MOSCOW, September 22. /TASS/. Russian scientists reconstructed the history of the formation of a heaving ridge typical of the north of Western Siberia near the Nadym River— a relief characterized by numerous elevations, reported the press service of Tyumen State University.
The processes of the formation of such convex relief areas from various types of deposits are widespread within large peat bogs in the Arctic regions of the Northern Hemisphere. They have long been the subject of study. Special studies of their age, developmental history and features are rarely carried out, although these questions are considered crucial in relation to the conditions of the northern taiga of Western Siberia.
“The lower loamy layer with a volumetric ice content of about 60% is subject to heaving. There are layers of pure ice underneath. Heaving processes have taken place there earlier, in colder climatic conditions compared to modern ones. During the formation of this ridge at the end of the Late Pleistocene, there was an accumulation of loamy and sandy sediments, at the beginning of the Holocene — about 10,000 years ago — waterlogging occurred," the press service quoted Director of the Research Institute of Ecology and Rational Use of Natural Resources of Tyumen State University, Doctor of Biological Sciences, Andrei Soromotin as saying.
He noted that the stage of active formation of uplands there began about 5,000 years ago, and now the upper organic layer of the ridge is gradually thinning. Scientists have presented new data on the cryolithological structure of such a ridge, typical for the north of Western Siberia, located in the lower reaches of the Nadym River. The study was supported by the Russian Foundation for Basic Research (RFBR) and the government of Yamalo-Nenets Autonomous Region and as part of a state assignment to the Institute of Geology and Mineralogy of the Siberian Branch of the Russian Academy of Sciences.
It showed that the ridge has a three-layer peat-sandy-loamy structure and belongs to the peat-mineral type. Scientists from St. Petersburg and Tyumen State Universities, Sobolev Institute of Geology and Mineralogy of the Russian Academy of Sciences (Novosibirsk) and the Earth Cryosphere Institute of Tyumen Scientific Center of the Russian Academy of Sciences took part in the study of heaving mounds near the Nadym River. Researchers, using radiocarbon analysis, determined the age of organic deposits, the shape and nature of the surface of sandy quartz grains in the soil. The data was obtained as a result of drilling two wells — at the top of the ridge and at the bottom. Then the recovered cores were analyzed. The authors of the article propose to consider similar peat-mineral and mineral forms of frost heaving in the form of mounds and ridges as a separate type of cryogenic relief.