Metamorphic zones in SW Finland: monazite and zircon U-Pb dating of leucosomes in paragneisses
: Vehkamäki T, Väisänen M, Kurhila M, O’Brien H, Hölttä P, Syrjänen JK
: Ilmo Kukkonen, Toni Veikkolainen, Suvi Heinonen, Fredrik Karell, ElenaKozlovskaya, Arto Luttinen, KaisaNikkilä, Vesa Nykänen, Markku Poutanen,PietariSkyttä, Eija Tanskanen, Timo Tiira
: LITHOSPHERE
Publisher: University of Helsinki
: Helsinki
: 2021
: LITHOSPHERE 2021: ELEVENTH SYMPOSIUM ON STRUCTURE, COMPOSITION AND EVOLUTION OF THE LITHOSPHERE: PROGRAMME AND EXTENDED ABSTRACTS
: Report / Institute of Seismology, University of Helsinki
: S-71
: 139
: 142
: 978-952-10-9604-4
: 0357-3060
: https://www.seismo.helsinki.fi/ilp/lito2021/Lithosphere_2021_Symposium_Abstract_Volume.pdf
: https://research.utu.fi/converis/portal/detail/Publication/51863298
The Central Svecofennian Arc Complex (CSAC) and the Southern Svecofennian Arc Complex (SSAC) show
different ages of peak metamorphism: ~1.88 Ga in the CSAC and ~1.83 Ga in the SSAC. In the present project we study the age of the metamorphism in SW Finland. We have collected two samples. Of these the Eurajoki leucosome zircons were > 1.92 Ga, i.e.,inherited, but monazites show two populations: ~1.83 Ga and ~1.7 Ga. The zircons from the Rauma leucosome yielded two populations: ~1.86 Ga and ~1.83 Ga. The monazites show ages of ~1.83 Ga and ~1.7 Ga. We interpret that the ~1.86 Ga zircons represent the older metamorphism and the 1.83 Ga zircon and monazite group to represent the younger metamorphism. The 1.7 Ga group is unusual and needs further investigation.
