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Gas Emission Craters (GEC) represent a new phenomenon in permafrost regions discovered in the north of West Siberia. In this study we use very-high-resolution Worldview satellite stereopairs and Resurs-P images to reveal and measure the geomorphic features that preceded and followed GEC formation on the Yamal and Gydan peninsulas. Analysis of DEMs allowed us to: (1) distinguish different terrain positions of the GEC, at the foot of a gentle slope (Yamal), and on an upper edge of a terrace slope; (2) notice that the formation of both Yamal and Gydan GECs were preceded by mound development; (3) measure a funnel-shaped upper part and a cylindrical lower part for each crater; (4) and measure the expansion and plan form modification of GECs. Although the general characteristics of both craters are similar, there are differences when comparing both key sites in detail. The height of the mound and diameter of the resulting GEC in Yamal exceeds that in Gydan; GEC-1 was surrounded by a well-developed parapet, while AntGEC did not show any considerable accumulative body. Thus, using very-high-resolution remote sensing data allowed us to discriminate geomorphic features and relief positions characteristic for GEC formation. GECs are a potential threat to commercial facilities in permafrost and indigenous settlements, especially because at present there is no statistically significant number of study objects to identify the local environmental conditions in which the formation of new GEC is possible.

This paper describes two gas‐emission craters (GECs) in permafrost regions of the Yamal and Gydan peninsulas. We show that in three consecutive years after GEC formation (2014–2017), both morphometry and hydrochemistry of the inner crater lakes can become indistinguishable from other lakes. Craters GEC‐1 and AntGEC, with initial depths of 50–70 and 15–19 m respectively, have transformed into lakes 3–5 m deep. Crater‐like depressions were mapped in the bottom of 13 out of 22 Yamal lakes. However, we found no evidence that these depressions could have been formed as a result of gas emission. Dissolved methane (dCH4) concentration measured in the water collected from these depressions was at a background level (45 ppm on average). Yet, the concentration of dCH4 from the near‐bottom layer of lake GEC‐1 was significantly higher (824–968 ppm) during initial stages. We established that hydrochemical parameters (dissolved organic carbon, major ions, isotopes) measured in GEC lakes approached values measured in other lakes over time. Therefore, these parameters could not be used to search for Western Siberian lakes that potentially resulted from gas emission. Temperature profiles measured in GEC lakes show that the water column temperatures in GEC‐1 are lower than in Yamal lakes and in AntGEC – close to values of Gydan lakes. Given the initial GEC depth > 50 m, we suggest that at least in GEC‐1 possible re‐freezing of sediments from below might take place. However, with the present data we cannot establish the modern thickness of the closed talik under newly formed GEC lakes.

Detailed analysis of five gas emission craters (GEC) found in the north of West Siberia is presented. Remote sensing data used in the study is verified by field surveys. Previous studies show that all of the GECs were preceded by mounds 2 to 6 m high and 20 to 55 m in diameter. GECs initially were 20–25 m in diameter, which increased in the first years of their existence. GECs are found in various environmental (shrublands or moss-grass tundra) and geomorphic (river valley, terrace, slopes) conditions. The objective of the paper is to identify common and differing geomorphologic and environmental characteristics of all the five GEC, and their mound-predecessors. The study is based on a compilation of DSMs before and after the GEC formation using very high-resolution satellite imagery stereo pairs compared to ArcticDEM project data. Diversity of terrain and environmental settings along with rather a narrow range of GEC and mound-predecessor morphometric parameters allows concluding that the mechanism of GEC formation is most likely similar for all the GEC and is controlled rather by internal geologic and cryolithologic structure than by any surface properties.

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.

Abstract. The present study examines the formation history and cryolithological properties of the late-Pleistocene Yedoma Ice Complex (IC) and its Holocene cover in the eastern Lena delta on Sobo-Sise Island. The sedimentary sequence was continuously sampled at 0.5 m resolution at a vertical Yedoma cliff starting from 24.2 m above river level (a.r.l.). The sequence differentiates into three cryostratigraphic units: Unit A, dated from ca. 52 to 28 cal kyr BP; Unit B, dated from ca. 28 to 15 cal kyr BP; Unit C, dated from ca. 7 to 0 cal kyr BP. Three chronologic gaps in the record are striking. The hiatus during the interstadial marine isotope stage (MIS) 3 (36–29 cal kyr BP) as well as during stadial MIS 2 (20–17 cal kyr BP) might be related to fluvial erosion and/or changed discharge patterns of the Lena river caused by repeated outburst floods from the glacial Lake Vitim in southern Siberia along the Lena river valley towards the Arctic Ocean. The hiatus during the MIS 2–1 transition (15–7 cal kyr BP) is a commonly observed feature in permafrost chronologies due to intense thermokarst activity of the deglacial period. The chronologic gaps of the Sobo-Sise Yedoma record are similarly found at two neighbouring Yedoma IC sites on Bykovsky Peninsula and Kurungnakh-Sise Island and are most likely of regional importance. The three cryostratigraphic units of the Sobo-Sise Yedoma exhibit distinct signatures in properties of their clastic, organic, and ice components. Higher permafrost aggradation rates of 1 m kyr−1 with higher organic-matter (OM) stocks (29 ± 15 kg C m−3, 2.2 ± 1.0 kg N m−3; Unit A) and mainly coarse silt are found for the interstadial MIS 3 if compared to the stadial MIS 2 with 0.7 m kyr−1 permafrost aggradation, lower OM stocks (14 ± 8 kg C m−3, 1.4 ± 0.4 kg N m−3; Unit B), and pronounced peaks in the coarse-silt and medium-sand fractions. Geochemical signatures of intra-sedimental ice reflect the differences in summer evaporation and moisture regime by higher ion content and less depleted ratios of stable δ18O and stable δD isotopes but lower deuterium excess (d) values during interstadial MIS 3 if compared to stadial MIS 2. The δ18O and δD composition of MIS 3 and MIS 2 ice wedges shows characteristic well-depleted values and low d values, while MIS 1 ice wedges have elevated mean d values between 11 ‰ and 15 ‰ and surprisingly low δ18O and δD values. Hence, the isotopic difference between late-Pleistocene and Holocene ice wedges is more pronounced in d than in δ values. The present study of the permafrost exposed at the Sobo-Sise Yedoma cliff provides a comprehensive cryostratigraphic inventory, insights into permafrost aggradation, and degradation over the last approximately 52 kyr as well as their climatic and morphodynamic controls on the regional scale of the central Laptev Sea coastal region in NE Siberia.

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