Abstract Recent stress observations from in situ measurements and earthquake focal mechanisms in the Norwegian onshore and offshore areas are evaluated with the aim of characterizing the most important mechanisms for the present stress field in and around Norway. The evaluation is based on a set of stress indicators that include both shallow measurements (overcoring and borehole breakouts) and deep data (earthquake focal mechanisms). Computer simulations of simple stress-generation models were used to constrain the relative importance of different stress-generating mechanisms. The ridge push force associated with sea-floor spreading in the North Atlantic is considered to be the primary source of the compressional stress field observed in Norway. Regional influences from the continental margin density contrast, topography and flexure induced by sediment loading are of limited lateral extent, but are important in reorienting the stress field in certain areas. The observed tectonics and stresses are generally also in accord with tectonics expected from Fennoscandian uplift.

ABSTRACT The development of the Baltic Sea during the Holocene was mainly controlled by climatically driven eustatic sea-level change and vertical crustal movements. Both factors affect sea-level changes interpreted from sedimentological investigations at coastal locations. Comparison of relative sea-level curves with a eustatic curve reveals the contribution of vertical crustal movements to coastal changes as expressed via a “coast index.” A coast index c(i) for the Baltic region can be derived, by which a location can be allocated to either a “crustal-uplift/subsidence type” or a “climate-controlled type.” Coastal locations investigated along the Fennoscandian Shield belong to the crustal-uplift type and locations along the southern and southwestern coast belong to the climate-controlled type, regardless of whether they are on the East European Platform or the West European Platform. Data on recent vertical crustal movements show a broad, predominantly subsiding zone between the rising blocks of Scandinavia (glacio-isostatic uplift) and the Carpathians (northward drift of the African Plate) to the west of the Tornquist-Teisseyre Zone (TTZ). Movements may additionally be influenced by processes initiated along the North Atlantic Mid-Ocean Ridge. The subsiding belt contiguous to the Fennoscandian Shield is interpreted as a collapsing as- thenospheric bulge originally surrounding the Pleistocene ice shield. The analysis of relative sea-level changes leads to the assumption that the process of collapse reached a steady state during the Late Litorina Stage. Crustal movement data, together with data from modeling of future sea-level change, can be used for calculating scenarios of relative sea-level development, providing a background for long-term planning of human activities in coastal areas.

Abstract The Central Graben area was filled with a thick pile of sediments during the Middle Miocene - Quaternary, corresponding to a period of 15 Ma. As hydrocarbon expulsion from the most prolific source rock, the Upper Jurassic Bo Member, was initiated only 20 Ma BP and still occurs today, the Middle Miocene - Quaternary evolution is important. In the Middle Miocene, the Central Graben area was covered by a sea with water depth of 500–700 m. During the Late Miocene (Tortonian), the basin was successively filled by prograding slope and deltaic sediments from the northeast. The progradational infill resulted in local tilting of the substratum due to the loading effect of the deposits. In the latest Late Miocene (Messinian), the main input of sediments occurred from the south, as illustrated by a thick onlapping succession of upper Messinian sediments. Pliocene sedimentation was characterized by regular infill from the east within a shelf to shallow marine depositional environment. Following the Miocene and Pliocene, the North Sea Basin tilted due to strong uplift of the Fennoscandian shield and increased subsidence and sedimentation rates within the Central Graben area. This further complicated the maturation of the source rock, migration pathways and accumulation of hydrocarbons. The consequence of this complex burial history is exemplified by the Kraka and Halfdan fields. The Kraka Field has a large down-flank oil accumulation, which is the result of a porosity anomaly resulting from an early invasion of oil in this position before the late tilting of the North Sea Basin. The history of the non-structural accumulation of the Halfdan Field can be readily modelled; it constituted a simple four-way dip closure during the Late Miocene when peak oil migration occurred. The Quaternary tilting of the North Sea Basin due to uplift of the Fennoscandian Shield and strong subsidence of the Central Graben area resulted in a distinct gradient favouring long-distance migration of hydrocarbons. The occurrence of viable migration routes, especially within Paleocene sand layers, has resulted in long-distance migration of oil into the Siri submarine valley system. The most northern indication of hydrocarbons has been recognized as far as 75 km from the source area. Long-distance migration of hydrocarbons is also indicated by direct hydrocarbon indications (DHIs) throughout the Cenozoic succession in the Danish North Sea. DHIs are particularly prominent above known hydrocarbon accumulations in the Central Graben. This indicates pronounced vertical migration, for instance along active faults, above these structures.

Abstract The Fennoscandian transition zone, including the Sorgenfrei–Tornquist Zone, constitutes the weakened and faulted bedrock between a craton, including the ancient continent Baltica to the north, and the boundary between Baltica and Avalonia along the Trans-European Fault Zone to the south. Early Permian subsidence in this transition zone resulted in the development of various basins and the initiation of a more or less continuous Permian–Paleogene depositional cycle. In southwestern Sweden, magmatic activity associated with transtensional deformation along the Sorgenfrei–Tornquist Zone prevailed during the Late Carboniferous–Permian. However, the transition zone is dominated by a Mesozoic sedimentary rock succession displaying both hiatuses and great lateral variability in composition and thickness, which can be related to several tectonic events including the progressive break-up of Pangaea. Much of the deposition took place in continental, coastal and shallow-marine settings. Early–Middle Jurassic block faulting and basanitic or melanephelinitic volcanism, as well as Late Cretaceous tectonic inversion along the Sorgenfrei–Tornquist Zone, related to a changeover to a predominantly compressive tectonic regime coeval with the Alpine orogeny, significantly influenced the depositional setting. Subsequent Paleogene–Neogene regional uplift of the southwestern margin of Baltica resulted in significant erosion of the bedrock.

Abstract The study focuses on the terminal moraine of a fast-flowing, temperate tidewater glacier that protruded in Oslofjorden trough, southern Norway, during one of the re-advances of the receding Fennoscandian Ice Sheet in the Younger Dryas time. Allostratigraphic mapping is used to reconstruct the moraine's morphodynamic development, showing how information on the dynamics of ancient glaciers can be derived from their grounding-line deposits. The Storsand moraine commenced its development in the latest phases of ice-margin advance and continued to grow during the stillstand phase, as long as the ice flux persisted. The thick moraine (>100 m) formed in a few decades, to be rapidly abandoned and later emerged by regional uplift. The study concludes that: (a) both meltwater and ice flow invariably supply sediment to the grounding line, and it is the varied preservation potential of ice-derived diamicton that results in misleading differences between moraines; (b) the glacier-front kinematics is asymmetrical with slow advances and rapid retreats; (c) no moraines can form during glacier retreat; (d) the front of an outlet glacier may stabilize while the adjacent ice margin is oscillating or virtually retreating; and (e) marine moraines are an important source of information about ancient ice margins and glacier dynamics.