Large-scale debrites and submarine landslides on the Barra Fan, west of Britain

Abstract: The Barra Fan is a large Neogene to Pleistocene composite fan that has built out into the deep-water basin of the Rockall Trough west of Britain. The bulk of the landward depocentre ofthe Barra Fan takes the form of a relatively undisturbed shelf-margin wedge, in places more than 600 m thick, that is perched above the deep-water basin and, together with the Donegal Fan, partially engulfs the Hebrides Terrace Seamount. A continuous series of slope-front channels and gullies incise into the shelf-margin wedge of the north-ernmost Barra Fan and are the likely transport paths for small- to medium-scale debrites found on the middle and lower slope-front. In contrast, at least four large-scale submarine landslide events making up the Peach Slide appear to have translated the bulk of the slope-front of the northern Barra Fan to the northwest, so that debrites and hemipelagic sedi-ments exhibit maximum composite thicknesses of approximately 450 m on the deep-water basin floor of the eastern Rockall Trough. The extent and volume of successive large-scale debrite units decrease with age. From an interpretation f a limited historical dataset i is thought hat the ground accelerations from earthquakes have been sufficient o trigger slope-front instability and sediment transfer