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A Middle‐Late Triassic 40 Ar/ 39 Ar age for the Paasselkä impact structure (SE Finland)
Author(s) -
SCHMIEDER Martin,
SCHWARZ Winfried H.,
BUCHNER Elmar,
TRIELOFF Mario,
MOILANEN Jarmo,
ÖHMAN Teemu
Publication year - 2010
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/j.1945-5100.2010.01041.x
Subject(s) - impact structure , impact crater , geology , ladinian , extinction event , paleontology , plateau (mathematics) , early triassic , population , permian , structural basin , biological dispersal , mathematical analysis , physics , demography , mathematics , astronomy , sociology
– 40 Ar/ 39 Ar 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.