Towards an understanding of the Neogene tectonostratigraphic framework of the NE Atlantic margin between Ireland and the Faroe Islands

Abstract

The Neogene succession preserved on the continental margin between Ireland and the Faroe Islands can be divided into two megasequences of Miocene and Pliocene–Holocene age. The base of each megasequence is marked by a regional unconformity. These are of latest Oligocene/early Miocene and early Pliocene age respectively and reflect major phases of Neogene margin evolution. The megasequences and their bounding unconformities reflect a gross two-stage depositional history; predominantly a response to intra-plate tectonism that modified sedimentation patterns and palaeoceanographic circulation. The latest Oligocene/early Miocene event marks a major change in the oceanographic regime, and can be linked to the establishment of deep-water exchange between the Arctic and North Atlantic oceans. The submergence of the Greenland–Scotland Ridge, which includes the Iceland–Faroe Rise and the Wyville–Thomson Ridge in the area of study, resulted in locally vigorous deep-water erosion as northern source deep water flowed through the Faroe conduit, which is part of the Southern gateway for deep-water exchange. Coeval deposition of sediment drifts occurred in the Faroe–Shetland Channel and Rockall Trough as the deep-water currents stabilised. The early Pliocene event marked the widespread instigation of shelf-margin progradation to the north–west of Britain and Ireland, and to the east of the Faroe Islands. This event is linked to the uplift and erosion of Britain, Ireland and the Faroe Islands, and is part of a larger North Atlantic-scale uplift. Significant deep-water erosion in the Rockall Trough suggests that the water circulation pattern was also modified by this event. The formation of the key megasequence boundaries occurred during times of significant plate rearrangement, and suggests that these events may be correlatable across the whole NW European margin.