HR: 08:30h
AN: OS41C-03    [Abstracts]
TI: Lomonosov Ridge off Greenland (LOMROG) 2007
AU: * Marcussen, C
EM: cma@geus.dk
AF: Geological Survey of Denmark and Greenland (GEUS), Oster Voldgade 10, Copenhagen, DK-1350, Denmark
AU: Jakobsson, M
EM: martin.jakobsson#geo.su.se
AF: Dept. of Geology and Geochemistry, Stockholm University Svante Arrhenius vag 8c, Stockholm, 106 91, Sweden
AB: The Lomonosov Ridge off Greenland was the primary focus for the LOMROG expedition. This part of the Arctic is virtually unexplored as difficult sea ice conditions have made it inaccessible for surface vessels. With Swedish icebreaker /Oden/ supported by new Russian nuclear icebreaker /50 Let Pobedy/, LOMROG managed to reach the southern most tip of the Lomonosov Ridge off Greenland to carry out multibeam mapping, subbottom and seismic reflection profiling, gravity measurements, geological coring and oceanographic station work. The LOMROG expedition is a Swedish/Danish collaboration project with participating scientists also from Canada, Finland, and USA. The data collection was made for the purpose of studying paleoceanography/oceanography, glacial history and the tectonic evolution of the of the Arctic Ocean as well as for Denmark's Continental Shelf Project under the United Nations Convention on the Law of the Sea Article 76. One of the reasons for targeting the ice-infested area north of Greenland was that it likely holds answers to key questions regarding the glacial history of the Arctic Ocean, such as whether immense ice shelves existed in the Arctic Ocean during past glacial periods./ /Previous expeditions with /Oden/ in 1996 and the US nuclear submarine /Hawkbill/ in 1999, have demonstrated the occurrence of ice grounding down to 1000 m present water depth at about 87°N 145°E on the Lomonosov Ridge crest. If this ice grounding event resulted from a much debated, but supposedly coherent and large floating ice shelf, the Lomonosov Ridge north of Greenland must also be scoured. To test the hypothesis of a huge Arctic Ocean ice shelf LOMROG mapped the areas of the Lomonosov Ridge north of Greenland using the new EM120 multibeam bathymetry and SBP120 subbottom profiling system installed on the /Oden/ during the spring of 2007. Glacial erosion was indeed found at water depth shallower than approximately 800 m and two sediment cores retrieved from the glacially scoured sea floor contain diamicton. These new results will help reconstructing the glacial models of the Arctic Ocean. The oceanographic component of LOMROG investigated (see presentation by Bjork et al) the pathways of the Atlantic water and deep water. Water masses originating from the Canadian Basin side, which have crossed the Lomonosov Ridge at about 88°30'N 154°E, were found following the slope along the southern Lomonosov Ridge slope on the Amundsen Basin side. This presentation is on behalf of the entire LOMROG Scientific Partly.
DE: 3025 Marine seismics (0935, 7294)
DE: 3640 Igneous petrology
DE: 4207 Arctic and Antarctic oceanography (9310, 9315)
DE: 4999 General or miscellaneous
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting