Monazite in the eclogite and blueschist of the Svalbard Caledonides: its origin and forming-reactions

Karolina Kośmińska; Kathrin Fassmer; William C. McClelland; Jarosław Majka; Matthew Coble; Jay Thomas; Maciej Manecki; Henning Lorenz; Jakub Bazarnik; Carsten Münker

doi:10.1007/s00410-023-02045-5

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Monazite in the eclogite and blueschist of the Svalbard Caledonides: its origin and forming-reactions

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Monazite in the eclogite and blueschist of the Svalbard Caledonides: its origin and forming-reactions

Karolina Kośmińska, Kathrin Fassmer, William C. McClelland, Jarosław Majka, Matthew Coble, Jay Thomas, Maciej Manecki, Henning Lorenz, Jakub Bazarnik and Carsten Münker

Contributions to mineralogy and petrology, Vol.178(9), 61

09/01/2023

DOI: 10.1007/s00410-023-02045-5

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Abstract

High-pressure low-temperature rocks from Svalbard are an excellent target for studying metamorphic reactions in Phanerozoic subduction zones. This study reveals the presence of monazite in an eclogite and a blueschist from the Vestgötabreen Complex, southwestern Svalbard. In order to investigate the monazite-forming reaction, we obtained pressure–temperature estimates coupled with U–Pb and Lu–Hf dating. Combined geothermobarometry allows to constrain three evolutionary stages of garnet growth in the eclogite: nucleation (1.6 ± 0.3 GPa at 460 ± 60 °C), peak-pressure (2.3 ± 0.3 GPa at 507 ± 60 °C), and peak-temperature (2.1 ± 0.3 GPa at 553 ± 60 °C). A zircon age of 482 ± 10 Ma is interpreted to belong to the prograde part of the pressure–temperature path. Monazite forms inclusions within garnet rims, or it is surrounded by allanite and apatite, altogether forming pseudomorphs of a tabular shape in the matrix. Textures, geothermobarometry and geochronology support the conclusion the monazite formed under high-pressure conditions at 471 ± 6 Ma. We propose that the monazite crystallization in the eclogite happened due to a decomposition of accessory phases during the decompression after peak-pressure of the metamorphic cycle. Monazite in the blueschist occurs as inclusions in garnet cores and gives an indicative age of 486 ± 6 Ma, which is interpreted to reflect the prograde growth of the garnet. Lu–Hf garnet dating resolves an age of peak-pressure metamorphism in the blueschist at 471.1 ± 4 Ma under conditions of 2.0 ± 0.03 GPa and 500 ± 30 °C. The Vestgötabreen Complex provides evidence for an early Ordovician modern-style subduction system in the proximity of the Baltica margin. Hence, this study also supports the tectonic models that favour a mixed Baltican and Laurentian provenance of south-western Svalbard.

Geology

Mineral Resources

Mineralogy

Earth and Environmental Science

Earth Sciences

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Title: Subtitle: Monazite in the eclogite and blueschist of the Svalbard Caledonides: its origin and forming-reactions
Creators: Karolina Kośmińska - AGH University of Krakow
Kathrin Fassmer - Universität Innsbruck
William C. McClelland - University of Iowa
Jarosław Majka - Uppsala University
Matthew Coble - GNS Science
Jay Thomas - Syracuse University
Maciej Manecki - AGH University of Krakow
Henning Lorenz - Uppsala University
Jakub Bazarnik - Polish Geological Institute
Carsten Münker - University of Cologne
Resource Type: Journal article
Publication Details: Contributions to mineralogy and petrology, Vol.178(9), 61
DOI: 10.1007/s00410-023-02045-5
ISSN: 0010-7999
eISSN: 1432-0967
Publisher: Springer Berlin Heidelberg
Grant note: FR700/18-1 / Deutsche Forschungsgemeinschaft (http://dx.doi.org/10.13039/501100001659) 2021/43/D/ST10/02305 / Narodowym Centrum Nauki (http://dx.doi.org/10.13039/501100004442)
Language: English
Date published: 09/01/2023
Academic Unit: Earth and Environmental Sciences
Record Identifier: 9984455616902771

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