Thirty-three regionally correlatable marine condensed sections containing maximum flooding surfaces have been recognized in the area allowing the North Sea Jurassic succession to be subdivided into 32 genetic stratigraphic sequences (sensuGalloway). Each event is biostratigraphically calibrated using microfossils (dinoflagellate cysts, radiolaria, ostracoda and foraminifera). The new scheme provides the basis for a basin-wide stratigraphic framework for the Jurassic of the North Sea basin.

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Sediments of Kimmeridgian to Late Ryazanian age form a group of key hydrocarbon play fairways in the syn-rift Jurassic of the North Sea. The perceived yet-to-find reserves of these often subtle plays, lying at or below seismic resolution, have attracted considerable industry attention over the past few years. Reserves are currently estimated by BP Exploration at 1 to 5 billion barrels of oil equivalent, reservoired in three play systems: (1) apron fans (e.g. Brae type); (2) basin floor fans (e.g. Miller, Galley, Ettrick and Magnus types); (3) shallow marine shelf (e.g. Ula, Gyda, Fulmar, Piper, Clyde types).In order to assess the future exploration potential of this play fairway, a high resolution, predictive, sequence stratigraphy was erected for the North Sea Late Jurassic. The stratigraphic framework combines data from over 500 exploration wells with seismic and field data (Magnus, Brae, Miller, Ula, Gyda and Clyde).In the Late Oxfordian to Late Ryazanian, a total of 11 genetic stratigraphic sequences have been defined. They are bounded by maximum flooding surfaces which, within the limits of the biostratigraphy, represent basin-wide isochronous events across NW Europe and can be recognized in exploration wells and at outcrop from Greenland to the Wessex Basin. The maximum flooding surfaces have been biostratigraphically calibrated to provide a consistent and easily identifiable stratigraphic framework. Candidate sequence boundaries have been interpreted within this stratigraphic framework, from basin-ward shifts of facies belts, using sedimentological and wireline log data. The combination of these stratigraphic methods has produced a very powerful tool to predict the presence and distribution of potential reservoirs and play types across the entire North Sea Basin from outcrop in East Greenland to the offshore Netherlands.The model suggests that three major cycles of sand input into the basin can be recognized with an overall marked decrease in net sand content with time. Each cycle is bounded by tectonically enhanced maximum flooding surfaces representing major periods of basin floor reorganization. The intervening maximum flooding surfaces temporarily switch off sediment supply to the basin but do not offset depocentres. These events can form important, field-wide permeability barriers.It is proposed that the tectonically enhanced maximum flooding surfaces are a response to tectonic subsidence during maximum relative sea-level rise, whereas maximum clastic progradation occurs from basin margin uplift during relative sea-level fall. The model is considered to have application at regional and field-specific scales; for example, prediction of both basin floor fan distribution and potential intra-reservoir permeability barriers.

Since the advent of North Sea exploration, a variety of new advances have been made in understanding basin dynamics and regional variations in structural style that are well-founded on the stratigraphy of the better known basins. New insights have also been made into the influence of Palaeozoic compressional and inversion tectonics on the structure of Mesozoic successor basins. This paper, based in part on these advances, offers a new, post plate tectonics, model for the structural and stratigraphic development of Mesozoic and Tertiary basins between mid-Norway and the Bay of Biscay.The tectono-stratigraphic evolution of this region can now be simply described in terms of a southward propagating ‘Arctic’ rift and a northward propagating ‘Atlantic’ rift. These rifts, formed by polyphase extension, remained largely separate entities until the Late Jurassic or Early Cretaceous. Thereafter, the rifts and their successor basins became a single entity represented by the Rockall Trough, Faeroe–Shetland Basin and Møre Basins only modified by later Cretaceous events and the Early Tertiary break-up of the North Atlantic and Norwegian–Greenland Sea.The ‘Arctic’ rift was initiated possibly as early as the Late Palaeozoic, nucleating on Caledonian and Late Devonian structures in the strike-parallel Caledonian terranes. Polyphase extensional events between the Permo-Triassic and Late Jurassic with intervening phases of passive subsidence resulted in rifts and basins of opposing polarity, sometimes superposed or offset, trending from the Barents Sea into the greater North Sea area.In contrast, the ‘Atlantic’ rift was probably initiated by rifting between North America and Africa in Late Triassic to Early Jurassic times. Its northward propagation was at first limited by the E-W and NE-SW Hercynian and Caledonian terranes of the British Isles and northeast Canada. The main subsequent major phase of extension initiated in the Late Jurassic and continuing through the Early Cretaceous progressively opened the North Atlantic from south to north through into the Bay of Biscay.The northward propagation of the Atlantic rift from Biscay into the Rockall Trough and Faeroe–Shetland Basin–Møre Basin completed the linkage to the Arctic rift possibly as early as the Late Jurassic and certainly by the Albo–Aptian. The ensuing rift, underlain by highly stretched continental crust, extended from the Barents Sea via the Vøring Plateau, Møre Basin into the Rockall Trough.The subsequent Late Cretaceous history of the linked system of rifts is characterized by both extension and inversion of unknown origin. In the Early Tertiary, rifting associated with voluminous volcanism along the entire margin and on the scale of the Deccan Traps heralded the break-up by spreading of the Norwegian–Greenland Sea and the northern North Atlantic. A subsequent phase of rifting elevated the Jameson Land Basin of East Greenland exhuming major oil accumulations. In contrast, co-eval phases of inversion in the Vøring Basin, Møre Basin and the Faeroe–Shetland Basin have had a positive impact on prospectivity. Inversion in the Celtic Sea is more probably related to the Pyrennean orogeny.The model of ‘Arctic’ and ‘Atlantic’ rifts offers a new and simpler predictive model of source and reservoir distribution. In the ‘Arctic’ rift, i.e. the North Sea, West of Shetland and offshore Norway–Greenland, volumetrically significant source-bed systems are confined to the Permo–Triassic, Toarcian, Middle and Late Jurassic. In the ‘Atlantic’ rift, between the Celtic Sea, Iberia and the Grand Banks, the major sources seem to be of Toarcian and Late Jurassic age. Cretaceous source beds are minor in the linked rift. However, the multiple phases of rifting and later burial or inversion history have severely affected the maturity of the Jurassic, although appeal to remigration is clearly necessary in the Faeroe–Shetland Basin.Distribution of the major reservoirs in both rifts can be best understood in relation to phases of rift propagation and subsequent subsidence. Thus, the early rifts and their immediate successor passive basins are characterized by shallow marine sedimentation. In contrast, the Late Jurassic-Early Cretaceous rifts were subject to stretching that resulted in initially deep marine environments and very thick infill of later Cretaceous sediments. Significant sand input to the linked rifts only began in the Early Tertiary as a result of the uplift and unroofing of Scotland that heralded the opening to the North Atlantic.

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