PALEOCEANOGRAPHIC RECONSTRUCTION FROM LGM TO HOLOCENE: A HIGH-RESOLUTION FORAMINIFERAL AND SEDIMENT ANALYSES FROM THE NW SHELF OF ICELAND

Core MD99-2264 was collected in 1999 during the IMAGES cruise on the Marion Dufresne from the Djupall trough, NW Iceland shelf. The study area is sensitive to changes to the oceanographic Polar front marked by the boundary between the East Greenland current (<0°C;S<34) and the Irminger Current (>4°C;S>35). Changes in the location of the Polar front can have significant meaning for climate and sea-ice cover around Iceland. Core MD99-2264 is 38 m long and contains the longest continuous sediment record ever collected from the Iceland shelf, extending back to 33,000 ¹⁴C BP. In this study, grain size, total carbonate, IRD (>2 mm clasts, X-radiographs used), lithofacies (visual description) and benthic foraminiferal assemblages are being used in order to reconstruct paleocurrents, sea-ice cover and climatic variations.

Our study focuses on the period from LGM to early Holocene. Today the characteristics of the watermass at our study side is Atlantic. We are interested in determining the income and strength of the Atlantic Irminger Current from LGM towards modern conditions. Additionally, how will our results compare to records from other study sides in the Nordic Seas. Our interest is also to determine the proximity of the local glacier to the study side.

The LGM interval is characterized by oxidized sediments with no IRD and the most dominant foraminifera species is Stainforthia feylingi (>70%). This indicates years of extensive sea-ice cover. After the LGM new environmental conditions are recorded, where the cold arctic species Cassidulina reniforme and Elphidium excavata f. clavata dominate. At the same time IRD is found again suggesting brake up of icebergs from the calving glacier. Additionally, the species Cibicides lobatulus and Astrononion gallowayi increase considerably indicating stronger bottom current conditions. Atlantic water indicators such as, Cassidulina laevigata, Stainforthia fusiformis and Trifarina angulosa are sparse at LGM and throughout deglaciation. Their appearance along with increased faunal diversity rise significantly around 9200 BP suggesting that Atlantic water was traversing the NW shelf at that time.

Stable isotopes measurements on benthic foraminifera is in progress and twelve more AMS dates on mollusks have been submitted to the Aarhus AMS laboratory.