The Scandinavian Caledonides

Gee, David G.; Gorbatschev, Roland; Ramberg, Hans

doi:10.1029/gd010p0045

Cited by 10 publications

(5 citation statements)

References 55 publications

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“…1b) can be divided into two geological domains (Koistinen et al 2001;Gaál & Gorbatschev 1987). The Caledonian domain across Norway is the result of the last orogenic episode in the North Atlantic region caused by the closing of the Iapetus ocean and the collision between Baltica-Avalonia and Laurentia (Gee et al 1982). The collision generated a stack of four major allochthonous nappes (Roberts & Gee 1985) with a vergence toward the west.…”

Section: Geological Settingmentioning

confidence: 99%

Crustal properties of the northern Scandinavian mountains and Fennoscandian shield from analysis of teleseismic receiver functions

Mansour

England

Fishwick

et al. 2018

Geophysical Journal International

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S U M M A R YThe presence of high mountains along passive margins is not unusual, as shown by their presence in several regions (Scandinavia, Greenland, East US, SW Africa, Brazil, West India and SE Australia). However, the origin of this topography is not well understood. The mountain range between the Scandinavian passive margin and the Fennoscandian shield is a good example. A simple Airy isostatic model would predict a compensating root beneath the mountains but existing seismic measurements of variations in crustal thickness do not provide evidence of a root of sufficient size to produce the necessary compensation. In order to better constrain the physical properties of the crust in northern Scandinavia, two broad-band seismic networks were deployed between 2007 and 2009 and between 2013 and 2014. A new map of crustal thickness has been produced from P-receiver function analysis of teleseismic data recorded at 31 seismic stations. The map shows an increase in crustal thickness from the Atlantic coast (38.7 ± 1.8 km) to the Gulf of Bothnia (43.5 ± 2.4 km). This gradient in thickness demonstrates that the Moho topography does not mirror the variation in surface topography in this region. Thus, classical Airy isostatic models cannot explain how the surface topography is supported. New maps showing variation in Poisson's ratio and Moho sharpness together with forward and inverse modelling provide new information about the contrasting properties of the Fennoscandian shield and crust reworked by the Caledonian orogeny. A sharp Moho transition (R > 1) and low value of V s (3.5 ± 0.2 km s −1 ) are observed beneath the orogen. The shield is characterized by a gradual transition across the Moho (R < 1) and V s of 3.8 ± 0.1 km s −1 which is more typical of average continental crust. These observations are explained by a Fennoscandian shield underplated with a thick layer of high velocity, high density material. It is proposed that this layer has been removed or reworked beneath the orogen.

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Section: Geological Settingmentioning

confidence: 99%

Crustal properties of the northern Scandinavian mountains and Fennoscandian shield from analysis of teleseismic receiver functions

Mansour

England

Fishwick

et al. 2018

Geophysical Journal International

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“…540 Ma and the final continent-continent collision occurred in the Mid-Silurian to Early Devonian (425-400 Ma, e.g. Gee 1982). In the collision, Baltica was pressed down beneath Laurentia and sedimentary and volcanic rocks, which were originally deposited on the floor of the Iapetus Ocean and along the margin of the continent Baltica, were thrust from the west/northwest onto Baltica.…”

Section: Caledonian Orogenmentioning

confidence: 99%

Structure of the Central Scandinavian Caledonides and the underlying Precambrian basement, new constraints from magnetotellurics

Korja¹,

Smirnov²,

Pedersen

et al. 2008

Geophysical Journal International

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S U M M A R YWe investigate the structure of the accretionary wedge of the Caledonian orogen, the underlying autochthonous/parautochthonous carbonaceous alum shales and the Precambrian basement. We have conducted 60 broad-band magnetotelluric soundings along a 180 km long profile in Jämtland, Sweden, across the eastern section of the Central Scandinavian Caledonides. Dimensionality analysis and regional strike estimates indicate that the conductivity structure can be approximated by a 2-D model having a N40 • E strike direction, consistent with the dominant geological strike. The determinant average of the impedance tensor, together with the tipper transfer function from the best 34 sites, were inverted by the REBOCC 2-D inversion code. An electrically highly conducting layer beneath the Caledonides images alum shales, the autochthonous Cambrian carbon-bearing black shales on top of the Precambrian basement. Based on the comparison of electrical conductivity and seismic reflectivity models, we suggest that the Caledonian accretionary wedge thickens in a step-wise manner from ca. 1 to 5-6 km towards the west. In the east, the wedge is composed of the lower allochthon. In the west, the wedge reaches the thickness of 15 km and is composed of the lower allochthon at the bottom, the middle/upper allochthons at the top and resistive allochthonous basement slices. The upper crust of the autochthonous Precambrian basement is homogeneous and resistive from surface down to 15 km and can be associated with the Revsund and Rätan granites. The border between the eastern Revsund-and western Rätan-type granites coincides in the Jämtland region, with the boundary between the northern Central Svecofennian Province and the southern Svecofennian volcanic belt and is marked by a subvertical conductor associated with a steeply dipping band of reflectors. The lower crust and uppermost mantle in the easternmost part of the profile are very resistive, whereas in west, they are 2-3 orders of magnitude more conductive. The increase of average crustal conductivity is related to the Caledonian processes or later opening of the Atlantic Ocean that have affected also the lower crust.

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“…In order to better understand the depositional environments, age and provenance of the sedimentary rocks associated with these outer margin dyke-swarms and compare them with those in the underlying tectonic units, a selection of samples from different tectonic units were collected along and in the vicinity of Silvervägen (the Silver Road) in 2010; zircons have been separated and their Gee et al (1985), Solli and Nordgulen (2006), Gorbatschev (2004), Bingen et al (2008), Roberts and Slagstad (in press) Kulling (1972Kulling ( , 1982, Andréasson et al (1985), Nordgren (1987), Albrecht (2000), Thelander (2009), Grimmer et al (2011), Kathol et al (2014. S: Silvergruvan window.…”

Section: Introductionmentioning

confidence: 99%

Detrital zircon signatures of the Baltoscandian margin along the Arctic Circle Caledonides in Sweden: The Sveconorwegian connection

Gee

Andréasson

Lorenz

et al. 2015

Precambrian Research

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The Scandinavian Caledonides

Cited by 10 publications

References 55 publications

Crustal properties of the northern Scandinavian mountains and Fennoscandian shield from analysis of teleseismic receiver functions

Crustal properties of the northern Scandinavian mountains and Fennoscandian shield from analysis of teleseismic receiver functions

Structure of the Central Scandinavian Caledonides and the underlying Precambrian basement, new constraints from magnetotellurics

Detrital zircon signatures of the Baltoscandian margin along the Arctic Circle Caledonides in Sweden: The Sveconorwegian connection

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