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

Gee, David G.; Andréasson, Per-Gunnar LU ; Lorenz, Henning; Frei, Dirk and Majka, Jaroslaw (2015) In Precambrian Research 265. p.40-56
Abstract
New evidence is presented here that the Sveconorwegian Orogen continued northwards from type areas in southwestern Scandinavia along the Baltoscandian outer margin into the high Arctic. The Silver Road (Silvervagen) profile through the Scandinavian Caledonides, located in Sweden along the Arctic Circle at 66-67 degrees N, provides a full section through the tectonostratigraphy of the Baltoscandian margin from the Autochthon, via the Lower Allochthon to the upperment parts of the Middle Allochthon. Metamorphic grade increases upwards through the nappes, being low greenschist facies at lowest levels and increasing to eclogite grade in the highest parts of the Seve Nappe Complex, the latter being related to early Ordovician subduction of the... (More)
New evidence is presented here that the Sveconorwegian Orogen continued northwards from type areas in southwestern Scandinavia along the Baltoscandian outer margin into the high Arctic. The Silver Road (Silvervagen) profile through the Scandinavian Caledonides, located in Sweden along the Arctic Circle at 66-67 degrees N, provides a full section through the tectonostratigraphy of the Baltoscandian margin from the Autochthon, via the Lower Allochthon to the upperment parts of the Middle Allochthon. Metamorphic grade increases upwards through the nappes, being low greenschist facies at lowest levels and increasing to eclogite grade in the highest parts of the Seve Nappe Complex, the latter being related to early Ordovician subduction of the Baltoscandian outermost margin. The sedimentary rocks range in age from Neoproterozoic to Ordovician and provide evidence of the changes of environment from the Baltoscandian platform, westwards out over the Cryogenian rifted margin to the continent-ocean transition zone; also the Ordovician foreland basin. Twelve samples of psammites from the different tectonostratigraphic levels have yielded U/Pb detrital zircon age-signatures that reflect the changing character of their provenance. Autochthonous sandstones are derived from late Paleoproterozoic (1800-1950 Ma) crystalline rocks in the vicinity to the east of the thrust front. Ediacaran-early Cambrian quartzites of the Lower Allochthon also yield mainly late Paleoproterozoic zircon signatures, but with subordinate Mesoproterozoic and late Archaean populations, whilst mid Ordovician, W-derived foreland basin turbidites are dominated by Sveconorwegian (950-1100 Ma) signatures, with subordinate older Mesoproterozoic to latest Paleoproterozoic populations. All samples from the lower parts of the Middle Allochthon (lacking dolerite dykes) have signatures that are dominated by latest Paleoproterozoic and early Mesoproterozoic ages, with subordinate populations down to Sveconorwegian ages; the latter dominate the overlying Sarv nappes and also the Seve Nappe Complex, where c. 945 Ma rhyodacites have been previously reported. This evidence of Sveconorwegian source rocks in the hinterland, taken together with previously published detrital zircon data farther south and north of the Arctic Circle, clearly favours the interpretation that the Sveconorwegian Orogen, during the Neoproterozoic, extended along the entire Baltoscandian outer margin into the high Arctic. (C) 2015 Published by Elsevier B.V. (Less)
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organization
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type
Contribution to journal
publication status
published
subject
keywords
Scandinavian Caledonides, Zircon dating, Provenance, Grenville-Sveconorwegian
in
Precambrian Research
volume
265
pages
40 - 56
publisher
Elsevier
external identifiers
  • wos:000357910200003
  • scopus:84939416839
ISSN
0301-9268
DOI
10.1016/j.precamres.2015.05.012
language
English
LU publication?
yes
id
f5dcf573-ac35-4941-9b01-82360393cd82 (old id 7773721)
date added to LUP
2015-09-21 08:54:37
date last changed
2017-05-21 03:24:36
@article{f5dcf573-ac35-4941-9b01-82360393cd82,
  abstract     = {New evidence is presented here that the Sveconorwegian Orogen continued northwards from type areas in southwestern Scandinavia along the Baltoscandian outer margin into the high Arctic. The Silver Road (Silvervagen) profile through the Scandinavian Caledonides, located in Sweden along the Arctic Circle at 66-67 degrees N, provides a full section through the tectonostratigraphy of the Baltoscandian margin from the Autochthon, via the Lower Allochthon to the upperment parts of the Middle Allochthon. Metamorphic grade increases upwards through the nappes, being low greenschist facies at lowest levels and increasing to eclogite grade in the highest parts of the Seve Nappe Complex, the latter being related to early Ordovician subduction of the Baltoscandian outermost margin. The sedimentary rocks range in age from Neoproterozoic to Ordovician and provide evidence of the changes of environment from the Baltoscandian platform, westwards out over the Cryogenian rifted margin to the continent-ocean transition zone; also the Ordovician foreland basin. Twelve samples of psammites from the different tectonostratigraphic levels have yielded U/Pb detrital zircon age-signatures that reflect the changing character of their provenance. Autochthonous sandstones are derived from late Paleoproterozoic (1800-1950 Ma) crystalline rocks in the vicinity to the east of the thrust front. Ediacaran-early Cambrian quartzites of the Lower Allochthon also yield mainly late Paleoproterozoic zircon signatures, but with subordinate Mesoproterozoic and late Archaean populations, whilst mid Ordovician, W-derived foreland basin turbidites are dominated by Sveconorwegian (950-1100 Ma) signatures, with subordinate older Mesoproterozoic to latest Paleoproterozoic populations. All samples from the lower parts of the Middle Allochthon (lacking dolerite dykes) have signatures that are dominated by latest Paleoproterozoic and early Mesoproterozoic ages, with subordinate populations down to Sveconorwegian ages; the latter dominate the overlying Sarv nappes and also the Seve Nappe Complex, where c. 945 Ma rhyodacites have been previously reported. This evidence of Sveconorwegian source rocks in the hinterland, taken together with previously published detrital zircon data farther south and north of the Arctic Circle, clearly favours the interpretation that the Sveconorwegian Orogen, during the Neoproterozoic, extended along the entire Baltoscandian outer margin into the high Arctic. (C) 2015 Published by Elsevier B.V.},
  author       = {Gee, David G. and Andréasson, Per-Gunnar and Lorenz, Henning and Frei, Dirk and Majka, Jaroslaw},
  issn         = {0301-9268},
  keyword      = {Scandinavian Caledonides,Zircon dating,Provenance,Grenville-Sveconorwegian},
  language     = {eng},
  pages        = {40--56},
  publisher    = {Elsevier},
  series       = {Precambrian Research},
  title        = {Detrital zircon signatures of the Baltoscandian margin along the Arctic Circle Caledonides in Sweden: The Sveconorwegian connection},
  url          = {http://dx.doi.org/10.1016/j.precamres.2015.05.012},
  volume       = {265},
  year         = {2015},
}