Abstract The giant Ormen Lange Gas Field is situated in the Møre Basin, Norwegian Sea, at water depths around 1000 m. The reservoir interval consists of a lower heterolithic unit mainly of Maastrichtian age (Jorsalfare Formation) and an upper sandstone unit of Danian age (Egga Member, Våle Formation), separated by a widely distributed mudstone unit (‘Våle Tight’), and consists of both high and low density turbidites in association with fine-grained background sediments. The reservoir interval spans the Cretaceous-Tertiary boundary, without any major stratigraphic breaks. The main architectural elements of the reservoir are: channel-dominated deposits, channelized lobe deposits and non-channelized frontal splay or fan fringe deposits. The spatial distribution of these facies elements indicates a dynamic system with changing sediment supply through time. Core and log studies from the wells have been integrated with high-resolution biostratigraphy to develop a dynamic depositional model. During latest Cretaceous and Paleocene times, a series of subtle sub-basins developed along the southeastern Møre Basin margin as a result of differential subsidence above Jurassic extensional faults. The sub-basins created a stepped slope topography that influenced the flow pattern of turbidity currents. In a landward position, east of the Ormen Lange Field, the Cretaceous-Tertiary boundary is characterized by a major unconformity, implying erosion and sediment by-pass. In early Danian time, uplift and rotation of the provenance area to the east (Norwegian mainland) led to extensive erosion and redistribution of sandy sediments into the Møre Basin and caused deposition of the Egga Member. The turbidites filled the intraslope basins initially in a basinwards-stepping sense, but later sedimentation switched landward. Onshore structural, provenance and geomorphological data, combined with offshore structural, seismic and sedimentological data, yield an integrated interpretation of the deep-water depositional system in the greater Ormen Lange area. Present fjords at M0re, controlled by the Møre-Trøndelag fault zone, were valley systems that fed sands to a point source updip of the Ormen Lange area. The point source was located at the transition/relay zone between a narrow shelf area in the south and a broad shelf area in the north. In addition to being a key transition zone for both Caledonian and Jurassic structures, this zone area is also the ‘landing’ point of the major oceanic Jan Mayen Fracture Zone.

Abstract The age and tectonic significance of two basement granitoids cored on the Utsira High, Viking Graben, North Sea, are constrained by zircon LA-ICPMS data. Syenite in well 25/10-2R is dated to 482±2 Ma, with ɛHf (482) values from −4.4 to −5.8, and granite in well 16/1-12 yields an age of 436±3 Ma with ɛHf (436) values from +3.7 to −0.5. The evolved Hf-signature of the syenite demonstrates 482 Ma reworking of Palaeoproterozoic–Archaean crust, interpreted to reflect Taconian–Grampian orogenesis. New and recently published data from the offshore Caledonides allow a first-order correlation of the Utsira High basement with the surrounding on- and offshore Caledonides. The Utsira High occupies a similar position with respect to Dalradian rocks as the Scottish Midland Valley terrane. Geophysical data indicate a volcanic arc beneath the East Shetland Basin, forming a northwards continuation of the Utsira High basement. We propose that the offshore volcanic arc segments represent the northeastern continuation of the Scottish Grampian orogen across the Mesozoic North Sea rift. A north-striking terrane boundary fault is proposed to separate the volcanic arc from the East Shetland Platform and merge northwards with the offshore extension of the Great Glen Fault–Møre Trøndelag Fault Complex. Supplementary material: U–Pb and Lu–Hf isotopic data are available at http://www.geolsoc.org.uk/SUP18705 .

Abstract The Norwegian Sea continental margin is dominated by two major basins with a very thick Cretaceous basin fill: the Vøring and Møre Basins. The basins are flanked by the uplifted mainland and the Cretaceous Trøndelag Platform to the east and by the Møre and Vøring Marginal Highs capped by Eocene lavas to the west. The tectonic development of the area is controlled by two structural trends: NE-SW and NW-SE. The area has been tectonically active from Carboniferous to Late Pliocene time with the main tectonic phases in Late Palaeozoic, late Mid-Jurassic-Early Cretaceous and Late Cretaceous-Early Tertiary time. The general tectonic development comprised a long period of extension and rifting that ended in Early Eocene time by continental separation, major volcanism and subsequent sea-floor spreading in the Norwegian-Greenland Sea. In Carboniferous to Early Cretaceous time the extensional tectonics were related to within-plate continental rifting. The tectonics of the Late Cretaceous and the Tertiary periods were controlled by the relative movements along plate boundaries. The overall NE-SW structural grain is constituted by faults and basin axes that probably originated in Late Palaeozoic time and were active during all subsequent tectonic phases. The transverse NW-SE trend is expressed as major lineaments that probably reflect the old, Precambrian grain of the basement. These lineaments, two of which are the continuation into the continental crust of major oceanic fracture zones, controlled the tectonic activity throughout Cretaceous and Tertiary time and constitute the boundaries between the major structural provinces of the area. The differentiation into the Cretaceous basins and the bounding platforms and marginal highs started by the late Mid-Jurassic-Early Cretaceous extensional phase. The subsequent Cretaceous subsidence history, where the basin flanks formed by flexuring rather than faulting, resulted in an exceptionally thick basin fill. In the Vøring Basin the Cretaceous development comprised an early thermal subsidence phase and a post-Cenomanian phase of tectonically driven subsidence involving intermittent phases of normal faulting and compression and folding. The Vøring Basin was tectonically active also during Tertiary time with the main phases of strike-slip-compression coinciding with the Alpine orogenies in Late Eocene and Mid-Miocene time. Within the Vøring Basin there is evidence of the formation of a fossil opal A-opal-CT transition and extensive regional marine erosion in Mid-Miocene and Late Pliocene times. In contrast, the Møre Basin was generally tectonically quiet throughout the Cretaceous and Tertiary periods, experiencing mainly continuous subsidence.