Diachronous collision in the Seve Nappe Complex: Evidence from Lu–Hf geochronology of eclogites (Norrbotten, North Sweden)

The collision of Baltica and Laurentia during the Caledonian Orogeny happened at c. 400–420 Ma. However, subduction and collision processes also took place before this main collisional phase and the tectonic history of these is still not fully resolved. The Seve Nappe Complex in Sweden has recorded...

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Autores: Fassmer, Kathrin, Froitzheim, Nikolaus, Janák, Marian, Strohmeyer, Merle, Bukała, Michal, Lagos, Markus, Münker, Carsten
Formato: artículo
Estado:Versión publicada
Fecha de publicación:2021
País:España
Recursos:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/259146
Acesso em linha:http://hdl.handle.net/10261/259146
Access Level:acceso abierto
Palavra-chave:Caledonian Orogeny
Garnet
High-P metamorphism
Lu–Hf geochronology
Seve Nappe Complex
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spelling Diachronous collision in the Seve Nappe Complex: Evidence from Lu–Hf geochronology of eclogites (Norrbotten, North Sweden)Fassmer, KathrinFroitzheim, NikolausJanák, MarianStrohmeyer, MerleBukała, MichalLagos, MarkusMünker, CarstenCaledonian OrogenyGarnetHigh-P metamorphismLu–Hf geochronologySeve Nappe ComplexThe collision of Baltica and Laurentia during the Caledonian Orogeny happened at c. 400–420 Ma. However, subduction and collision processes also took place before this main collisional phase and the tectonic history of these is still not fully resolved. The Seve Nappe Complex in Sweden has recorded these earlier phases. The Seve Nappe Complex in Norrbotten (North Swedish Caledonides) comprises four superimposed nappes emplaced by eastward thrusting (from base to top according to the conventional structural interpretation): Lower Seve Nappe, Vaimok, Sarek, and Tsäkkok Lenses. Eclogites occur in the Vaimok and Tsäkkok Lenses. The Vaimok Lens represents rocks of the Baltican continental margin intruded by Neoproterozoic dolerite dikes which were later eclogitized and boudinaged. By contrast, eclogites of the Tsäkkok Lens are former oceanic basalts associated with calcschists, possibly representing the ocean–continent transition between Baltica and Iapetus. Previous age determinations for eclogitization yielded various ages between c. 500 and 480 Ma, in contrast to younger (460–450 Ma) ages of ultra high-P metamorphism in the Seve Nappe Complex further south in Jämtland. Eclogites from the Vaimok (one sample) and Tsäkkok (three samples) lenses were dated using Lu–Hf garnet geochronology. Garnet from all samples shows prograde zoning of major element and Lu contents and yielded well-defined isochrons of the following ages: 480.4 ± 1.2 Ma (Vaimok); 487.7 ± 4.6 Ma, 486.2 ± 3.2, 484.6 ± 4.6 Ma (Tsäkkok). The ages from Tsäkkok are interpreted to date the burial of the Iapetus–Baltica ocean–continent transition in a west-dipping subduction zone around c. 485 Ma, and the age from the structurally deeper Vaimok Nappe the following subduction of the continental margin. Previously reported ages of 500 Ma and older are not supported by this study. The age difference between eclogites in the Seve Nappe Complex in Jämtland (c. 460–450 Ma) and Norrbotten (c. 488–480 Ma) may reflect the collision of an island arc with an irregularly shaped passive continental margin of Baltica or alternatively the collision of a straight margin with a microcontinent (Sarek Lens) accreted to the upper plate.We thank Christopher Barnes (AGH University of Science and Technology, Kraków) for providing us with some of the studied samples. Kathrin Fassmer thanks Svenja Trapp and Matthias Hauke (University of Bonn) for help during Lu–Hf laboratory work. We would also like to thank M. Smit, F. Corfu and A. Kylander-Clark for their reviews which greatly contributed to improving the manuscript. This research was funded by DFG-Grant FR700/18-1 to N. F. and the Slovak Research and Development Agency project APVV-18-0107 to M.J, and partially supported by the National Science Centre (Poland) project 2014/14/ST10/00321 to J. Majka. M.Bukała acknowledges The Polish National Agency for Academic Exchange for the scholarship no. PPN/IWA/2018/1/00046/U/0001. This is contribution no. 64 of the DFG-funded LA-ICP-MS Laboratory at the Institute for Geosciences, University of Bonn, GermanyWiley-BlackwellConsejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]2022202220212022info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Publisher's versioninfo:eu-repo/semantics/publishedVersionhttp://hdl.handle.net/10261/259146reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Ingléshttp://dx.doi.org/10.1111/jmg.12591Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/2591462026-05-22T06:33:51Z
dc.title.none.fl_str_mv Diachronous collision in the Seve Nappe Complex: Evidence from Lu–Hf geochronology of eclogites (Norrbotten, North Sweden)
title Diachronous collision in the Seve Nappe Complex: Evidence from Lu–Hf geochronology of eclogites (Norrbotten, North Sweden)
spellingShingle Diachronous collision in the Seve Nappe Complex: Evidence from Lu–Hf geochronology of eclogites (Norrbotten, North Sweden)
Fassmer, Kathrin
Caledonian Orogeny
Garnet
High-P metamorphism
Lu–Hf geochronology
Seve Nappe Complex
title_short Diachronous collision in the Seve Nappe Complex: Evidence from Lu–Hf geochronology of eclogites (Norrbotten, North Sweden)
title_full Diachronous collision in the Seve Nappe Complex: Evidence from Lu–Hf geochronology of eclogites (Norrbotten, North Sweden)
title_fullStr Diachronous collision in the Seve Nappe Complex: Evidence from Lu–Hf geochronology of eclogites (Norrbotten, North Sweden)
title_full_unstemmed Diachronous collision in the Seve Nappe Complex: Evidence from Lu–Hf geochronology of eclogites (Norrbotten, North Sweden)
title_sort Diachronous collision in the Seve Nappe Complex: Evidence from Lu–Hf geochronology of eclogites (Norrbotten, North Sweden)
dc.creator.none.fl_str_mv Fassmer, Kathrin
Froitzheim, Nikolaus
Janák, Marian
Strohmeyer, Merle
Bukała, Michal
Lagos, Markus
Münker, Carsten
author Fassmer, Kathrin
author_facet Fassmer, Kathrin
Froitzheim, Nikolaus
Janák, Marian
Strohmeyer, Merle
Bukała, Michal
Lagos, Markus
Münker, Carsten
author_role author
author2 Froitzheim, Nikolaus
Janák, Marian
Strohmeyer, Merle
Bukała, Michal
Lagos, Markus
Münker, Carsten
author2_role author
author
author
author
author
author
dc.contributor.none.fl_str_mv Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
dc.subject.none.fl_str_mv Caledonian Orogeny
Garnet
High-P metamorphism
Lu–Hf geochronology
Seve Nappe Complex
topic Caledonian Orogeny
Garnet
High-P metamorphism
Lu–Hf geochronology
Seve Nappe Complex
description The collision of Baltica and Laurentia during the Caledonian Orogeny happened at c. 400–420 Ma. However, subduction and collision processes also took place before this main collisional phase and the tectonic history of these is still not fully resolved. The Seve Nappe Complex in Sweden has recorded these earlier phases. The Seve Nappe Complex in Norrbotten (North Swedish Caledonides) comprises four superimposed nappes emplaced by eastward thrusting (from base to top according to the conventional structural interpretation): Lower Seve Nappe, Vaimok, Sarek, and Tsäkkok Lenses. Eclogites occur in the Vaimok and Tsäkkok Lenses. The Vaimok Lens represents rocks of the Baltican continental margin intruded by Neoproterozoic dolerite dikes which were later eclogitized and boudinaged. By contrast, eclogites of the Tsäkkok Lens are former oceanic basalts associated with calcschists, possibly representing the ocean–continent transition between Baltica and Iapetus. Previous age determinations for eclogitization yielded various ages between c. 500 and 480 Ma, in contrast to younger (460–450 Ma) ages of ultra high-P metamorphism in the Seve Nappe Complex further south in Jämtland. Eclogites from the Vaimok (one sample) and Tsäkkok (three samples) lenses were dated using Lu–Hf garnet geochronology. Garnet from all samples shows prograde zoning of major element and Lu contents and yielded well-defined isochrons of the following ages: 480.4 ± 1.2 Ma (Vaimok); 487.7 ± 4.6 Ma, 486.2 ± 3.2, 484.6 ± 4.6 Ma (Tsäkkok). The ages from Tsäkkok are interpreted to date the burial of the Iapetus–Baltica ocean–continent transition in a west-dipping subduction zone around c. 485 Ma, and the age from the structurally deeper Vaimok Nappe the following subduction of the continental margin. Previously reported ages of 500 Ma and older are not supported by this study. The age difference between eclogites in the Seve Nappe Complex in Jämtland (c. 460–450 Ma) and Norrbotten (c. 488–480 Ma) may reflect the collision of an island arc with an irregularly shaped passive continental margin of Baltica or alternatively the collision of a straight margin with a microcontinent (Sarek Lens) accreted to the upper plate.
publishDate 2021
dc.date.none.fl_str_mv 2021
2022
2022
2022
dc.type.none.fl_str_mv info:eu-repo/semantics/article
http://purl.org/coar/resource_type/c_6501
Publisher's version
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/259146
url http://hdl.handle.net/10261/259146
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv http://dx.doi.org/10.1111/jmg.12591
Sí
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv Wiley-Blackwell
publisher.none.fl_str_mv Wiley-Blackwell
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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