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Geophysical Research Abstracts
Vol. 14, EGU2012-5933, 2012
EGU General Assembly 2012
© Author(s) 2012
Watermass evolution and ice-drift patterns in the subarctic Norwegian
Sea during the Holocene
H.A Bauch (1) and E.S. Kandiano (2)
(1) Mainz Academy c/o GEOMAR, Kiel, Germany (hbauch@geomar.de), (2) GEOMAR, Kiel, Germany
(ekandiano@geomar.de)
Holocene climate records from the polar North show a strong tie to changes in insolation in general and, on the
regional scale, to the particular post-glacial environmental development. Because the eastern Nordic seas act as
through road for the oceanic heat into the Arctic Ocean we have investigated two crucial oceanographic compo-
nents in the southern Norwegian Sea, the Arctic Front (AF) and the Norwegian Atlantic Current (NAC). Using
deep-sea sediment records we analyzed different foraminiferal species for O-isotopes and interpreted the planktic
foraminiferal assemblage variations in combination with records of ice-rafted detritus (IRD). It is shown that after
adjacent ice shelves and glaciers had retreated inland and away from the coastlines highest surface temperatures oc-
curred between 10.5 and 8.5 ka. An intermittent cold phase around 8 ka is associated with both IRD and increased
abundance of polar species N. pachyderma (s). Afterwards, high surface temperature were regained but started
to decrease at the AF after 6 ka, concomitant with a persistent occurrence of IRD. This cooling trend continued
into the latest Holocene when highest IRD input is noted. Within the NAC, relatively stable and warm conditions
are still found between 2.5 and 1 ka, in both planktic and benthic O-isotopes. Although variability among certain
foraminiferal species would indicate some surface changes, the abundance of N. pachyderma (s) increased from
30 % to 70 % during the last 1ka (Little Ice Age). This increase is associated with highly variable O-isotope values
throughout the entire water column. We interpet the records of the past 10.5 ka, and in particular the times when
rather cold surface conditions prevailed, to be the result of changes in overall atmospheric circulation. These caused
an intensification of the gyre system in the Greenland and Iceland seas thereby rerouting polar water masses, and
probably winter sea ice, far into the eastern Nordic seas.