Some new insights into the geochronology of the Western Karelia Subprovince, Finnish Lapland

Johanna Tepsell, O. Tapani Rämö, Aku Heinonen, Yann Lahaye, Pieti Haapala, Tapio Halkoaho, Jussi S. Heinonen, Henri Höytiä, Jukka Konnunaho, Ville Järvinen

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Archean terranes are generally poorly exposed and structurally complicated, making models of geological evolution difficult to establish. Because of pervasive metamorphism, strong deformation, and poorly exposed bedrock, the stratigraphy, geochronology, and geological evolution of the northeastern part of the Archean Western Karelia Subprovince, Finnish Lapland, is still deficient. Three new U-Pb age determinations were made using the LA-ICP-MS method on zircon in search of more profound understanding of the geochronology of the area. Data from the Pultoselka granite yield an age of 2795 +/- 5 Ma, providing a minimum age of 2.8 Ga for the Tulppio suite. The age is coeval with widespread 2.74-2.70 Ga granitoids of the Karelia Province, likely representing the same magmatic event. The data from the Kontioselka pegmatite define a maximum age for the pegmatite and a minimum age for mafic volcanic rocks in Kontioselka at 1781 +/- 27 Ma. The age coincides with major deformation and metamorphism in the Karelia Province around 1.76 Ga. Zircon from the Janesselka mafic-ultramafic complex yields a minimum age of 2425 +/- 17 Ma, complying rather well with the 2.5-2.4 Ga mafic layered intrusions of the northern Fennoscandian Shield. Our new data show that the Archean of the northeastern part of the Western Karelia Subprovince was affected by Proterozoic thermal events more extensively than thus far perceived.

Translated title of the contributionUutta tietoa Länsi-Karjalan alaprovinssin geokronologiasta Suomen Lapissa
Original languageEnglish
JournalBulletin of the Geological Society of Finland
Issue number1
Pages (from-to)5-17
Number of pages13
Publication statusPublished - Jun 2020
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 1171 Geosciences
  • Geochronology
  • U-Pb
  • Zircon
  • ICP-MS
  • Eastern Lapland
  • Archean
  • Finland
  • 2.44 Ga mafic layered intrusions
  • GA

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