A Paleozoic age for the Tunnunik impact structure

• Published in: Meteoritics & Planetary Science
• Main Authors: Lepaulard, Camille, Gattacceca, Jérôme, Swanson-Hysell, Nicholas, Quesnel, Yoann, Demory, François, Osinski, Gordon
• Other Authors: Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Lawrence Berkeley National Laboratory Berkeley (LBNL), University of Western Ontario (UWO), French Polar Institute IPEV (Institut Paul Emile Victor); Natural Sciences and Engineering Research Council of Canada; Northern Research Supplement program; Industrial Research Chair (IRC) program; Canadian Space Agency; MDA
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: victoria island; polar wander; paleomagnetism; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Tilting; Geomagnetic Pole; Victoria Island
• Online Access: https://hal.science/hal-02048190; https://hal.science/hal-02048190/document; https://hal.science/hal-02048190/file/Lepaulard-MAPS2019-preprint.pdf; https://doi.org/10.1111/maps.13239

International audience We report paleomagnetic directions from the target rocks of the Tunnunik impact structure, as well as from lithic impact breccia dikes that formed during the impact event. The target sedimentary rocks have been remagnetized after impact-related tilting during a reverse polarity interval. Their magnetization is unblocked up to 350 degrees C. The diabase dikes intruding into these sediments retained their original magnetization which unblocks above 400 degrees C. The impact breccia records a paleomagnetic direction similar to that of the overprints in the target sedimentary rocks. The comparison of the resulting virtual geomagnetic pole for the Tunnunik impact structure with the apparent polar wander path for Laurentia combined with biostratigraphic constraints from the target sedimentary rocks is most consistent with an impact age in the Late Ordovician or Silurian, around 430-450 Ma, soon after the deposition of the youngest impacted sedimentary rocks. Our results from the overprinted sedimentary rocks and diabase dikes imply that the postimpact temperature of the studied rocks was about 350 degrees C.