Norwegian Petroleum Directorate

About: Norwegian Petroleum Directorate is a based out in . It is known for research contribution in the topics: Continental margin & Continental shelf. The organization has 179 authors who have published 173 publications receiving 6824 citations.

The tectonic evolution of the Norwegian Sea Continental Margin with emphasis on the Vøring and Møre Basins

Abstract: 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.

A giant three-stage submarine slide off Norway

Abstract: One of the largest submarine slides known, The Storegga Slide, is located on the Norwegian continental margin. The slide is up to 450 m thick and has a total volume of about 5,600 km3. The headwall of the slide scar is 290 km long and the total run-out distance is about 800 km. The slide involved sediments of Quaternary to Early Tertiary age and occurred in three stages. Earthquakes combined with decomposition of gas hydrates are believed to be the main triggering agents for the slides. The first slide event is tentatively dated to be about 30,000 to 50,000 years B.P. and the two last major events are dated to be at 6,000 to 8,000 years B.P.

Glaciomarine sedimentation in a modern fjord environment, Spitsbergen

Abstract: By means of high resolution acoustic profiling and correlation of echo character and sediment lithology, fjords in western and northern Spitsbergen are shown to be blanketed by a 5-20 m layer of acoustically transparent sediments consisting mainly of soft homogeneous mud with ice rafted clasts. Acoustically semi-transparent material is found on slopes and sills reflecting their coarser composition. The areal average depositional rate in the outer fjord is in the range of from 0.1 to l.Omm/year, increasing towards the glaciers. In Kongsfjorden, 5&100mm/year of muddy sediments is deposited at a distance of lOkm from the calving Kongsvegen glacier. Close to the ice front ( 4 . 5 km) coarser grained, interbedded (sanqmud) sediments are deposited. The main sediment sources are from settlement out of the turbid surface sediment plume, combined with various types of gravity flow (sediment creep, minor slides, and slumping). Material deposited from turbidity current is probably of minor importance. On shallow sills the sediments are remobilized by icebergs. The sediment adjacent to the ice front is reworked and compacted during surges, a common form of glacial advance for Spitsbergen glaciers. During the surge considerable amounts of coarse-grained sediment are deposited by meltwater in front of the ice margin.