New data on the problem of the origin of Griva and Lake landscapes in the south of Western Siberia

Abstract

The characteristic of the upper part of the borehole 486 drilled in 1981 on the Tyumensky Peninsula, located in the center of the Chany Reaches agglomeration is given. The main feature of the section is the presence of a horizon of large frost cracks in the roof of clays of the Lower Pliocene Novostanichnaya Formation, on which the upper Quaternary cover of Griva deposits occurs. The nature of the filling of cracks by the sediments of the overlying layer indicates that they were constantly filled with ice, which had already melted under the influence of the Grosswald Flow. This horizon is important for the reconstruction of the paleoclimate and paleogeography of the region. For the first time, data of palynological study of sediments of a typical Griva in the south of Western Siberia on the example of a section on the Cape Kazantsevsky Peninsula (the northern part of Lake Chany) are presented. Sediments contain pollen of woody and herbaceous plants, single spores of mosses and ferns, as well as microphytoplankton. The presence of cells of colonial algae of the genus Pediastrum suggests the accumulation of sediments in lacustrine conditions.