3-D CRUSTAL-SCALE MODELS OF EASTERN CANADA’S RIFTED CONTINENTAL MARGINS FROM NOVA SCOTIA TO BAFFIN BAY, DERIVED FROM CONSTRAINED 3-D GRAVITY INVERSION

Seismic refraction/wide-angle reflection methods arguably provide the best geophysical tool for resolving crustal structure and the depth to Moho (the crust-mantle boundary). Unfortunately, existing surveys along Canada’s eastern seaboard are sparsely distributed and of varying vintage and quality. Regional 3-D constrained gravity inversion methods provide one means of bridging between available seismic refraction surveys to allow 3-D models of the crust to be constructed. A number of these inversions have been independently undertaken along Canada’s eastern seaboard from the Nova Scotian margin in the south, along the margins of Newfoundland and Labrador, and to Baffin Bay in the north, capturing the along-strike variations in the crustal structure of these rifted margins. In this presentation, all of the individual inverted models are combined into a 3-D model of the entire eastern offshore margin of Canada, revealing contrasts in crustal thickness, extension factors, crustal density distribution, and depth to Moho. These variations are interpreted to reflect inheritance from pre-rift orogenic structures, rheological and thermal variations (both pre- and syn-rift), as well as variations in rifting style, extension rates, and the influence of magmatism (or lack thereof) during rifting. Interpretation of these regional 3-D models provides the broader tectonic context to understand the evolution of overlying basins and to gauge the resulting impact on resource prospectivity.