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NARROW
GeoRef Subject
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all geography including DSDP/ODP Sites and Legs
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Arctic Ocean
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Barents Sea (1)
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Norwegian Sea (1)
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Atlantic Ocean
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North Atlantic
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North Sea (1)
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Europe
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Lapland (1)
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Western Europe
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Scandinavia
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Norway
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Nordland Norway
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Lofoten Islands (1)
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commodities
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petroleum
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natural gas (1)
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Primary terms
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Arctic Ocean
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Barents Sea (1)
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Norwegian Sea (1)
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Atlantic Ocean
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North Atlantic
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North Sea (1)
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Europe
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Lapland (1)
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Western Europe
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Scandinavia
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Norway
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Nordland Norway
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Lofoten Islands (1)
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geophysical methods (1)
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petroleum
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natural gas (1)
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New aeromagnetic and gravity compilations from Norway and adjacent areas: methods and applications
Abstract The Geological Survey of Norway (NGU) has produced new aeromagnetic and gravity maps from Norway and adjacent areas, compiled from ground, airborne and satellite data. Petrophysical measurements on core samples, hand specimens and on in situ bedrock exposures are essential for the interpretation of these maps. Onshore, the most prominent gravity and magnetic anomalies are attributed to lower crustal rocks that have been brought closer to the surface. The asymmetry of the gravity anomalies along the Lapland Granulite Belt and Kongsberg–Bamble Complex, combined with the steep gradient, points to the overthrusted high-density granulites as being the main source of the observed anomalies. The Kongsberg–Bamble anomaly can be traced southwards through the Kattegat to southern Sweden. This concept of gravity field modelling can also be applied to the Mid-Norwegian continental shelf and could partially explain the observed high-density rocks occurring below the Møre and Vøring basins and in the Lofoten area. Extrapolations of Late-Caledonian detachment structures occurring on the mainland can be traced on aeromagnetic and gravimetric images towards the NW across the continental margin. Subcropping Late Palaeozoic to Cenozoic sedimentary units along the mid-Norwegian coast produce a conspicuous magnetic anomaly pattern. The asymmetry of the low-amplitude anomalies, with a steep gradient and a negative anomaly to the east and a gentler gradient to the west, relates the anomalies to gently westward dipping strata. Recent aeromagnetic surveys in the Barents Sea have revealed negative magnetic anomalies associated with shallow salt diapirs. Buried Quaternary channels partly filled with gravel and boulders of crystalline rocks generate magnetic anomalies in the North Sea. The new maps also show that the opening of the Norwegian–Greenland Sea occurred along stable continental margins without offsets across minor fracture zones, or involving jumps in the spreading axis. A triple junction formed at 48 Ma between the Lofoten and Norway Basins.
Abstract A voluminous magmatic complex was emplaced in the Vøring and Møre basins during Paleocene/Eocene continental rifting and break-up in the NE Atlantic. This intrusive event has had a significant impact on deformation, source-rock maturation and fluid flow in the basins. Intrusive complexes and associated hydrothermal vent complexes have been mapped on a regional 2D seismic dataset (c .150 000km) and on one large 3D survey. The extent of the sill complex is at least 80 000 km 2 , with an estimated total volume of 0.9 to 2.8 × 10 4 km 3 . The sheet intrusions are saucer-shaped in undeformed basin segments. The widths of the saucers become larger with increasing emplacement depth. More varied intrusion geometries are found in structured basin segments. Some 734 hydrothermal vent complexes have been identified, although it is estimated that 2–3000 vent complexes are present in the basins. The vent complexes are located above sills and were formed as a direct consequence of the intrusive event by explosive eruption of gases, liquids and sediments, forming up to 11 km wide craters at the seafloor. The largest vent complexes are found in basin segments with deep sills (3–9 km palaeodepth). Mounds and seismic seep anomalies located above the hydrothermal vent complexes suggest that the vent complexes have been re-used for vertical fluid migration long after their formation. The intrusive event mainly took place just prior to, or during, the initial phase of massive break-up volcanism (55.0–55.8 Ma). There is also evidence for a minor Upper Paleocene volcanic event documented by the presence of 20 vent complexes terminating in the Upper Paleocene sequence and the local presence of extrusive volcanic rocks within the Paleocene sequence.