Abstract This paper presents the Microbial Prospection for Oil and Gas (MPOG) method, which uses microbiological techniques to explore for oil and gas. These techniques are based on the principle that light hydrocarbons from oil and gas fields escape to the earth’s surface, and this increased hydrocarbon supply above the fields creates conditions favorable for the development of highly specialized bacterial populations that feed on the hydrocarbons. This leads to significant increases in the microbial cell numbers and cell activity of these specialized microbes. By developing methods to establish the separate activities of methane-oxidizing bacteria (a gas indicator) and those bacteria that oxidize only ethane and higher hydrocarbons (oil indicators), it is possible to differentiate between oil fields with and without a free gas cap, and gas fields. This microbial method of surface prospection has been applied in Germany since 1961. The technique has also been used offshore in the North Sea since 1995. The total area that has been investigated to date is 6000 km 2 , most of which has undergone wildcat prospection. To investigate the influence of geologic structure on the results of microbial prospection, model investigations were carried out, with the close cooperation of exploration geologists, on fields that had already been developed. Investigations were conducted on an unfaulted field, on fields with faults within salt, on fields with faults in the supra- or subsalt, and on a completely destroyed field. The case histories presented here support the following conclusions. (1) In microbial prospection, the results do not show a fault-related dependence. (2) The microbial anomalies occur vertically above the respective field. (3) Thick salt seals (Zechstein salt as thick as 800 m) have no effect on microbial prospection. (4) Tectonically destroyed fields without hydrocarbons do not create any microbial anomalies. (5) Recent biogenic methane formation in marsh areas does not lead to significant MPOG anomalies. To date, a total of 17 oil and gas fields, as well as several seismically identified structures without hydrocarbons—both onshore and offshore—has been confirmed subsequently by the results of 220 wells drilled in the area. The success rate of microbial surface prospecting has therefore reached 90%; i.e., the probability is about 90% that MPOG can indicate the occurrence or absence of hydrocarbons. Seven case histories will be discussed in this paper. In unexplored areas, MPOG represents a cost-effective method for preliminary exploration work. In mature areas, the method is helpful for ranking seismically defined geologic structures by indicating possible infill locations, as a contribution to reservoir characterization.

Abstract Early Jurassic plesiosaurian fossils are rare in the Scandinavian region, with a few isolated bones and teeth known from Bornholm, and anecdotal finds from East Greenland. The only other identifiable specimens derive from Toarcian-aged (based on ammonites) erratics deposited during Late Pleistocene glacial advances near the town of Ahrensburg, NE of Hamburg in northern Germany. The geographical source of these transported clasts is debated, but reconstructed ice-flow directions and lithofacies comparisons implicate either the offshore Baltic Sea between the Island of Bornholm and Mecklenburg–Vorpommern (Germany) or, less probably, south of the Danish Archipelago (Mecklenburg Bay). These regions collectively bordered the Fennoscandian landmass and adjacent Ringkøbing-Fyn Island in the late Early Jurassic, and were dominated by near-shore marine deltaic to basinal settings. The Ahrensburg plesiosaurian remains include postcranial elements reminiscent of both the microcleidid Seeleyosaurus and the rhomaelosaurid Meyerasaurus . These occur alongside other classic ‘Germanic province’ marine amniotes, such as the teleosaurid crocodyliform Steneosaurus and ichthyosaurian Stenopterygius cf. quadriscissus : thus, advocating faunal continuity between Scandinavia and southern Germany during the Toarcian, and a less pronounced marine reptile faunal provinciality than previously assumed.

Abstract Based on reprocessed offshore seismic lines acquired during oil and gas exploration in the 1980s, we reconstruct the formation and reactivation of major fault systems in the southern Baltic Sea area since the late Paleozoic. The geological evolution of different crustal blocks from the Caledonian Avalonia–Baltica collision until the Late Cretaceous–Paleogene inversion tectonics is also examined. The detected fault systems occur in the northern part of the Trans-European Suture Zone (TESZ) and belong either to the late Paleozoic Tornquist Fan or to the complex Western Pomeranian Fault System (WPFS) generated during Mesozoic extensional movements. While the NW–SE-trending deep Wiek Fault separates the Arkona High from the Middle Rügen Block, the NNW–SSE-trending Agricola Fault demarcates the Middle Rügen Block to the Falster Block in the west. Together with the Plantagenet Fault and numerous younger faults in the Mesozoic cover, it forms the Agricola Fault System. Furthermore, structural analyses of the Prerow Fault Zone above the Prerow salt pillow and the Werre Fault Zone crossing the Grimmen High indicate a complex fault history.

Abstract We report new ichthyosaur material excavated in lower Toarcian levels of the LafargeHolcim Val d'Azergues quarry in Beaujolais, SE France. A partially articulated skull and a smaller, unprepared but likely subcomplete skeleton preserved in a carbonate concretion are identified as stenopterygiids, a family of wide European distribution during the Early Jurassic. These specimens are among the finest preserved Toarcian exemplars known from Europe and, in one of them, soft tissue preservation is suspected. Their state of preservation is attributed to the combination of prolonged anoxic conditions near the water–sediment interface and early carbonate cementation resulting from the activity of sulfate-reducing bacteria. We also present carbon and strontium isotope values obtained from the study site that allow detailed temporal comparisons with other Toarcian vertebrate-yielding sites and environmental perturbations associated with the Toarcian Oceanic Anoxic Event (T-OAE). These comparisons suggest that the relatively high abundance and good preservation state of Toarcian vertebrates was favoured by a prolonged period of low bottom water oxygenation and accumulation rates. The environmental conditions that prevailed during the T-OAE were probably responsible for the extensive nature of Lagerstätte-type deposits with exceptional preservation of marine organisms. Testing whether the T-OAE had a biological impact on marine vertebrates requires a precise chemostratigraphic context of the fossil record spanning the Pliensbachian–Toarcian interval.