High-resolution benthic foraminiferal records of the last glacial termination in the northern North Atlantic

• Main Author: Nees, Stefan
• Other Authors: Hass, H. Christian, Kaminski, Michael A.
• Format: Book Part
• Language: English
• Published: Grzybowski Foundation 1997
• Subjects: Greenland; Norwegian Sea; Rockall Plateau; Fram Strait; Iceland; North Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/31039/; https://oceanrep.geomar.de/id/eprint/31039/1/Nees%201997.pdf

Large oceanic changes occurred during the last transition from glacial to interglacial conditions (Termination I), which significantly affected pelagic and benthic environments. This study presents results of a quantitative investigation of benthic foraminifera at four sites distributed along a north-south transect across the northern North Atlantic with a high temporal resolution (k 200 years). Benthic foraminifera are examined in samples (1-2 cm sampling intervals) from four long sediment cores located in the southern Fram Strait, the Greenland-Iceland-Norwegian Sea (GIN Sea), and the Rockall Plateau. The most prominent species of benthic foraminifera include Oridorsalis nnlbolzatlls, Cibicidoides wl~ellerstoufi,C assidulina spp. group, P!jrgo rotalaria, Globocassidrrliiza sllbg-lobosa and tubes of agglutinated taxa. In each core, the climatic amelioration at Termination I is recorded to have occurred in two steps. A first INDAR maximum (INDividuals Accumulation Rate = ind/cm2 ky; GIN Sea: average 3,000-6,000 ind/cm2 ky, Rockall Plateau: average 150 ind/cm2 ky) is followed by a period of lower values. A second maximum reveals slightly lower values than the older maximum. Interglacial INDAR values average 700 ind/cm2 ky for the GIN Sea and 200 ind/cm2 ky on the Rockall Plateau. This is roughly twice that of typical glacial values. Meltwater events, identified by stable isotope data and sea-surface temperature reconstructions based on planktic foraminiferal transfer functions, are marked by an increase in endobenthic and opportunistic species. A decrease of reconstructed sea-surface temperatures appears synchronous with the relative INDAR minimum that occurs between the two INDAR maxima. The results indicate a close coupling of sea-surface processes to the benthic realm ("pelagic-benthic coupling") with a longitudinally variable strength. The climate signal at the Rockall Plateau revealed by the fossil benthic foraminifera shows a lower amplitude than that of the GIN Sea. The second, younger INDAR maximum is ...