New Permafrost Feature – Dep Crater in Central Yamal (West Siberia, Rusia) as a Response to Local Climate Fluctuations

Abstract

this paper is based on field data obtained during short visits to a newly formed permafrost feature in a form of relatively narrow, deep crater. excluding impossible and improbable versions of the crater's development, the authors conclude that it originated from warmer ground temperatures and an increase in unfrozen water content, leading to an increase in pressure from gas emissions from permafrost and ground ice. this conclusion is also supported by known processes in the palaeo-geography of yamal lakes and recent studies of gas-hydrate behavior and subsea processes in gas-bearing provinces.

Gas‐emission craters of the Yamal and Gydan peninsulas: A proposed mechanism for lake genesis and development of permafrost landscapes

“…Presumably, gas is continuously delivered from the gassaturated sediments under the lake and further oxidized in the water column. The extensive filling of the newly formed lakes with sediments from the retreating walls of GEC-1 and AntGEC 8,9 implies that initial gas flows can be restrained by a thick and relatively impermeable layer of silty-clayey and sandy sediments. Given average ground temperatures around the GEC-1 area of −1 to −5°C 28 we assume further freezing of sediments from below under the GEC-1 lake, probably forming a seal for further gas flows from beneath.…”

“…For the first time in the terrestrial permafrost environment, gas emission craters (GECs) have been observed on the Yamal 7 and Gydan 8 peninsulas in summer and autumn 2014 ( Figure 1). The Yamal GEC (69.9711 N, 68.3703°E), 42 km from Bovanenkovo gas field, was named GEC-1 9 and the Gydan GEC near Antipayuta settlement (69.7946 N, 75.035°E) was named AntGEC. 8 Initially, these two permafrost-related features were deep and relatively narrow cylinder-shaped depressions with subvertical frozen walls and a funnel-shaped top.…”

“…8 Initially, these two permafrost-related features were deep and relatively narrow cylinder-shaped depressions with subvertical frozen walls and a funnel-shaped top. 9 The first field expeditions to GEC-1 in 2014 described the surrounding landscape of the area, provided morphometric descriptions of GEC-1 and proposed an origin of this landform as resulting from the emission of methane from permafrost. 7,[9][10][11] Later, more accurate morphometric parameters of GEC-1 were defined.…”

“…9 The first field expeditions to GEC-1 in 2014 described the surrounding landscape of the area, provided morphometric descriptions of GEC-1 and proposed an origin of this landform as resulting from the emission of methane from permafrost. 7,[9][10][11] Later, more accurate morphometric parameters of GEC-1 were defined. 12,13 Geophysical surveys using electrical-resistivity tomography techniques revealed a possible layer of gas hydrates at a depth of 60-80 m and established the base of permafrost at depths of 160-180 m surrounding GEC-1.…”

“…22 Since our first observations, it became evident that GECs could potentially evolve into new lakes, which would be unrecognizable from other lakes. 9,11 Despite the prevailing hypothesis that the majority of Yamal lakes have resulted from thermokarst processes, 21 the occurrence of GEC features has allowed us to hypothesize that gas emission has played some role in the initial stages of lake formation on the Yamal and Gydan peninsulas during the Holocene. 9 To test this hypothesis, we analyzed a number of hydrochemical parameters both for GEC lakes and other "normal" lakes of the Yamal and Gydan peninsulas in order to find similarities between them and to establish specific hydrochemical features of GEC lakes that could be used to search for other lakes that have possibly appeared as a result of gas emission.…”