Late Caledonian extension in the scandinavian Caledonides—the Røragen Detachment revisited

Gee, David G.; Lobkowicz, Michal; Singh, Sandeep

doi:10.1016/0040-1951(94)90126-0

Cited by 36 publications

(31 citation statements)

References 38 publications

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“…The profile is reproduced from Hurich et al (1989) and Palm et al (1991). Interpretation of the tectono-stratigraphic units is after Palm et al (1991) and Gee et al (1994). The kinematic interpretation of the faults (shown by arrows) is drawn by the present author and is based on interpretations by Sjöström et al (1991) and the structural geometry.…”

Section: Extensional Structures East Of the Faltungsgrabenmentioning

confidence: 97%

“…3) are less well studied. The interpretation from eastern Norway relies on reconnaissance observations by the present author, but mostly on published maps (Sigmond et al, 1984;Nilsen and Wolf, 1989), short papers and abstracts from the Trondheim-Ö stersund transect Bergman, 1989, 1994;Sjöström et al, 1991) and observations adjacent to the Røragen Devonian basin (Norton, 1987;Gee et al, 1994).…”

Section: Extensional Domains and Structures In South Norwaymentioning

confidence: 99%

“…Work by Bergman (1989, 1994), however, demonstrates that the basement windows are exposed not merely as a result of contractional antiformal stacking (Hurich and Kristoffersen, 1988;Gee et al, 1994), but also as a result of inhomogeneous vertical shortening and horizontal extension of the nappe stack. The earliest structures thinning the nappe complexes in the structural level along the lower and middle allochthon boundary are described by Sjöström and Bergman (1994) from the Trondheim-Ö stersund transect.…”

Section: Extensional Structures East Of the Faltungsgrabenmentioning

confidence: 99%

“…4 reproduced here is based on the published seismic reflection profile (Hurich et al, 1989;Palm et al, 1991), with geological interpretation from the same authors, and clearly indicates the extensional geometries. If the interpretation is correct, it is difficult to envisage how the sole thrust may have been active as a top-to-the-east contractional structure along its entire E-W length at the same time as the upper units where thinned by top-to-the-west extensional shear zones and faults as suggested by Gee (1988) and Gee et al (1994). The surface expression of the normal faults eventually controlled formation and sedimentation in the Devonian Røra-gen basin (Fig.…”

Section: Extensional Structures East Of the Faltungsgrabenmentioning

confidence: 99%

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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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Section: Extensional Structures East Of the Faltungsgrabenmentioning

confidence: 97%

Section: Extensional Domains and Structures In South Norwaymentioning

confidence: 99%

Section: Extensional Structures East Of the Faltungsgrabenmentioning

confidence: 99%

Section: Extensional Structures East Of the Faltungsgrabenmentioning

confidence: 99%

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Extensional tectonics in the Caledonides of southern Norway, an overview

1998

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“…Roberts and Gee 1985;Gee et al 1994;Greiling et al 1998). The final, post-Wenlockian (Scandian) nappe transport considered here succeeded continental Laurentia-Baltica collision in mid-Sil- Fig.…”

Section: Discussionmentioning

confidence: 93%

A thin orogenic wedge upon thick foreland lithosphere and the missing foreland basin

Garfunkel

Greiling

1998

Geologische Rundschau

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Along the Caledonian front in central Scandinavia, the expected peripheral or pro-foreland basin is neither physically present nor are there any significant traces in the sedimentary record. In order to explain and quantify this situation, the authors assess the major geometric and mechanical constraints on the Caledonian orogenic wedge and model the orogenic load and its influence on the foreland lithosphere of Baltica. Geologic and geophysical data show a strong foreland lithosphere with a flexural parameter (α) of approximately 100 km. The shape of the orogenic wedge and its critical taper angle are dependent mainly on basal friction and wedge strength. In the external part organicrich black shales provide a low-friction horizon both at the basal detachment surface and within the wedge itself. The more internal part of the wedge is composed of metamorphic and crystalline rocks, which cooled and strengthened prior to thrusting. As a result, the external part of the wedge had a lower strength and a smaller critical taper angle than its internal part, so the orogenic load is upward concave. Modelling of the effect of such a load on the Baltica lithosphere shows a very small depression in front of the load (2 km). The flexural depression produced by the main part of the orogenic load is filled up by the thickening thrust-andfold belt, so that there is little space left for a foreland basin. These results imply that the missing foreland basin in front of the central Scandinavian Caledonides is not due to subsequent erosion, but is a primary feature.

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Extensional deformation along the late Precambrian-Cambrian Baltoscandian passive margin: the Sarektj�kk� Nappe, Swedish Caledonides

Svenningsen

1995

Geol Rundsch

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Late Caledonian extension in the scandinavian Caledonides—the Røragen Detachment revisited

Cited by 36 publications

References 38 publications

Extensional tectonics in the Caledonides of southern Norway, an overview

Extensional tectonics in the Caledonides of southern Norway, an overview

A thin orogenic wedge upon thick foreland lithosphere and the missing foreland basin

Extensional deformation along the late Precambrian-Cambrian Baltoscandian passive margin: the Sarektj�kk� Nappe, Swedish Caledonides

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