A Middle‐Late Triassic 40Ar/39Ar age for the Paasselkä impact structure (SE Finland) |
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| Authors: | Martin SCHMIEDER Winfried H SCHWARZ Elmar BUCHNER Mario TRIELOFF Jarmo MOILANEN Teemu ÖHMAN |
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| Institution: | 1. Institut für Planetologie, Universit?t Stuttgart, Herdweg 51, D‐70174 Stuttgart, Germany;2. Institut für Geowissenschaften, Universit?t Heidelberg, Im Neuenheimer Feld 234‐236, D‐69120 Heidelberg, Germany;3. HNU Neu‐Ulm University, Wileystrasse 1, D‐89231 Neu‐Ulm, Germany;4. Department of Geosciences, P.O. Box 3000, University of Oulu, FI‐90014 Oulu, Finland;5. Department of Physical Sciences, P.O. Box 3000, University of Oulu, FI‐90014 Oulu, Finland |
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| Abstract: | Abstract– 40Ar/39Ar dating of recrystallized feldspar glass particles separated from clast‐rich impact melt rocks from the approximately 10 km Paasselkä impact structure (SE Finland) yielded a Middle to Late Triassic (Ladinian‐Karnian) pseudo‐plateau age of 228.7 ± 3.0 (3.4) Ma (2σ). This new age makes Paasselkä the first known Triassic impact structure dated by isotopic methods on the Baltic Shield. The new Paasselkä impact age is, within uncertainty, coeval with isotopic ages recently obtained for the Lake Saint Martin impact structure in Canada, indicating a new Middle to Late Triassic impact crater population on Earth. The comparatively small crater size, however, suggests no relationship between the Paasselkä impact and a postulated extinction event at the Middle/Late Triassic boundary. |
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