Palaeo-oceanography of the Rockall Trough during the Oligocene.

Today the main source of bottom water in Rockall Trough (offshore Ireland) is dense water formed in the Greenland-Iceland-Norwegian (GIN) Sea that flows south through the Faeroe-Shetland Channel. Sediment deposited by contour-following bottom currents began to accumulate on the southwest margin of Rockall Trough during the Late Eocene/Early Oligocene. The source of the bottom currents has been attributed to Arctic intermediate water flowing through the Faeroe-Shetland Channel into Rockall Trough. However, a deep connection between the Arctic and GIN Seas did not exist prior to the Late Miocene. Paleobathymetric reconstructions assuming two different thermal histories for the region around Rockal Plateau and Faeroe Bank offer new potential source areas for dense water in the Early Oligocene. The thermal model based on Cretaceous rifting of the Rockall. Trough and Faeroe-Shetland Channel without uplift in the Paleocene predicts a broad shelf north of Rockall Trough in the Early Oligocene. This shelf could have been a site of dense water formation if the area were cold enough. The thermal model based on Paleocene uplift from reheating of the lithosphere, reconstructs a shallow to subaerial Rockall Plateau in the Early Oligocene.