Mesozoic alkaline dykes in the Sunnhordland region, western Norway: ages, geochemistry and regional significance

Færseth, Roald B.; Macintyre, R. M.; Naterstad, J.

doi:10.1016/0024-4937(76)90023-2

Cited by 81 publications

(55 citation statements)

References 29 publications

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“…K-Ar, Ar-Ar and palaeomagnetic age determinations indicate two pulses of dyke intrusion (Faerseth et al, 1976;Løvlie & Mitchell, 1982;Torsvik et al, 1997;Fossen & Dunlap, 1999). The older group is Permian (270-250 Ma; Fig.…”

Section: Triassic-early Jurassic: Differential Uplift and Erosionmentioning

confidence: 99%

“…comm. (2010; (4) Ksienzyk et al (2014); (5) Faerseth et al (1976), Løvlie & Mitchell (1982), Fossen & Dunlap (1999), Torsvik et al (1997); (6) Fossen et al (1997); (7) , ; (8) , 1993, , Pedersen et al (1995), Dahlgren et al (1996Dahlgren et al ( , 1998, Corfu & Dahlgren (2008); (9) Viola et al (2016); (10) Torgersen et al (2015), (11) Torsvik et al (1992), Eide et al (1997); (12) Andersen et al (1999). GF*…”

Section: Ytrebygdsvegen (Bg-115) and Terminalvegen (Bg-116)mentioning

confidence: 99%

“…The older group is Permian (270-250 Ma; Fig. 6) in age, and a relationship with the formation of the Oslo Rift and the North Sea rift system has been suggested (Faerseth et al, 1976(Faerseth et al, , 1995Fossen & Dunlap, 1999;Valle et al, 2002).…”

Section: Triassic-early Jurassic: Differential Uplift and Erosionmentioning

confidence: 99%

“…(3) Fault activity: Field evidence shows that there was fault activity both before and after the intrusion of the Permian dykes (Faerseth et al, 1976;Fossen, 1998;Valle et al, 2002). On Sotra, Set II faults of Larsen et al (2003) tend to strike parallel to the dykes and, at one locality, one of the dykes underwent cataclastic deformation.…”

Section: Triassic-early Jurassic: Differential Uplift and Erosionmentioning

confidence: 99%

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Post-Caledonian brittle deformation in the Bergen area, West Norway: results from K–Ar illite fault gouge dating

Ksienzyk¹,

Wemmer²,

Jacobs³

et al. 2016

NJG

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Post-Caledonian extension during orogenic collapse and Mesozoic rifting in the West Norway-northern North Sea region was accommodated by the formation and repeated reactivation of ductile shear zones and brittle faults. Offshore, the Late Palaeozoic-Mesozoic rift history is relatively well known; extension occurred mainly during two rift phases in the Permo-Triassic (Phase 1) and Mid-Late Jurassic (Phase 2). Normal faults in the northern North Sea, e.g., on the Horda Platform, in the East Shetland Basin and in the Viking Graben, were initiated or reactivated during both rift phases. Onshore, on the other hand, information on periods of tectonic activity is sparse as faults in crystalline basement rocks are difficult to date. KAr dating of illite that grows synkinematically in fine-grained fault rocks (gouge) can greatly help to determine the time of fault activity, and we apply the method to nine faults from the Bergen area. The K-Ar ages are complemented with X-ray diffraction analyses to determine the mineralogy, illite crystallinity and polytype composition of the samples. Based on these new data, four periods of onshore fault activity could be defined: (1) the earliest growth of fault-related illite in the Late Devonian-Early Carboniferous (>340 Ma) marks the waning stages of orogenic collapse; (2) widespread latest Carboniferous-Mid Permian (305-270 Ma) fault activity is interpreted as the onset of Phase 1 rifting, contemporaneous with rift-related volcanism in the central North Sea and Oslo Rift; (3) a Late Triassic-Early Jurassic (215-180 Ma) period of onshore fault activity postdates Phase 1 rifting and predates Phase 2 rifting and is currently poorly documented in offshore areas; and (4) Early Cretaceous (120-110 Ma) fault reactivation can be linked either to late Phase 2 North Sea rifting or to North Atlantic rifting.

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Section: Triassic-early Jurassic: Differential Uplift and Erosionmentioning

confidence: 99%

Section: Ytrebygdsvegen (Bg-115) and Terminalvegen (Bg-116)mentioning

confidence: 99%

Section: Triassic-early Jurassic: Differential Uplift and Erosionmentioning

confidence: 99%

Section: Triassic-early Jurassic: Differential Uplift and Erosionmentioning

confidence: 99%

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Post-Caledonian brittle deformation in the Bergen area, West Norway: results from K–Ar illite fault gouge dating

Ksienzyk¹,

Wemmer²,

Jacobs³

et al. 2016

NJG

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“…South of Bergen, Triassic (?) to Jurassic dolerites (K/Ar dating; Faerseth et al, 1976) have been emplaced along the N-S-trending fractures system, hence a Mesozoic age is suggested for this system north of Bergen . Although the precise age of fault rocks along the Laerdal-Gjende and other normal faults along the Faltungsgraben lineament is presently unknown, it is tentatively suggested that their brittle reactivation represents the easternmost expression of the late Palaeozoic to Mesozoic extension on the S Norwegian mainland.…”

Section: Continued Late Palaeozoic-early Mesozoic Extensionmentioning

confidence: 99%

Extensional tectonics in the Caledonides of southern Norway, an overview

1998

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The extensional collapse of the Scandinavian Caledonides resulted in rapid tectonic denudation of the orogen, exhumation of high-and ultra-high-pressure metamorphic rocks and provided a structural template for the formation of Devonian supra-detachment sedimentary basins. The geometry and intensity of the extensional deformation show considerable variation vertically in the crustal section as well as horizontally from east to west across the orogen. The most prominent structural feature related to the extension in central-south Norway is the change in the direction of tectonic transport, from the easterly directed nappe translation during the Silurian Scandian Orogeny, to top-westerly directed sense of shear during the extension. The Fennoscandian basement was little affected by extension in the eastern Caledonides. In the west, however, top-to-the-west shear zones are commonly observed in basement windows. Deformation affecting the Cambrian to Late Silurian rocks in the Caledonian foreland developed a typical of foreland fold and thrust belt geometry. Deformation in the foreland was apparently contemporaneous with the extension-related decompression of the high-pressure rocks in the hinterland. Thrusting in the foreland may thus have been driven by gravitational collapse, and as such have important similarities to the foreland-hinterland relationships of the Himalayan-Tibetan region. The basal contacts of the Jotun and other major nappes constitute prominent shear zones in which fabrics related to thrusting have been mostly destroyed by extensional shearing. The high structural levels of the Western Gneiss Region, adjacent to the western margin of the Jotun Nappe, were only moderately affected by the extensional deformation. Consequently, the Proterozoic orthogneiss complexes are generally well preserved in this area. The westernmost and structurally lowermost parts of the Western Gneiss Region have, however, been subjected to extreme overburden during the Caledonian continental collision. Initial, near-isothermal decompression of the high-pressure rocks occurred by non-rotational vertical shortening-horizontal stretching at eclogite-to amphibolite-facies conditions; at a later stage, decompression and cooling from amphibolite to greenschist facies occurred by rotational deformation associated with the large-scale extensional detachments. The initial extensional deformation in the hanging wall of the detachments in western Norway commenced at greenschist-facies conditions, and became progressively more brittle and localised as the complexes were exhumed in the Late Silurian to Middle Devonian. Major syn-depositional normal faults in the hanging wall of the extensional detachments eventually controlled sedimentation in the Devonian supra-detachment basins.

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Mega‐scale Moho relief and the structure of the lithosphere on the eastern flank of the Viking Graben, offshore southwestern Norway

et al. 2015

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The International Lithosphere Project deep reflection seismic survey in the Norwegian sector of the North Sea has been reprocessed, particularly focusing on the deep crust, the reflection Moho, and the upper mantle. The data display shifting reflection patterns of the crust and the upper mantle parallel to the eastern margin of the Viking Graben. In the upper crust, which is mainly seismically transparent by the processing techniques utilized here, large-scale structural features like detachment shear zones and master faults can be identified. Several of the major onshore faults and shear zones match seismic features in the seismic lines. Many of these structures acted as extensional shear zones in the Devonian. The middle crust is of variable reflectivity, whereas the lower crust is generally strongly reflective and is particularly so in the southern domain. The reflection Moho is identified throughout the study area but is of variable character. The presence of a S(E) dipping structure (Hardanger Moho Offset) that displaces the Moho by approximately 10 km, extends deep into the mantle (below the 50 km line depth), is positioned where the shallower Hardangerfjord Shear Zone, which flattens on the level of the middle crust, is situated. The Hardangerfjord Shear Zone/Hardanger Moho Offset-system coincides with change of the crustal thickness (depth to Moho), a change that also coincides with the transition from thin-to thick-skinned Caledonian deformation. Intramantle reflections are common in the study area, some of which are interpreted as shear zones, whereas others most likely represent magmatic intrusions.

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Mesozoic alkaline dykes in the Sunnhordland region, western Norway: ages, geochemistry and regional significance

Cited by 81 publications

References 29 publications

Post-Caledonian brittle deformation in the Bergen area, West Norway: results from K–Ar illite fault gouge dating

Post-Caledonian brittle deformation in the Bergen area, West Norway: results from K–Ar illite fault gouge dating

Extensional tectonics in the Caledonides of southern Norway, an overview

Mega‐scale Moho relief and the structure of the lithosphere on the eastern flank of the Viking Graben, offshore southwestern Norway

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