LATE QUATERNARY CHANGES IN SURFACE-WATER AND DEEP-WATER MASSES OF THENORDIC SEAS AND NORTH-EASTERN NORTH-ATLANTIC - A REVIEW

Quantitative and semiquantitative proxy data based on more than 200 co re-top samples and 100 deep-sea cores lead to important new insights a bout late Quaternary changes in paleo-oceanography, climate and microf aunal habitats in the north-eastern North Atlantic and Nordic Seas, in sights resulting from a detailed investigation by the Kiel research pr oject SFB 313/B2 summarized in this paper. Planktonic foraminifera spe cies provide reliable tracers of past sea surface temperatures and cur rents. The genus Beella in particular was found to trace subtropical w ater masses up to the far north. Benthic foraminifera species served a s sensors of bottom currents and local flux rates of organic matter. N ew orders of time resolution are reached via stable isotope stratigrap hy and accelerator mass spectrometry carbon-14 dating, allowing the id entification of meltwater events lasting a few hundred years and short er, a time range where, however, the yet unquantified role of bioturba tion presents a growing problem. Based on this high-resolution stratig raphy a number of 'time slices' (synoptic time intervals) are defined to reconstruct the incursion of Atlantic water masses, to map paleocur rent patterns within the Nordic Seas and the north-eastern North Atlan tic and to test alternative circulation models - for example, for the last glacial maximum (LGM) and various meltwater episodes. These are c learly coeval with Dansgaard-Oeschger events found in Greenland ice co res, with the actual cause of the flickering climate as yet unknown. L ikewise, there is ongoing controversy about the extent of past sea-ice cover and about possible,changes from the present anti-estuarine to e stuarine mode of deep water exchange between the North Atlantic and th e Nordic Seas during the LGM. South of Iceland, however, the history o f deep water renewal over the last glacial cycle covering the last 30 000 years was largely deciphered.