Sveconorwegian orogeny
The Sveconorwegian orogeny was an
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 and 980 million years ago.[1] From west to east the segments are the terranes of Telemarkia, Bamble, Kongsberg and Idefjorden plus the Eastern Segment. The segments are separated from each other by large-scale shear zones.[5]
- Bamble Terrane: The Bamble Terrane lies together with Kongsberg Terrane as a small sliver between the larger Idefjorden and Telemarkia terranes. The terrane displays granulite facies metamorphism.[6]
- Idefjorden Terrane: The Idefjorden Terrane originated from magmatic activity 1660 to 1520 million years ago and is composed of
- Kongsberg Terrane: The Kongsberg Terrane displays amphibolite to granulite facies metamorphism. It is positioned as a small wedge between the larger Idefjorden and Telemarkia terranes.[6]
- Telemarkia Terrane: The Telemarkia Terrane formed about 1520 to 1480 million years ago by a brief Amazonia.[3]
- Eastern Segment: In difference to the other segments that are granulite facies metamorphism. Eclogites found in the Eastern Segment were at 35–40 kilometres (22–25 mi) depth during the orogeny-caused metamorphism that turned their protoliths into eclogite.[8] The boundary of the Eastern Segment and the Sveconorwegian orogen with Svecofennian and Transcandinavian rocks of Fennoscandia consist of the Sveconorwegian Frontal Deformation Zone and the Protogine Zone.[5]
Development
The period between 1050 and 980 million 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.[5] 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.[4]
The southern part of what would eventually become the
References
- ^ a b 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.
- ^ "Sveconorwegian Orogen". Britannica.com. Retrieved 26 August 2015.
- ^ a b c d e Bingen, Bernard; Nordgulen, Øystein; Viola, Giulio (2008). "A four-phase model for the Sveconorwegian orogeny, SW Scandinavia". Norwegian Journal of Geology. 88: 43–72.
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- ^ a b c d e Bingen, Bernard; Andersson, Jenny; Söderlund, Ulf; Möller, Charlotte (2008). "The Mesoproterozoic in the Nordic countries". Episodes. 31 (1): 29–34.
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- Bibcode:2015EGUGA..1714883S.