Advanced Seismic Imaging of Eastern Canadian Margins and Crustal Analogues

Rifted continental margins form by extension and breakup of the continental lithosphere, as one major component of the Earth's plate tectonic cycle. They also contain major deposits of the world's hydrocarbon resources. The nature of rifting varies dramatically by the amount of melt produced: from margins with little or no melt (magma-poor) to margins with large volumes of melt (magma-rich). The purpose of this proposal is to investigate the nature of the rifting process by imaging structures formed across the rifted margins of eastern Canada and analogues of these structures on the Southeast Indian Ridge. Reconstructing the geometry of the crust and sediment throughout their extensional histories and comparing these geometries with theoretical model archetypes will help to identify fundamental attributes of the extensional processes. Three key elements are to better understand: i) the depth-dependent distribution of continental crustal deformation, ii) the nature of basement and mantle within the ocean-continent transition zone and on ultraslow mid-ocean ridges, and iii) the cause of variations between magma-rich and magma-poor rifting. Existing images can define the basic overall structure of margins but specific regions or transitions within such images are often poorly defined. For instance, the ocean-continent transition zone can exhibit complex structures, including highly extended continental crust, exposed mantle and thin oceanic crust, which are difficult to distinguish with existing data. These complexities are critically important for an improved understanding of such widely-held concepts as the continent-ocean boundary, the breakup unconformity, and the nature of early oceanic seafloor spreading. Occurrences of exhumed mantle in similar rifted margin settings have also been recognized in continental orogens, such as the Alps and the northern Canadian Cordillera. These studies thus have broad application to a wide range of fundamental Earth processes with additional applied value to further understanding the formation of offshore hydrocarbon resources.