LATE QUATERNARY PALEOCEANOGRAPHY OF THE MID-CONTINENTAL-SHELF TO OUTER-CONTINENTAL-SHELF, EAST GREENLAND

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.