THE CONCEPT OF MAPPING THE CRYOGENIC DYNAMICS TENDENCY OF THE COASTAL ZONE (BY THE EXAMPLE OF EAST SIBERIAN ARCTIC SECTOR)

• Main Authors: A. V. Gavrilov, E. I. Pizhankova
• Format: Article
• Language: English
• Published: Laboratory of Complex Mapping, Faculty of Geography, MSU 2017-01-01
• Series: InterCarto. InterGIS
• Subjects: permafrost and chilled rocks; subaerial and submarine permafrost; coastal erosion; coastalmarine and alluvial-marine sedimentation; permafrost degradation and aggradation
• Online Access: http://intercarto.msu.ru/jour/article/view/511

<p>We have proposed a conceptual model of dynamics of frozen and cooled below 0°С rocks of the coastal zone. The map shows the areas of degradation, formation, and a stable state of permafrost. The basis of mapping is the type assignment of the coastal zone based on the transformation factors. This geological structure is characterized by ground ice occurrence, ice-bearing rocks, modern vertical movements, hydrodynamic processes, and solid runoff. Depending on the combination of these factors, in some cases sedimentation, accompanied by syngenetic freezing of rocks occurs in the coastal zone. In other cases, the seashores retreat, and the frozen deposits of the underwater coastal slope thaw. In other cases, the banks retreat, and the permafrost sediments of the underwater coastal slope are thawed. This happens due to intensive salinization at the sea depths of 0- 2 m, where sea ice adfreezes with a bottom, as well as due to summer warming of near-bottom water. In the third case, under stable shores, the bottom rocks in the depth interval 0-2 m basical remain frozen and only in the interval from 2 to 3-5 m they are cooled. Alluvial-marine sedimentation in the mouths of rivers depends on a ratio of the volume of solid runoff and vertical tectonic movements. This can lead to formation of new permafrost or to submersion of sediments under the sea level and following thawing.</p><p>Mapping of the tendency of the cryogenic dynamics of the coastal zone is based on its typing, the regional permafrost, aerospace and cartographic data. Such a map has been compiled for the eastern part of the Laptev Sea and for the western part of the East Siberian Sea. It shows the types of frozen and cooled rocks—degrading, aggradating, stable—and their subtypes. The basis for identifying the rock types has been provided by the factors that determined the dynamics of the state of frozen and cooled rocks. Selected subdivisions have been characterized by a cryogenic structure, the presence of ground ice, bulk ice content, neotectonics and cryogenic processes. </p>