Integrating Seismic Interpretation of the Orphan Basin, Offshore Newfoundland, with Deformable Plate Tectonic Modelling of the Southern North Atlantic

The massive Orphan Basin, offshore Newfoundland, preserves evidence of a complex, multiphase rift history influenced by structural inheritance tied to the Appalachian-Caledonian orogen. Despite recent advances in plate kinematic reconstructions of the Southern North Atlantic, the tectonic evolution of the Orphan Basin remains poorly constrained, largely due to limited seismic and well coverage. As a result, the contributions of structural constraints on deformation have been oversimplified, leading to the misrepresentation of their influence on continental breakup.

This study prioritizes the interpretation of recently available 2D seismic reflection datasets acquired by TGS/PGS and ION Geophysical, developing stratigraphic and structural constraints to inform plate kinematic modelling. An analysis of the spatial distribution of Jurassic to Early Cretaceous syn-rift sediments and the geometries of major fault systems provide new insights into rift migration and the temporal variability of strain localization in the Orphan Basin during continental breakup.

Seismic interpretation and fault analysis identify two temporally distinct hyperextended rift basins separated by a region of thick crust, highlighting the importance of mechanically rigid blocks, such as the Orphan Knoll, in focusing strain, controlling basin development, and influencing the timing and geometry of rift propagation. While previous reconstructions have represented extension within the Orphan Basin as continuous and uniform, our analysis indicates that strain was instead focused within discrete extensional corridors controlled by large detachment faults.

Using GPlates, these seismic constraints are integrated into a deformable plate tectonic reconstruction, refining the kinematic plate model of the Southern North Atlantic while improving its geological accuracy and reducing the reliance on uniform crustal stretching assumptions. The updated reconstruction aims to provide a significant step towards a reproducible analogue model for hyperextended rift basins during magma-poor continental breakup.