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
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 ass...
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| Format: | Article |
| Language: | English |
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Earth Science Institute, Slovak Academy of Sciences, Slovakia
2019-12-01
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| Series: | Geologica Carpathica |
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| Online Access: | http://www.degruyter.com/view/j/geoca.2019.70.issue-6/geoca-2019-0029/geoca-2019-0029.xml?format=INT |
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| author | Ziemniak Grzegorz Kośmińska Karolina Petrík Igor Janák Marian Walczak Katarzyna Manecki Maciej Majka Jarosław |
| author_facet | Ziemniak Grzegorz Kośmińska Karolina Petrík Igor Janák Marian Walczak Katarzyna Manecki Maciej Majka Jarosław |
| author_sort | Ziemniak Grzegorz |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-12-17T07:21:25Z |
| format | Article |
| id | doaj.art-81841f6e2e8c41749649179da99a04bf |
| institution | Directory Open Access Journal |
| issn | 1336-8052 |
| language | English |
| last_indexed | 2024-12-17T07:21:25Z |
| publishDate | 2019-12-01 |
| publisher | Earth Science Institute, Slovak Academy of Sciences, Slovakia |
| record_format | Article |
| series | Geologica Carpathica |
| spelling | doaj.art-81841f6e2e8c41749649179da99a04bf2022-12-21T21:58:45ZengEarth Science Institute, Slovak Academy of Sciences, SlovakiaGeologica Carpathica1336-80522019-12-0170649451110.2478/geoca-2019-0029geoca-2019-0029Th–U–total Pb monazite geochronology records Ordovician (444 Ma) metamorphism/partial melting and Silurian (419 Ma) thrusting in the Kåfjord Nappe, Norwegian Arctic CaledonidesZiemniak Grzegorz0Kośmińska Karolina1Petrík Igor2Janák Marian3Walczak Katarzyna4Manecki Maciej5Majka Jarosław6Faculty of Geology, Geophysics and Environmental Protection, AGH — University of Science and Technology, Mickiewicza 30, 30-059Kraków, PolandFaculty of Geology, Geophysics and Environmental Protection, AGH — University of Science and Technology, Mickiewicza 30, 30-059Kraków, PolandEarth Science Institute, Slovak Academy of Sciences, Dúbravská cesta 9, P.O. Box 106, 840 45 Bratislava 45, SlovakiaEarth Science Institute, Slovak Academy of Sciences, Dúbravská cesta 9, P.O. Box 106, 840 45 Bratislava 45, SlovakiaFaculty of Geology, Geophysics and Environmental Protection, AGH — University of Science and Technology, Mickiewicza 30, 30-059Kraków, PolandFaculty of Geology, Geophysics and Environmental Protection, AGH — University of Science and Technology, Mickiewicza 30, 30-059Kraków, PolandFaculty of Geology, Geophysics and Environmental Protection, AGH — University of Science and Technology, Mickiewicza 30, 30-059Kraków, PolandThe 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.http://www.degruyter.com/view/j/geoca.2019.70.issue-6/geoca-2019-0029/geoca-2019-0029.xml?format=INTscandinavian caledonidesskibotn nappe complexmigmatitegeochronology |
| 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 Geologica Carpathica scandinavian caledonides skibotn nappe complex migmatite geochronology |
| 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_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_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_sort | th u total pb monazite geochronology records ordovician 444 ma metamorphism partial melting and silurian 419 ma thrusting in the kafjord nappe norwegian arctic caledonides |
| topic | scandinavian caledonides skibotn nappe complex migmatite geochronology |
| url | http://www.degruyter.com/view/j/geoca.2019.70.issue-6/geoca-2019-0029/geoca-2019-0029.xml?format=INT |
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