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Barbara Balestra, Patrizia Ziveri, Simonetta Monechi, Simon Troelstra:
Late Quaternary coccolithophorid paleoceanography from the SE Greenland Margin
(Poster)

The northern North Atlantic Ocean is an important area for the understanding of climate change driven by thermohaline circulation. The purpose of this study is to use coccolithophorid and sedimentological data to reconstruct the palaeoceanography of the Denmark Strait region from the Late Quaternary to the present. Water-samples and high-resolution sediments were obtained during the Denmark Strait Expedition, from August 16th to September 15th, 1997.

We will present here the coccolithophorid results from the water-samples collected from various depths (10, 60, 200, 400, 600m) along three transects perpendicular to the coastline of SE Greenland (Irminger Basin), and from two box-cores (DS97-7B, DS97-16B, corresponding to two water-stations). In addition, data from a piston core (DS97-2P) from the Reykjiansen Basin will be compared with the results from the Irminger Basin. In the water-samples, at all stations, the maximum coccosphere densities were recorded at 10m water-depth, with highest cell density of 2´105 cells/l at the boundary between the seasonally ice-covered Greenland margin and open ocean. The lowest cell density was in the proximity of the coast (1.7´102 cells/l). These major coccolithophorid productivity changes are mainly linked to the influence of the Irminger current in this region.

The distribution of coccolith assemblages in the surface sediments of the two box-cores partially reflects the living coccolithophore communities in the surface-waters, although species-selective dissolution is occurring during the transit to the sea-floor. The comparison of the data obtained from the two box-cores shows a greater palaeoproductivity, species richness and an increase in abundance of temperate taxa in the offshore site. The ecological differences are mainly controlled by the changing dynamics of the Irminger current during the Late Quaternary.

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 [Division of Micropalaeontology] [Department of Geosciences] [Bremen University]

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