HR: 11:35h
AN: PP42B-06 INVITED    [Abstracts]
TI: Arctic Ocean: Glacial History From Multibeam Mapping and Coring During the HOTRAX (2005) and LOMROG (2007) Expeditions.
AU: * Jakobsson, M
EM: martin.jakobsson@geo.su.se
AF: Dept. of Geology and Geochemistry, Stockholm University, Stockholm University SE-106 91, Stockholm, SE-106 91, Sweden
AU: Polyak, L
EM: polyak.1@osu.edu
AF: Byrd Polar Research Center, Ohio State University, 108 Scott Hall, 1090 Carmack Rd, Columbus, OH 43210-1002, United States
AU: Darby, D A
EM: ddarby@odu.edu
AF: Dept. of Ocean, Earth, and Atmospheric Sciences, Old Dominion University, Oceanography and Physical Sciences Building, 4600 Elkhorn Avenue, Norfolk, Va 23529-0276, United States
AB: During the Healy-Oden Trans-Arctic 2005 (HOTRAX) expedition, a transect from Bering Strait across the central Arctic Ocean to Svalbard was accomplished. Multibeam mapping and chirp sonar profiling along this transect revealed an abundance of glaciogenic bedforms on the Chukchi Borderland including iceberg keel scours, mainly at water depths shallower than 350-400 m, flutes and mega-scale glacial lineations extending as deep as 900 m below the present sea level, small drumlin-like features, and morainic ridges and grounding-zone wedges. The Lomonosov Ridge off Greenland 2007 (LOMROG) expedition with Swedish icebreaker /Oden/ supported by the new Russian nuclear icebreaker /50 Let Pobedy/ reached the previously unexplored areas of the southernmost Lomonosov Ridge. Ice erosion was mapped on the ridge crest above 800 m water depth with /Oden's/ newly installed multibeam and chirp sonar system. From this ice eroded area two cores were taken that contained a stiff diamicton below a slightly less than 2 m thick drape of mud deposited after the ice erosional event. These cores will allow dating of the ice erosional event. After mapping portions of the Lomonosov Ridge, the Morris Jesup Rise protruding from the Northern Greenland Continental shelf, was investigated for glacial features. Remarkably large iceberg scours as deep as 1050 m below present sea level were mapped crossing the Morris Jesup Rise from West to East. These new glaciogenic data suggest that large ice shelves occupied parts of the Arctic Ocean during glacial maxima, ice rises were formed over the Chukchi Borderland and portions of the Lomonosov Ridge, and icebergs with drafts deeper than 900 m scoured the Morris Jesup Rise. This presentation is on behalf of the entire LOMROG Scientific Partly and the coring group of the HOTRAX scientific party.
DE: 3022 Marine sediments: processes and transport
DE: 3045 Seafloor morphology, geology, and geophysics
DE: 4540 Ice mechanics and air/sea/ice exchange processes (0700, 0750, 0752, 0754)
DE: 4926 Glacial
DE: 4994 Instruments and techniques
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting