پديدآورندگان :
Abdi Leila le_abdi@yahoo.com M.Sc. of sedimentology and sedimentary rocks, University of Tehran; , Rezaeian Langeroudi Saeed rezaeiansaeed26@gmail.com M.Sc. of sedimentology and sedimentary rocks, Kharazmi University; , Lak Razyeh lak_ir@yahoo.com Ph.D. of Sedimentology, Research Institute for Earth Sciences, Geological Survey of Iran, Tehran, Iran;
كليدواژه :
Hydrogeochemistry , Brine evolution , Meyghan Playa , Hoz , e , Soltan Playa
چكيده فارسي :
This research is focused on study of hydrogeochemistry and brines evolution of Meyghan and Hoz-e-Soltan Playas, based on studying brines and hydrogeochemistry evidences. Meyghan (34° 09´ to 34° 16´ north and 49° 46´ to 49° 55´ east) and Hoz-e- Soltan (34° 56´ to 35° 31´ north and 50° 53´ and 51° 20´ east) Playas as an intra-continental sedimentary basin are located in Qom watershed, in central part of Iran. Both Playas are influenced by the volume of input groundwater, intermittent streams, precipitation and evaporation. In order to study the brines and their evolution process, 19 and 25 water samples were taken from center of Playas to the margins, respectively by digging holes. Physico-chemical parameters such as electrical conductivity (EC), total dissolved solids (TDS), pH, salinity, color, size and appearance were measured in the site and geochemical analysis of brines was performed in laboratory.
Also, 95 and 109 sediments samples were collected from Meyghan and Hoz-e-Soltan Playas, respectively by handy auger and analyzed mineralogy and sedimentary characters of them. Mineralogy of samples was identified by the X-ray diffraction (XRD) technique. For this aim, bulk powdered samples (air-dried or oven-dried at 35 °C) as well as smeared slides prepared out of the 2 μm clay fraction. Major cations of both Playas are Sodium, Magnesium, Calcium and Potassium and anions include Chloride, Sulfate, and Bicarbonate, respectively. Dominant evaporative minerals in Meyghan Playa sediments are Calcite, Gypsum, Halite, Glauberite, Thernadite, Mirabilite and Polyhalite and in Hoz-e-Soltan Playa sediments are Gypsum, Calcite, Halite, Anhydrite, Polyhalite, Carnallite, Thernadite, Bassanite and
Hexahydrite. Hydrochemical analysis of input water of both Playas indicates that the water has molar ratio of HCO3 Ca + Mg and follow the second geochemical path (II) in the Brine Evolution Flow Diagram. The input water of the basin is from the Na-(Ca)-(Mg)-SO4-Cl-(CO3) type which changes into Na-Cl- SO4 type in Meyghan Playa and Na-Ca-(Mg)-Cl type in Hoz-e- Soltan Playa during the geochemical evolution and deposition of evaporate minerals.
