GENEZA I CHEMIZM SKŁADU GAZOWEGO WÓD PODZIEMNYCH W BLOKU GÓRNOŚLĄSKIM

Abstract

THE ORIGIN AND CHEMISTRY OF GASES DISSOLVED IN GROUNDWATER IN THE UPPER SILESIAN BLOCKAbstract. The origin and chemistry of gases dissolved in groundwater of a regional flow system in the Upper Silesian Variscan sedimentary basin are investigated in this paper. In the geological profile of the Upper Silesian sedimentary basin, a few potential sources of gas generation occur. Gases were generated in various geological periods as a result of thermogenic coalification as well as microbial reduction of carbon dioxide. Thermogenic processes of coalification of organic matter occurring in the productive Carboniferous deposits were of the prime importance in water saturation with methane. Water saturation with gases is of a regional character. Individual groundwaters in the sedimentary basin have a hydraulic connection. Migration of gases is included in the groundwater flow system. Taking into account the paleohydrogeological development of the Upper Silesian depression, it could be concluded that the infiltrational stages of the basin developmentresulted not only in waters exchange but also in a change in their gaseous composition. Within the Upper Silesian depression, a distinct gaseous zonation of waters can be observed, characteristic of sedimentary basins. There are the following zones: nitrogen, nitrogen-methane, methane and methane-nitrogen. The origin and chemical composition of gases dissolved in waters of the individual zones are different, butthey may also be different within the range of a particular zone. The authors assumed that the gaseous zonation of waters may be related to their location in the groundwater flow system and is correlated with the hydrogeochemical zonation.