Permafrost of the east Siberian Arctic shelf and coastal lowlands
Introduction
The shelf and coastal lowlands of the Laptev and East Siberian seas (Fig. 1) represent a virtually flat accumulative plain. The largest part of the shelf has sea depths of less than 60 m. The shelf edge (transition to the continental slope) lies at a distance of 400–800 km from the modern shoreline; sea depths in this area range from 80 to 100 m.
Section snippets
Relic offshore permafrost: methods and the main results of its study
Up to the beginning of the 1990s, it was generally believed that relic offshore permafrost had a limited distribution within the shelf of the Laptev and East Siberian seas. These notions were analyzed in detail by Gavrilov et al. (2001). It was also believed that the thickness of submarine (offshore) relic permafrost was considerably lower than that of permafrost within coastal lowlands shown on the Geocryological Map of the USSR, 1:2.5M scale (1996).
In the 1990s, the results of joint
The concept of shelf development in the Late Pleistocene and Holocene
As mentioned above, the table of relic offshore permafrost has an uneven topography. Within sandy shoals at sea depths up to 20 m, permafrost with ground ice is overlain by a relatively thin (2–3 m) layer of unconsolidated cryotic sediments, predominantly of marine genesis. At the same time, there are many places within the inner part of the shelf (at sea depths up to 30–40 m) and in the straits separating the New Siberian Islands, the permafrost table lies at a depth of 100 m and more from the sea
Conclusions
- (1)
Relic offshore permafrost exists within the vast Arctic shelf in Eastern Siberia. This permafrost has a continuous character within the inner part of the shelf (to sea depths of about 60 m) and a discontinuous character at greater sea depths (down to the transition from the shelf to the continental slope).
- (2)
The average thickness of permafrost within most of the shelf is estimated at 300–350 m; maximum values (500 m and more) are typical of the shoals near the Kotel’nyi Island.
- (3)
The thawing of relic
Acknowledgments
This study has been supported by the Russian Foundation for Basic Research (Grant nos. 97-05-64206 and 00-05-64430), joint Russian–German programs “Laptev Sea System” and “Laptev Sea System 2000,” OSL, and the National Science Foundation (USA) Grant no. 0PP 99 86 826. The authors express their special gratitude for constant support and valuable scientific consultations to Drs. S.S. Drachev, I.A. Dmitrenko, and A.V. Sher.
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Thermal properties of sediments in the East Siberian Arctic Seas: A case study in the Buor-Khaya Bay
2021, Marine and Petroleum GeologyCitation Excerpt :Massive methane emissions to the water column and atmosphere from sediments of the East Siberian Arctic Shelf infer the presence of gas-release pathways (Shakhova et al., 2010a, b, 2017; Anisimov et al., 2014; Overduin et al., 2015a; Thornton et al., 2016; Leifer et al., 2017; James et al., 2016; Yurganov et al., 2016; Ruppel and Kessler, 2017). These observations emphasize the need to revise the present views on the state of subsea permafrost, which is potentially more vulnerable to thawing than its terrestrial counterpart (Romanovskii et al., 2004, 2005; Shakhova et al., 2014). This requires an interdisciplinary approach, combining fast-ice drilling with geochemical and geophysical investigations (Sergienko et al., 2012; Chuvilin et al., 2013; Lobkovskiy et al., 2015; Koshurnikov et al., 2016; Charkin et al., 2017; Sapart et al., 2017; Shakhova et al., 2017).
Permafrost active layer
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