USING CONSTRAINED 3-D GRAVITY INVERSION TO INVESTIGATE ALONG-STRIKE ONSHORE TO OFFSHORE CRUSTAL-SCALE APPALACHIAN OROGENIC TRENDS IN ATLANTIC CANADA

While geological mapping has enabled the tracking of Appalachian terranes across Atlantic Canada, following these trends offshore into the late Paleozoic Maritimes Basin and beyond the island of Newfoundland into the Mesozoic basins of the North Atlantic can be more challenging due to variations in the distribution and depth extent of available seismic constraints and the paucity of wells that intersect basement. We present results from using constrained 3-D gravity inversions to reveal offshore crustal thicknesses, density distributions, and inferred extension factors, linking them to the onshore mapped accreted terranes and colliding Laurentian and peri-Gondwanan realms that were amalgamated during the closing of the Iapetus Ocean during the early to mid-Paleozoic Appalachian Orogenesis. The revealed densities and Moho depths are compared against 2-D velocity models from seismic refraction/wide-angle reflection profiles, where available, in order to gauge the reliability of the inverted results. The regional view provided by these inversions allows the Appalachian orogenic trends to be tracked continuously across the entire Atlantic Canadian margin and provides maps of zones of inheritance that may have impacted later extensional tectonism during the opening of the modern North Atlantic Ocean.