Th–U–total Pb monazite geochronology records Ordovician (444 Ma) metamorphism/partial melting and Silurian (419 Ma) thrusting in the Kåfjord Nappe, Norwegian Arctic Caledonides
Abstract The northern extent of the Scandinavian Caledonides includes the Skibotn Nappe Complex of still debated structural position. This paper is focused on part of this complex and presents new U–Th–total Pb monazite dating results for the migmatitic gneiss of the Kåfjord Nappe. The rocks show mi...
Published in: | Geologica Carpathica |
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crdegruyter:10.2478/geoca-2019-0029 2024-09-15T18:15:45+00:00 Th–U–total Pb monazite geochronology records Ordovician (444 Ma) metamorphism/partial melting and Silurian (419 Ma) thrusting in the Kåfjord Nappe, Norwegian Arctic Caledonides Ziemniak, Grzegorz Kośmińska, Karolina Petrík, Igor Janák, Marian Walczak, Katarzyna Manecki, Maciej Majka, Jarosław 2019 http://dx.doi.org/10.2478/geoca-2019-0029 https://content.sciendo.com/view/journals/geoca/70/6/article-p494.xml http://www.geologicacarpathica.com/data/articles/929.pdf unknown Walter de Gruyter GmbH http://creativecommons.org/licenses/by-nc-nd/4.0 Geologica Carpathica volume 70, issue 6, page 494-511 ISSN 1336-8052 journal-article 2019 crdegruyter https://doi.org/10.2478/geoca-2019-0029 2024-07-15T04:11:08Z Abstract The northern extent of the Scandinavian Caledonides includes the Skibotn Nappe Complex of still debated structural position. This paper is focused on part of this complex and presents new U–Th–total Pb monazite dating results for the migmatitic gneiss of the Kåfjord Nappe. The rocks show mineral assemblage of garnet + plagioclase + biotite + white mica + kyanite + rutile ± K-feldspar ± sillimanite. Thermodynamic modelling suggests that garnet was stable at P–T conditions of ca. 680–720 °C and 8–10 kbars in the stability field of kyanite and the rocks underwent partial melting during exhumation following a clockwise P–T path. This episode is dated to 444 ± 12 Ma using chemical Th–U–total Pb dating of the Y-depleted monazite core. Second episode highlighted by growth of secondary white mica resulted from subsequent overprint in amphibolite and greenschist facies. Fluid assisted growth of the Y-enriched monazite rim at 419 ± 8 Ma marks the timing of the nappe emplacement. Age of migmatization and thrusting in the Kåfjord Nappe is similar to the Kalak Nappe Complex, and other units of the Middle Allochthon to the south. Nevertheless, the obtained results do not allow for unambiguous definition of the tectonostratigraphic position of the Skibotn Nappe Complex. Article in Journal/Newspaper Kåfjord Skibotn De Gruyter Geologica Carpathica 70 6 494 511 |
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Abstract The northern extent of the Scandinavian Caledonides includes the Skibotn Nappe Complex of still debated structural position. This paper is focused on part of this complex and presents new U–Th–total Pb monazite dating results for the migmatitic gneiss of the Kåfjord Nappe. The rocks show mineral assemblage of garnet + plagioclase + biotite + white mica + kyanite + rutile ± K-feldspar ± sillimanite. Thermodynamic modelling suggests that garnet was stable at P–T conditions of ca. 680–720 °C and 8–10 kbars in the stability field of kyanite and the rocks underwent partial melting during exhumation following a clockwise P–T path. This episode is dated to 444 ± 12 Ma using chemical Th–U–total Pb dating of the Y-depleted monazite core. Second episode highlighted by growth of secondary white mica resulted from subsequent overprint in amphibolite and greenschist facies. Fluid assisted growth of the Y-enriched monazite rim at 419 ± 8 Ma marks the timing of the nappe emplacement. Age of migmatization and thrusting in the Kåfjord Nappe is similar to the Kalak Nappe Complex, and other units of the Middle Allochthon to the south. Nevertheless, the obtained results do not allow for unambiguous definition of the tectonostratigraphic position of the Skibotn Nappe Complex. |
format |
Article in Journal/Newspaper |
author |
Ziemniak, Grzegorz Kośmińska, Karolina Petrík, Igor Janák, Marian Walczak, Katarzyna Manecki, Maciej Majka, Jarosław |
spellingShingle |
Ziemniak, Grzegorz Kośmińska, Karolina Petrík, Igor Janák, Marian Walczak, Katarzyna Manecki, Maciej Majka, Jarosław Th–U–total Pb monazite geochronology records Ordovician (444 Ma) metamorphism/partial melting and Silurian (419 Ma) thrusting in the Kåfjord Nappe, Norwegian Arctic Caledonides |
author_facet |
Ziemniak, Grzegorz Kośmińska, Karolina Petrík, Igor Janák, Marian Walczak, Katarzyna Manecki, Maciej Majka, Jarosław |
author_sort |
Ziemniak, Grzegorz |
title |
Th–U–total Pb monazite geochronology records Ordovician (444 Ma) metamorphism/partial melting and Silurian (419 Ma) thrusting in the Kåfjord Nappe, Norwegian Arctic Caledonides |
title_short |
Th–U–total Pb monazite geochronology records Ordovician (444 Ma) metamorphism/partial melting and Silurian (419 Ma) thrusting in the Kåfjord Nappe, Norwegian Arctic Caledonides |
title_full |
Th–U–total Pb monazite geochronology records Ordovician (444 Ma) metamorphism/partial melting and Silurian (419 Ma) thrusting in the Kåfjord Nappe, Norwegian Arctic Caledonides |
title_fullStr |
Th–U–total Pb monazite geochronology records Ordovician (444 Ma) metamorphism/partial melting and Silurian (419 Ma) thrusting in the Kåfjord Nappe, Norwegian Arctic Caledonides |
title_full_unstemmed |
Th–U–total Pb monazite geochronology records Ordovician (444 Ma) metamorphism/partial melting and Silurian (419 Ma) thrusting in the Kåfjord Nappe, Norwegian Arctic Caledonides |
title_sort |
th–u–total pb monazite geochronology records ordovician (444 ma) metamorphism/partial melting and silurian (419 ma) thrusting in the kåfjord nappe, norwegian arctic caledonides |
publisher |
Walter de Gruyter GmbH |
publishDate |
2019 |
url |
http://dx.doi.org/10.2478/geoca-2019-0029 https://content.sciendo.com/view/journals/geoca/70/6/article-p494.xml http://www.geologicacarpathica.com/data/articles/929.pdf |
genre |
Kåfjord Skibotn |
genre_facet |
Kåfjord Skibotn |
op_source |
Geologica Carpathica volume 70, issue 6, page 494-511 ISSN 1336-8052 |
op_rights |
http://creativecommons.org/licenses/by-nc-nd/4.0 |
op_doi |
https://doi.org/10.2478/geoca-2019-0029 |
container_title |
Geologica Carpathica |
container_volume |
70 |
container_issue |
6 |
container_start_page |
494 |
op_container_end_page |
511 |
_version_ |
1810453697497399296 |