Mechanisms responsible for degradation of submarine permafrost on the eastern arctic shelf of Russia
| Autor: | N. V. Libina, Natalia Shakhova, N. N. Dmitrevskii, Sergey Nikiforov, L. I. Lobkovskii, R. A. Anan’ev, Igor Semiletov |
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| Rok vydání: | 2013 |
| Předmět: | |
| Zdroj: | Doklady Earth Sciences. 449:280-283 |
| ISSN: | 1531-8354 1028-334X |
| Popis: | In 2011, a marine interdisciplinary expedition on the R/V Akademik M.A. Lavrentyev was carried out in the eastern Arctic seas. The expedition was conducted within the framework of the project of targeted basic investigations under the aegis of the Russian Founda� tion for Basic Research. These investigations regis� tered intense methane blowouts related to degradation of submarine permafrost (SMPF) in these basins. The mechanisms responsible for their degradation are determined by paleogeographic factors and recent sedimentation, as well as by structural features of the Arctic region. Under continuing degradation of sub� marine permafrost, methane emission should inten� sify. This process results in the formation of significant values of both gas and water, which migrate upward through the sedimentary section of the shelf and along the bedding surfaces from coastal heated areas to colder deeper parts of the basins forming subhorizon� tal convective cells, thus, stimulating permafrost deg� radation even under negative bottom temperatures. Submarine permafrost rocks are widespread mostly on the shelf in the eastern sector of the Russian Arctic region. This is explained by the peculiar paleogeo� graphic development of the region: due to the absence of the ice shield during the Quaternary glacial epochs, the shelf was dominated by subaerial settings with low temperatures. Alternation of subaerial and marine environments on the shelf resulted in the formation of a stratified sedimentary sequence. The regressive cycles (cooling epochs) were accompanied by intense frosting of the primary surface and formation of com� pact dehydrated members (for example, during the last Late Quaternary regression). On the contrary, the transgressive cycles (warming epochs) were marked by accumulation of unconsolidated sediments. In these periods, stable negative temperatures of the bottom water favored conservation of the stratified structure in the sedimentary section [1, 2]. |
| Databáze: | OpenAIRE |
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