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

Nees, Stefan (1997) High-resolution benthic foraminiferal records of the last glacial termination in the northern North Atlantic. In: Contributions to the micropaleontology and paleoceanography of the northern North Atlantic (collected results from the GEOMAR Bungalow Working Group). , ed. by Hass, H. Christian and Kaminski, Michael A.. Grzybowski Foundation, Krakow, pp. 167-197.

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Abstract

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 characterized by an increased abundance
of epibenthic species at all core locations, suggesting extended lateral bottom currents.
In comparison with various palaeo-climatological data sets, the variability of fossil benthic
foraminiferal abundances in the GIN Sea show a distinct coherence with changes of atmospheric
temperatures, sea-surface temperatures and the postglacial sea level rise. The variability
of the benthic foraminiferal fauna is principally in phase with climate change events.

Document Type: Book chapter
Keywords: benthic foraminifera, Termination I, northern North Atlantic
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Date Deposited: 19 Jan 2016 08:12
Last Modified: 19 Jan 2016 08:35
URI: http://oceanrep.geomar.de/id/eprint/31039

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