Abstract - The Porcupine Basin is a large underexplored sedimentary basin located offshore west of Ireland within the
structurally complex European North Atlantic Margin. The basin has evolved through multiple Jurassic–Recent phases of deformation
and although the overall plate tectonic context of the margin is well-documented, there are still uncertainties regarding the phases
of tectonic activity, and their associated strain distribution and fault kinematics. Based on the analysis of large volumes of 2D and
3D seismic data from the Porcupine Basin we provide an overview of the nature and origin of multiple fault systems, both tectonic and
non-tectonic, with links to regional tectonic events where possible.
Three distinct basin-wide phases of tectonically induced extensional faulting are recognised: (i) Late Jurassic N-S to NE-SW
trending rift faults, (ii) Late Cretaceous E-W to ENE-WSW trending normal faults, and (iii) Mid Eocene N-S trending faults. The
Jurassic faults were active over a period of 11.5 Myr between the Oxfordian and Kimmeridgian but with an intervening 4.5 Myr period
of quiescence providing a two-stage rift evolution. The Late Cretaceous faulting in the Porcupine Basin broadly correlates with
extension in the Celtic Sea basins and is tentatively attributed to the rotational spreading of the Bay of Biscay in the south. The
Mid Eocene phase of extension, which coincides with the onset of spreading between Europe and Greenland (Atlantic spreading), resulted
in partial reactivation of the Jurassic faults. A series of non-tectonic fault systems occur within specific stratigraphic intervals
suggesting a compactional or gravitationally-driven origin, including basinward dipping normal faults within a Paleocene–early Eocene
deltaic sequence, and multiple tiers of polygonal faults within Cretaceous, late Eocene and Neogene strata.
Basin Research, https://doi.org/10.1111/bre.12535, 2020.