Home – Home – Jornals – Russian Geology and Geophysics 2018 number Неопубликованное

This study analyzes the mineral and chemical composition of water and sediment, as well as the isotopic compositions of water, carbon, and oxygen in dissolved and precipitated carbonates, sulfate sulfur, and hydrogen sulfide. It has been established that the groundwater and surface water supplying saline sulfate lakes belong to the sulfate-bicarbonate geochemical type with a pH of less than 9. The research indicates that the region predominantly features soda and sulfate types of saline lakes. It has been revealed that in these types of lakes, the sulfate coefficient of the water exceeds 1, while the value of this coefficient decreases with increasing salinity due to the precipitation of thenardite and the process of sulfate reduction. It has been demonstrated that changes in the hydrochemical types of lakes lead to alterations in the mineral composition of their bottom sediments. During low-water periods, autochthonous sediment accumulation predominates, with an increased proportion of dolomite and clay minerals such as kaolinite and hydromica, while montmorillonite is additionally prominent in soda lakes. Concurrently, isotopically heavy oxygen accumulates in carbonates. Further increases in water salinity are accompanied by the precipitation of gelyusite, trona, and anhydrite, as well as a transition from soda to sulfate types. The formation of thenardite results in a shift from the sulfate to the chloride type. During the period of lake desalinization, allochthonous sedimentogenesis prevails, leading to the accumulation of clastic material in lake sediments, primarily represented by plagioclases and feldspars, alongside carbonates with an isotopically lighter composition of oxygen in the carbonates.