(U-Th)/He Thermochronology of the Ottawa Embayment, Eastern Canada: the Temperature-time History of an Ancient, Intracratonic Rift Basin

Abstract

The Ottawa Embayment is a intracratonic rift basin that preserves a unique and eventful history through deep time. Its evolution records opening of the Iapetus Ocean with the break-up of Rodinia, followed by the formation of a continental passive margin, trapping siliciclastic sediments eroded from the adjacent Grenville Province. Samples were collected from a transect across the crystalline rift flank and through the embayment. We investigate the influence of crystallinitiy and non-ideal crystal chapes on He diffusion and resulting zircon (U-Th)/He age with the use of zircon (U-Th)/He thermochronometry, raman spectroscopy and x-ray micro-computed tomography. We then integrate our thermochronology data with regional geology to utilize multi-sample numerical modelling to improve our understanding of the thermal history of the Ottawa Embayment and the evolution of intracratonic rift basins. The works collected within define a comprehensive temperature-time history for the basin and rift flank from the Late-Mesoproterozoic to present day.