The distribution of calcareous, siliceous and organic-walled planktic microfossils has been investigated in surface sediments from the Nordic Seas, Planktic foraminifers, coccolithophores, radiolarians, diatoms and dinoflagellate cysts generally reflect major oceanographic domains in the distribution of sediment assemblages, The occurrence of fossilizable plankton in the water column and in sediments has been compared to describe processes which alter the composition of assemblages.The distribution of calcareous microfossil assemblages and calcium carbonate contents in surface sediments is generally related to warm water inflow into the Nordic Seas because dissolution in the water column and sediments does not alter the general composition of assemblages and carbonate fluxes. Most planktic foraminifer and coccolithophore species are adapted to warmer surface waters, and the number of species is low in sediments underlying the colder water masses of the western Nordic Seas. Therefore, the Polar and Arctic Domains cannot be clearly recognized in the distribution of calcareous assemblages.The composition of siliceous and organic-walled microfossil assemblages is more variable in the Greenland and Iceland Seas than is that of calcareous microfossil assemblages, and permit to separate the Atlantic, Arctic and Polar Domains, Theoretically, the varying environments of the Nordic Seas are better reflected in diatom and radiolarian assemblages than in coccolithophore and planktic foraminifer assemblages, but selective dissolution in the water and sediment columns, particularly in the Greenland Sea, cause a strong distortion of siliceous microfossil assemblages in the sedimentary records.Although opal fluxes and fluxes of siliceous microfossils are much higher in the Greenland Sea than in the Norwegian Sea, this cold-water signal is not preserved in surface sediments.Therefore, the spatial variability in the sedimentation of carbonate and opal in the water column is only partly reflected in surface sediments. The distribution of biogenic carbonate and opal in sediments suggests that the Nordic Seas are predominately characterized by production related to warm water inflow. Additionally, the low diversit y of calcareous microfossils and the low preservation potential of siliceous microfo ssils limits their applicability in cold-water environments of the Nordic Seas, where organic-walled dinoflagellate cysts may have the best potential to reflect the complex hydrographic conditions in the fossil record.
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- Distribution of Calcareous, Siliceous and Organic-Walled Planktic Microfossils in Surface Sediments of the Nordic Seas and their Relation to Surface-Water Masses
- Springer Berlin Heidelberg
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