Surface oceanographic changes in the eastern Labrador Sea: Nannofossil record of the last 31,000 years

Abstract

Calcareous nannofossils in two AMS 14C dated piston cores from the eastern Labrador Sea yield oceanographic information of the last 31 kyr. Moderate nannofossil productivity and abundance of North Atlantic warm water taxa in the southern Labrador Sea (core 91-045–094P) suggest cool surface ocean condition between 31 and 26 thousand years ago (ka). The Irminger Current was absent in this interval. Thus we attribute this cool condition to weak advection of North Atlantic water from the southeast. We found evidence of cold and/or seasonally ice-covered surface conditions between 26 and 13 ka in the southern Labrador Sea and between 31 and 12.6 ka in the northeastern Labrador Sea (core 90-013-013P). Increase of nannofossil productivity and abundance of North Atlantic taxa at about 10.7 ka in core 91-045–094P suggests that the southern Labrador Sea was influenced by warm North Atlantic surface water. The polar water of the Labrador Current had little or no influence on the surface ocean in this area before 9 ka. The Labrador Current started to flow or intensify after 9 ka and became strong by 8.4 ka. The northeastern Labrador Sea remained cold until 8.4 ka perhaps because of discharge of cold meltwater from the Greenland ice sheet. At this time, productivity increased sharply and the assemblage of nannofossils changed. These suggest a significant improvement in surface ocean conditions and the establishment of the warm Irminger Current, which marked the onset of the modern circulation pattern characterized by warm West Greenland Current and strong Labrador Current.