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

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