The Slyne Trough to the west of Ireland is divided into three sections: North, Central and South. The South and Central sub-basins are separated by a seismic ‘dead zone’ along the line of the Clew Bay disturbance. The Central and North sub-basins are separated by a zone transferring the fault bounding the main basin from the western margin in the Central sub-basin to the eastern margin in the North sub-basin.
Five stratigraphic sequences from the Slyne Trough, which span the Rhaetian to Middle Jurassic, are recognized in the 27/13–1 well, and they are compared to the equivalent sequences in the Hebrides Basin. The Late Jurassic Hebridean sequences are expected in the deeper parts of the Central Slyne Trough. The Slyne Trough and Hebrides Basin sediments are mainly tectonically controlled, although major eustatic events in the Early Toarcian and Late Bathonian are recognized.