Quaternary active faults effect on the abundance of underground water resources in Maharlu Basin, Central Zagros
Pages 281-291
https://doi.org/10.22034/irqua.2016.701877
Maryam Deh Bozorgi, Mohsen Rezaei
Abstract Introduction: The assessment of major faults to identify the effect of their recent activity on the tectonic evolution of the hydrogeological characteristics of drainage basins is essential. The number of springs as well as the amount of wells discharge often change corresponding to the distribution of fault zones. The 78 km long Sarvestan fault zone is the most typical case according to the distribution of springs. The fault zone, cutting across the fold-thrust belt of Zagros, is dominated by strike-slip (Berberian, 1995), and has deformed some of the previously formed folds. Furthermore, The Sabz-Pushan is an active strike-slip fault zone with length of 220 km, extended along the Zagros fold-thrust belt from northwest of the Shiraz toward the southeast. Since class 1 of Iat, indicative of the most active tectonics, and class 2 of Iat corresponding to highly active tectonics, occurs mainly in the southwestern part of the study area along the Sabz-Pushan fault zone and also the Sarvestan fault zone, in this research, the relation between these large scale faults which are active in quaternary and the abundance of water resources (spring and well) have been studied.
Materials and methods: In this research, using geological maps, satellite images and field studies, we have analyzed the faults, the springs and the wells of study area through GIS 10.1. The study area, covering an area of 9732 (km^2), is located along a simply folded belt of southeastern Zagros. It is underlain by Phanerozoic sedimentary sequences in elongated, doubly-plunging, box-shaped anticlines, and the synclines are partly buried by younger Quaternary alluvium. The SW–NE oriented contraction that initiated in the Late Cretaceous and strengthened during the Early Miocene due to the collision of the Arabian and Eurasian plates, has led to the development of NW–SE trending, SW-verging folds, and NE-dipping thrusts in the Phanerozoic sedimentary strata covering the Afro-Arabian basement, above a detachment zone of the Infracambrian–Cambrian Hormuz evaporite (Kadinsky-Cade and Barzangi, 1982; Alavi, 1994). In this research, Firstly, all available information for the area of interest was collected and compiled by using geological and topographic maps, satellite images as well as fieldwork. Then, all data were converted to digital format and consequently different layers were created, such as tectonic elements, lithology, slope, elevation and drainage density. The relationship between the number of springs and distance from structural elements is generated by cross operation between springs layer and structural elements layer using buffer and distance operation in the GIS environment. In order to identify the relationship between the amount of slope and the number of springs, the topo-spring layer was crossed with the slope map in the GIS. Springs layer was, also, crossed with 400 m altitude zones of a DEM (digital elevation model) to present the relationship between the elevation levels and the number of springs.
Results and discussion: The springs at large distance from the main structural elements can be explained by local geologic conditions, including fracturing not mapped at the scale used. The result of topo-spring layer on the the slope map is showing that there is a good correlation between slope class and the frequency of springs located in each class and represent that the number of springs is a function of slope. The output of the existence of springs on different elevation levels clears that the vast majority of springs are in 1400-2200 meter. Springs at high altitude indicate local geologic control. Drainage density has been measured as total stream length per unit area of each basin. The results reveal that high drainage density is correspondent with impermeable sub surface units and mountainous relief, whereas, the low drainage density reveals that the subsurface material are permeable and low relief which results in more infiltration capacity in the basins.
Conclusion: According to the results, there is a tendency for springs to occur at short distances from structural elements. It can be concluded that many of tectonic elements, are conduits of water. However, the water surface is not necessarily on the element itself. Most of the springs are either faulted ones or identified with major faults through the study area. It has been proved not only by correspondence between the location of springs and the trend of main faults such as Sabz Pushan and Sarvestan, but also by the huge differences in the amount of wells’ discharge. Furthermore, it is concluded that there exists an entwined relationship between the abundance of water resources and structural elements.
Introduction: The assessment of major faults to identify the effect of their recent activity on the tectonic evolution of the hydrogeological characteristics of drainage basins is essential. The number of springs as well as the amount of wells discharge often change corresponding to the distribution of fault zones. The 78 km long Sarvestan fault zone is the most typical case according to the distribution of springs. The fault zone, cutting across the fold-thrust belt of Zagros, is dominated by strike-slip (Berberian, 1995), and has deformed some of the previously formed folds. Furthermore, The Sabz-Pushan is an active strike-slip fault zone with length of 220 km, extended along the Zagros fold-thrust belt from northwest of the Shiraz toward the southeast. Since class 1 of Iat, indicative of the most active tectonics, and class 2 of Iat corresponding to highly active tectonics, occurs mainly in the southwestern part of the study area along the Sabz-Pushan fault zone and also the Sarvestan fault zone, in this research, the relation between these large scale faults which are active in quaternary and the abundance of water resources (spring and well) have been studied.
Materials and methods: In this research, using geological maps, satellite images and field studies, we have analyzed the faults, the springs and the wells of study area through GIS 10.1. The study area, covering an area of 9732 (km^2), is located along a simply folded belt of southeastern Zagros. It is underlain by Phanerozoic sedimentary sequences in elongated, doubly-plunging, box-shaped anticlines, and the synclines are partly buried by younger Quaternary alluvium. The SW–NE oriented contraction that initiated in the Late Cretaceous and strengthened during the Early Miocene due to the collision of the Arabian and Eurasian plates, has led to the development of NW–SE trending, SW-verging folds, and NE-dipping thrusts in the Phanerozoic sedimentary strata covering the Afro-Arabian basement, above a detachment zone of the Infracambrian–Cambrian Hormuz evaporite (Kadinsky-Cade and Barzangi, 1982; Alavi, 1994). In this research, Firstly, all available information for the area of interest was collected and compiled by using geological and topographic maps, satellite images as well as fieldwork. Then, all data were converted to digital format and consequently different layers were created, such as tectonic elements, lithology, slope, elevation and drainage density. The relationship between the number of springs and distance from structural elements is generated by cross operation between springs layer and structural elements layer using buffer and distance operation in the GIS environment. In order to identify the relationship between the amount of slope and the number of springs, the topo-spring layer was crossed with the slope map in the GIS. Springs layer was, also, crossed with 400 m altitude zones of a DEM (digital elevation model) to present the relationship between the elevation levels and the number of springs.
Results and discussion: The springs at large distance from the main structural elements can be explained by local geologic conditions, including fracturing not mapped at the scale used. The result of topo-spring layer on the the slope map is showing that there is a good correlation between slope class and the frequency of springs located in each class and represent that the number of springs is a function of slope. The output of the existence of springs on different elevation levels clears that the vast majority of springs are in 1400-2200 meter. Springs at high altitude indicate local geologic control. Drainage density has been measured as total stream length per unit area of each basin. The results reveal that high drainage density is correspondent with impermeable sub surface units and mountainous relief, whereas, the low drainage density reveals that the subsurface material are permeable and low relief which results in more infiltration capacity in the basins.
Conclusion: According to the results, there is a tendency for springs to occur at short distances from structural elements. It can be concluded that many of tectonic elements, are conduits of water. However, the water surface is not necessarily on the element itself. Most of the springs are either faulted ones or identified with major faults through the study area. It has been proved not only by correspondence between the location of springs and the trend of main faults such as Sabz Pushan and Sarvestan, but also by the huge differences in the amount of wells’ discharge. Furthermore, it is concluded that there exists an entwined relationship between the abundance of water resources and structural elements.
Morphotectonic analysis and dynamics of north_western Central iran, the Qom-Saveh Basin
Pages 292-306
https://doi.org/10.22034/irqua.2016.701878
Elham Ghorbani, Asghar Dowlati, Mohsen Pour Kermani
Abstract The study area with almost 13000 km2, Qom-Saveh basin, is located in most northern boundary of the Central Iran, where Eocene-Oligocene volcanic rocks and associated sediments as well as Qom Formation crops out between the dextral Koshk-Nosrat fault in the north and the Talkhab fault in the south. The Koshk-Nosrat, Saveh, Indes, Tafresh, Nobaran, Talkhab, Alborza and Koh Qermez fault zone are the most important faults, are delineated in geological maps with 1:100,000 Scale. The faults are covered by the Quaternary alluvium in the major part of its length, so morphotectonical characteristics gives more evidences about the regional activity.
Materials and Methods
Three morphotectonic indices, Stream Length-Gradient (SL), Mountain Front Sinuosity (Smf) and Valley height ratio (Vf), are used to determine the tectonic activities of 175 adjacent catchment draining in the study area, which are determined by ArcGIS 10.1 and Arc hydro software. The SL index depended to the gradient of the rivers and high value indicate higher exhumation in the basin so it can confirm activities of faults with higher dip displacement than lateral component. Smf index related to activities of faults in front of mountains and lower value indicate higher activities of faults than erosional process. The Vf index depended to of dip slip fault movements, therefore less Vf value shows higher uplift than erosion and makes V shape valley in the area.
Results and Discussion
The morphotectonic analysis consist of high SL value (>950) in south of Indes and Tafresh faults, which indicate a high exhumation in these area. Measurements on 396 mountain front for calculation of smf index, indicate low value of the index on main part of Nobaran, Indes, Alborz, Saveh, Koh Qermez, Tafresh and Kosh-Nosrat faults (<1.10), which points to high activities of the faults. Usually, faults in southern part of the study area such as Tafresh does not show such a value and activities. 40 valley, distributed all over the study area, are chosen to calculate vf index. The calculation indicate valleys related to Koh Qermez fault zone, and all over the Indes fault (whithin the study area) have lowest value of vf (<0.5), which points to high uplifting in these basins.
Fieldwork studies and satellite image processing are done to control the results obtained from the morphotectonic indices. High resolution satellite images of Google Earth and Bing have used to determine deflection and offsets of streams and rivers. Usually, main rivers near to all of the main faults of the study area show a systematic right-deflection and offsets, which suggest right lateral component activities of the faults. The right-deflection are observed on fieldworks and minimum offsets of the streams and Quaternary sediments are about 2m. Usually, Small streams and youngest Quaternary alluvial near to the Koshk-Nosrat and Nobaran Faults (NW segment of Indes fault) show a small left-deflection and offsets, which indicate the last activities of the faults are sinistral in these faults.
South of Koshk-Nosrat fault, in hanging wall, several NW-SE reverse faults are recorded in Quaternary terraces with total displacements of 5 to 10 cm. since the strike of the Quaternary faults are parallel to the Koshk-nosrat fault and have same dip directions (to south) so most probably the Quaternary faults are splayed out from the Kosh-Nosrat fault.
A clear WNW-ESE lineation with streams deflection and effected on morphology of Quaternary sediments is visible in north of Nobaran Fault in satellite images. Just adjust to the lineation several almost N-S reverse faults with dipping 30ºE with total displacements of 20 to 30cm is recorded in Quaternary terraces. Normal faults, almost parallel to the Quaternary reverse faults but with opposite dips (52W), are extended in hanging wall of the reverse faults. The total displacement of the normal faults are much less than the reverse faults (5-7cm). The reverse faults are created by activities of the lateral component of a branch of the Nobaran fault. The normal faults should form by activities of reverse fault by moving material toward foreland (west) and so breed normal faults by collapse in soft Quaternary sediments.
Conclusion
In general based on morphotectonic indices and fieldwork data and observations all the study area but south eastern part (fault zone around Qom city) and Talkhab fault, are active. The most activities of faults are seen in Koshk-Nosrat, where reverse faults cuts Quaternary sediments, Koh Qermez fault zone, Indes and its NW continuation (Nobaran fault), where reverse and normal faults cuts Quaternary sediments clearly, Saveh and Tafresh in order.
Mineralogy and geochemistry of aeolian sand dunes in south of Seh-Qaleh, Sarayan, Southern Khorasan province
Pages 307-321
https://doi.org/10.22034/irqua.2016.701879
Hamzeh Abdian Ghotb abadi, Gholam Reza Mirab Shabestari, Arash Amini
Abstract I
ran is located in arid belt of the earth that the effect of the wind erosion is one of the main phenomena in this area. In global scale, it can be said that the risk and importance of wind erosion would not be less than water erosion. Sand dunes are the common and dominant shapes in these regions. So far, detailed geochemical analysis of these dunes, e.g. barchanoids, has not been carried out in Iran; thus, research on this subject can answer to fundamental questions about the geochemistry of these sand dunes in this area of Iran. Therefore, totally 27 sand dunes within 4 different zones were sampled and studied in this research that geographically coordinates N33° 28´ to 33° 34´ latitude and E58° 21´ to 58° 22´ longitude which are located in 13 Km south of Seh-Qaleh, Sarayan city in east of Iran that is a part of northern Lut Block and is greatly affected by wind erosion due to the climatic condition, several droughts, wind blow and lack of vegetation. For this purpose, firstly mineralogical compositions of Sarayan sand dunes have been studied by Rooney and Basu (1994) method and then 12 samples were collected and analyzed using XRF method for geochemical investigations. The mineralogical study in sand dunes of Sarayan indicates that the rock fragments has the highest frequency with 50 to 62 percent abundance (mean 60.11 percent), then quartz with 33 to 46 percent (mean 36.62 percent) and finally feldspar has 1 to 5 percent (with an average of 3.14 percent) abundance. Study on major oxides shows that the SiO2 with 64.20 percent is mostly frequent oxide in comparison with the other major oxides of the studied samples. The resultant data of different oxides and relevant diagrams indicate an igneous, intermediate to felsic origin with normal quartz content and tectonically an active continental margin environment for Sarayan sand dunes. Calculated chemical index of Weathering (CIW) ranges between 82.81 to 84.96 percent which indicates an arid and warm climate. Also, slight chemical weathering and strong physical weathering in this region were approved. The study of heavy minerals can provide some evidences for recognition of probable source of sediments. Also, the values of major oxides such as MgO, Fe2O3 and TiO2 can provide evidence of abundance or lack of heavy minerals. For this reason, firstly the amounts of Fe2O3, TiO2 and MgO major oxides in 12 samples of sand dunes from four zones in a north-south direction were analyzed and no remarkable trend were found. Then the values of these major oxides in samples from four zones within a west-east direction were examined and revealed an east-ward decreasing trend. This issue related to northwestern winds that have a significant erosional influence and is in agreement with the direction of main northwestern wind which is responsible for the formation of barchanoid sand dunes in this region. The analysis of major oxides indicates that SiO2 and Al2O3 are the most abundant oxides in the studied samples. The Al2O3 values plotted versus Na2O and SiO2 show a positive relationship whereas Al2O3 versus the other major oxides such as Fe2O3, K2O, MgO, TiO2 and MnO reveal negative trend that it can be related to lack of notable amounts of clay minerals and feldspar within the studied samples. On the other hand, positive relationship of Al2O3 and NaO2 might be caused due to the presence of Na within the structure of alumino-silicate minerals. Moreover, the values of TiO2 in the studied samples indicate a felsic to intermediate composition for source rock. The study of most important trace elements in the studied sand dunes showed high values of barium and zircon and also low amount of strontium which could be caused by frequency of original minerals such as K-feldspar and also deficiency of plagioclase within the source rocks. The low values of Sr might be related to negligible amounts of carbonate minerals, e.g. calcite and dolomite, within the studied samples. In addition, the amounts of trace elements such as Ba and Zr suggest a granitic and/or reworked sedimentary source rocks, associated with high concentration of heavy minerals. Furthermore, the application of weathering indices and graphs showed that plagioclase are slightly weathered and also weathering determination graphs suggest a negligible effect of chemical weathering in this area. Consequently, the main type of weathering in Sarayan region could be considered as physical weathering.
Glacial Evidences in the Border Mountainous Areas among the Iran, Turkey and Iraq (Bozsina and Dalamper Mountains)
Pages 223-237
https://doi.org/10.22034/irqua.2016.701880
Manizheh Ghahroudi Tali, Rasul Hasani Gharnaei
Abstract In the Azarbayeghan Gharbi Province, Bozesina and Dalamper mountains are located through Oshnavieh and Uromieh devisions and near the frontiers of Iran, Iraq and Turkey. This area as mountainous curve are overlook to Margavar plain. Dalamper summit which is located in the north of Bozsina with 3 kilometers distance. Bozesina is located in the northern section of Zagros Mountain Range and through the Sanandaj-Sirjan geologic zone, which is fractured by the pressures of Arabian Tectonic plate on western areas of Iran. These glaciers are begun from 3483 m asl and its components are continued to 2500 m asl. There are some small and big cirques and many glacial valleys in the vicinity of Bozesina. In this study, we have investigated the glacial evidences of Bozesina and Dalamper mountains. Based on synoptic data of Uromieh and Oshnavieh’s weather stations in the period 1995-2012, we have deduced that annual rainfall in this region is 325 to 448 mm, 68% of the total precipitation occur in cold period, the mean of temperature is C 11º and snow cover on the mountain can remain until the late September. The study area is mainly influence of western moist air masses from Mediterranean Sea and Atlantic Ocean. Snow melting provides water flows in permanent tributaries of Baranduz River.
2-Data and methods
The interested area was initially extracted from topographic maps, scale of 1:25000, Digital Elevation Model from Aster sensor and observation in a field campaign from late August to early September in 2012-2014. Some samples were taken from the valleys’ sediments of the mountain and sediments’ sites were recorded by GPS. At first, some large and small cirques have been detected in this study area that they have extended in the northeast. This field work was very laborious in the harsh insecure and inhospitable region. Through the field of studies, we detected some cirques with unique characteristics. In Bozsina glacier valley, there are many evidences of glacial sedimentation in altitudes of 2600-3005 meters. There are many alluvial terraces downstream the rivers of Baranduz river. These terraces indicate the changing of climate in the past of the region. From detection of their sources we could achieve, 50 coarse grains have been prepared for roundness and sphericity analysis and 200 g of each sample for granulometric analysis.
3-Results and discussion
The regression model of Temperature - height and coincidence with field’s evidences have created three domains on the slopes of the Bozsina and Dalampr mountains. Some large cirques have been presented in the cirque realm spatially in the slopes of Bozesina. The most obvious Bozesina cirque includes three cirques. The cirque which is located in the northeast is larger than two others. Also, there are some cirques exists between Dalampr and Bozesina such as Myrgehfal; furthermore some big glacial valleys be on the slopes of dalamper and Bozesina Mountains. Three to four river terraces can be seen in downstream river of Baranduz. These terraces indicate that the changing of past climate in this region. Heavy snowfall in Dalamper Mountain is continued from October to May in this region and the rivers are originated from the mountain and left some sediments as alluvial fans and terraces. Snow melting at the end of ices age produced powerful flows draining and these materials evacuated from mountainous’ area. The investigation indicated that these sediments of the terraces are very angular grains and originated from Dalamper and Bozesina Mountains.
4- Conclusion
The glacial periods have left their traces and evidence such as cirques, valleys, craved lines on hard rocks. The evidences of the effecting of glacial erosion indicate the prevalence and dominance of ice and permanent snow. Accumulation effects of the glaciers include types of some moraines. These aforementioned explanations represent peri-glacial areas or freeze- thaw activity in quaternary. The results of field observations and sedimentology analyses indicated that in the last cold period the glaciers were dominant in that region and remained their traces, cirques and glacial valleys. The comparison between the roundness and sphericity coefficient with the researches of Powers (1953) demonstrated that the particles are relatively angular, stretched and not completely rounded and these indicate their durability and movements inside the ice. Given that the samples were taken from glacial valleys, with increase in distance from Bozesina cirque, 1 any significant differences in these samples. This is the typical of movements of glacier tongue in glacial period.
البرز میانی، الموت، انحلال، کارست، GIS
Pages 339-352
https://doi.org/10.22034/irqua.2016.701881
Parviz Ghazanfari, Mahdi Bakhtiari, Nader Jalali
Abstract 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 landscapes are characterized by fluted and pitted rock surfaces, shafts, sinkholes, sinking streams, springs, subsurface drainage systems, and caves. The unique features and three-dimensional nature of karst landscapes are the result of a complex interplay between geology, climate, topography, hydrology, and biological factors over long time scales. Alamut Valley is located in north of Qazvin provenance and Central Alborz structural zone. Karst develops in many types of rock, including limestone, dolostone, gypsum, salt, and some others. These rocks, subjected to different climates, assume many morphologies and landforms. Limestone purity (%CaCO3) is one of the most important controls on karst development. Karst landforms develop best on pure, dense and thick limestones and marbles. The area of Alamut is 1866 Km2. Average rainfall in this area is more than 300 mm and average of temperature is under 13 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 units of carbonate formations of Alamut are Soltanieh (Cambrian), Rute (Permian), Elika (Triassic), Lar (Jurassic) and Tizkuh (cretaceous). 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 (in comparison with dolostone, limestone is more soluable). Bedding planes and fractures (joints and faults) are of the greatest importance because they host and guide almost all parts of the underground solutional conduit networks that distinguish the karst system. The availability of water is the key climatic factor in karst development. It is certainly the principal variable controlling total denudation by dissolution.
Materials and methods
Investigation of remote sensing was performed by Landsat satellite images using ILWIS software to separate and calculate the area of carbonate formations, digital elevation model, distribution of carbonate formations, natural lineaments, slope directions as well as drainage map. Lineaments of carbonate formations extracted from satellite images and geological maps.
Results and discussion
The region is located in an area with two climatic regimes of Mediterranean rainfall (semihumid) and Siberian high pressure (cold-ultracold). Water is the main factor of karst development. The most important 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. This research show more ratio of lineament intensity of Elika and Rute formations compare to others. The drainage intensity of Tizkuh is more than Elika and Ruteh formations (Table 1).
Conclusion
Based on the combination of all field works and remote sensing data, the intensity of karstification in the Alamut area from high to low, respectively are: Elika, Rute and Tizkuh, and also 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 has less intensity of karstification among all carbonate rock units. This difference is because of less thickness and outcrop of Lar Formation in study area.
The Sinistral slip rate of Chupanan Fault during the Quaternary period (Pleistocene)
Pages 353-367
https://doi.org/10.22034/irqua.2016.701882
Fatemeh Barzi, Alireza Nadimi
Abstract Khur area as the study area is located in the northern part of Central Iran Micro continent. The Central Iran contains three smaller tectonic blocks that consist Lut, Tabas and Yazd blocks. The Khur area is located in the Yazd block and Anarak-Khur sub zone and is surrounded by the GreatKavir Fault (Dorouneh Fault) to the north. The Chupanan Fault is considered as a major branch of the Great Kavir Fault and is the most important fault of the north Khur area. Reason to absence of great systematical earthquake data along the Chupanan fault, checking of seismicity of the area based on earthquake catalog is impossible. In this research, according to the several morphotectonic evidences along the Chupanan fault and its branches, including the displacement of large and small streams and alluvial fans, activity of the faults during Quaternary period is studied.
Method
The methods used in this research, can be classified into several parts: Satellite images interpretation, field observations, structural analysis. In this research, Satellite images (SAS Planet, Google Earth, ETM and DEM) were used and processed and several faults were identified for the first time. For processing and detection of faults, we used ER Mapper, Global Mapper and Oasis Montaj software's. During geological and structural fields, every observed fault trace was mapped as accurately as the scale of the maps allowed. Fault traces were identified mainly in places where they cut competent rocks. Based on length and role of the faults, faults were separated into principal displacement zones, and minor, secondary faults. Shear sense along the faults was recognized during field studies from analysis of slickenlines and drag of beds along faults. Fault data analyzed by using FaultKinwin5 and Dips software.
For checking the tectonic activity of the Chupanan Fault zone and Khur area, Earthquake events data during the period between 1958 and 2015were calculated and then the seismic map is compared with distribution of the study area faults. A few earthquakes with magnitude approximately Mw=5 along the major and map-scale faults have been recorded.
Result
Field studies and satellite image interpretations indicated that the study area is cut by several sets of faults with different orientations. The distributions of the faults are classified in NE-SW, NW-SE, E-W and N-S. Our analysis showed that the most important set of faults have NE-SW direction and stretched parallel to the Chupanan Fault and have sinistral strike-slip component of movement along the fault planes. The Chupanan Fault has the greatest length and is an active fault because the fault and its branches faults are displaced and cut streams, alluvial fans and terraces and other Quaternary deposits. Chupanan Fault is divided into two major segments to the north and south. The northern segment is an ENE-WSW-trending sinistral fault that disruption and displaced Proterozoic to Quaternary rock units and sediments and streams. Based on several observed offsets along the fault we tried to reconstruct the movement of the fault during the time. The fault slip rate according to the amount of horizontal displacement and the age of tectonic movement was calculated. Reconstruction and calculated slip rate for the northern segment of Chupanan Fault is about 0.09 mm/yr that calculated based on 71 meters offset during 0.790 million years. In the northern Arusan village, the NW-SE-trending faults are displaced Pleistocene sediments about 250 and 500 meters and the calculated slip rates are about 2 and 4 mm/yr, respectively.
Conclusion
According to the geometry and mechanism of the faults several structures such as pull- apart basin were observed. Abbas Abad basin is one of the examples of structures related to sinistral strike-slip movement of Chupanan fault and its branches faults.
The presented morphotectonic evidences in the Khur area indicate that the major movement of the Chupanan fault during Pleistocene is sinistral strike-slip. By considering the horizontal offsets along the Chupanan fault zone in different parts of the area, maximum slip rate is measured about 4mm/yr in the north Arusan village area. By considering faults long, high rate of faults slip rates and large earthquakes recorded around this area, there is the possibility of destructive earthquakes with a long return period. According to this evidence, tectonically, the Khur area in the Central Iran is active.
Potential evaluation of economic elements in Urmia lake brine
Pages 369-379
https://doi.org/10.22034/irqua.2016.701884
Najmeh Davari, Razieh Lak, Sarmad Rouzbeh Karegar, Javad Darvishi Khatouni
Abstract Urmia Lake, with total area of 5200 km2 (before drought) , is located between 44°14' to 47°53'E and 35°40' to 38°30'N. It is the largest and saltiest permanent lake of Iran as well as one of the largest ultra-saturated lakes of the world that is compared with the Great Salt Lake of the United States These lakes, due to their exclusive characteristics, enjoy high economic value from aquatic ecosystems and strategic minerals points of view. In spite of several diverse investigations, the trend of elements deposition in relation with the evaporation has not been studied up to now. Therefore, in this study, the trend of changes and elements deposition has been studied under laboratory conditions based on the lake salinity (450g/l).
Materials and Methods
Solar evaporation method and evaporation pond used and were established to study sedimentation trend and exploitation of economic elements of the brines. At first, samples were taken from 10 aquatic regions of the lake highest water density was measured to be about 1.320 gr/ml. approximately 2025 lit brines pumped and evaporated in pre-constructed evaporation pond. The dimensions of evaporate pond are water density was measured in sampling site making use of densitometer. Evaporation lasted 3 months and 3 days. In the first two months, 3-4 samples and in the last month 2 samples, were taken daily form the evaporation pond that their volume was 120 ml. Some parameters recorded during sampling include. Date and time of sampling, air and brine temperatures, wind speed, air humidity, brine height and density. Samples were sent to the chemistry laboratory to be analyzed by Flame Photometer Corning and Titration in order to measure exact amount of Li, K, Mg and Na elements. All analyses were carried out at the first hour before salt depositions in sampling container. Sampling continued where brine height was readable and maximum mixing of brine with the deposited salts observed. In diagram 1, changes of the elements have been drawn based on Reduce the height (Elevation) of the brine in pond.
Results and discussion
According to figure 4, correlation of magnesium and potassium is the lowest. It means that when epsomite or loweit minerals are composed, potassium is higher relative to the magnesium, otherwise potassium has more than Concentration in Brine remain and when kainite is composed, all of the magnesium doesn't react with the potassium. The amount of the magnesium consumption is equivalent to the amount of the remained potassium and sulfate. Therefore, Potassium compounds excluded, but magnesium remains in the solution. At the next step, namely formation of magnesium-potassium chloride and magnesium chloride, the amount of magnesium that enters to the composition is proportional to the remained potassium and chlorine. After bonding Potassium, chlorine, and deposition of sylvite in Brine, potassium and magnesium remain combined with the chlorine to form Bischofite. At the end, due to Bischofite solubility, magnesium chloride is concentrated at the maximum amount, destructed and finally deposited. maximum Correlation of the lithium and magnesium indicates that these elements are excluded synchronously and accompanied with the remained chloride. Considering that both elements indicate high correlation with the chlorine, while chlorine is existed in the brine, magnesium and lithium illustrate ascending trend. It must been noted that the amount of Lithium is negligible in the Urmia Lake, but it could be considered that in this project, evaporation pond has not been changed in the failure point of each element. Therefore, there is a high possibility for composition change and re-sedimentation in the pond. As a result, elements with the Maximum concentration aren’t completely excluded from the environment however, with the change of brine composition these elements participate in the next reactions and chemical bonds as a chain and re-deposited in the environment again.
Conclusion
We were monitoring the brine evaporation ponds for 96 days. During this days the volume of brine showed reduction from2025 liters to881.25 (reduced by2.3 times), Increase of magnesium concentration from 56grams per liter to104 grams per liter (1.85-fold increase). Increase of potassium concentration from 10 grams per liter to 23 grams per liter (2.3-fold increase).Decrease of sodium concentration from37 grams per liter to 4 grams per liter (9.25-fold decrease) decreased and reduction of the lithium concentration from 21 ppm 34 ppm (increased 1.61-fold).Magnesium sulfate compounds (such Pntahdryt) simultaneously precipitate with mineral halite and Sylvite. In next step the amount of sulfate in brine gradually decrease, affinity of magnesium and chlorine increase and if there is potassium in the brine environment, precipitation of magnesium chloride (Carnallite) starts. At the final stage, there is the least amount of potassium in the brine and the magnesium chloride compounds (Bischofite) can been see independently.
