The integration of low-temperature thermochronometers, including apatite and zircon (U-Th)/He (AHe, ZHe) and apatite fission-track (AFT) methods, allows for a quantification of the thermal history experienced by rocks as they heat and cool through upper crustal temperature regimes (<200°C). Whereas these methods are practical in geologic terranes that have undergone rapid cooling, application to strata with protracted cooling histories is complicated by the enhanced role of grain-specific parameters (volume, chemistry, radiation damage) on the kinetics of helium diffusion and fission track annealing. The effects of these variables are most prevalent in sedimentary samples, where natural variance in detrital accessory mineral populations results in a broad range of diffusion kinetics and great dispersion in corresponding cooling dates. This thesis integrates contemporary thermochronometer diffusion and annealing kinetics to investigate the burial and exhumation history of two natural laboratories. In the Mackenzie Mountains and Plain of the Northwest Territories, long-term radiation damage accumulation in zircon from Neoproterozoic siliciclastic units produces ZHe dates that track Albian to Paleocene burial and exhumation in front of the foreland-propagating fold-thrust belt. For the Phanerozoic stratigraphic section, AFT annealing kinetics are calculated from Devonian and Cretaceous samples, and are incorporated into multi-kinetic AFT modeling. These kinetics also constrain AHe date-radiation damage trends, and when combined allow for an estimation on the magnitude of eroded sediment across regional pre-Albian and post-Paleocene unconformities. Finally, conodont (U-Th)/He data from Anticosti Island, Québec in the Gulf of the St. Lawrence are compared with ZHe, AHe and AFT data to test their utility as a thermochronometer for carbonate basin analysis. These data evince a Mesozoic thermal history previously unattributed to the region. Ultimately, this thesis provides a novel assessment on the ways in which thermochronometer date dispersion can be quantified to assess the thermal evolution of sedimentary basins from burial through to inversion.

The lithosphere of northwestern Canada recorded more than 2.5 Gy of complex tectonic evolution, from the formation of the ancient cores of the continental lithosphere such as the Slave craton to the Phanerozoic Cordilleran orogeny with substantial variations in crust and upper mantle structures that led to the concentration of natural resources (i.e., diamonds in cratons). Present-day northwestern Canada juxtaposes a thin and hot Cordilleran lithosphere to the thick and cold cratonic lithosphere, which has important implications for regional geodynamics. Recently, seismic station coverage has drastically increased across northwestern Canada, allowing the development of seismic tomography models and other passive-source seismic methods at high resolution in order to investigate the tectonic evolution and dynamics of the lithosphere in this region. The P- and S-wave upper mantle structures of northwestern Canada reveal that the distribution of kimberlite fields in the Slave craton correlates with the margin of fast and slow seismic mantle anomalies, which could delineate weak zones in the lithosphere. Based on our tomographic models we identify two high-velocity seismic anomalies straddling the arcuate Cordillera Deformation Front that have controlled its regional deformation, including a newly identified Mackenzie craton characterized by high seismic velocities extending from the lower crust to the upper mantle to the north of the Mackenzie Mountains. Furthermore, our P-wave tomography model shows sharp velocity contrasts beneath the surface trace of the Tintina Fault. Estimates of seismic anisotropy show a progressive rotation of fast-axis directions when approaching the fault zone. Together, they provide seismic evidence for the trans-lithospheric nature of the Tintina Fault. We further propose that the Tintina Fault has chiseled off small pieces of the Laurentian craton between the Late Cretaceous and the Eocene, which would imply that large lithospheric-scale shear zones are able to cut through small pieces of refractory cratonic mantle and transport them over several hundred kilometers.