ISSN:
1437-3262
Schlagwort(e):
Paleo-oceanography
;
Abrupt climatic change
;
Deep-sea micropaleontology
;
Late Quaternary
;
North Atlantic
;
Atlantic Salinity Conveyor Belt
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Geologie und Paläontologie
Notizen:
Abstract Quantitative and semiquantitative proxy data based on more than 200 core-top samples and 100 deep-sea cores lead to important new insights about late Quaternary changes in paleo-oceanography, climate and microfaunal habitats in the north-eastern North Atlantic and Nordic Seas, insights resulting from a detailed investigation by the Kiel research project SFB 313/132 summarized in this paper. Planktonic foraminifera species provide reliable tracers of past sea surface temperatures and currents. The genus Beella in particular was found to trace subtropical water masses up to the far north. Benthic foraminifera species served as sensors of bottom currents and local flux rates of organic matter. New orders of time resolution are reached via stable isotope stratigraphy and accelerator mass spectrometry carbon-14 dating, allowing the identification of meltwater events lasting a few hundred years and shorter, a time range where, however, the yet unquantified role of bioturbation presents a growing problem. Based on this high-resolution stratigraphy a number of ‘time slices’ (synoptic time intervals) are defined to reconstruct the incursion of Atlantic water masses, to map paleocurrent patterns within the Nordic Seas and the north-eastern North Atlantic and to test alternative circulation models — for example, for the last glacial maximum (LGM) and various meltwater episodes. These are clearly coeval with Dansgaard-Oeschger events found in Greenland ice cores, with the actual cause of the flickering climate as yet unknown. Likewise, there is ongoing controversy about the extent of past sea-ice cover and about possible changes from the present anti-estuarine to estuarine mode of deep water exchange between the North Atlantic and the Nordic Seas during the LGM. South of Iceland, however, the history of deep water renewal over the last glacial cycle covering the last 30000 years was largely deciphered.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00192244
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