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In August – September 2020, during cruise 49 of the R/V Akademik Nikolay Strakhov, comprehensive geological, geophysical, hydroacoustic, geomorphological and hydrophysical research studies of the western segment of the Arctic zone within the Pechora and Kara Seas began in 2018–2019 were continued. As previously, the work was aimed at mapping the relief and modern sediments in order to assess the possible negative consequences of changes in natural conditions on the Arctic coast of the Russian Federation. The main purpose of the research was to assess the evolution of natural environments within the southwestern part of the Kara Sea shelf in connection with the observed global climate change in the Arctic, as well as with the expected increase in anthropogenic load on the Arctic shelf due to the development of oil and combustible natural gas fields. Bottom grab and a shock ground tube were used to obtain samples of recent sediments of the Kara Sea. The sampling sites were determined based on the analysis of data from bathymetric bottom survey and continuous seismic profiling. During the research, the boundaries of the distribution of various facies of bottom sediments within the southwestern part of the Kara Sea shelf have been clarified. The main feature of the modern bottom sediments in the southwestern part of the Kara Sea shelf is a wide areal distribution of thin facies – pelitic muds. Along the eastern and southern coasts of the Archipelago Novaya Zemlya, a distribution zone of iceberg sediments with a width of at least 150 km has been established. The formation of icebergs should be associated with the movement of the Novaya Zemlya cover glacier, formed 30–20 thousand years ago during the Sartan Ice Age. As the studies have shown, the general Holocene transgression in the Kara Sea was periodically replaced by short regressions, at least in the southwestern part of the basin.

Global climate warming and increased anthropogenic pressure on the Arctic shelf contribute to the development of thermoabrasive processes along the coast of the western sector of the Russian Arctic.Comprehensive geophysical, hydroacoustic, geological-geomorphological, and hydrophysical scientific studies were carried out within the Kara and Pechora Seas in June – July 2019, during the 41st cruise of the R/V Akademik Nikolai Strakhov.To test modern sediments, bottom grabbers and shock tube were used. The sampling points were selected based on the materials of continuous seismic profiling and bathymetric bottom survey.As a result of the studies, mapping of the relief and modern sediments within the Kara and Pechora Seas has been carried out and it has been found that the Pechora basin is characterized by various types of sediments and deposits (pelitic mud, aleurite-pelitic mud, clay, silt, sand, moraine deposits), and the Kara Sea is mainly inhabited by thin sediments (pelitic mud). A small amount of sand and siltstone among the bottom sediments of the Kara basin should be associated with an insignificant introduction of terrigenousclastic material from the continent and its deep water. The wide distribution in the southern and central parts of the Pechora Sea of psammiticfacies is due to its shallow water, intensive supply of a large amount of sand-silty material by river flow, processes of solifluction and thermal abrasion of the coasts. In 2020, the next flight of the R/V Akademik Nikolai Strakhov is planned to continue the study of the upper sedimentary stratum and topography of the seabed of the western sector of the Russian Arctic. The purpose of the study is to substantiate the most likely scenario for the development of changes in the natural environment on the shelf, associated primarily with a reduction in the area of ice cover.

The Pechora Sea is of great economic importance for the Russian Federation. Knowledge of the history of the shelf of the Russian Western Arctic seas is impossible without studying the modern processes of sedimentation and lithological structure of the sections. Therefore, the spatial distribution and variety of types of bottom sediments was studied by direct methods of geological testing in August – September 2018 during the 38 route of the research vessel "Academician Nikolai Strakhov". The link of lithological types of bottom sediments to the forms of bottom topography of different origin was established. The characteristics of the late Quaternary sedimentary cover in the Pechora Sea were revealed. The sampling of bottom sediments of the Pechora Sea was carried out using a dredger and a shock ground tube. The sampling points were selected based on the materials of continuous seismic profiling and bathymetric bottom survey. As a result of the study, the following types of bottom sediments were identified: pelitic mud, aleurite-pelitic mud, clay, silt, sand, moraine deposits. The lithological characteristic of various types of the Pechora Sea modern sediments has been presented in the paper. It has been shown that in the most shallow water – the southern and central part of the Pechora Basin – psammitic facies dominate. This is connected with the intensive flow of sandy-silt material from the continent due to river runoff. In the northern – the deepest part of the Pechora basin – thin sediments (pelitic and aleurite-pelitic silts) are mainly distributed. The presence of moraine deposits in the southeastern part of the Pechora Sea suggests that there was a glacier here during the Late Valdaian, while the rest of the Pechora Basin was a lowland with a cryoarid subaerial landscape