This paper examines the mineral and geochemical features of lake sediments and waters in intermittent Lake Taloe, located in a semiarid climate. Minerals that belong to groups of oxides, sulfides, aluminosilicates, carbonates, sulfates, and halides are identified through the use of precision methods. The resulting mineral species are divided by genetic features into two associations: terrigenous and hydrogenic. The terrigenous association includes water-insoluble minerals, while the hydrogenic association combines typical hydrogenic minerals. The regularities of the accumulation and distribution of minerals along the lake laterally and to a depth of up to one meter are also examined. The order of deposition of hydrogenous association minerals from sulfate-chloride lake waters was established. The obtained results are confirmed and supplemented by physicochemical calculations, which show the equilibrium of lake waters with hydroxides, oxides, aluminosilicates, carbonates, and sulfates. It has been established that the formation of minerals mainly occurs through evaporative concentration in conjunction with bedrock weathering.

Results of study of mineral composition of Uskol lake bottom sediments are given in the present work. Uskol lake is located on the territory of Uybatskaya steppe, South-Minusinsk basin. These are modern alluvial-deluvial sediments mostly consisting of clays and silts. Presence of such mixed-layer compounds as rectorite, Na-monmorillonite-Na-mica, swelling chlorites at the studied object was stated the first time. Regularity of clay minerals distribution through the section was observed. It’s importance is conditioned by clay minerals ability to serve as indicators of paleoclimate and environmental conditions of sediments formation in the region. Bottom sediments mineral composition was defined: clay minerals, zeolite (analcime), quartz, feldspars, calcite, gypsum, halite.

This is a detailed study of mineralogical and geochemical characteristics of Uskol Lake sediments and waters. Uskol Lake exists in semiarid conditions and belongs to South-Minusinsk salt lakes group, Southern Siberia of Russia. It consists of three reservoirs, two of which are intermittent. Using X-ray diffraction analysis allowed determination of mineral species, among which are oxides (quartz), aluminosilicates (illite, Na- and Ca-Mg-montmorillonite, analcime, albite and sanidine), carbonates (calcite, dolomite), sulfates (gypsum, thenardite) and halides (halite). According to their origin, the minerals can be divided into two associations: terrigenous and hydrogenous. Terrigenous association includes non-soluble minerals and corresponds well to the bed rocks composition. Hydrogenous association includes minerals, which form due to evaporation processes. While studying the regularities of vertical and lateral distribution of mineral species it was stated that mostly they are evenly distributed. However, there is a tendency of gypsum and halite accumulation in the upper parts of cross sections; also it was noted that at the depths of 30-100 cm there is illite and Ca-Mg montmorillonite contents increase in relation to Na-montmorillonite content. Carbonate (calcite, mostly) contents increase at about 200 m from lake shore. The order of hydrogenous minerals sedimentation from chloride-sulfate waters of the Lake Uskol was determined. In general, minerals are precipitating as following: CO32- -> HCO3- -> SO42- -> Cl- for anions, Ca2+ -> Mg2+ -> Na2+ for cations. Obtained results are confirmed and enhances by physicochemical calculations, which show balance between lake waters and oxides, aluminosilicates, carbonates and sulfates. It is stated that evaporation processes as well as rocks weathering greatly influence the mineral formation.