НАХОДКА МАРКЕРОВ МЕЖЛЕДНИКОВИЙ В ПЕЩЕРЕ УСЬВИНСКАЯ-1 (СРЕДНИЙ УРАЛ)1

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Mineral formation due to water freezing in caves causes supersaturation of the unfrozen part of the solution and deposition of some dissolved compounds in the form of minerals. Evaporation of water and degassing of the solution are associated processes in deposition of minerals. Cryogenic minerals of caves differ in morphology and isotopic composition from similar mineral cave formations not subject to glaciation. The morphology and mineralogy of cryogenic cave minerals depend on the initial chemical composition of karst water, the thickness of the freezing layer of water, and also on the freezing rate. Slow freezing of cave waters at 0°C in permafrost conditions leads to the formation of coarse cryogenic calcite. These carbonates can be used as indicators of permafrost thawing during interglacial periods. Morphological and isotopic study of samples from Usvinskaya-1 Cave (Middle Urals), as well as their 230Th / 234U dating, made it possible to conclude that the calcite is cryogenic. The calcite is represented by aggregates (up to 5 cm in size) of split crystals and spherulites from milky brown to black in color. This calcite, formed during the interglacial periods, indicates the existence of several periods of degrading permafrost in the Middle Urals, namely in the periods MIS9 (295.7 thousand years ago), MIS7 (205.1 thousand years ago), GI23 (approx. 102-104 thousand years ago) and GI22 (89.4-90.0 thousand years ago).