NORWEGIAN SEA OVERFLOW VARIABILITY AND NE ATLANTIC SURFACE HYDROGRAPHY DURING THE PAST 150,000 YEARS

The long-term variability of Norwegian Sea Overflow through the Faeroe Bank Channel and its relation to NE Atlantic surface hydrography is r econstructed based on sedimentological, micropalaeontological and stab le isotope analysis, as well as AMS C-14 dating, of a sediment core (E NAM-33) retrieved near the outlet of the channel. Additional palaeocea nographic information has been obtained from three nearby sediment cor es (ENAM-30, -32, 94-13). Our results demonstrate enhanced circulation of Norwegian Sea Overflow Water (NSOW) at times of increased Sea Surf ace Temperature (SST), and a reduction or cessation of NSOW flow at ti mes of low SST During the Last Glacial Maximum (LGM), NSOW activity wa s at a minimum from about 22 ka to 16 ka. After the LGM, NSOW circulat ion was weak until a major Row pulse of NSOW occurred, dated at betwee n 13.4 ka and 12.0 ka. Thereafter, NSOW flow was once again reduced. R enewed intensification of NSOW Row did not occur until after 9.8 ka, w hereas a further increase in NSOW activity is observed after the early Holocene. The timing of both glacial-interglacial and deglacial NSOW variability is similar to the timing of changes in deep-water circulat ion reconstructed from cores from the open North Atlantic in previous studies. Whereas most of these studies involve the reconstruction of c hanges in the proportion of North Atlantic Deep Water (NADW) relative to southern-source deep waters, the lithology of the cores from near t he Faeroe Bank Channel outlet provides a qualitative but direct indica tion of the strength of NSOW currents. This study confirms that the NA DW changes observed in the North Atlantic are due to a reduction in NS OW, and cannot be attributed only to an increase in southern-source de ep waters. Furthermore, our results indicate that NSOW flow through th e Faeroe Bank Channel was not a source of Glacial North Atlantic Inter mediate Water (GNAIW), and that a subpolar source for this water mass is likely. (C) 1998 Elsevier Science B.V. All rights reserved.