Abstract Natural geological accumulations of carbon dioxide occur widely throughout Europe, often close to population centres. Some of these CO 2 deposits leak, whereas others are sealed. Understanding these deposits is critical for selecting and designing underground storage sites for anthropogenic CO 2 . To provide confidence that the potential risks of geological CO 2 storage are understood, geologists are required to predict how CO 2 may behave once stored underground. Natural CO 2 accumulations provide a unique opportunity to study long-term geochemical and geomechanical processes that may occur following geological storage of anthropogenic CO 2 . In addition, natural CO 2 springs and gas vents can provide information on the mechanisms of gas migration and the potential effects of CO 2 leakage to the surface. This paper provides a description of some natural, European CO 2 occurrences. CO 2 accumulations occur in many basins across Europe. In addition, volcanic areas and seismically active areas allow CO 2 -rich fluids to migrate to the near surface. Many of these occur in areas that have been populated for hundreds and thousands of years. Stratigraphic traps have allowed CO 2 to accumulate below evaporite, limestone and mudstone caprocks. Comparisons between reservoir sandstone and equivalent nearby sandstones that contain no CO 2 indicate that reservoir sandstones may experience increased secondary porosity development through feldspar dissolution. Where fracture reactivation allows CO 2 -rich fluids to migrate, limited self-sealing may take place through calcite precipitation. Gas migration experiments indicate that, due to geochemical interactions, fine-grained seals would be able to trap smaller volumes of CO 2 compared to, for example CH 4 . In natural systems most leakage from depth occurs along fractures and is typically extremely localized on a metre-scale.

Abstract: A natural CO 2 reservoir system with a sandstone lithology in NW Hungary has been studied due to its similarities to a large saline reservoir formation that is widespread in the the Pannonian Basin (Central Europe) and is suggested to be one of the best candidates for industrial CO 2 storage. A range of analytical techniques has been used on core samples from CO 2 -containing sandstone layers that represent a wide range of pressures (90–155 bar), temperatures (79–95°C) and pore fluid compositions (total dissolved solids between 18 000 and 50 700 mg l −1 ) to identify the mineralogy and textural characteristics of the natural reservoir. The only clear CO 2 -related feature in the studied lithology was the occurrence of dawsonite (NaAlCO 3 (OH) 2 ) in a close textural relationship with albite. This is in clear agreement with our geochemical modelling results, which also underline the presence of albite as a precondition for the crystallization of dawsonite at the given P – T – X conditions. Our results suggest that, at least in the Pannonian Basin, dawsonite may be an important mineral for the safe sequestration of industrial CO 2 in the subsurface.

Abstract The past decade has witnessed spectacular progress in the collection of observational data and their interpretation in the Pannonian Basin and the surrounding Alpine, Carpathian and Dinaric mountain belts. A major driving force behind this progress was the PANCARDI project of the EUROPROBE programme. The paper reviews tectonic processes, structural styles, stratigraphic records and geochemical data for volcanic rocks. Structural and seismic sections of different scales, seismic tomography and magnetotelluric, gravity and geothermal data are also used to determine the deformational styles, and to compile new crustal and lithospheric thickness maps of the Pannonian Basin and the surrounding fold-and-thrust belts. The Pannonian Basin is superimposed on former Alpine terranes. Its formation is a result of extensional collapse of the overthickened Alpine orogenic wedge during orogen-parallel extrusion towards a ‘free boundary’ offered by the roll-back of the subducting Carpathian slab. As a conclusion, continental collision and back-arc basin evolution is discussed as a single, complex dynamic process, with minimization of the potential and deformational energy as the driving principle.

ABSTRACT This chapter presents new data and statistics on the economic importance of giant oil and gas discoveries. Giant discoveries are major economic events—they reveal previously unknown subsoil riches and preview a flow of investment and revenues to countries throughout the coming decades. For lower-income countries, they can exceed in net present value terms the entire annual GDP of the country. We discuss how countries have managed these opportunities—for some it has led to decades of sustained prosperity; for others it has failed to generate anticipated benefits, creating a dependence on resource revenues; and in some cases, it has exacerbated problems of economic mismanagement, corruption, and conflict. A new strand of social science literature is now interested in the effect of discoveries in isolation from the longer-term effects of a country becoming resource dependent. We review this work, concluding that the news of a giant discovery can significantly shift the economic and political trajectories of countries, for better and for worse.

ABSTRACT An evolution of the Slovak part of the Danube Basin has started with transtension-extension spreading of the crust [Paleogene(?) to Ottnangian(?), Karpatian, and lower Badenian]. This pro-tostage of the evolution has been an important factor in the further evolution of the basin, but the dominant element, from the viewpoint of the evolution of the Slovak part of the Danube Basin and also its broader surroundings, appears to be the Ulany ridge. This ridge connected (as an interbasinal ridge) the evolution of the Slovak part of the Danube Basin and of the Vienna basin into one dynamic context until the end of the crustal extension phase (lowest Panno-nian). In that way, the Ulany ridge controlled the bivergent extension (toward northwest-west and southeast–east) from the north–northeast–south–southwest axis of the ridge uplift. The recent structural inexpressiveness of this ridge is caused by its tectonic unroofing in the crustal extension phase, erosion, and later (upper lower Pannonian to Holocene) thermal collapse in the basin.

ABSTRACT There have been 248 giant fields (>500 MMBOE) found since 2000. Information gleaned from studying these giant fields’ data has shown that the industry has undergone at least five major paradigm shifts in the past 20 years. First, unconventional and tight gas exploration has transformed the industry. It is expanding to South America, Oman, Bahrain, China, and other countries. Second, creaming curves show step changes in success in finding giant combination and stratigraphic traps. These traps now comprise 60% of the volumes, up from 10% to 15% historically, and attributed to improved seismic imaging. The most important trends are salt-sealed carbonate reef complexes in the Caspian Basin, Egypt, Brazil, and Turkmenistan. Of equal importance are passive margin turbidites, commonly de-risked with amplitude vs. offset (AVO) and 3-D seismic reservoir imaging. Third, ultra-deep drilling to 5–9 km below mudline is finding oil, rich liquids, and porosity. Some of this can be explained by lowered geothermal gradients beneath thick salt, but other oils occur at temperatures of 160°C–180°C with very high pressures. We discuss new concepts to explain these deep liquids from the standpoint of pressure, volume, temperature (PVT) data and fractionization during migration. Fourth, giant fields have been found overlying oceanic crust, breaking a long-held paradigm that these kinds of plays do not work. Last, deep, overpressured upward hydrodynamic flow and tilted hydrocarbon contacts have been documented in many basins. This may ultimately turn out to be more of a “norm” than an exception.

Abstract The Alps and Western Carpathians constitute that part of the Alpine-Mediterranean orogenic belt which advances furthest to the north into Central Europe. They were formed by a series of Jurassic to Tertiary subduction and collision events affecting several Mesozoic ocean basins, continental margins, and continental fragments. The Western Alps form a pronounced, westward-convex arc around which the strike of the tectonic units changes by almost 180° ( Fig. 18.1 ). The Western Carpathians are a northward-convex arc of similar size but with minor curvature. The two arcs are connected by an almost straight, WSW-ENE striking portion including the Eastern Alps Stresses produced by tectonic processes in the Alps also influenced the tectonics of large parts of central and northern Europe, leading, for example, to basin inversion and strike-slip faulting. In this chapter, we will discuss the present-day structure of the different tectonic units in the Alps and Western Carpathians in relation to their palaeotectonic history in order to illustrate the plate tectonic evolution using geological data. Many tectonic problems of the Alps and Western Carpathians are still unsolved, although dramatic progress has been made, especially over the last c. 20 years. Therefore, some of the interpretations presented below are still controversial and do not always express the opinion of all three authors. Given that the main theme of this book is Central Europe, the Southern and Western Alps are discussed in less detail than those parts of the Alps which belong to Central Europe: the Central Alps, the Eastern Alps and the Western Carpathians.

Abstract Over the last 65 Ma, our world assumed its modern shape. This timespan is divided into the Palaeogene Period, lasting from 65 to 23 Ma and the Neogene, which extends up to the present day (see Gradstein & Ogg (2004) and Gregory et al. (2005) for discussion about the Quaternary). Throughout the Cenozoic Era, Africa was moving towards Eurasia in a northward direction and with a counterclockwise rotation. Numerous microplates in the Mediterranean area were compressed, gradually fusing, and Eurasia underwent a shift from a marine archipelago to continental environments, related to the rising Alpine mountain chains ( Figs 17.1 & 17.2 ). Around the Eocene-Oligocene boundary, Africa's movement and subduction beneath the European plate led to the final disintegration of the ancient Tethys Ocean. The Indo-Pacific Ocean came into existence in the east while various relict marine basins remained in the west. In addition to the emerging early Mediterranean Sea, another relict of the closure of the Tethys was the vast Eurasian Paratethys Sea. The Oligocene and Miocene deposits of Central Europe are largely related to the North Sea in the north, the Mediterranean Sea in the south and the intermediate Paratethys Sea and its late Miocene to Pliocene successor Lake Pannon. At its maximum extent, the Paratethys extended from the Rhône Basin in France towards Inner Asia. Subsequently, it was partitioned into a smaller western part consisting of the Western and the Central Paratethys and the larger Eastern Paratethys. The Western Paratethys comprises the Rhône Basin and the Alpine Foreland Basin of Switzerland, Bavaria and Austria. The Central Paratethys extends from the Vienna Basin in the west to the Carpathian Foreland in the east where it abuts the area of the Eastern Paratethys. Eurasian ecosystems and landscapes were impacted by a complex pattern of changing seaways and land bridges between the Paratethys, the North Sea and the Mediterranean as well as the western Indo-Pacific (e.g. Rögl 1998 ; Popov et al. 2004 ). This geodynamically controlled biogeographic differentiation necessitates the establishment of different chronostratigraphic/geochronologic scales. The geodynamic changes in landscapes and environments were further amplified by drastic climate changes during the Cenozoic. The warm Cretaceous climate continued into the early Palaeogene with a distinct optimum near the Palaeocene-Eocene boundary (Palaeocene-Eocene Thermal Maximum) and the Early Eocene (Early Eocene Climate Optimum). A gradual decrease in temperature during the later Eocene culminated in the formation of the first icesheets in Antarctica around the Eocene-Oligocene boundary ( Zachos et al. 2001 ; Prothero et al. 2003 ). A renewed warming trend that began during the Late Oligocene continued into the Middle Miocene with a climax at the Mid-Miocene Climatic Optimum. The turning point at around 14.2 Ma led to the onset of the Middle Miocene Climate Transition indicated by the cooling of surface waters and the expansion of the East Antarctic icesheet ( Shevenell et al. 2004 ). A final trend reversal during the Early Pliocene is reflected by a gentle warming until 3.2 Ma ( Zachos et al. 2001 ) when the onset of permanent Arctic glaciation heralded the Pleistocene ice ages (see Litt et al. 2008 ). The Cenozoic history of Central Europe is chronicled in a dense pattern of Palaeogene and Neogene basins. In addition to the more stable North Sea Basin, the majority of these basins were strongly influenced by the Alpine compressive tectonics which caused a general uplift of Europe during the Cenozoic (see Froitzheim et al. 2008 ; Reicherter et al. 2008 ). The marginal position of the seas covering the area and the considerable synsedimentary geodynamic control resulted in incomplete stratigraphic sequences with frequent unconformities, erosional surfaces and depositional gaps. This chapter deals with the Paleogene and Neogene (“Tertiary”) geological development of Central Europe and its adjacent areas. It is structured according to the main geological regions relevant for the Cenozoic: (1) The European Plate; (2) the Alps and Alpine Foredeep; (3) the Carpathians, their foredeep and the Pannonian Basins System; and (4) the Southern Alps and Dinarides. Each subchapter is arranged from west to east, and north to south.

Abstract The Western Carpathians in the territory of Moravia (the eastern part of the Czech Republic) and northeastern (Lower) Austria represent the westernmost segment of the entire Carpathian orogenic system linked to the Eastern Alps. Based on differences in their depositional and structural history, the Carpathians are divided into two primary domains: the Inner Carpathians deformed and thrusted in the Late Jurassic to Early Cretaceous, and the Outer Carpathians deformed and thrusted over the European foreland during the Paleogene and Neogene. These two domains are separated by the Pieniny Klippen Belt, which bears signatures of both these domains and stands out as a primary suture in the Western Carpathians. Only the Outer Carpathians, including the thin-skinned thrust belt partly overlain by the Vienna basin and the undeformed Neogene foredeep, are present in the territory of Moravia and, as such, are subjects of our deliberation. The foreland of the Carpathians in Moravia is represented by the Bohemian Massif, which is a part of the West European plate. It consists of the Hercynian orogenic belt and the late Precambrian (Cadomian) foreland terrane of the Brunovistulicum. The unmetamorphosed sedimentary cover of the cratonic basement of the Bohemian Massif in Moravia extends through two plate-tectonic cycles, the Paleozoic Hercynian and the Mesozoic to Cenozoic Tethyan-Alpine. The Bohemian Massif continues far below the Carpathian foredeep and the thin-skinned Outer Carpathian thrust belt. Various deep antiformal structures have been identified in the subthrust plate by seismic methods and drilling. Some of these structures apparently formed during the Hercynian orogeny, whereas others are related either to the Jurassic rifting or to the compressional Alpine tectonics extending from the Late Cretaceous to Miocene. During the Laramide uplifting of the European foreland, in the Late Cretaceous to early Paleogene, two large paleovalleys and submarine canyons were cut into the foreland plate and filled with deep-water Paleogene strata. The Carpathian orogenic system, as we know it today, evolved during the late Paleozoic, Mesozoic, and Cenozoic through the divergent and convergent processes of the plate-tectonic cycle. In the Outer Western Carpathians of Moravia, the divergent stage began in the Middle to Late Jurassic by rifting, opening of Tethyan basins, and development of the passive margins dominated by the carbonate platforms and basins. Further rifting and extension occurred in the Early Cretaceous. The convergent orogenic process in the Outer Carpathians began in the Late Cretaceous by the subduction of the Penninic-Pieninic oceanic basin and collision of the Inner Carpathians with the fragmented margins of the European plate. Since the Late Cretaceous, a major foreland basin dominated by the siliciclastic shelf and deep-water flysch sedimentation has formed in the Outer Carpathian domain. The Carpathian foreland basin, especially during the Late Cretaceous to the early Eocene, displayed a complex topography marked by an existence of intrabasinal ridges (cordilleras) such as the Silesian cordillera. We interpret them as preexisting rift-related crustal blocks activated during the Late Cretaceous-early Paleocene uplifting as foreland-type compressional structures. During the Paleogene and early Miocene, the Upper Jurassic to lower Miocene sequences of the Outer Carpathian depositional system were gradually deformed and thrusted over the European foreland. The tectonic shortening occurred not only in the decoupled thin-skinned thrust belt but also at the deeper crustal level, where various blocks of the previously rifted margins were apparently at least partly accreted back to the foreland plate instead of being subducted. Since the early Miocene, the synorogenic, predominantly deep-water flysch sedimentation was replaced by the shallow-marine and continental molasse-type sedimentation of the Neogene foredeep, which remained mostly undeformed. Also during the Miocene, the Vienna basin formed in the Carpathian belt of southern Moravia and northeastern Austria as a result of subsidence, back-arc extension, and the orogen-parallel pull-apart strike-slip faulting. During its entire history, the evolution of Outer Western Carpathians in Moravia was significantly affected by the existence of two main structural elements, the Western Carpathian transfer zone and the Dyje-Thaya depression. The southwest-northeast-trending Western Carpathian transfer zone actually separated the Alps from the Carpathians. During the divergent stage, in the Early Cretaceous, the dextral motion in this zone accommodated a significant extension in the Outer Carpathian domain. Conversely, during the convergent stage in the Paleogene and Neo-gene, the sinistral transpressional motion in this zone facilitated the northeastern translation (escape) of the Carpathian belt and the opening of the pull-apart depocenter in the Vienna basin. The northwest-southeast-trending Dyje-Thaya depression, in southern Moravia and northeastern Austria, formed, or at least was activated, during the Jurassic rifting. Within the fault-bounded limits of this depression, thick, organic-rich marls were deposited in the Late Jurassic, shallow-marine clastic strata were laid down and preserved in the Late Cretaceous, two paleovalleys were excavated in the Late Cretaceous-early Paleogene, and finally, the Vienna basin formed in the Miocene. The complex structural and depositional history of the depression and its surroundings created one of the most prolific petroleum systems in the entire Carpathian region, from which more than 850 million bbl of oil has been produced to date. Historically, the Vienna basin has been the dominant producer in Austria and Moravia. More recently, however, the subthrust European platform with multiple hydrocarbon plays has become the main producing province in Moravia. Some of the identified deep subthrust structures represent significant exploration prospects, which yet have to be tested.