Abstract This excursion gives an introduction to the geoscience education region of north-eastern Bavaria. Thanks to its rich mining history, the geological variability and the long record of geological research in the area itself and its eastward continuation into Bohemia, northeastern Bavaria is a prime destination for geoscience education of non-geologists. Ordinary people experience to what extent their living environment is related to geology. Geoscientific knowledge is a major requirement for future sustainable development, but it is currently underrepresented in society. The geological outreach center at the continental deep drilling site is based on the famous Continental Deep Drilling Program (KTB) that probed the deeper crust of the Earth between 1987 and 1994. The outreach center communicates modern geoscience research results from the perspective of a dynamic Earth, which directly affects everybody’s life. Centrally positioned in a geologically unique area, it highlights the geological significance of the entire region. It is an almost natural development that such a region qualified to become the Czech-Bavarian Geopark. Its key topics are geodynamic and morphodynamic processes, human activity as a factor of landform development, geology as a fundamental base of economic and cultural development, the geological center of Europe, and the development from neptunism to the System Planet Earth. Geological outreach of the geopark obviously combines with social and cultural aspects. The geopark aims to emphasize the specific regional features in order to improve the public understanding of geological objects and their meaning in nature, and it provides an opportunity for the identification of the population with their regional living environment. Last but not least, geoscience outreach in the area is widely recognized as providing a significant benefit to the tourism industry.

Abstract An experimental study of the samples collected from a depth of 3.8–11.4 km in the Kola and KTB superdeep boreholes, and from the Earth's surface at the Kola drilling site was carried out at temperatures up to 600°C and pressures up to 150 MPa. The study was focused on the estimation of in situ permeability of the deep-seated rocks, their palaeopermeability during metamorphic transformations, and their protective properties for HLW disposal. Permeability dependencies on pressure and temperature were obtained. An increase in confining pressure leads to a decrease in rock sample permeability. The temperature trends obtained are of different types: permeability may decrease within the entire temperature range, or it may firstly decrease, reach its minimum and then decrease. It was found that this permeability behaviour is due to rock microstructure transformations caused by the competing effects of temperature and effective pressure. A possible in situ permeability trend for the superdeep section was proposed. A numerical simulation of convective transport was performed in order to determine a safe depth for the HLW well repository. The estimates obtained show that HLW well repositories can be used safely at relatively shallow depths.

Abstract This chapter summarizes the style, timing, composition and tectonic setting of the main occurrences of Cambrian to early Permian magmatic rocks in central Europe, which are here described within the framework of the Cadomian and Variscan Orogenies. In general terms, the Variscan Orogeny may be considered to be the result of Silurian to early Carboniferous accretion onto the southern margin of Laurussia of various Gondwana-derived terranes or microplates of predominantly Neoproterozoic (Cadomian/Pan-African) crust, together with their passive margin sequences and accreted island arcs ( Franke 1989 ; Matte 1991 ; Ziegler 1993 ). These microplates originated from various parts along the northern margin of Gondwana in the Early Palaeozoic, and moved northward towards Laurentia and Baltica (see Krawczyk et al. 2008 ). These rifting, spreading, subduction, accretion and collision events occurred over a long period and were associated with magmatic activity of varying styles, compositions and volumes, of which the variously deformed and metamorphosed equivalents are found throughout Variscan Europe. Another important, late to post-Variscan phase of magmatism which occurred throughout Europe was of late Carboniferous to early Permian age. The magmatic rocks and their metamorphosed equivalents are exposed in basement uplifts (the Variscan massifs), such as the Bohemian Massif, Odenwald, Spessart, Black Forest, Vosges, Massif Central, Iberia and the Rhenohercynian Zone (Fig. 12.1 ). In these internal parts of the Variscan Orogen, magmatic rocks are ubiquitous but are predominantly plutonic rocks and their metamorphosed equivalents, since mainly deep crustal levels are exposed. To the south, von Raumer (1998 )

Abstract This paper summarizes the current knowledge on the nature, kinematics and timing of movement along major tectonic boundaries in the Bohemian Massif and demonstrates how the Variscan plutonism and deformation evolved in space and time. Four main episodes are recognized: (1) Late Devonian–early Carboniferous subduction and continental underthrusting of the Saxothuringian Unit beneath the Teplá–Barrandian Unit resulted in the orogen-perpendicular shortening and growth of an inboard magmatic arc during c. 354–346 Ma; (2) the subduction-driven shortening was replaced by collapse of the Teplá–Barrandian upper crust, exhumation of the high-grade (Moldanubian) core of the orogen at c. 346–337 Ma and by dextral strike-slip along orogen-perpendicular NW–SE shear zones; (3) following closure of a Rhenohercynian Ocean basin, the Brunia microplate was underthrust beneath the eastern flank of the Saxothuringian/Teplá–Barrandian/Moldanubian ‘assemblage’; this process commenced at c. 346 Ma in the NE and ceased at c. 335 Ma in the SW; and (4) late readjustments within the amalgamated Bohemian Massif included crustal exhumation and mainly S-type granite plutonism along the edge of the Brunia indentor at c. 330–327 Ma, and peripheral tectonothermal activity driven by strike-slip faulting and possibly mantle delamination around the consolidated Bohemian Massif's interior until late Carboniferous–earliest Permian times.

Abstract In order to portray the main differences and similarities between the Northeastern Variscan segments (French Massif Central (FMC), Vosges, Black Forest and Bohemian Massif (BM)), we review their crustal-scale architectures, the specific rock associations and lithotectonic sequences, as well as the ages of the main magmatic and metamorphic events. This review demonstrates significant differences between the ‘Moldanubian’ domains in the BM and the FMC. On this basis we propose distinguishing between the Eastern and Western Moldanubian zones, while the Vosges/Black Forest Mountains are an intermediate section between the BM and the FMC. The observed differences are the result of, first, the presence in the French segment of an early large-scale accretionary system prior to the main Variscan collision and, second, the duration of Saxothuringian/Armorican subduction, which generated long-lived magmatic arc and back-arc systems in the Bohemian segment, while the magmatic activity in the FMC was comparably short-lived.

Abstract The Cambrian (c. 545-488 Ma) is probably the most poorly studied and least documented of all Phanerozoic systems in Central Europe. Cambrian deposits in Central Europe are generally of limited extent, often largely covered by vegetation and slightly to strongly metamorphosed so that data on depositional environments and palaeogeographic history are very limited. Regional differences in the tectonic and resulting sedimentary history as well as faunal characteristics indicate a melange of plates and terranes in a configuration that differs extremely from their original spatial distribution. Despite considerable interest in the Cambrian on a global scale following recognition of the ‘Cambrian Explosion’, and various areas with peculiar regional and faunal aspects (e.g. Burgess Shale, Chengjiang, Kaili), there has been a lack of detailed and general research on the Cambrian of Central Europe during the last two decades. Relevant studies have concentrated on a few areas such as Lusatia, the Holy Cross Mountains, or the Barrandian area in Bohemia. The most relevant surface exposures are found in Bohemia, the Franconian Forest area in Bavaria, in western Thuringia, in the Lusatia area in Saxony, the Holy Cross Mountains of southern Poland, and in the Brabant Massif of Belgium (Fig. 4.1 ). These outcrops are of relatively limited extent, but some yield important fossil assemblages. In addition, Cambrian strata are known from a number of drillholes such as in the Delitzsch-Torgau-Doberlug Syncline of NW Saxony, Upper Silesia, and a large area in north and east Poland, which is part of the East European Platform. Our

Abstract Major bodies of high-pressure (HP) rocks in the Saxo-Thuringian Belt in East Germany (Saxonian Granulite Massif, Erzgebirge) are investigated using a variety of geophysical methods (seismic reflection and refraction survey, magnetotelluric studies, gravity modelling). The Saxonian Granulite Massif and the Erzgebirge are not a continuous feature, as can be seen from discontinuous reflections, offset of upper-crustal seismic refraction velocity layers, and crustal resistivity increasing towards the Erzgebirge. Their juxtaposition during the evolution of two Variscan-age thrust wedges may have controlled this geometry. The earlier thrust wedge emplaced the supracrustal Erzgebirge HP nappes from the southeast to the northwest onto the Saxo-Thuringian Basin, whereas the later one propagated southwards and uplifted the Saxo-Thuringian granulites from deeper levels. To the southwest, the granulites are observed at shallow depth as far as the Franconian Line; to the southeast they extend down to the Moho, or they continue at mid-crustal levels. The granulites beneath the Saxo-Thuringian Belt can only have originated in one of two subduction zones: either through 'subduction erosion' and subsequent underplating of parts of the Saxo-Thuringian Plate from the north, or by intracrustal plug flow of overheated material from the southeast.

Abstract The evolution of the crystalline internal zone of the European Variscides (i.e. Moldanubian and Saxo-Thuringian) is best understood within a framework of two distinct subduction stages. An early, pre-Late Devonian (older than 380 Ma), subduction stage is recorded in medium-temperature eclogites and blueschists derived from low-pressure basaltic and gabbroic protoliths now found as minor relics in amphibolite facies meta-ophiolite or gneiss–metabasite nappe complexes. A second subduction and exhumation event produced further nappe complexes containing different types of mantle peridotites, along with their enclosed pyroxenites and high-temperature eclogites, associated with large volumes of high-T–high- P (900–1000°C, 15–20 kbar) felsic granulites. Abundant geochronological evidence points to a Carboniferous age (c. 340 Ma) for the high- P –high- T metamorphism as well as an extremely rapid exhumation because the fault-bounded, granulite–peridotite-bearing tectonic units are also cut by late Variscan granitic plutons (315–325 Ma). The massive heat energy for the characteristic, and most widespread feature of the Variscan event, the low- P –high- T metamorphism (750–800°C, 4–6 kbar) and voluminous granitoid magmatism (325–305 Ma), comes from three sources. An internal heat component comes from imbrication of crust with upper-crustal radiogenic heat production potential in the region parallel to the subduction zone; an external mantle heat component is undoubtedly contributing to the transformation of crust taken to mantle depths (i.e. the granulites); and a heat component advected to the middle and lower crust seems inescapable if the hot granulite–peridotite complexes were exhumed and cooled as rapidly as petrological and geochronological evidence seems to suggest. Major mantle delamination and asthenospheric upwelling as a cause of heating in Early Carboniferous times is not supported by geo-chemical, geophysical or petrological–geochronological studies, although slab break-off probably did occur.

Abstract The Mariánské-Lázně Complex is a Cambro-Ordovician terrane of oceanic affinity tectonically emplaced between the Saxothuringian Zone and Teplá-Barrandian Unit, NW Czech Republic. It forms a SE-dipping allochthonous body that comprises the largest contiguous exposure of metamorphosed basic and ultrabasic lithologies in the Bohemian Massif. Petrographic evidence indicates that a significant proportion of protoliths underwent eclogite facies metamorphism (570 to 720°C, 1.44 to 2.10 GPa), followed by an increase in temperature (up to around 800°C) and a subsequent widespread retrograde amphibolite facies event (550 to 680 °C, 0.75 to 1.20 GPa). New major and trace element geochemical analyses of metamorphosed basic and ultrabasic lithologies indicate that they exhibit geochemical characteristics attributable to a sea floor origin. The metabasites were generated at a spreading centre that interacted with deep-seated upwelling mantle asthenosphere. Separate, independently fractionating basic melt batches existed: these were derived from depleted and enriched asthenosphere and depleted sub-continental lithosphere sources. Geochemical correlation of the Mariánské-Lázně Complex with other early Palaeozoic metabasic provinces facilitates comparison of metabasic lithologies occurring in tectonically dislocated nappe pile thrust sheets, and allows delineation of important suture zones in the European Variscides.

Abstract Multidisciplinary investigations of the western margin of the East European Craton (EEC) by EUROPROBE projects since 1992 have confirmed that the Trans-European Suture Zone (TESZ) is the most fundamental lithospheric boundary in Europe, extending 2000 km from the North Sea to the Black Sea-Crimean region. The crust of the EEC is thicker and denser than that of Phanerozoic-accreted Europe, and the base of the lithospheric mantle significantly deeper. These characteristics persist throughout the length of the TESZ, despite the variation in age of the accreted crust along strike. Geological studies of key deep borehole cores and the limited outcrop data confirm that the crust of Phanerozoic-accreted Central Europe comprises a number of terranes, each thought to be derived from Gondwana during several episodes of rifting, ocean formation, ocean destruction and sequential accretion to the EEC throughout Palaeozoic time. There is still much discussion about the identity, provenance and history of these orogenic terranes. The process of accretion led to the formation of terrane-bounding orogenic sutures, which may be marked in outcrop by ophiolitic and eclogitic relics. Recognition of concealed sutures is obviously more difficult, and relies on a variety of geophysical techniques, used in an integrated way by multidisciplinary teams; the evidence from deep seismic reflection and refraction surveys, teleseismic tomography, magnetotelluric experiments and from geophysical potential-field modelling is crucial for such studies. Since the European Geotraverse, much has been learnt about the geometry of the Thor, Iapetus, Rheic, Saxo-Thuringian and Moldanubian oceanic sutures, through the crust and sometimes into the mantle. This has led to a much better understanding of the 3D crustal structure of the Western Accretionary Margin of the EEC, and the lithospheric processes that have shaped it. From this, the influence of tectonic heterogeneities within the orogenic crust on the development of post-orogenic structures and basins can be much better constrained.