Depositional pattern of sediments in a dry-lake Playa in NE Iran; Implication for geomorphologic characteristics (original) (raw)
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Carbonates and Evaporites, 2023
This study aims to investigate Sabzevar playa in the northeast of the Great Kavir in terms of geomorphology, bulk and clay mineralogy, as well as the geochemistry of core sediments from the surface to a depth of 1 m. The results suggest that up to 50% of Sabzevar playa is made of clastic components (mostly quartz and clay minerals), which increases toward the depth, though this trend is bucked by evaporite minerals (mostly gypsum, calcium carbonate, and halite). According to the mineralogical trend and geochemical evidence, Sabzevar brine has evolved into a Na-SO 4-Cl type. Granulometry studies suggest drastic fluctuations and higher energy costs during sediment deposition at a depth of 1 m compared to the surface. The micro-morphology of quartz grains is due to the windborne surface sediments and waterborne deep grains. A combination of clay mineralogy and geochemistry of elements exhibits a higher evaporation rate at the surface than at a depth of 1 m, suggesting that the area has witnessed a climate change from a warm humid climate in the past to a warm arid climate in recent years. Sabzevar playa is characterized by an unconventional Bull's-eye pattern with a concentration of calcite around the playa, gypsum in the center, and halite in the west. This research also explores the hydrological characteristics of the study area based on geomorphologic surfaces findings revealing that the groundwater level was higher in the west than in the center and east of Sabzevar playa, leading to the formation of halite and the development of a salt pan in the margin.
A Quaternary study by mineral compositions along salty-clay surfaces of Sabzavar dry-lake playa
2018
We studied mineral and deposition records in a dry lake playa, Sabzevar, northeastern, Iran. For sampling soil and depositional records, 12 samples were taken along Playa surfaces including firm puffy ground, clay-carbonate plain, and salty pan with the dominance of Halite salts. All profiles were excavated by hand auger with a 5 cm diameter head to a depth of ~5 cm. Sediment analysis was carried out through soil physicochemical properties and XRD/XRF were done for mineralogy. According to the XRF results, main minerals of quartzite and calcite are observed over the playa. After XRD results, the major minerals in the sediments were categorized as quartzite, halite, calcite, and gypsum. Afterward, the minerals of halite, calcite, gypsum indicate dominant evaporate process. Enrichment of evaporate minerals on the surface grounds are an evidence of a variation hydrostatic level of Sabzevar playa, which can be a signal for a wet lake in the past and dried one in the present day.
Sedimentology and origin of Meyghan lake/playa deposits in Sanandaj–Sirjan zone, Iran
Carbonates and Evaporites, 2012
The inland lake/playa of Meyghan is a closed basin in the Sanandaj-Sirjan tectonic zone of Iran, containing largest mineable sodium sulfate deposit of the Middle East. The Late Pleistocene-Holocene sediments of this lake/playa were studied for sedimentological and mineralogical characteristics, brine evolution path and the record of climatic variations in the area. Minerals of this lake/playa are mainly evaporites along with some finegrained clastic components. Evaporite minerals include calcite, gypsum, halite, glauberite, thernadite, polyhalite, natron along with minor volumes of bassanite and sylvite. Gypsum and halite abundances show increasing trend from margin to the center forming a Bull's-eye pattern. Main clastic components are fine-grained quartz, muscovite, clay minerals, calcite and organic matters. Clay minerals are the most dominant clastic minerals in these sediments. In the surface sediments of Meyghan lake/playa, illite and chlorite abundances reduce from the margin to the center which is contrary to the general patterns of clay distribution in other playas. Inflowing water with low percentage of ions and Na-(Ca)-(Mg)-SO 4-Cl-(CO 3) type evolve into a brine with high ions concentration during the geochemical evolution and mineral deposition. Finally, geochemical evolution resulted in a Na-SO 4-Cl type brine. While clastic components (calcite, quartz and so on) show increasing trend with depth, evaporites abundances show opposite trends. Furthermore, the average grain size of sediments increases with depth indicating higher energy in the past. Typical sedimentary structures of lake/playa environment that are present include efflorescent salt crusts composed of halite, tepees, polygonal structures as the most common sedimentological features of this basin as well as Puffy Grounds. In conclusion, sedimentary records of this lake/playa represent important climatic changes in the area from relatively more humid cold climate in the Late Pleistocene to semi-arid warm climate in the Holocene, with higher evaporation rate.
A study on the Salt (Urmia) Lake in northwest of Iran focused on sediments lakebed
2019
Lake Urmia, as the largest and saltiest permanent lake in Iran, being also known as one of the world’s largest and saltiest lakes, has emerged after the last glacial period due to the tectonic activity of compressive faults specially Tabriz and Zarrineh-Rud faults in the northwest of Iran. This relatively young lake has stone foundation being composed of limestone and marlstone without any folding (Qom Formation) in Miocene Epoch on which about 30 meters of soft lake sediments are deposited. More than 80% of these deposits are chemical and evaporative along with mainly aragonite, calcite, and halite minerals with biological origin. The presence of clastic thin layers consisting of quartz, feldspar and kaolinite, especially at the entrance points of the rivers, indicates temporary climate change and lake salinity. The thickness of the evaporitic sediments has remarkably increased with depth decrease in the southern part of the lake along with the increase in evaporation, causing the ...
Geochemical Evaluation Sediments and Water of Shurabil Lake, Northwest of Iran
2013
Shurabil Lake, situated in south west of Ardebil City (Northwest of Iran) with 2 km distance from city centre, is one of the natural and continental lakes in Iran. It was created as a result of Shurabil fault activity within the limy hillocks in early Quaternary. This is the type of pluvial lake and has been formed along with argillite interlayers on the synclinal bed with limymarl basement rock. The samples taken from sediments deposited on the surface of the lakebed and investigation of the results from granulometry and chemical analyses indicate that these sediments are actually limy sands carried into the lake as a result of erosion of marls in surrounding hills. On the western coast of the lake, the above mentioned sediments are characterized with clayey sand texture, while towards the eastern side as the presence of clastic materials decreases and granules within the sediments get finer, the texture becomes silty. Lakebed sediments with PH>7, contain 3 – 12% of organic mate...
Study Clastic Sediments and Evaporite Deposits’ Changes in the Sedimentary Core Lake Maharlou, Iran
Modern Applied Science, 2016
The continental environments, lakes are proper for deposition locations of evaporites. Evaporite minerals are formed wherever the evaporation rate is more than incoming water to the basin. In this article the evaporate deposits (Calcite, Gypsum and Halite) are studied in a sedimentary core of Lake Maharlou, Zagros Mountains, South of Iran. The core sample treated for getting Magnetic Susceptibility values along with the core as well as basic sedimentological data including grain size, Total Organic Matter and carbonate contents. NaCl is determin ed by gravimetric analysis. Loss on Ignition is applied to measure and estimate the amount of (OC), (Ca) and (SO4) mineralogy of which is determined by SEM method. The exists a direct relation between evaporation deposit formation of lake water level reduction. Accordingly, the change in the sediment stratum indicating the level of evaporations. The results indicate a lower extant of gypsum than Ca and NaCl. The sequence of layers principle,...
Scientific Reports, 2020
Jazmurian playa was an ephemeral lake with a large catchment in southeast Iran, which dried up over the last 10 years as a result of prolonged drought. As the lake was recipient of incoming industrial water with trace metals deposited to the sediment, the dust is the cause of environmental concern of the region and requires evaluation and better management. The aim of this study was to evaluate the environmental and ecological pollution of Jazmurian playa. Hence, 24 collected surface sedimentary samples were analyzed with ICP-OES. The environmental pollution indices including degree of contamination (Cd), geoaccumulation index (Igeo), enrichment factor (EF), pollution load index (PLI) and potential ecological risk (PER) were determined. The study revealed moderately to strongly pollution levels of Pb, Ni and Al, while Dy, Pb, Y, Yb, Sm, Te, U, Cu, Mn, Sc represented moderate pollution. The EF values indicated four sites were highly enriched with Dy, Pb and Ni. The PER results showed...
Open Journal of Geology, 2016
As sediments are produced and accumulated in sedimentary basins especially in dams' reservoirs and they highly affect the reservoirs life span, it is essential to scrutinize the effect of lithology and types of geological formations of an area on the life span of reservoirs specifically from the viewpoints of the erodability of these formations due to their lithology type. Lali area, Khuzestan, Iran and the water catchment of the intended area (based on geological situation and Taraz dam situation) are placed in the sedimentary-structural zone of the folded Zagros. The method of this research is based on analyzing the topography and geology maps and field work in order to identify the lithology of the geological formations. In fact, the amount of its erodability has been characterized by the type of the geological formations. The current research aims at putting the geological results, lithological data of the formations types and the outcrop of the soil-lithological units together in order to evaluate the sedimentary and erosive factors of these units and precisely identify the area's geological formations to remove the ambiguities in this issue. Studies indicate that formations made of looser gypsum and marl like Pabde-Gurpi and Gachsaran are exposed to more sedimentation and erosion than the formations made of compacted lime stone and conglomerate with silica-lime cement such as Bakhtiary and Asmari formations and the sand stones of Aghajari formation reveal the moderate to high resistance. Thus, the lithological identification of the formations, the type of sedi