Sedimentology
Mahmoud Sharafi; Mahdi Jafarzadeh; Aram Bayet-Goll; Razieh Lak
Abstract
The Urmia Lake, which is a tectonic depression in the northwest of Iran, has received a lot of eroded sediments of the geological records of the lake watershed. Because of the constant drought in the recent years, sediments have been subjected to the wind erosion and thus are an important source for ...
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The Urmia Lake, which is a tectonic depression in the northwest of Iran, has received a lot of eroded sediments of the geological records of the lake watershed. Because of the constant drought in the recent years, sediments have been subjected to the wind erosion and thus are an important source for local and regional emission during dust storms. In this research the south and west sediments of the Urmia playa lake have studied on the parent rock issue. Bivariate plots such as Th/Co versus La/Sc and TiO2 versus Al2O3 and comparison proportion of the trace elements such as La/Sc, Th/Sc, La/Co, Th/Co and Cr/Th display mainly the felsic and partly basic rocks source for the studied sediments. Major and trace spider plots of the studied sediments display their depletion with respect to Sc, V, Cr, Ni and enrichment with respect to Th and Sr, confirm mainly a felsic and partly mafic and ultramafic source rocks. Geochemistry of the major elements shows the dry climatic conditions during deposition of Urmia Lake sediments, suggested by bivariate plots of SiO2 against the sum of Al2O3, K2O and Na2O as well as the amount of chemical index of weathering.
Sedimentology
Sh. Erfan; K. Rezaei; R. Lak; S. M. Ale Ali
Abstract
Lake Urmia is the greatest hayper salin Lake in the world. This Lake, located in Azerbaijan area, Northwest of Iran is an intra-continental sedimentary basin. Its area is about 6000 km2 with an average water depth of 6 meter. Evaluation of past climate change in Lake Urmia, according to Clay Minerals, ...
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Lake Urmia is the greatest hayper salin Lake in the world. This Lake, located in Azerbaijan area, Northwest of Iran is an intra-continental sedimentary basin. Its area is about 6000 km2 with an average water depth of 6 meter. Evaluation of past climate change in Lake Urmia, according to Clay Minerals, is the main subject for current study. For mineralogical and sedimentological investigations 18 sediment cores were collected from the east and west of Urmia lake. 96 samples from 18 sediment cores in transect to the center of lake were collected and studied by X-ray diffraction (XRD) technique. The clay minerals include Kaolinite, Illite and Montmorillonite. Kaolinite and Illite are the most important clay minerals in the Coastal plain of urmia lake. Origins of clay minerals in the Coastal plain of urmia lake are generally detrital, occurred by physical weathering and indicate composition of bed rock. The study of surface sediments indicates that amount of clay minerals from margin to center of the lake such as another detrital mineral (Quartz) is decreased. In addition, amount of them towards depth is increased. Therefore, it shows the presence of a high water level and cold - humid climate in the past (late Pleistocene).
S. Alipour; Kh. Mosavi-ovenlegi; E. Hosseini; Sh. Aslanpour; Z. Haseli
Abstract
The Urmia Salt Lake as the largest hyper saline lake of the world is located between west and east Azerbaijan provinces, NW Iran. Geochemistry of trace and rare earth elements of bed sediments taken from 25 Cm of the lower most of 1.5 meters depth of drilled holes in 130 samples between 2014-2015 ...
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The Urmia Salt Lake as the largest hyper saline lake of the world is located between west and east Azerbaijan provinces, NW Iran. Geochemistry of trace and rare earth elements of bed sediments taken from 25 Cm of the lower most of 1.5 meters depth of drilled holes in 130 samples between 2014-2015 were investigated. General geochemical composition of samples revealed a very heterogeneous variation of major oxides at NW, NE, SW and SE parts of the lake. MgO, CaO and Na2O show a high enrichment compared to UCC, PAA and NASC values. Main minerals of the bed sediments include halite, calcite, ankerite, quartz, orthoclase, augite, hornblende and chlorite. The overall geochemical composition of sediments, resemble ferruginous shale and graywacke sandstone. Weathering in the various parts of the bed sediments is relevant to general climatological characters in the region. Rb and Sr among trace elements show high anomaly in respect to UCC, PAAS and NASC, while Eu indicated high depletion, especially at SW corner of the lake. Geochemical comparisons indicate the major role of different rock units in forming bed sediments rather than sediments carried by entering rivers to the lake.
Hydrology
A. Shemshaki; Gh. H. Karami
Abstract
The water level of Urmia lake during the last twenty years has been significantly declining. Along with changes in quantity, water quality has also substantially changed. In this article, attempts has been made to identify the relationship between water quality and quantity to have a better understanding ...
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The water level of Urmia lake during the last twenty years has been significantly declining. Along with changes in quantity, water quality has also substantially changed. In this article, attempts has been made to identify the relationship between water quality and quantity to have a better understanding of the changing history of the lake during the geological past. This can help to better explore the risk factors influencing the drying process of the lake. This understanding can therefore be employed to appropriate planning and management procedures in order to revive this lake effectively. Based on this study, the lake water in the levels higher than 1286 meters (MSL) is brackish to fresh and is not of saline type. Thus, it seems that, in the late Pleistocene, the lake water was of a fresh type where the water level was higher than 1297 meters. The study revealed that the lake become to a playa-type environment in water level of about 1273 MSL. The present water level of 1270 meters suggests that the lake has a dominantly playa-type environment. In this environment, increase in precipitation and inflows will lead to a rapid increase in reservoir volume; and vice versa, a stop or decrease in the precipitation and inflows with an increase of temperature and evaporation will lead to a rapid reduction in reservoir volume. This study estimates that a volume of over 9.5 billion cubic meters of water is necessary to revive the Urmia Lake.
M Nakhaei; M Vadiati; KH Mohammadi
Abstract
In the last few years, saline water intrusion in the Urmia aquifer has deteriorated groundwater quality. As a result of irremediable environmental impacts and deterioration of aquifer conditions, study on groundwater vulnerability due to saline water intrusion is very serious. This study focuses on the ...
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In the last few years, saline water intrusion in the Urmia aquifer has deteriorated groundwater quality. As a result of irremediable environmental impacts and deterioration of aquifer conditions, study on groundwater vulnerability due to saline water intrusion is very serious. This study focuses on the application of the new method, GALDIT, for the assessment of aquifer vulnerability due to saline water intrusion in the Urmia Lake. The computing of the GALDIT index is based on six parameters:Groundwater occurrence (G), Aquifer hydraulic conductivity (A), High groundwater Level above sea level (L), Distance from shore (D), Impact of existing amplitude and extensive of saline water intrusion (I), and Thickness of aquifer (T). The results of this study showed GALDIT indices were very high, high, moderate, and low in the northeast, southeast, north, and low in east of the aquifer, respectively.The GALDIT approach assists to managers for evaluation of aquifer conditions.
j Darvishi Khatouni; R Lak; A Mohammadi
Abstract
The Lake Urmia is the greatest hyper saline Lake in the world. This lake, located in Azerbaijan area, Northwest of Iran is an intra-continental sedimentary basin. Its area is about 6000 km2 with an average water depth of 6 meters. Hydrochemistry of the water resources of the basin showed mainly chloridic ...
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The Lake Urmia is the greatest hyper saline Lake in the world. This lake, located in Azerbaijan area, Northwest of Iran is an intra-continental sedimentary basin. Its area is about 6000 km2 with an average water depth of 6 meters. Hydrochemistry of the water resources of the basin showed mainly chloridic and sulfidic composition due to the geology of the surrounding areas and its variable lithology and Inlet water are supplied from the permanent and seasonal rivers. The hydrochemical investigations were carried out over a time period from 2007 to 2012 using previously published data together with newly collected water samples. 120 samples were collected during 6 years. The analaysis results showed Na-Mg-Cl type of the brinefrom 2007 to 2010, which is comparable with the Great Salt Lake in the USA. The chemical composition of lake in 2007 showed the percentage of sodium is higher than Magnesium. In 2011 and 2012 water composition is HCO3<<Ca+Mg. That is, the path of brine composition on the Eugster and Hardie flow diagram has changed from row III2b (Na-Mg-Cl) to (Mg-Na-Cl) in 2011 and 2012 after halite crystallization and may finally result in Mg-Cl-SO4 brine type in the future. The Sodium to Magnesium ratio is 5.12 in 2007. However, this amount in 2011 is 0.68 and 0.56 in 2012. In future, with Increasing ofevaporation, the Magnesium to sodium ratio increases and chemical compositions of the brine in the north and south of the Shahid Kalantari Highway experience more difference.
F Khademi; H Pirkharrati; S Shahkarami
Abstract
The Urmia Lake is one of the old and very important water bodies in Iran. Nowadays, for various reasons, this lake has become an environmental crisis. What is happening today to this lake happened to the Aral Sea not long ago and converts it to a salt marsh with huge damaging environmental effects. Drying ...
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The Urmia Lake is one of the old and very important water bodies in Iran. Nowadays, for various reasons, this lake has become an environmental crisis. What is happening today to this lake happened to the Aral Sea not long ago and converts it to a salt marsh with huge damaging environmental effects. Drying of the Urmia Lake has many environmental consequences such as degradation and salination of soils. In this study, using Landsat satellite images, Remote sensing (RS) techniques and GIS software, salt marsh around the lake was studied. First, saline areas were detected in satellite data and then the desired color combinations defined in the ENVI software. At last, after extracting the maps from images, area changes were studied and environmental impacts that will occur due to increased saline lands were studied. In a 13-year study period of Landsat satellite images, the trend shows a very rapid increasing of saline lands. In 1998, an area of salt marsh 28.516 km2 has increased to 744.411 km2in 2011.This amount is nearly 26 times since 1998. Increasing of the saline lands, lead to the degradation and loss of soil fertility, and if this trend continues itcan lead to areas of fertile land out of agricultural production.
A. Amini; M. Shahosseini; A. Mohammadi; M. Shahrabi
Abstract
The hypersaline UrmiaLake is the most important intra-continental environment in Iran, with distinctive geological, environmental, and biological, characteristics. The Shahid-Kalantari Highway (under construction) between Urmia and Tabriz cities passes through this lake. Some 14 km dyke is constructed ...
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The hypersaline UrmiaLake is the most important intra-continental environment in Iran, with distinctive geological, environmental, and biological, characteristics. The Shahid-Kalantari Highway (under construction) between Urmia and Tabriz cities passes through this lake. Some 14 km dyke is constructed in the lake for this passage and about 1400 meter is left for a bridge construction. The role of the constructed dyke on sedimentation pattern seems significant, as understood from satellite images and field observations. This study deals with sedimentological characteristics and origin of deposits along the Shahid-Kalantary Highway of UrmiaLake. Availability of 4 cores from boreholes drilled for geotechnical studies provided a good opportunity for this study. This study is carried out on the cores of the 4 boreholes (340 m thick in total) and samples collected from the sea floor along the dyke. Mineralogical, textural and structural characteristics of the sediments were studied for determination of chemical, biological and physical processes responsible for their development. Some 396 plugs from the cores (0.7 to 1 m interval) and 15 samples from the sea floor (cores of 20-40 cm long) were selected for these purposes. To investigate the role of surrounding rivers in providing detritus material to the study site, samples from suspension load of the major feeding rivers are collected. Major characteristics of these samples are studied and compared with those from the study area. All available data on the discharge and sediment load of the major feeding rivers are collected and analyzed for this study. Size and shape are two major textural characteristics investigated in this study using petrographic methods (including SEM). Chemical composition of sediments is studied by petrographic (coarse material) and XRD (fine material and clay minerals) methods. Organic mater, carbonate content, and evaporate portion of the sediments are measured using standard techniques introduced in the literature. Results from this study shows that 25 to 40 % of the studied sediments are derived from the land, through feeding rivers and 60 to 75 % of them are formed within the basin by chemical and biological processes. Quartz, feldspar, volcanic lithics, heavy minerals including pyrite and pyroxene, and clay minerals are major detrital constituents of the sediments. Kaolinite, illite, and montmorillonite are common clay minerals in the sediments, which characteristics are similar to those determined in the suspension load of feeding rivers. Some carbonates, as carbonate lithics, and organic material are also found detrital in origin. Gypsum, halite, calcite, and aragonite are the chemical components of the sediments occur as evaporate and mud crusts, or coated grains. Fecal pellets and some coated grains (produced by algae) are the main biological components of the studied sediments. Pyritization of pellets, especially in lower parts of the cores, is commonly observed, so that, pyrite is presented in the sediments both in detrital and diagenetic forms. Distribution pattern of the major constituents along the studied cores reflect the significant role of sea level fluctuation in their development. Results from this study show that the chemical components of sediments developed during the stages of sea level fall, during which the sea was barely receiving sediments from the land (dry periods). The coated grains of this origin were developed in the basin margin, where the wind-induced waves produced a relatively high energy sub-environment in the margin. The biological constituents of the sediments were developed during sea level rise (lower salinity conditions), during which environmental conditions were not suitable for development of chemical sediments. The origin of detrital material is related to the feeding rivers. TalkeRud in the eastern part of the sea had a major role in providing coarse terrigenous particles to the basin. Major characteristics of the detrital quartz, feldspars, pyroxene and volcanic lithics are similar to those find in the volcanic outcrops of the IslamiIsland and TalkeRud alluvial fans. The Shahr Chay, Nazlu Chay, and Barandoz Chay in the west and ZarinehRud and SiminehRud in the south had significant role in providing fine terrigenous (clay minerals) to the studied area.
On the basis of distribution pattern of terrigenous sediments and their ratio to chemical and biological sediments, the feeding rivers around the lake (major suppliers of the terrigenous sediments) are classified into three groups (most, moderate and low effective). This is designed for further investigation on the controls of sediments accumulation along the highway. This study emphasizes on more significant role of chemical and biological processes on the sediments accumulation in the studied area, than that of physical processes. Due to significant role of sea level fluctuation in chemical and biological sediments development, a thorough control on sea level fluctuation (dam construction, artificial evaporation for salt acquisition, and etc.) is vital in this basin. In this regard any program for sedimentation control along the dyke must take greater consideration on chemical and biological deposition.
