Abstract
Methane is a powerful greenhouse gas, and the abrupt degassing events that recently have formed large craters on the Russian Arctic Yamal and Gydan Peninsulas have caused major concern. Here we present field data on cover sediments and evolution of a gas-emission crater discovered in the Erkuta–Yakha River valley in the southern Yamal Peninsula in June 2017. The crater is located south of other similar craters discovered over the past decade in northern West Siberia. Data were collected during a field trip to the Erkuta crater in December 2017 which included field observations and sampling of permafrost soil and ground ice from the rim of the crater. All soil and ice samples were measured for contents of methane and its homologs (ethane and propane) and carbon dioxide. The contents of carbon dioxide in some samples are notably higher than methane. The strongly negative δ13С of methane from ground ice samples (−72‰) is typical of biogenic hydrocarbons. The ratio of methane to the total amount of its homologs indicate a component of gases that have migrated from a deeper, thermogenic source. Based on obtained results, a potential formation model for Erkuta gas-emission crater is proposed, which considers the combined effect of deep-seated (deep gas migration) and shallow (oxbow lake evolution and closed talik freezing) causes. This model includes several stages from geological prerequisites to the lake formation.
Highlights
Methane is a powerful greenhouse gas, and the recent abrupt events of degassing and crater formation on the Yamal and Gydan Peninsulas (Figure 1) have caused major concern that a warmingArctic may lead to increased thawing of permafrost and gas emissions
The Yamal Crater has been better documented [4,5,6,7] than the others, which are only imaged in few photographs, but the available data are insufficient to concede about the conditions and causes of its origin
The Erkuta crater formed in the winter of 2016–2017 in the southern Yamal Peninsula (Figure 1), in typical conditions of continuous permafrost described in a number of publications [12,13]
Summary
Methane is a powerful greenhouse gas, and the recent abrupt events of degassing and crater formation on the Yamal and Gydan Peninsulas (Figure 1) have caused major concern that a warming. The deep-seated causes of crater formation [7,8,9] include increased deep heat flux, upward migration of deep gaseous fluids through fault zones and fault intersections to shallow permafrost and dissociation of intrapermafrost gas hydrates driven by ascending heat and gas flows. The hypothesized shallow prerequisites of crater formation are associated with permafrost temperature variations under the effects of climate and surface heat transfer These models involve permafrost is warming from above and the ensuing destabilization of relict gas hydrates in the upper permafrost [2,5]. We provide substantive background on the cover sediments of the Erkuta crater in the southern Yamal Peninsula (Figure 1) and propose a formation model that could provide a basis for further assessment with more field data
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