PYRITIZATION OF THE MIDDLE CARBONIFEROUS SANDSTONES OF THE DONBAS

Abstract

Coal mining is linked with such phenomena as sudden gas outburst, explosions, and ignition of coal seams. Among the preconditions for explosions, emissions and possible inflammations, the process of pyritization of rocks of the geological cross-sections of the Donbas basin is poorly known, and the transformation of accessory pyrite minerals has not been studied. The purpose of the work is research of the pyritization of Carboniferous sandstones of coal-bearing sediments of this basin. Diagenetic and catagenetic pyrite can be distinguished. The investigation of secondary (сatagenetic) mineral transformation of terrigenous coal deposits shows the interaction of geochemical and tectonic processes. Pyritization is part of a geochemical process, they occur discretely in coalbearing strata. Catagenesis is accompanied by the phenomenon of heating and burning. Pyrite activates these phenomena, and promotes the burning of coal seams and gases. The authors demonstrate a highly variable distribution of ferrous compounds in a sandstone layer either along-strike or across layer thickness. Variations in the content of FeS2 can be related to the transformation of marcasite to pyrite. The results can be the basis for the development of criteria for assessing the tendency of coal deposits to spontaneous combustion.