The Expedition ARK-XXIII/3

The expedition ARK-XXIII/3 will start on 12 August 2008 in Reykjavik (Iceland) and will terminate on 19 October 2008 in Bremerhaven. In order to reach the East Siberian Sea Polarstern will transit through the NW Passage into the research area, and will leave it via the NE Passage. Research activities will concentrate on geoscience at the junction of the Mendeleev Ridge with the East Siberian Shelf. Depending on the sea ice conditions, it is planned to conduct seismic investigations at the junction of the ridge with the shelf to investigate the tectonic evolution of this feature. In an optimum case several long profiles from the Canada Basin across the Mendeleev Ridge into the Makarov Basin would provide clues on the relative ages of the basins and the ridge. In the shallow part of the ridge areas with high sediment accumulations rates the target will be to unravel the climate history with cores. Thus, special attention will be given on the definition of potential drill sites for an already submitted IODP pre-proposal.

In conjunction with the geophysical activities the geological programme aims to retrieve cores from the ridge and the basins to gather information on the younger glacial history of the Amerasia Basin. Furthermore, wherever the seismic reflection data provide information on outcropping older geological units, we will try to core them. The oceanographic investigations will concentrate to collect CTD profiles in conjunction with geological stations to document the actual changes in the water mass composition. In addition, XCTD will be deployed from a helicopter. In the eastern Nansen Basin meteorological/oceanographic buoys will the deployed on ice floes to monitor via satellite the ice movements, salinity and temperature of the water. Biological investigations will use a multi-net to investigate the abundance of the copepod Oithona simili. Biodiversity studies will be performed in addition along the Mendeleev and Gakkel ridges. Finally, tracers in the water column will be investigated with the pumping system of Polarstern and the water bottle of the CTD casts to track geochemically the transport paths in the water column of the Arctic Ocean.

If ice conditions permit we will try to penetrate as deep as possible into the Canada Basin to investigate core sites on the Alpha Ridge, where Mesozoic sediments were recovered in the 50’s and 60’s from drifting ice islands.

Cruise schedule

12 August 2008: Departure from Reykjavik (Iceland)

19 October 2008: Arrival in Bremerhaven

Chief Scientist
Wilfried Jokat

Coordinator
Eberhard Fahrbach

Current position of Polarstern