Sveconorwegian orogeny

Geological map of Fennoscandia. The Sveconorwegian orogen is shown (at lower left) in salmon. In blue are the parts of Transscandinavian Igneous Belt that escaped major deformation by the Sveconorwegian orogeny. The nappes emplaced by the much younger Caledonian orogeny are shown in dark green.

The Sveconorwegian orogeny, also known as the Dalslandian, Gothian or Gothic orogeny,[1] was an orogenic system active 1140 to 960 million years ago and currently exposed as the Sveconorwegian orogenic belt in southwestern Sweden and southern Norway.[2][3] In Norway the orogenic belt is exposed southeast of the front of the Caledonian nappe system and in nappe windows.[4] The Sveconorwegian orogen is commonly grouped within the Grenvillian Mesoproterozoic orogens.[5] Contrary to many other known orogenic belts the Sveconorwegian orogens eastern border does not have any known suture zone with ophiolites.[4]

Tectonic segments

The Sveconorwegian orogen orogenic belt is composed of five segments largely made up of gneiss that were disrupted by both extension and compression in the timespan between 1140 to 980 million years ago.[2] From west to east the segments are the terranes of Telemarkia, Bamble, Kongsberg and Idefjorden plus the Eastern Segment. The segments are separed from each other by large-scale shear zones.[6]

Development

A "classical" reconstruction of Rodinia for 750 Ma, with orogenic belts of 1.1 Ga age highlighted in green.[10] Red dots indicate 1.3–1.5 Ga A-type granites.

The period between 1050 and 980 millions years ago was the Sveconorwegian orogeny's most active phase with the Telemarkia and Idefjord Terranes being subject to metamorphism, thickening of their crust and deformation. This episode, known as the Agder phase, was followed by the Falkenberg phase that lasted until 970 million years ago during which the orogeny propagated eastward.[6] There are differing views on the nature of the orogeny. One view, known as the "classical", postulates that a continent–continent collision, possibly with Amazonia, was responsible for giving the orogenic belts its current characteristics. An alternative view postulated in 2013 claims such collision did likely not occur as the characteristics of the orogen would be explained solely as the result of subduction and accretion of smaller terranes. These different views have implications for the configuration of the ancient supercontinent Rodinia.[5]

References

  1. Allaby, A. (2013). A Dictionary of Geology and Earth Sciences (4th ed.). OUP Oxford. ISBN 9780191078958. Retrieved December 2015.
  2. 1 2 Andesson, Jenny; Bingen, Bernard; Cornell, David; Johansson, Leif; Möller, Charlotte (2008). "The Sveconorwegian orogen of southern Scandinavia: setting, petrology and geochronology of polymetamorphic high-grade terranes". 33 IGC excursion No 51, August 2 – 5.
  3. "Sveconorwegian Orogen". Britannica.com. Retrieved 26 August 2015.
  4. 1 2 3 4 5 Bingen, Bernard; Nordgulen, Øystein; Viola, Giulio (2008). "A four-phase model for the Sveconorwegian orogeny, SW Scandinavia". Norwegian Journal of Geology 88: 43–72.
  5. 1 2 3 4 Slagstad, Trond; Roberts, Nick M. W.; Markens, Rogens; Røhr, Torkil; Schiellerup, Henrik (2013). "A non-collisional, accretionary Sveconorwegian orogen". Terra Nova 25: 30–37. doi:10.1111/ter.12001.
  6. 1 2 3 4 5 6 Viola, G.; Henderson, I.H.C.; Bingen, B.; Hendriks, B.W.H. (2011). "The Grenvillian–Sveconorwegian orogeny in Fennoscandia: Back-thrusting and extensional shearing along the "Mylonite Zone"". Precambrian Research 189: 368–388. doi:10.1016/j.precamres.2011.06.005.
  7. 1 2 3 4 5 Bingen, Bernard; Andersson, Jenny; Söderlund, Ulf; Möller, Charlotte (2008). "The Mesoproterozoic in the Nordic countries". Episodes 31 (1): 29–34.
  8. Gorbatschev, Roland; Bogdanova, Svetlana (1993). "Frontiers in the Baltic Shield". Precambrian Research 64: 3–21. doi:10.1016/0301-9268(93)90066-b.
  9. Möller, Charlotte; Andersson, Jenny; Dyck, Brendan; Ildiko Antal, Lundin (2015). "Exhumation of an eclogite terrane as a hot migmatitic nappe, Sveconorwegian orogen". Lithos 226: 147–168. doi:10.1016/j.lithos.2014.12.013.
  10. "Research paper suggests East Antarctica and North America once linked". The Antarctic Sun (United States Antarctic Program). 26 August 2011. Retrieved 15 November 2012.
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