HR: 0800h
AN: OS21A-1522    [Abstracts]
TI: Late Neogene Submarine Mega-slides on the SW Barents Sea Margin
AU: * Hjelstuen, B
EM: berit.hjelstuen@geo.uib.no
AF: Department of Earth Science University of Bergen, Allegt 41, Bergen, 5007 Norway
AU: Eldholm, O
EM: olav.eldholm@geo.uib.no
AF: Department of Earth Science University of Bergen, Allegt 41, Bergen, 5007 Norway
AU: Faleide, J
EM: j.i.faleide@geo.uio.no
AF: Department of Earth Sciences University of Oslo, POBox 1047 Blindern, Oslo, 0316 Norway
AB: The Late Neogene history of the NE Atlantic continental margin is characterized by numerous mass movement features reflecting a variety of scales and processes. Such slide processes have also been reported on the margin off the western Barents Sea, where the Bjornoyrenna Slide is a major feature. We have now further studied the Late Neogene sequences in this area by analyzing high quality multi-channel seismic lines on the continental slope and in the adjacent Lofoten Basin, allowing resolution of these features at depth. The seismic data reveal the existence of three pre-Holocene mega-slides, Slides I-III, of which we have calculated the extent, timing and the volume of sediment involved in the mass movements. We document that major sliding may occurred as a far back as 1.5 Ma, and that the largest slide, Slide II (0.5-1.0 Ma), affected an area of 120 000 km2 and involved about 25 000 km3 of sediments. The dimensions of even the smallest slide, Slide I, is comparable with the Holocene Storegga Slide, considered the world's largest exposed submarine slide, affecting an area of about 95 000 km2. In terms of sediment volume, the two largest mega-slide events are as much as a magnitude larger than the Storegga Slide. Since about 2.6 Ma, the Northern Hemisphere Glaciations have left a thick cover of dense deposits over a softer substratum, inducing potential instability. The initial slide activity appears coeval with a glacial intensification at about 1.6 Ma, when ice sheets advanced to the shelf edge. We interpret that the repetitive advance of ice sheets to their maximum position caused an increased sediment supply onto the continental margin creating instable conditions, contributing to the release of these huge slide events.
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 3022 Marine sediments: processes and transport
DE: 3070 Submarine landslides
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005