Recurrent Pleistocene mega-failures on the SW Barents Sea margin

摘要

Submarine slides have been instrumental in shaping the Late Neogene NE Atlantic continental margin. We document a margin setting north of 70 degrees N capable of generating recurrent huge Pleistocene mass-movements. The 1.0-0.2 Ma old Bjornoya Fan Slide Complex includes three buried mega-slides, which have left scars containing up to 500 m-thick debris units. The two largest slides may have had a retrogressive development, cover areas of the order of similar to 120 x 10(3) km(2), and involved similar to 25 x 10(3) km(3) of sediments. Thus, the failures involved an order of magnitude more sediment than the Storegga Slide, the world's largest exposed slide. The mega-slides occurred during the Northern Hemisphere Glaciations, characterized by greatly enhanced deposition rates leading to the construction of the 3-km-thick Bjornoya Trough Mouth Fan that progressively loaded a softer Miocene-Oligocene substratum. This setting induced excess pore pressure and sediment instability, conditions favorable for sliding. External trigger mechanisms, such as earthquakes, may have facilitated the mass-wasting process. (C) 2007 Elsevier B.V. All rights reserved.