ИСТИНА

Recently, due to climate change in scientific literature great attend to the degradation of permafrost in the Arctic zone. But the process of new formation of frozen ground, which is important for understanding evolution of the permafrost zone, has not been researched. In 2015 and 2016 author observed the young accumulative low surfaces, called in Russian laida, at the Marre-Sale station on the Western Yamal. Two types of low surfaces were studied in the Marre-Sale region: The first type – estuaries flowing into the sea where river and partly marine sediments freeze (estuaries of the Marre-Yakha River); the second type – sea laida where marine deposits are accumulated (the site called Mayak in 11 km to the south of the Marre-Sale meteorological station). In the cold climate sediments accumulates and immediately freeze here i.e. syngenetically. Different conditions of sedimentation affect to the amount of organic matter and salts in the sediment that influences on their thermophysical properties during freezing.In 2015-2016 the boreholes were drilled to a depth of 3.20 m, 19 samples of sediments were taken to determine the granulometric composition, moisture, salinity and organic matter content on laida Mayak. In 2016 5 samples of the sediments were taken for determine the organic carbon and ice content from the Marre-Yakha River estuary sediments. Some samples were studied on the floodplain of the river in 2010-2011. Sediments on the low surfaces are represented by interbedding of sand, sandy loam and loam layers. In wells on the laida sites were used long-term data loggers LPC to characterize the temperature of grounds. The wells temperatures of rocks on low accumulative surface of Marre-Yakha river showed that estuaries outside zone of influence the sea waters has depth of zero annual ground temperature is 7-8 m. The same depth on the sea laidas is no more than 4-5 m. The established average annual temperature of rocks in the river mouths is about mines 5.7 below zero, which is lower than on the marine laides, where the temperature is about mines 4 below zero. The examinations of temperature regime show correlation between the temperature of permafrost and air. Low surfaces are more susceptibleto changes of external conditions than watersheds. This is explained by the features of the composition of the sediments because the sand composition of sediments and high salinity increase the thermal conductivity of the sediments. The study was supported by the RFBR grant #16-05-00612.