Formation and distribution of permafrost and taliks under channels of the Lena River Delta

Abstract

The Arctic deltas represent the scene for active permafrost formation and, at the same time, the place for talik zones development. Due to the wide distribution of shallow waters in the Arctic deltas under channels freezing to the bottom in winter, the area of newly formed underwater permafrost significantly exceeds the area of thawed under-channel massifs. During the field research in the Lena River Delta we have revealed features and patterns of formation of both 

newly formed permafrost within the channels and under-channel taliks. On the basis of drilling, geophysical and bathymetric data obtained in the course of expedition research in 2014–2020, we have found that permafrost under the channels almost always forms at low water depths of less than 2–2.5 m, but can also occur at depths of 3–5 m. The depth of thawing of underwater permafrost in shallow waters in summer reaches from 1 to 3 m. Under-channel taliks develop under channels with a depth of more than 3 m, where talik zones are formed. The results obtained can be used by river fleet specialists to clarify changes in the position of river fairways in the Arctic deltas