Cenozoic Exhumation History of the Eastern Margin of the Northern Canadian Cordillera

• Published in: Tectonics
• Main Authors: Mckay, Ryan, Enkelmann, Eva, Hadlari, Thomas, Matthews, William, Mouthereau, Frédéric
• Other Authors: Géosciences Environnement Toulouse (GET), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: apatite (U Th)/He; Canadian Cordillera; North America; Northwest Territories; Richardson Mountains; thermochronology; [SDU]Sciences of the Universe [physics]; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Canada
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-03661470; https://hal-insu.archives-ouvertes.fr/insu-03661470/document; https://hal-insu.archives-ouvertes.fr/insu-03661470/file/Tectonics%20-%202021%20-%20McKay%20-%20Cenozoic%20Exhumation%20History%20of%20the%20Eastern%20Margin%20of%20the%20Northern%20Canadian%20Cordillera.pdf; https://doi.org/10.1029/2020TC006582

International audience New low temperature thermochronology data from clastic sedimentary rocks in the northern Richardson Mountains, Canada, indicate significant exhumational cooling during late Eocene-early Oligocene time. Apatite (U Th Sm)/He (AHe) data were collected from 19 Proterozoic-Paleocene rocks across a 115 km transect. Eighty eight single grain AHe dates range from 16-300 Ma and are generally younger than stratigraphic ages, indicative of thermal resetting by burial. Additionally, zircon (U Th)/He (ZHe) dates from two Proterozoic-Cambrian rocks range from 49-123 Ma and suggest burial to >160°C. In contrast, ZHe dates from Jurassic sandstones are older than the stratigraphic age, which limits maximum burial to <160°C. Thermal history modeling reveals three phases of cooling, during the Paleocene-early Eocene (>65-50 Ma), late Eocene-early Oligocene (40-30 Ma), and late Oligocene-early Miocene (30-15 Ma). Most samples cooled during the first and second phases, whereas the third phase is less well constrained. In general, most rocks were below the sensitivity of AHe analysis since the early-middle Miocene. The results suggest a previously unrecognized phase of inferred deformation in the northern Richardson Mountains between 40-30 Ma. Our findings contribute to previous work that recognizes Late Cenozoic deformation along the eastern margin of the Northern Cordillera. We further investigated the potential mechanisms of this widespread deformation and suggest exhumation may relate to kinematic changes of the North American plate relative to structural trends along the margin of the Northern Cordillera.