Abstract Although shale gas systems constitute a new target for commercial hydrocarbon production, only a little attention has been paid to the evolution of these unconventional systems with increasing thermal maturation. This study reports the characterization of samples of the Lower Toarcian (Lower Jurassic) Posidonia Shale from northern Germany at varying levels of thermal maturity. Observations were made using an original combination of focused ion beam-scanning electron microscopy (FIB-SEM) and transmission electron microscopy (TEM). The paper documents the formation of microfracture-filling bitumen in close assotiation with kerogen residues with increasing maturity. Porosity evolves from mostly submicrometric interparticle pores in immature samples to intramineral and intraorganic pores in overmature (gas mature) samples. This intraorganic nanoporosity has most likely come about by the exsolution of gaseous hydrocarbon and been hydrocarbon wet during the thermal maturation processes. Although FIB-SEM and TEM images are small compared to field size, this study emphasizes the need for nanoscale imaging to better constrain hydrocarbon generation processes in gas shale systems.

Abstract The mining of metallic and non-metallic commodities in Central Europe has a history of more than 2000 years. Today mainly non-metallic commodities, fossil fuels and construction raw materials play a vital role for the people living in Central Europe. Construction raw materials, albeit the most significant raw material, are not considered further here; for details refer to thematic maps issued by local geological surveys and comprehensive studies such as the textbook by Prentice (1990) . Even if many deposits in Central Europe, especially metallic deposits, are no longer extensive by world standards, the huge number and variety of deposits in Central Europe is unique and allows the student of metallogenesis to reconstruct the geological history of Central Europe from the Late Precambrian to the Recent in a way best described as ‘minerostratigraphy’. The term ‘deposit’ is used in this review for sites which were either mined in the twentieth century or are still being operated. A few sites that underwent exploration or trial mining have also been included in order to clarify certain concentration processes. They are mentioned explicitly in the text to avoid confusion with real deposits. Tonnage and grade are reported in the text only for the most important deposits. Production data for the year 2005 are listed in Table 21.1 for the countries under consideration. Reserves and production data of hydrocarbons in Central European basins are given in Table 21.2 . In the present study, Central Europe covers the Variscan core zones in the extra-Alpine part of Central Europe stretching from eastern France (Massif Central) into Poland where the contact between the Variscan Orogen and the Baltic Shield is concealed by a thick pile of platform sediments. In a north-south direction, Central Europe stretches from central Denmark to the southern boundary of the Po Plain in Italy, making the entire Variscan Foreland Basin, the Alpine Mountain Range, the Western Carpathians and the North Dinarides part of the study area. An outline of the geological and geographical settings is shown in Figure 21.1 . The precise geographical position of mineral sites, wells of special interest, hydrocarbon provinces, oil shale deposits and coal fields may be deduced from Tables 21.3 to 21.11 and the map ‘Mineral and energy resources of Central Europe’, at a scale 1:2 500 000 (see CD inside back cover).