Thermo-kinematic and geodynamical evolution of the Brooks Range and North Slope (Alaska-Canada)

• Main Author: Bigot-Buschendorf, Maelianna
• Other Authors: Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris VI, Loïc Labrousse, Frédéric Mouthereau
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2015
• Subjects: Low-T thermochronology; Brooks range; Orogenic processes; North Slope; Analyses (U-Th)/He; Traces de fission; Thermochronologie basse-Température; Alaska; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Arctic; Canada; Pacific; Yukon; Brooks Range; north slope
• Online Access: https://tel.archives-ouvertes.fr/tel-01408454; https://tel.archives-ouvertes.fr/tel-01408454/document; https://tel.archives-ouvertes.fr/tel-01408454/file/2015PA066688.pdf

The kinematics and geodynamics associated with the compressional deformation in the Brooks Range and British-Barn Mountains, respectively in Alaska (USA) and North Yukon (Canada), in a back-arc setting has long been debated. In particular, the tectonic history of the Arctic Alaska continental block located in the foreland of the Brooks Range has been diversely interpreted in the plate reconstructions proposed for the Canadian basin. The Brooks Range mountain chain develops from the Lower Cretaceous to the Cenozoic. Constraining its exhumational history and its link with shortening evolution is essential in this arctic area where plate tectonics, associated to the Canadian basin opening in the North, has led to controversial geodynamic models. Tectonic coupling with the active Pacific subduction in the south as well as major seismogenic strike-slip faulting make this orogen a key area where to refine the regional plate reconstructions and understanding of orogenic processes. The Cenozoic evolution of the Brooks Mountains is poorly understood although it is a nearly unique example of arctic orogen, which have potentially recorded major climate changes like Paleocene-Eocene Thermal Maximum, the Oligocene cooling and Quaternary glaciations. This orogen is a key to study and quantify the climate impact on the north-alaskan topographic growth. This study combined low-temperature thermochronometry (FT, U-Th/He) on granitic and sedimentary rocks, which were thermo-kinematically modeled using Pecube in order to define the orogenic evolution of this arctic region since 100 Ma. In parallel, a field-based structural study (North Yukon and Brooks Range) was combined with the analysis of subsurface data. Thermochronological data, coupled to thermometric RSCM analyses and thermal modeling first define a slow exhumation period (0.2 km/Ma) from Upper Cretaceous up to the Eocene. With the Eocene, exhumation rates drastically increased to reach 1.25-1.29km/Ma as the deformation also migrates from SW toward NE. In both alaskan and ...