Structure of rifted continental margins and gas hydrates

Rifted continental margins form during breakup of the continental lithosphere, as a major part of the Earth's plate tectonic cycle. The purpose of this proposal is to investigate the nature of this process by defining structures formed across the rifted margins of eastern Canada and their associated margin conjugates. These structures are determined by combining wide-angle seismic velocity models with deep multi-channel reflection data to produce integrated depth profiles. We have recently collected a number of such profiles across the eastern Canadian margins. I will complete the analysis of these data and combine them with similar profiles across the conjugate margins of NW Africa and NW Europe. Reconstructing the geometry of the crust and sediment during continental extension and comparison with recent theoretical models will help to identify fundamental attributes of the extensional processes. A key element is to understand the enigmatic nature of basement and mantle within the continent-ocean transition zone. Existing seismic models indicate that this zone can exhibit significant variability along strike of the margin, possibly related to the location of accommodation zones where rifting geometries suddenly change. I will study two such regions previously identified offshore Canada and Greenland using new seismic data with improved resolution and new processing and modeling procedures. Continental margins also contain major deposits of the world's hydrocarbon resources, both in conventional form as deep oil and gas reservoirs and in unconventional form as shallow methane trapped in hydrate structures. If released to the atmosphere, this methane could also form a potent source of greenhouse gas, potentially resulting in rapid warming. A second focus of this proposal will be to better define the nature of hydrates off eastern Canada, which have only recently been identified.