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The Eocene-Oligocene boundary in the Paratethys area represents a period associated with a major extinction event followed by anoxic events. A good understanding of the factors controlling the formation of organic-rich layers is a key for prediction of source rock distributions. An excellent opportunity to study these factors is provided by the Loucka section situated in the Silesian Unit of the Czech Republic. The Menilite Formation is subdivided into the Subchert Member, Chert Member, Dynow Marlstone and Sitbořice Member and comprises non-calcareous shales, marlstones and cherts. The lithological variations reflect strongly depositional environment, which caused strong changes in geochemical parameters and source rock potential. The ratio of total organic carbon to total sulphur (TOC/TS) and methylated 2-methyl-2 (trimethyltridecyl) chroman (MTTC) ratios supported by paleontological evidence show normal marine to brackish water conditions. Pr/Ph ratios indicate strictly anoxic conditions during deposition of the upper part of the Subchert Member and the lower part of the Chert Member. Very low steranes/hopanes ratios reflect strong bacterial activity during deposition of the Chert Member. Very high HI values (>600 mg HC/g TOC) and the apparent absence of terrestrial macerals suggest that high amounts of C29 steranes and long-chain n-alkanes in this member result from the input of algal material. The Menilite Formation contains mainly type II kerogen and typically holds a “good” source rock potential. HI values > 600 mg HC/g TOC are observed in the Chert Member, while values The source potential index (SPI) of the entire succession of the Menilite Formation is about 1.25 t HC/m2, which is significantly lower than SPI determined for the Polish and Ukrainian Carpathians, but mainly due to the lower thickness.

The work presented here provides a complex environmental impact of sediments in vicinity to the area of the former Lazy coal mine site in the Upper Silesian Coal Basin (Czech Republic). The main aim of this work has been to determine the degree of contamination, to describe the organic matter, and to carry out sorption isotherms to see the size and distribution of pores in the monitored sediments that are the crucial parameters to assumption of removal mechanisms of elements carried in mine water. The results show that the greatest enrichment of Mn, Sr, Ba, and was in sediments of the first tens of meters from the mine water discharge sediments. Ba and Sr were precipitated as mineral barite and thus formed a dominant insoluble component in the river sediments, which were further carried by water flow towards the water reservoirs. Predominant amounts of fossil material and smaller quantities of carbonized and recent organic matter were altered by weathering and erosion processes. The coal materials have a relatively beneficial sorption capacity, which increases with the carbon content. The overburden waste should be considered for use in removing heavy metals in-situ., This study was financially supported by the Czech Academy of Science within the Research and Mobility Support of Starting Researchers Programme (Project No. MSM 100462001, under the title Vanadium Migration in Coal Mining Areas: Sorption of V on Selected Clay Minerals). The authors also thank the ERASMUS + programme for supporting PhD student Lujza Medvecká with a research fellowship at RWTH Aachen University, Germany, and we thank Ivana Perná and Lenka Borecká for their aid in the laboratory work. The work also received support from Operational Program Prague—Competitiveness project “Centre for Texture Analysis” (No.:CZ.2.16/3.1.00/21538), and from the long-term conceptual development of research organisation RVO: 67985891.

The Most Basin represents a coal basin with a long mining history in the Czech Republic. The majority of palaeo-environmental and geochemical studies have been focused on the upper part of the coal-bearing Most Formation where the coal is generally enriched in As, Cr, Ni, Cu and Zn. This study evaluated the distribution of V, Cr, Ni, Cu, Zn, Pb, Se, As, and Mn from the lower part. Regarding to the transport of inorganic elements into environment, the evaluation of mobility potential was also conducted. The total of 51 samples were collected from the Lower Bench in the Holesice Member. The chemical analyses were performed together with optical microscopy. The X-ray spectroscopy and ICP-MS were used to detect trace element contents in the study set of samples. 4 samples were subjected to the Sequential Extraction Procedure. The prepared leachates were analysed using the ICP-MS method. In total, 13 elements were screened in samples within the study profile. The mode of occurrence is the key factor for identifying a potential source of the trace elements. All evaluated trace elements (V, Cr, Ni, Cu, Zn, Pb, Se, As and Mn) leached most in the oxidisable fraction. On the other hand, As, Mn, Ni, Zn and Cd leached in more mobile fractions, e.g. reducible and acid.

The Upper Jurassic Marls of Mikulov present a formation that is considered to be the most promising strata to produce hydrocarbons in the Vienna basin. The marls are composed of dark pelagic marlstones that frequently contain layers of limestone with thickness reaching several hundreds of meters. Twenty-seven core samples from selected wells located in the south-eastern portion of the Czech Republic representing depths ranging from 2300 to 4500 m were analyzed by x-ray diffraction to assess bulk mineralogy and the progress of smectite illitization. Bulk mineralogy of the Mikulov Marls comprises carbonates (mean value = 54.4 mass%), clay minerals (26.6 mass%), quartz (15.0 mass%), and feldspar (1.6 mean%). In the decreasing order, the clay mineral fraction is composed of illite/mica, kaolinite, illite-smectite, and chlorite. The amount of smectite in illite-smectite decreases with depth from 70% to 28%. There is a change from random to ordered interstratification at the depth of 3300 m. The transition from short-range ordering (R1) to long-range ordering (R3) occurs at depths greater than 4,500 m. There was a good correspondence between thermal maturity parameters: the percentage of smectite in illite-smectite structures and vitrinite reflectance as a parameter of organic matter. The increase of the metamorphic grade was compared in respect to the geothermal gradient with adjacent basins.

The topmost Lower and Middle Jurassic formations of organic-rich clastics with minor carbonate deposits were recognized as very significant source/reservoir rocks in the North Western Desert of Egypt. Although several studies are devoted to their source rock characteristics and petroleum potential, the depositional paleoenvironment and paleoredox conditions are still poorly understood. In the current study, these sediments were assessed in terms of their organic matter richness, hydrocarbon generative potential and thermal maturity, total sulfur (TS) contents and organic petrographic characteristics. Depositional paleoenvironment was investigated using dinoflagellate cysts (dinocysts) and the composition of particulate organic matter along with organic petrographic characteristics. Redox conditions were assessed based on TS- total organic carbon (TOC) relationship and type of kerogen that was derived mainly from palynofacies analysis. TOC contents show fair to excellent generative potential of hydrocarbons mainly of kerogen type III (gas-prone). The thermal maturity, based on Tmax and Rr, indicates mature stage of oil window. Palynological analysis yielded poor to rich intervals of moderately-preserved, biostratigraphically useful dinocysts in the upper part of the Khatatba Formation. An assemblage of 81 species belonging to 54 genera of moderately diverse dinocysts, spores and pollen grains was identified. Freshwater algae, acritarchs and microforaminiferal test linings are sporadically documented within the studied interval. Based on the first downhole appearance (FDA) of the recovered marker dinocyts, the upper part of the Khatatba Formation was palynologically dated as late Bathonian-Callovian. The depositional environment was interpreted and three environments were deduced. The lower interval representing the topmost Ras Qattara and Yakout Red Shale Member was deposited in a fluvial-lacustrine environment, where oxic conditions prevailed as deduced from the color of reddish-brown sandstone and red shale. The middle interval spans Unit IIB, Kabrit and Unit III, which accumulated in a deltaic to shallow marine environment under dysoxic-suboxic settings. The upper interval covers Unit I and Unit IIA that have been deposited in a fluvio-deltaic to shallow marine with high paleoproductivity under suboxic conditions. One sample in the upper interval in Unit IIA reflected anoxic setting.

Rocks deposited in the Oligocene Paratethys are recognized as one of the most important source rocks in the Flysch Carpathians. The Sitbořice Member (uppermost NP23 to lowermost NP25 zone) represents the upper part of the Menilite Formation in the Outer Flysch Carpathians of the Czech Republic. This paper presents results of bulk geochemical analysis, Rock-Eval pyrolysis and organic petrography. The geochemical evaluation, source rock potential, kerogen type and thermal maturity were studied using borehole cores. Based on the classification of Peters (1986), the evaluated Sitbořice Member is mostly classified as a “very good” source rock according to TOC and variable, mostly “poor” to “good” according to the petroleum potential. However, the average petroleum potential value assigned the member to “good” source rock which is in accordance with the TOC classification if the “live” TOC is used. A comparable distribution between kerogen type II and III has been indicated by HI. Unlike this, the organic petrography observations show the organic matter belongs to the kerogen type II which corresponds to the relationship of residual hydrocarbon potential versus TOC and HI calculated based on “live” organic carbon. Presumed immaturity was confirmed by Rr and Rock-Eval T max . Oxygen-restricted conditions or a dysoxic environment have been indicated by the TOC/TS ratio

Over the past 100 years, the area along the River Bilina has been influenced by open-cast brown-coal mining, coal processing, petroleum refineries, and chemical plants. As a result, the extensive industrial activity has changed the overall character as well as the morphology of the landscape. A survey was underway to investigate the occurrence and distribution of various elements in the sediments of the River Bilina—a tributary of the River Elbe, a watercourse running through the Czech Republic and Germany—in order to discern the natural background from anthropogenic pollution. The study evaluated the content of selected elements (As, Zn, Pb, Cr, Ni, V, and Cu) in stream sediments of the River Bilina. Samples were taken at 20 sampling sites throughout the 82-km-long watercourse. For all the samples, the content of the elements was determined using ICP-MS after each of the sample was digested using HF and HNO3. The results of analyses of elemental composition of stream sediments were compared with those found through such analyses made within the surrounding geological units—more specifically, Proterozoic crystalline, Tertiary volcanic, Quaternary loess, Neogene sediments, and Neogene coal. All the samples of the stream sediments examined revealed increased amounts of As, V, Ni, Cr, and Pb. Using the enrichment factor established on the basis of the regional geological background values proved that elevated levels of elements in stream sediments are not always the result of industrial contamination.

The deep boreholes in the Upper Silesian Coal Basin provide a valuable material to evaluate thermal maturity of the present Carboniferous units. 17 boreholes were used for evaluating expected paleothicknesses of the missing units and the maximum temperatures reached via 1D modelling. The models consider the geological evolution concepts accepted for the region. The reliability of the final thermal models was calibrated with vitrinite reflectance data. Vitrinite reflectance varies between 0.46 and 2.32 %Rr indicating thermally early mature to over mature organic matter for the Ostrava Fm. and Karvina Fm. The coal rank increases from the east to the west. Based on the data from RockEval pyrolysis all samples from the Ostrava and Karvina Fm. belong to type III kerogen. The RE results show that the source potential of the Carboniferous sediments was not spent in full as part of the Variscan tectogen. Burial and thermal history on the Czech side of the Upper Silesian Coal Basin was reconstructed. The set of several 1D simulations proved that the thickness of the missing Palaeozoic Molasses association is 2,500 to 3,400 m in the foreland and 1,800 to 2,000 m for the platform. The maximum burial is expected at the end of the Westphalian. The consequent sedimentation of the Carpathian Foredeep and nappe thrusting did not change the Palaeozoic thermal maturity pattern within the tested area of the USCB.

In this study a Rock-Eval pyrolysis, a petrographic composition of organic matter, vitrinite reflectance and gas chromatography were undertaken on borehole cores from the Mikulov Marls in order to define the organic matter type and determine the thermal maturity. The analyzed samples covered a depth interval of between 2,300 m and 4,500 m. The studied sediments were dark-colored, moderately laminated shale’s throughout which appear uniform upon visual examination. The geochemical analyses revealed that the source rock potential of the Mikulov Marls is from fair to good. According to the Rock-Eval pyrolysis, the organic matter in the samples was classified as kerogen type II-III. This classification is not supported by the results from the other used methods. The evaluation of the organic macerals demonstrated the dominant role of liptinite with prevailing liptodetrinite accompanied by a variable content of alginite, bituminite, and sporadic sporinite and resinite. The alginite consists mainly of lamalginite, derived from colonial planktonic or benthonic algae. Based on these results, the Mikulov Marls represent the kerogen type II. These results are also supported with a strong n-alkane odd-carbon-number predominance at n-C15, n-C17 and n-C19 range on the gas chromatography.

Coaly material enters various environmental compartments from different emission sources and on diverse pathways. The complexity of both the emission processes and the quality of contamination in the Ostrava region avoids a simple source correlation for coal-derived pollution. Hence, this study focused on the application of different geochemical approaches for source apportionment using bulk parameters, aliphatic biomarkers and source-specific PAH ratios. Major aim was to prove the effectiveness of the applied methods for characterizing the impact of coal-derived contamination in complex emission systems such as in the Ostrava region. Individual emission sources were discriminated sufficiently by TOC vs. TEH relationship and two-dimensional correlations of PAH ratios. Additionally, aliphatic biomarkers revealed individual signatures for all classes of samples and pointed to a widespread distribution of fossil material also in the hydrosphere. On the contrary, indicative PAH ratios documented a dominance of pyrogenic over petrogenic-derived organic matter in the lake sediments investigated. These contradictory descriptions demonstrate clearly that only a comprehensive application of different marker systems allows a detailed view on the quality and quantity of coal-derived pollution. Lastly, it remains unclear whether coaly material in aquatic sediments acts as sink or source for PAHs. A proposed indicative marker, the ratio of phenanthrene over retene, failed.