PERMAFROST THICKNESS MODEL FOR NOVAYA SIBIR ISLAND (THE NEW SIBERIAN ISLANDS, RUSSIA)
A.V. Gavrilov1, V.V. Malakhova2, E.I. Pizhankova1, A.A. Popova3
1Lomonosov Moscow State University, Faculty of Geology, Moscow, Russia
2Institute of Computational Mathematics and Mathematical Geophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
3LLC “Northern Research”, Moscow, Russia
Keywords: The New Siberian Islands, glacioisostatic movements, paleotemperature scenario, evolution of permafrost, numerical modeling
Abstract
The thickness of permafrost on Novaya Sibir Island was estimated using numerical modeling, geothermal data obtained in the 1970s, and an analysis of the region’s geological history. Because of the late onset of freezing at the subaerial stage of development during MIS 4 (75-55 ka ago) combined with prolonged marine stages in the Middle and Late Pleistocene and reduced cooling under the glacial cover during MIS 6 (190-135 ka ago), the current thermal regime of the island permafrost is nonstationary. A map showing the thickness of permafrost on Novaya Sibir Island has been compiled based on the simulation results. Permafrost with an estimated thickness ranging from 316 to 337 meters covers most of the island. The thickest permafrost (550 m) is found in the areas, where hard rocks of the basement with high thermal conductivity lie close to the surface. A reduction in permafrost thickness to 256 meters is due to the presence of brown coal layers with low thermal conductivity. The results of the study indicate that, under similar cryolithological conditions, permafrost in Novaya Sibir Island is 100-200 meters thinner than that in the coastal lowlands of northern Yakutia.
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