been preferable for feldspar. But usually luminescence labs has chosen either red or yellow orange light for preparing both quartz and feldspar. Therefore, we decided to find the suitable light available in Iran and analyses their suitability for our purpose.  2- Materials and methods
 The choice of laboratory illumination for use with optical dating samples involves a compromise between minimizing the unwanted bleaching of light-sensitive signals while providing sufficient visibility to allow efficient and safe workplace practice.  We found that the light with wavelength between 575 to 625 nanometer satisfy both conditions.  Since 1998 the first author has used Oxford luminescence lab and laboratory illumination has changed in different periods. Here, we summarize our own adoption of such lighting by presenting some spectra from representative LED lighting available in Iran and compare it with the spectra of LED lights that is used in Oxford.  Due to the compatibility of both light, the effect of light on sample signal loess was measured in Oxford.  We made 2 lamps each consist of 5 orange LED (612 nm) and 5 red LED (633 nm) from KB technology and investigated their spectrum and intensity to recognize if they can be used to produce safelight. Unfortunately, their spectra did not correspond with company specification. 
3- Results and discussion
There was a 4% green tale in orange LED lamp spectrum. We also measured the spectra of a portable orange light which is made and used in Oxford luminescence laboratory. There was a 5.3% green tale in oxford light spectrum. We tested the effect of a 24 hours exposure to the orange light on a 90-150 µm feldspar sample (Sk1A collected from Iran) in Oxford.  Three aliquots were exposed 2 meters below the orange LED lights with minimum intensity (the intensity at 2 meter distance was 0.1 Lx). The exposure reduced the signal 1±1% which was safe for sample preparation. However, when the aliquot were exposed 1 meter below the orange light with maximum intensity (the intensity at 1 meter distance was 9.3 Lx) exposure reduced the signal 30±3%. The red LED (633 nm) lamp produced no green tale and is safe for sample preparation but does not provide safe workplace practice. 
4- Conclusion, Keywords
We deduce that the exposures of quartz and feldspar either to orange LED lamp with minimum intensity or red LED lamp for up to a few hours would have no significant effect on luminescence signal accumulated in the grains.  However, to use maximum intensity of orange LED lamp an optical orange filter is required and spectral and sample signal lost experiments should be performed.  

Abstract -Intrudaction
One of the evidences of the Quaternary climate changes in Iran , are glacial topography in mountainous areas. Understanding glacier forms such as cirques, as the accumulation of snow and ice sites and mountain glaciers supply, is very important in glacial geomorphology. Shah Alborz Mountain situated in Alborz chain system and is the only famous peak in southern part of Western Alborz. The mountain masses, including parts of Taleghan and Alamut catchment areas. Glaciers cirques topography is gentile and the main dividing lines as cliffs generally. Some of the cirques has large holes, so the native peoples called the Alborz chall (pit) mountain. The northern flank of the Shah Alborz, especially in areas where the Tertiary formations formed, influenced by water erosion processes and floods heavily. According to different formations in divide line, middle and down slopes have different landscapes.
The main objective of this paper is reconstruction of paleo-glacier equilibrium lines during the Pleistocene in the Shah Alborz Mountain (western part of the Alborz Mountain Range, Iran).
 
2-Material and methods
The main objective of this study is to identify evidence of Pleistocene geomorphological mountain glaciers on the northern flank of the Shah Alborz Mountain using experimental methods(such as Porter and  Wright methods) and field studies. Two main access routes to Shah Alborz peak include:
1-The North slope route (Alamut), respectively: Qazvin Plain – Rajae dasht- Moalem kolaye-Garmarud-hiking to Shah Alborz summit and cirque of C from Evank village.
2-The South slope route (Taleghan), respectively: Qazvin - Taleghan- Hassan Jvn village-hiking to the summit.
 After reviewing the available literature, field studies take place by using of GPS and collection data was transferred in maps of 1 : 25,000. For analyze temperature and precipitation, used synoptic stations of Taleghan (southern slope) and Moallem Kalayeh(northern slope)data . Exception of the initial field visit for general identifying, the main field works in three stages, was conducted in the summer of 2013. After identifying the glacial landforms, coordinates and other characteristics of each landforms were recorded. To display data from ArcGIS version 9.3 and analysis of location and altitude of the digital terrain model(DEM) with resolution of 90 m(SRTM) and 30(SRTM)was used .In the end, after geomorphological mapping and profiles drawing, analysis was performed on the relationship between glacial landforms and prevailing processes in the Pleistocene.
In this study, morph metric parameters of the cirque-like features with use of digital elevation model(DEM) and topographic profiles have been considered and analyzed.
 
 
3-Results and discussion
Pleistocene glacial reliefs were studied in Shah Alborz mountain based on field works and satellite image analyses. According to field studies and analyzing, glacial landforms were divided into two main groups, namely:
 
-Erosional landforms
One of the most striking landforms in Shah Alborz mountain are  glacial cirques that key to the reconstruction of Pleistocene Equilibrium Line Altitude (ELA).Cirques are an amphitheater-like shape, formed at the head of  glacier valley.
Evidence indicates the dominance of glacial erosion ice and permanent snow. According to studies, on the northern flank of Shah Alborz in the Pleistocene, there were four glacial cirques from West to East A, B, C and D, respectively. Cirque of C to 205 hectares area is the largest glacier circus in Sah Alborz Mountain. But there was no circus in southern slopes.
 
 
-Depositional Landforms
Depositional Evidence comprised of a variety of moraines, which represents preiglaciers territory. There is a huge amount of moraines in Shah Alborz cirques. Adequate supply of c and d cirques leads to the formation of a large glacier toungue.Therfore, in C and D cirques and its downstream valleys, the highest moraines can be viewed. Using Porter and Wright methods, Equilibrium Line Altitude (ELA) in the Pleistocene, was estimated to be 3472 and 3660 meters respectively.
 
 
4-Conclusion
The main objective of this research is reconstruction of the altitude of paleo-glacier equilibrium lines during the Pleistocene in the northern flank of Shah Alborz Mountain (western alborz of Iran). More glacial landforms identified in this study are, Erosional type, glacial cirques mainly. Probably in the Quaternary, in Shah Albrz, four cirques  in the northern flank and two in southern flank had actived. Snow and ice equilibrium line in Shah Alborz was located at a higher altitude than other regions like the Shahrestanak, Jajrood Valleys and Alam Kohe Mountain. At present, the areas above the height of 2000 meters are in periglacial territory or cryo-nival. In terms of Morphdynamic process, ice and melting in outcrops, gelifluction and Solifluction in fine-grained material of slopes are prevails.

Abstract Introduction
Examinations of sedimentological and mineralogical characteristics of the closed-basin cores due to the very high susceptibility to precipitation and evaporation balance are beneficial for determination and evolution of late Quaternary sedimentary specification. Orogenic movements and volcanic eruptions at the end of Cretaceous and early Eocene led to formation of Eocene volcanics in the north and some central parts of Iran. As a result of faulting which took place following the volcanism at this area, a graben was formed. This graben formed a closed basin such as Hoz-e-Soltan and Garmsar Playa, which has since become partially filled with interbedded clastic and evaporite sediments. Hoz-e-Soltan Lake with 195 km² catchment area located at 85 km of southwest of Tehran-Qom highway, in Central Part of Iran. It is sited between 34º 56´ and 35º 31´ north and 50º 53´ and 51º 20´ east at western-north of Hoz-e-Masileh. It is surrounded by Ali-Abad and kushk-e-Nosrat mountains in north and northeast, Manzarieh and Chahar mountains in west and Mohammad-Abad and Badamcheh mountains in south and southeast. The Garmsar Playa, with an area of 700 km², is located in the north of Central Iran and adjacent to the southern slopes of Central Alborz Mountains (north of Iran). The altitude of the studied area is 750-760 meters above sea level. The geology of the highlands flanking the Garmsar Basin comprises mainly Tertiary sedimentary rocks. Within the Tertiary sedimentary sequence, the Oligocene-Miocene rocks and salt diapirs, which are widely exposed in the north and west, are mainly composed of siliciclastics and evaporites, which are an important source rocks for the Garmsar Playa. The present research is aimed to separate sedimentary sub-environments of Hoz-e-Soltan and Garmsar Playas and it is based on study of sedimentary cores and sedimentary and mineralogical evidencens.
2-Materials and methods
In the research, 9 cores were obtained from Hoz-e-Soltan Playa using a handy auger in Feb 2010. Sampling from surface down to 20 cm depth of Garmsar Playa was done. The core samples were then dissected in halves longitudinally, underneath the sediments, Playa environment was detected. In total, 113 samples of sedimentary facies related to Hoz-e-Soltan Playa and 30 samples from Garmsar Playa were prepared and then analyzed using grain and mineral analytical methods such as granulometery and mineralogy. Samples were dried in an oven at 60 ̊C for 48 hours in laboratory. Analysis of particles ˃63μ and ˂63μ was performed by using a wet Vibratory Sieve Shaker and Laser Particle Sizer, respectively. Also the analyses of all clastic, carbonate and evaporite minerals were determined semi-quantitative. Field studies of the Garmsar Playa were conducted in 2008 and 2009. Depositional environment, minerals, color, grain size and other distinctive features were noted. Over forty sediment samples were collected from the Playa surface to 25 cm below the surface. X-Ray Diffraction analyses were performed for more than 20 samples. All of analyses were done in the laboratory of Geological Survey of Iran and Kansaran Binaloud laboratory.
3-Results and discussion
After obtaining the results of different laboratory studies such as granulometery, mineralogy, scanning electron microscope, morphometry and morphoscopy from 1 core (HS4) and processing the data, final investigations were done. Sediments in the central part of both Playas is almost entirely chemical (evaporite and carbonate) and in the margin of the Lake is clastic-chemical. Between the carbonate minerals, calcite is the most abundant mineral as cement in the alluvial fans and sand dunes. Quartz and calcite dominated in mud flat and saline mud flat sub-environments of Hoz-e-Soltan Playa. The clastic fraction of the Hoz-e-Soltan Playa sediment consists of quartz, feldspar and clay minerals such as kaolinite and illite, but other minerals such as muscovite, magnetite, hematite, amphibole, and pyroxene were found. Hoz-e-Soltan evaporite minerals include calcite, gypsum, halite, bassanite, thernadite, carnalite along with minor volumes of polyhalite and hexahydrite. Halite is the most abundant lithofacies in the basin. There are two main types of halite: massive halite and hopper halite. Gypsum is in the lens form, semi-translucent prismatic crystals in white, grey and yellowish brown colors. Halite and gypsum dominated in salt pan and ephemeral Lake sub-environment. From north to south, the Garmsar Basin comprises a variety of environments and their deposits including a big alluvial fan, ephemeral fluvial rivers and Playa. Their sediments generally rang from gravel size in the north through sand to mud size in the south. The Garmsar Playa comprises a variety of sub-environments, including gravel/sand sheets, dry mud flat, saline mud flat and saline pan. The sediments found in saline pans consist of alternating layers of crystalline salts and siliciclastic-rich mud. The mineralogy of salt deposits depends on the composition of the inflow waters and ground water discharge. In Garmsar Playa, various evaporite minerals such as halite, gypsum and carnalite were indentified. Halite is the dominant evaporite mineral in the studied area. The salt crusts of Garmsar Playa are characterized by elongate halite crystals chevron and other forms of crystals. Continued dissolution and reprecipition of halite and other soluble salts in the vadose and capillary portion of the crust can destroy much of the initial aligned chevron texture. Complete desiccation of the pan causes the halite crust to break up into polygons and tepees.
4- Conclusion
The type of sediments in both Playas includ slightly gravelly sandy mud, slightly gravelly muddy sand, mud, sandy mud and muddy sand. In the Hoz-e-Soltan Playa, there are three facies: clastic, carbonate and evaporite. In Garmsar Playa there are three facies: siliceous clastic, mixture of siliceous clastic with evaporative and evaporite. The minerals of the Hoz-e-Soltan Playa are quartz, feldspar, clay minerals, calcite and rarelt aragonite, gypsum, halite, anhydrite, basanite, tenardite, carnalite, polyhalite, thenardite and hexahydrite were found in Hoz-e-Soltan Playa. The minerals of Garmsar Playa are halite, gypsum, calcite, bassanite, carnalite, carnalite ammonium, sylvite, chloride magnesium potash quartz, albite, anortite, muscovite, chlorite and illite. Mud cracks, Aeolian sands, tepees and cauliflower surfaces are the commonest recognized features in both Playas. Sub-environments of both Playas include (from outer parts to inner parts) aluviall fan, snady flat, dry mud flat, saline mud flat, salt pan and ephemeral Lake. Most of the saline pan surface is covered by halite. These sedimentary sub-environments are based on changing of sedimentary environment according affected by climate change in Holocene.