Giant submarine landslide triggered by Paleocene mantle plume activity in the North Atlantic

The 290-km-long ‘Halibut Slide’ is the world’s largest epicontinental submarine landslide. Between 64 and 62 Ma, plume-related uplift in the North Atlantic and far-field stresses caused reactivation of major intra-plate faults. This reactivation caused instability of Cretaceous chalk slopes across the North Sea Basin, triggering the Halibut Slide. Megascours, up to 1 km wide, 150 m deep, and 70 km long, indicate slope failure from an intra-shelf high east of mainland Scotland, and subsequent flow down an ~1.1° slope. Megascours were gouged by cuboid chalk blocks, up to 1 km wide and 170 m high, some of which out-ran the main slide body by up to 10 km. The Halibut Slide has a decompacted volume of 1450 km3 and a basal slide surface extending over ~7000 km2. Subsequent clastic sediment input points and dispersal pathways were controlled by the underlying Slide topography for ~10 m.y. The discovery of this major submarine landslide provides new insights into the response of sedimentary systems to regional and deeply rooted tectonic events, and the initiation of long-term sediment routing patterns.