Cryovolcanism on the Earth: Origin of a Spectacular Crater in the Yamal Peninsula (Russia)

Abstract

Geological activity on icy planets and planetoids includes cryovolcanism. Until recently, most research on terrestrial permafrost has been engineering-oriented, and many related phenomena have received too little attention. Although fast processes in the Earth’s cryosphere were known before, they have never been attributed to cryovolcanism. The discovery of a couple of tens of meters wide crater in the Yamal Peninsula aroused numerous hypotheses of its origin, including a meteorite impact or migration of deep gas as a result of global warming. However, the origin of the Yamal crater can be explained in terms of cryospheric processes. Thus, the Yamal crater appears to result from collapse of a large pingo, which formed within a thaw lake when it shoaled and dried out allowing a large talik (that is layer or body of unfrozen ground in a permafrost area) below it to freeze back. The pingo collapsed under cryogenic hydrostatic pressure built up in the closed system of the freezing talik. This happened before the freezing completed, when a core of wet ground remained unfrozen and stored a huge amount of carbon dioxide dissolved in pore water. This eventually reached gas-phase saturation, and the resulting overpressure came to exceed the lithospheric confining stress and the strength of the overlying ice. As the pingo exploded, the demarcation of the crater followed the cylindrical shape of the remnant talik core.

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

“…Our dataset on methane isotopes suggests that the source of methane is primarily microbial (Table ), as the values of δ 13 C are, in general, less than −60‰ which is also consistent with the data presented by Buldovicz et al Values of δ 13 C in methane extracted from deep boreholes of Bovanenkovo gas field (depths 28–120 m) vary from −74.6 to −70.4‰, also suggesting a microbial origin . Similarly, methane released due to decomposition of methane hydrates extracted from a 451 m borehole in Taglu gas field (Canada) from depths of 56.9–354.3 m has shown δ 13 C values between −90 and −78‰, and δD values between −314 and −162‰, again suggesting microbial methane …”

“…Decomposition of gas hydrates and associated explosive gas emission was proposed as one of explanantions for this crater's appearance . An alternative hypothesis proposed that GEC‐1 formed as a result of the collapse of a large pingo formed after lake drainage allowing the existing sub‐lake talik (a layer of year‐round unfrozen ground in permafrost areas) to re‐freeze accompanied by the growth of cryogenic hydrostatic pressure . Based on SPOT‐5 and Landsat‐8 satellite images, the eruption date of GEC‐1 was narrowed to an interval between October 9 and November 1, 2013 .…”

“…15 An alternative hypothesis proposed that GEC-1 formed as a result of the collapse of a large pingo formed after lake drainage allowing the existing sub-lake talik (a layer of year-round unfrozen ground in permafrost areas) to re-freeze accompanied by the growth of cryogenic hydrostatic pressure. 16 Based on SPOT-5 and Landsat-8 satellite images, the eruption date of GEC-1 was narrowed to an interval between October 9 and November 1, 2013. 12 According to information provided by the local Nenets community, AntGEC formed on October 27, 2013.…”

Formation and Accumulation of Pore Methane Hydrates in Permafrost: Experimental Modeling

“…In general, the performed experiments corroborate the possibility for the formation of pore gas hydrates at negative temperatures (−2-8 • C) in porous media of gas-bearing sandy-silty soils as the pressure is (2.5-6 MPa). These conditions of hydrate formation in frozen soils may occur at depth intervals from 250 to 600 m. In addition, in the permafrost, required pressure conditions may occur at depths below 250 m associated with freezing of methane-saturated sediments in a closed system [2,[12][13][14]57], and may result from loading by overlying glaciers (thickness from 100 m) [8,11,15] or transgression of the Arctic seas [11,40,58]. Proceeding from published evidence described above and the reported experimental results, the formation of pore gas hydrates in gas-bearing permafrost can be explained with several geological models.…”

“…Glaciation changes the temperature and pressure conditions as permafrost thickens up in the periglacial zone but it degrades from below in the subglacial zone [8,15]. The top of the hydrate The process comprises three main stages: freezing of a gas-saturated closed talik in permafrost leading to cryogenic concentration of gas and related excess pressure (can reach several MPa) [57] (Figure 12a); onset of hydrate formation from some portion of pore gas in the freezing talik ( Figure 12b); further cooling of the frozen talik and ensuing additional hydrate formation (Figure 12c). Thermodynamic description of this model is given in Reference [59].…”