FEATURES OF DETERMINATION OF MODERN GAS MIGRATION IN THE UPPER LAYERS OF THE LITHOSPHERE

Abstract

The study of modern gas migration is a topical issue both to determine its impact on mineral deposits and the environmental impact of gases released into the Earth's atmosphere. The redistribution of gases in the lithosphere and their release to the surface correspond to geological processes that last for millions of years. Each geologic structure can have both more active periods and periods of relative dormancy. Discontinuous faults in the lithosphere are the paths of migration of gases (fluids). 
 The modern migration in different geological structures was determined on the basis of gas samples taken from the surface. The author's methodology is based on determining the gas state of the upper layers of the lithosphere and establishing individual compositions of gas mixtures from the selected samples. The development is based on geological, structural and geochemical studies to determine gas migration to the surface. The results can also be used to identify discontinuities and areas with anomalous gas content, which are mainly characteristic of oil and gas and coal deposits. 
 Based on the change in quantitative and qualitative gas indicators compared to the generally accepted data on the gas composition of the atmosphere, areas with the most abnormal gas indicators, in particular methane or its homologues, are identified, which allows us to identify areas with active modern gas migration. It is worth noting that gas indicators may differ at different times of the year. Such peculiarities are usually determined by the intensity of migration to the surface, which is characteristic of each structure, and not only by the change of season. 
 On the basis of studies of gas mixtures (methane, heavy hydrocarbons, hydrogen, nitrogen, carbon dioxide and helium), the polygenetic composition of natural gas in the studied areas opened by mine workings at the surface and at depth is substantiated. This allows us to attribute them to mobile gas-geodynamic systems, in which intensive gas transfer processes are still taking place in the near-surface layers of the lithosphere.