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The project risks in relation to the tasks of Rosneft Oil Company for the exploration and development of hydrocarbon resources on the Arctic shelf of the Russian Federation are determined mainly by the geocryological situation (permafrost distribution, their thickness, average annual temperature, cryogenic structure and ice content, their thermophysical and strength properties). Therefore, the development of methods of geocryological mapping and the creation of geocryological maps are very relevant. The article presents the methods and results of mapping of the Kara Sea permafrost zone are presented. The methodology is based on a retrospective approach to the study of subaquatic cryolithozone. It consists in the use of thermal mathematical modeling, in which the conditions of one of the studied periods of the past are taken as initial conditions, and modern permafrost conditions are predicted. The stages of mapping are given. This is compiling a database, zoning according to the history of the development of the shelf, creating a paleogeographic scenario, a geological model, testing them and, finally, a geocryological forecast using mathematical modeling. The use of simulation results and their linking with field data is the final phase of the mapping. The results of research in the form of geocryological map are given. The map shows: distribution, depths of the roof and thickness of permafrost, as well as the distribution of cooled and thawed rocks. Cooled rocks are developed in the west and north-west of the sea area, where during the marine isotope stage MIS – 2 (25-15 thousand years ago) there was a glacier. The periglacial zone at the time of MIS-2 occupies the region of modern sea depths from 0 to 80-100 m adjacent to the continent. In the southwest and in the center of this zone, in the distribution of thawed, cooled, frozen rocks and their parameters, a connection with the main natural events of the Late Pleistocene-Holocene is traced. The distribution of permafrost is mainly insular in the southwest and in the center of the periglacial zone, in the northeast - mostly continuous. The central part of this zone, on the site of the continental extension of the Ob, Yenisei and other rivers, inherits the dammed subglacial basin of fresh water that existed during the MIS-2 glaciation. The thickness of permafrost in the southwest does not exceed 100 m, in the northeast it ranges from 100 to 300 m. References 1. Baulin V.V., Ivanova N.V., Rivkin F.M. et al., Coastal cryolithozone of the Northwest Yamal: problems of development (In Russ.), Kriosfera Zemli = Earth's Cryosphere, 2005, V. IX, no. 1, pp. 28–37. 2. Vasil'ev A.A., Rekant P.V., Oblogov G.E., Korostelev Yu.V., Novaya GIS – orientirovannaya karta subakval'nykh mnogoletnemerzlykh porod Karskogo morya (New GIS – oriented map of subaquatic permafrost rocks of the Kara Sea)b Proceedings of enlarged meeting of the Scientific Council on Earth Cryology RAS, 2018, V. 1, pp. 291–295. 3. Kulikov S.N., Rokos S.I., Identifying permafrost soil bodies in seismoacoustic records of shallow areas in the Pechora and Kara seas (In Russ.), Geofizicheskie izyskaniya, 2017, no. 3, pp. 34–42. 4. Mel'nikov V.P., Spesivtsev V.I., Inzhenerno-geologicheskie i geokriologicheskie usloviya shel'fa Barentseva i Karskogo morey (Engineering-geological and geocryological conditions of the shelf of the Barents and Kara Seas), Novosibirsk: Nauka Publ., 1995, 198 p. 5. Romanovskiy N.N., Tumskoy V.E., Retrospective approach to the estimation of the contemporary extension and structure of the shelf cryolithozone in East Arctic (In Russ.), Kriosfera Zemli = Earth's Cryosphere, 2011, V. XV, no. 1, pp. 3–14. 6. Certificate of State Registration no. 2016614404, Programma dlya modelirovaniya geokriologicheskikh usloviy na EVM “Qfrost” (Qfrost - the program for modeling geocryological conditions on a computer), Author: Pesotskiy D.G. 7. Certificate no. 940281, Programma rascheta teplovogo vzaimodeystviya inzhenernykh sooruzheniy s vechnomerzlymi gruntami WARM (The WARM thermal interaction calculation program for engineering structures with permafrost soils), Authors: Khrustalev L.N., Emel'yanov N.V., Pustovoyt G.P., Yakovlev S.V., 1994. 8. Khutorskoy M.D., Akhmedzyanov V.R., Ermakov A.V. et al., Geothermics of the Arctic seas (In Russ.), Trudy Geologicheskogo instituta, 2013, V. 605, 232 p. 9. Hughes A.L.C., Gyllencreutz R., Lohne Ø.S. et al., The last Eurasian ice sheets – a chronological database and time-slice reconstruction, DATED-1. Boreas, 2016, V. 45, pp. 1–45, DOI: 10.1111/bor.12142. 10. Vasil'chuk Yu.K., Izotopno-kislorodnyy sostav podzemnykh l'dov (opyt geokriologicheskikh rekonstruktsiy) (Isotope-oxygen composition of underground ice (experience of geocryological reconstructions)), Moscow: Mosobluprpoligrafizdat Publ., 1992. 11. Volkov N.G., Prognoz temperaturnogo i vodno-ionnogo rezhima zasolennykh merzlykh porod i kriopegov (na primere p-va Yamal) (Forecast of temperature and water-ion regime of saline frozen rocks and cryopegs (on the example of the Yamal Peninsula)): thesis of candidate of geological and mineralogical science, Moscow, 2006. |
