Km. Williams et al., LATE QUATERNARY PALEOCEANOGRAPHY OF THE MID-CONTINENTAL-SHELF TO OUTER-CONTINENTAL-SHELF, EAST GREENLAND, Arctic and alpine research, 27(4), 1995, pp. 352-363
Cores from a transect along the Kangerdlugssuaq Trough, southeast Gree
nland shelf, were analyzed for sediment properties, foraminifera, diat
oms, opal, and palynomorphs. The transect lies in one of the most clim
atically sensitive areas in the Northern Hemsiphere, in the path of th
e outflow of Polar Water from the Arctic Ocean, and in direct proximit
y of the confluence of Arctic and Atlantic water masses. Mass suscepti
bility, total organic carbon (TOC), and grain size change markedly aro
und 8 ka, indicating major changes in sediment source and/or depositio
nal environment and mechanisms. However, this period also marks a majo
r change in sediment accumulation rate associated with the retreat of
the ice sheet margin into the fiords. We found that the biogenic and i
norganic content of the surface and bottom waters show dramatic change
s over the past ca. 14 ka. Surface water changes are indicated by diat
oms and opal variations between ca. 13.5 and 9 ka in the form of cool/
warm pulses on the outer shelf, where surface water temperature genera
lly declines after 9 ka, On the inner shelf, surface water warming/coo
ling pulses occur from ca. 9 to 6 ka with a general cooling after ca.
6 ka to present. Dinoflagellates corroborate this interpretation in th
at they indicate meltwater pulses between 13 and 12 ka on the outer sh
elf with a warming of surface water around 11 ka. After 6 ka they also
suggest a surface water cooling. The 6 ka cooling is also reflected i
n Baffin Island shelf flora and fauna and is probably caused by a chan
ge in Arctic Ocean outflow through the northeastern Canadian archipela
go, where the Atlantic Water component was sharply reduced because of
isostatic uplift. This change then increased the Arctic Ocean outflow
along the East Greenland coast. Transport paths of exotic pollen show
marked changes during three time periods, 12-10 ka, 10-8 ka, and 8 ka-
present. The changes may show changing intensities of cyclogenesis alo
ng the east coast of North America and a deepening of a trough positio
ned north of the study sites during 12-10 ka and 8 ka to present, maki
ng it possible for cyclones to be brought farther into the Arctic.