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New data on the geochemistry and isotopic composition of chloride brines of the Siberian Platform are presented. The distribution of stable isotopes (2H, 18O, and 37Cl) in brines of the Tunguska, Angara-Lena, western part of the Yakutian and Olenek artesian basins and 87Sr/86Sr in brines of the western part of the Olenek artesian basin was studied in the context of the problem of genesis of highly mineralized groundwaters. Results of the study and comparative analysis of the geochemical and isotopic peculiarities of the Siberian Platform brines conform to the theory of brine formation through the interaction of connate waters with enclosing rocks.

Perennial frost mounds identified as lithalsas occur in the Sentsa River valley of the Eastern Sayan Mountains, Russia. We report the first detailed study of permafrost in this region, based on analysis of the cryostructure and distribution of stable isotopes of oxygen and hydrogen, and ion concentrations from the ice‐rich cores of two lithalsas 3–7 m high. Their main cryostructures are reticulate and lenticular, with visible ice contents exceeding 50–60%. The vertical and lateral distribution of δ18О and δD values show a step‐by‐step mechanism of lithalsa growth: in the first stage a large lithalsa formed, and in the second stage a small lithalsa formed. The more negative isotope values of ice in the large lithalsa ice probably resulted from gradual release of isotopically depleted water from the central to peripheral part of the massif during ice segregation in water‐saturated fine‐grained lake sediments. Minor variations of isotope values suggest intensive recharge of lake‐fen and meteoric water supply during freezing and lithalsa growth. Copyright © 2015 John Wiley & Sons, Ltd.

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The Late Cenozoic alluvial deposits in the Tunka depression of the Baikal Rift Zone, Russia, contain wedge-shaped structures and involutions that provide valuable palaeogeographic information about the southern part of eastern Siberia. The structure of the unconsolidated host deposits, the shape and size of the deformation structures (wedge shaped, wave like or drop like) and the physical-mechanical properties of the sediments (particle size, density, porosity, water content and colour) point to a cryogenic origin of the deformation structures, as ice wedge pseudomorphs and cryoturbations, rather than an origin associated with seismic activity or sedimentation. The oldest pseudomorphs and cryoturbations developed during climate-warming periods of the subboreal climatic phase (3600-2600 years ago).