TRACES OF CRYOGENIC PROCESSES IN THE LATE PLEISTOCENE SEDIMENTS OF THE PUR-TAZ INTERFLUVE (WEST SIBERIA)
E.A. Slagoda1,2,3, A.A. Novoselov2, E.S. Koroleva1, A.O. Kuznetsova1, V.I. Butakov3, Ya.V. Tikhonravova4, E.P. Zazovskaya5
1Earth Cryosphere Institute, Tyumen Scientific Centre SB RAS, Malygina str. 86, Tyumen, 625026, Russia
2Tyumen State University, Volodarskogo str. 6, Tyumen, 625003, Russia
3Tyumen Industrial University, Volodarskogo str. 38, Tyumen, 625000, Russia
4Melnikov Permafrost Institute, SB RAS, Merzlotnaya str. 36, Yakutsk, 677010, Russia
5Institute of Geography, RAS, Staromonetny per. 29, Moscow, 119017, Russia
Keywords: cryogenic structure, post-cryogenic formations, origin of sediments, sediment age, sediment compositio, microstructure of sediments, authigenic minerals
Abstract
Reconstruction of paleoenvironmental conditions, origin of sediments and permafrost evolution as well as identification of cryogenic and paleocryogenic formations based on sediment cores (small fragments of geological record) are among key scientific problems of cryolithology. We have analyzed grain-size distribution, geochemistry, and water content of sediments from the permafrost section in the North of Pur-Taz interfluve (West Siberia). Moreover, we have described the floristic composition of plant remnants, their age and the cryostructures found within these sediments. Optical and electron microscopy revealed the micromorphological features of thin sections and specimens of rocks. Based on the sediment core data from the borehole, we have established the alluvial, lacustrine and proluvial origin of sediments. Furthermore, we have reconstructed the conditions of sedimentation in this area and have established the Karginsky age of these sediments. This age corresponds to formation of 3rd lacustrine-alluvial plain in the lower course of Taz river. The conditions of early diagenetic transformations of sediments as well as epigenetic and syngenetic permafrost were reconstructed based on cryogenic and post-cryogenic formations, cryostructures, microstructure and authigenic minerals. We were also able to reconstruct the Late Pleistocene sequences of freeze-thaw cycles in the upper part of the permafrost section of the Pur-Taz interfluve.
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