Abstract - In contrast to much of the European Atlantic margin, the influence of salt on basin evolution has received little attention to date
in the basins west of Ireland, despite salt being proven in several boreholes. Using an extensive seismic reflection database coupled with data from exploration
wells and shallow boreholes, this study maps the distribution and composition of salt layers and investigates their role in the structural evolution of the
Slyne and Erris basins offshore west of Ireland. Two salt-prone intervals have been proven. The Upper Permian Zechstein Group is present throughout the Slyne
and Erris basins, while the Upper Triassic Uilleann Halite Member is only developed in the Northern Slyne and Southern Erris sub-basins. Both sedimentary units
mechanically detach pre-, post-, and intra-salt stratigraphy. Both salt layers underwent halokinesis during basin development, creating a variety of salt-related
structures. Salt pillows and salt rollers formed in the Zechstein Group, causing folding and rafting in the overlying Mesozoic section, driven by active faulting
within the pre-salt basement. Halokinesis in the Uilleann Halite Member caused thin-skinned crestal collapse of the overlying Jurassic section above anticlines
cored by Zechstein salt. Where both Triassic and Permian salt are present, unique structural geometries are formed when two stratigraphically discrete but
kinematically linked halokinetic structures develop. The most common structural configuration consists of a Zechstein salt pillow and an Uilleann Halite salt wall
separated by Lower Triassic sandstones. The fold-axis of the salt pillow trends parallel to the strike of the salt wall. The results of this study provide a
framework for the evolution of halokinetic structures in other basins on the Irish Atlantic margin, give a greater insight into the Permian and Triassic
paleogeography of the region, and have more general implications for the evolution of salt-related structures in rift basins with multiple stratigraphically
discrete salt layers.
Basin Research, doi: https://doi.org/10.1111/bre.12546, 2021.