Determining continuous basins across conjugate margins: The East Orphan, Porcupine, and Galicia Interior basins of the southern North Atlantic Ocean

The East Orphan, Porcupine, and Galicia Interior basins are several of the most promising basins for hydrocarbon exploration along the rifted continental margins of the southern North Atlantic Ocean. Despite having formed at similar geological times, the basins exhibit fundamental differences in symmetry, crustal thickness, sedimentary cover thickness, and amount of extension. Interpretation of seismic reflection and well data was integrated with published 3D grids of depth-to-basement and Moho proxy depth to interpret and restore select seismic reflection lines. Publicly available kinematic evolution models were also integrated to evaluate and compare the restored seismic reflection lines in a more global regional context. Interpretation of five seismo-stratigraphic units and three tectonostratigraphic megasequences along the East Orphan, Porcupine, and Galicia Interior basins reveals similar seismic character for each unit and comparable tectonic history. The structural restoration of the selected lines indicates that evolution, sedimentary cover thickness, faulting style, crustal structure, and kinematic evolution of the East Orphan and Porcupine basins differ significantly. A variable and asymmetrical crustal structure is found in the East Orphan Basin contrasting with the elongated and symmetric Porcupine and Galicia Interior basins. Rift domain maps of the three basins reveal that they are each underlain by hyperextended crust, with possible exhumed mantle in the centre of the Porcupine Basin. Based on a holistic analysis of the results obtained, the linkage between the East Orphan and the Porcupine basins seems implausible, but rather a contemporaneous relationship is interpreted. Moreover, a potential connection between the Galicia Interior Basin and the Porcupine Basin during the Early to Late Jurassic is proposed. Such scenarios imply an oblique and synchronous rifting evolution around the Bay of Biscay triple junction of the southern North Atlantic.