East Siberian glaciers presently exist on the De Long Islands. Massive ice beds of glacial origin have been found in the Kanarchak formation on Faddevskii and Novaya Sibir Islands (Anisimov & Tumskoi, 2003). During the Pleistocene cryochrons, the ice saturated syncryogenic deposits with ice wedges were formed on the coastal lowlands of Yakutia and New Siberian Islands and on the shelves of the Laptev Sea and the western part of the East Siberian Sea. Features attesting to the development of thin passive glaciers or ice-firn fields along the coasts of the islands and continent are discussed herein. It is suggested that partial melting of these ice bodies resulted in formation of ground ice. The spatial distribution of the latter can be judged from the analysis of thermokarst phenomena. The existence of passive glaciers in the past is confirmed by a number of interrelated facts.

(1)  High geothermal gradients (6°-6.5°C/100 m) are registered in the wells on the New Siberian Islands. The aggradational relationship of the gradients in the permafrost and and the underlying rocks, and the abnormally low thickness of permafrost in the coastal zone between rivers Anabar and Lena suggest an ice cover during the Sartan cryochron. That ice blanket protected the underlying sediments from deep freezing.

(2) The content of chlorides in the permafrost and subpermafrost cryopegs suggest that freezing front temperatures in the coldest epochs were not very low, which can be explained by former glaciers near the area of the drilling site (in the Olenyok River mouth), or by a cover protecting the sediments from deep freezing in the north of the Khallercha Tundra, in the Van'kina Guba Bay, and on the Lyakhovsky Islands.

(3) Marine terraces on the continent and on Kotelnyi and Severanaya Zemlya islands had appeared by 3000-5000 years earlier than the Holocene sea level stabilized at the modern datum (0 m). This implies the glacioisostatic origin of the terraces. The Early Holocene dates show that the glaciers could exist during the pre-Holocene cold phases in the areas adjacent to the transgressing sea. At present, the July temperature on these islands is low, and it could drop below 0°C during these cold phases.

(4) Considerable rates (2-6 mm/year) of the modern uplift and the lack of concordance between it and the geological structure of coastal areas attest to a predominantly glacioisostatic nature of the uplift, thus supporting this origin for the Early Holocene sea terraces.

(5) The passive glaciation could reach its largest extent during MIS 6, when there was no frost cracking of the rocks composing the Bolshoi Lyakhovsky Island despite the very low air temperatures in January. The latter fact is inferred from isotopic analyses of ice wedges in silty sediments of the Kuchugui formation which indicate temperatures by 10°C lower than during the Sartan and the Late Karginsky intervals.

In the Sartan cryochron the extent of passive glaciation was minor as compared to the Zyryanka cryochron. Thus, the thickest ice beds buried on Arga Muora Sise Island date back to the Zyryanka cryochron. The development of ice wedges, judging by their parameters, took place during the coldest phase of the Sartan cryochron. Passive glaciation could be enhanced in the final Sartan as a response to the cooling and humidifying impact of the encroaching Arctic Ocean.

Reference:

Gavrilov A.V. Passive glaciation in the East Siberian Arctic. Correlation of Pleistocene Events in the Russian North. International Workshop Abstracts. 4-6 December 2006. Saint-Petersburg, 2006, p. 28.