The First-Order Crustal Structure and Basin Architecture of the Canadian Arctic Margin

Abstract

First-order sedimentary isopach and depth-to-Moho maps have been produced for the first time along the Canadian Arctic margin from legacy seismic profiles, calibrated with two-dimensional gravity and magnetic modeling and augmented by some younger passive seismic and exploration seismic data. These maps show margin-scale structural patterns that can be interpreted in terms of fundamental tectonic processes of lithosphere deformation. The Canadian Arctic margin from the Beaufort Sea to Sever Spur, but not beyond it, is a typical passive continental margin along the Canada Basin ocean. However, beyond Sever Spur through to the Lincoln Shelf, the margin comprises a narrow linear sedimentary basin overlying an axis of crustal thinning embedded within continental lithosphere. This basin formed by intracontinental (trans)extension at least in part after the main HALIP magmatic events that helped build Alpha Ridge on its northern margin. This segment of the margin has a tectonic affinity more facing the Late Cretaceous and Cenozoic North Atlantic-Baffin Bay-Arctic extensional regime rather than the earlier Canada Basin extensional regime. These interpretations, which together provide a “Canadian” boundary condition on models of Amerasia Basin origin and evolution, are clearly speculative given the resolution of the available geophysical data. They are presented here, nevertheless, accompanied by a thorough overview of pertinent recent literature, with the aim of helping to prompt and inform further debate about the tectonic history of the Arctic Ocean.