(
2015-09-21)
Elmore, Aurora C.; Wright, James D.; Chalk, Thomas B.
Benthic foraminiferal stable isotopic records from a transect of sediment cores south
of the Iceland-Scotland Ridge reveal that the penetration depth of Iceland-Scotland Overflow
Water (ISOW) varied on orbital timescales with precessional pacing over the past ~ 200 kyr.
Similar, higher benthic foraminiferal δ13 C values (~ 1.0 ‰) were recorded at all transect sites
downstream of the Iceland-Scotland Ridge during interglacial periods (Marine Isotope
Chrons 5 and 1), indicating a deeply penetrating ISOW. During glacial periods (Marine
Isotope Chrons 6, 4, and 2), benthic foraminiferal δ13C values from the deeper (2700-3300
m), southern sites within this transect were significantly lower (~ 0.5 ‰) than values from the
northern (shallower) portion of the transect (~ 1.0 ‰), reflecting a shoaling of ISOW and
greater influence of glacial Southern Component Water (SCW) in the deep Northeast
Atlantic. Particularly during intermediate climate states, ISOW strength is driven by
precesional cycles, superimposed on the large-scale glacial-interglacial ISOW variability.
Millennial-scale variability in the penetration of ISOW, likely caused by high-frequency
Heinrich and Dansgaard-Oeschger Events, is most pronounced during intermediate climate
states.
