The 8200 year B.P. event in the slope water system, western subpolar North Atlantic
Keigwin, Lloyd D.
Sachs, Julian P.
Boyle, Edward A.
MetadataShow full item record
Stable isotope, trace metal, alkenone paleothermometry, and radiocarbon methods have been applied to sediment cores in the western subpolar North Atlantic between Hudson Strait and Cape Hatteras to reveal the history of climate in that region over the past ∼11 kyr. We focus on cores from the Laurentian Fan, which is known to have rapid and continuous accumulation of hemipelagic sediment. Although results among our various proxy data are not always in agreement, the weight of the evidence (alkenone sea surface temperature (SST), δ18O and abundance of Globigerinoides ruber) indicates a continual cooling of surface waters over Laurentian Fan, from about 18°C in the early Holocene to about 8°C today. Alternatively, Mg/Ca data on planktonic foraminifera indicate no systematic change in Holocene SST. The inferred long-term decrease in SST was probably driven by decreasing seasonality of Northern Hemisphere insolation. Two series of proxy data show the gradual cooling was interrupted by a two-step cold pulse that began 8500 years ago, and lasted about 700 years. Although this event is associated with the final deglaciation of Hudson Bay, there is no δ18O minimum anywhere in the Labrador Sea, yet there is some evidence for it as far south as Cape Hatteras. Finally, although the 8200 year B.P. event has been implicated in decreasing North Atlantic ventilation, and hence widespread temperature depression on land and at sea, we find inconsistent evidence for a change at that time in deep ocean nutrient content at ∼4 km water depth.
Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 20 (2005): PA2003, doi:10.1029/2004PA001074.
Showing items related by title, author, creator and subject.
Kurowska, Zuzanna; Kordower, Jeffrey H.; Stoessl, A Jon; Burke, Robert E.; Brundin, Patrik; Yue, Zhenyu; Brady, Scott T.; Milbrandt, Jeffrey; Trapp, Bruce D.; Sherer, Todd B.; Medicetty, Satish (2016-06)Recent research suggests that in Parkinson’s disease the long, thin and unmyelinated axons of dopaminergic neurons degenerate early in the disease process. We organized a workshop entitled ‘Axonal Pathology in Parkinson’s ...
Species-specific control of external superoxide levels by the coral holobiont during a natural bleaching event Diaz, Julia M.; Hansel, Colleen M.; Apprill, Amy; Brighi, Caterina; Zhang, Tong; Weber, Laura; McNally, Sean; Xun, Liping (Nature Publishing Group, 2016-12-07)The reactive oxygen species superoxide (O2·−) is both beneficial and detrimental to life. Within corals, superoxide may contribute to pathogen resistance but also bleaching, the loss of essential algal symbionts. Yet, the ...
Influence of the Icelandic Low latitude on the frequency of Greenland tip jet events : implications for Irminger Sea convection Bakalian, F.; Hameed, S.; Pickart, Robert S. (American Geophysical Union, 2007-04-26)The occurrence of Greenland tip jet events has been reported as the dominant factor controlling the formation of intermediate water in the Irminger Sea. It has been suggested that the frequency of these events is correlated ...