Simulated maturation by hydrous pyrolysis of bituminous coals and carbonaceous shales from the Upper Silesian and Lublin basins (Poland): Induced compositional variations in biomarkers, carbon isotopes and macerals

Hydrous pyrolysis (HP) to simulate the maturation of organic matter (OM) and a variety of organic geochemical analyses and petrographic analyses of OM were performed to establish the origin and depositional environment in the Serpukhovian (Mississippian) and Pennsylvanian coals and carbonaceous shales from the Upper Silesian and Lublin coal basins. OM of coals and shales is dominated by vitrinite- with subordinate liptinite- and inertinite-group macerals, derived from C3 plants. The OM in both coals and shales is of humic origin, deposited in terrestrial, paralic and terrestrial, deltaic and lacustrine environments. The OM is rich in resins related to the presence of waxes derived from the coat of vascular plants. Shales were deposited in a more brackish-lacustrine environment than coals with algae and microbially reworked OM. Shales occurring above coal seams were deposited in more dynamic conditions than shales below seams. Coal sedimentation occurred in a stagnant setting reflected in the presence of paleosols and diverse plant groups. After heating at HP 330 °C and 360 °C, various new vitrinite forms appear, and semicoke, in the OM. The distributions of some biomarkers and polycyclic aromatic hydrocarbons are characteristic of specific macerals, and their ratios are controlled by OM type and thermal maturity related to the conditions of the HP experiments. This behaviour can be related to OM of type III and chemical reactions at two maturation stages. No significant geochemical or genetic differences in the OM of coals or shales from either basin are evident.