This paper presents geochemical data for 171 core samples of the Carboniferous coal-bearing series and the Miocene cove from the central part of the Upper Silesian Coal Basin. Major oxide concentrations (Al ₂O ₃, SiO ₂, Fe ₂O ₃, P ₂O ₅, K ₂O, MgO, CaO, Na ₂O, K ₂O, MnO, TiO ₂, and Cr ₂O ₃) were obtained using XRF. Trace and major elements (Mo, Cu, Pb, Zn, Ni, Co, U, Cr, V, Mn, As, Th, Sr, Cd, Sb, Bi, Ba, Ti, W, Zr, Ce, Nb, Ta, Be Sc) were analysed ICP-MS. The main goals of this study were to demonstrate the distribution, as well as the stratigraphical variability, of the selected elements and to determine whether chemostratigraphy tools could be effectively applied to analyze Carboniferous and Miocene deposits of the USCB. Geochemical studies have shown showed different geochemical features of the samples from the Carboniferous and the Miocene. The diversity is mainly expressed in the enrichment of Miocene sediments in Ca and Sr related to biogenic carbonate material. It was also stated that the concentrations of trace elements associated with the detrital fraction, such as Zn, Cr, Co, Ba, Ti, Zr, Nb, and Sc show slightly higher values in Carboniferous sediments. On the basis of the content of Ti, Zr, and Nb, as well as ratios such as Th/U, Zr/Th, Ti/Zr, and TiO ₂/K ₂O, units with different inputs of the terrigenous fraction can be identified in both Carboniferous and Miocene formations. The paper shows that chemostratigraphy can be used as a stratigraphic and correlation tool for the Carboniferous and the Miocene deposits of the USCB.

The paper presents new data on the Miocene development within the Upper Silesian Coal Basin. The Miocene succession of the study area is characterized by high thickness and highly variable lithology. In the Miocene sediments of the studied area, the presence of organic matter in the form of a coal layer, coal crumbs, and dispersed organic matter has been found. The research focused mainly on the analysis of organic matter in terms of its origin, degree of coalification, and depositional environment. The degree of coalification of organic matter was determined by the huminite/vitrinite reflectance. The hard brown coal layer with a thickness of about eight meters was identified within the Kłodnica Formation. Based on the textural properties and degree of coalification, brown coal was classified as dull brown coal and bright brown coal. Organic matter in the form of coal crumbs and dispersed organic matter were found within a package clastic sedimentary. On the basis of petrographic analysis, two types of allochthonous organic matter with different degrees of coalification were identified. The coal clasts are mainly of Carboniferous origin, while the Miocene redeposited brown coal grains dominate within the dispersed organic matter. Coal fragments and dispersed organic matter derived from the Miocene brown coal were also found within the black claystones. The study of organic matter of the Miocene sediments in the Upper Silesian Coal Basin showed both its autochthonous and allochthonous origins.

Trace elements contained in rocks, especially those classified as potentially toxic elements (PTEs), can be largely harmful. Knowledge of the geochemical composition of waste is of great importance due to the potential possibility of contamination with these elements in the environment. The paper presents the geochemical characteristics of the sedimentary rocks from the Carboniferous coal-bearing series of the USCB. The present study used data for 120 samples from borehole WSx representing Zaleskie layers and Orzeskie layers within the Mudstone Series (Westphalian A, B). Major oxide concentrations (Al2O3, SiO2, Fe2O3, P2O5, K2O, MgO, CaO, Na2O, K2O, MnO, TiO2, Cr2O3, Ba) were obtained using an X-ray fluorescence spectrometry. The concentration of potentially toxic elements (Be, Sc, V, Cr, Co, Ni, Cu, Zn, As, Rb, Sr, Zr, Mo, Cd, Sn, Sb, Ba, W, Tl, Pb, Bi, Th, and U) was analyzed using inductively-coupled plasma mass spectrometry. As there are no relevant standards for the content of toxic elements in post-mining waste stored in dumps, the concentrations of elements were compared to their share in the Upper Continental Crust. Most elements, such as B, Sc, V, Cr, Ni, Cu, Zn, As, Sb, W, Tl, Pb, Bi, Th, and U had higher mean concentrations than those of the Upper Continental Crust (UC). Concentrations of the analyzed toxic elements in the studied samples did not exceed permissible values for soils, therefore they are not a potential threat to the environment. The results of the Pearson correlation analysis showed differing relationships among the analyzed toxic elements in the studied samples.

The geochemistry of sedimentary rocks is increasingly being used in palaeoenvironmental studies, in the identification of marine versus continental stratigraphy and in chemostratigraphic correlation. The selection of an appropriate research methodology, particularly in terms of sample digestion, can have a significant impact on the accuracy of the results obtained. Depending on the type of rock being studied and the aim of the analysis, a suitable mixture of acids should be used. The most commonly used sample digestion methods are based on a mixture of four acids (multi-acid), aqua regia and inverse aqua regia. As opposed to multi-acid whole-rock digestion, the use of aqua regia and inverse aqua regia result in only the partial digestion of sedimentary rocks. Geochemical analyses using these two different methods were carried out on Carboniferous sedimentary rocks from the Lublin Coal Basin from Poland.The elemental concentrations obtained showed essentially different results for some of the elements. A comparison of the elemental concentrations allowed the distinction of three groups of elements:

 - those that showed small differences between the results from the preparation methods (Co, Mn, Bi, Cu, Zn and Fe),

- those where the elemental concentrations were 20–50% lower using aqua regia digestion (i.e. Ni, P, Pb, Mg, Cd, Th, Mo, Sr),

 - elemental concentrations that were significantly lower (by up to 80%) following aqua regia digestion (U, Cr, Ba, Na, V, Al, Rb, K, Zr).