Gas emission funnels as an object of geocryology (Part 3 "Local gas dynamic geosystems")

The object of study in this publication is local cryogenic gas-dynamic geosystems, the development of which leads to pneumatic explosions and the formation of gas emission craters. The subject of the research is cryogenic formations recorded in frozen rocks composing the gas emission craters discovered in northern Western Siberia. The authors provide a detailed examination of the cryogenic formations found in various elements of the craters, analyzing their structure, morphology, plastic, and brittle deformations. Special attention is given to the processes that could have led to the formation of certain cryogenic elements, such as ring structures, cellular ice, and fracture structures on the crater surfaces. Due to the insufficient study of many cryogenic processes recorded in the craters, analogies from other fields of technical and natural sciences were widely used. Currently, researchers are primarily focused on searching for hypothetical schemes linking the genesis of gas with the formation of gas emission craters. The authors of this work have shown that without considering the cryogenic factor, it is impossible to address the problem of pneumatic explosions in permafrost, even in the context of gas genesis. The main method used in this article is the analysis of scientific publications on the topic under consideration, as well as data from laboratory modeling conducted by the authors. The synthesis of the analyzed materials was carried out based on a geosystem approach. The novelty of the research lies in the justification of the cryogenic basis for the staged development of the gas dynamic geosystem in frozen rocks, which conditions the preparation for pneumatic explosions and the formation of gas emission craters. For the first time, four stages of development of the cryogenic gas dynamic geosystem in frozen rocks have been identified. The first stage is the initial formation of a gas-saturated zone with increased pressure of the subsurface gas, located at the base of the gas dynamic geosystem. The second stage is the formation of a transit zone for the redistribution of subsurface gas. The concluding stage is where the gas pressure at its upper part reaches values exceeding the strength of the overlying soils. The final stage of development of the cryogenic gas dynamic geosystem is the pneumatic explosion that forms the gas emission crater. The main conclusions of the conducted research are as follows: the processes preparing for the formation of gas emission craters are cryogenic. They are determined by the structural-textural features of frozen rocks, mass transfer processes, and phase transitions occurring within them, as well as their strength and deformation properties.