Deglacial diatom productivity and surface ocean properties over the Bermuda Rise, northeast Sargasso Sea
Gil, Isabelle M.
Keigwin, Lloyd D.
Abrantes, Fatima G.
MetadataShow full item record
Diatom assemblages document surface hydrographic changes over the Bermuda Rise. Between 19.2 and 14.5 ka, subtropical diatom species and Chaetoceros resting spores dominate the flora, as in North Atlantic productive regions today. From 16.9 to 14.6 ka, brackish and fresh water diatoms are common and their contribution is generally coupled with total diatom abundance. This same interval also contains rare grains of ice-rafted debris. Coupling between those proxies suggests that successive discharge of icebergs might have stimulated productivity during Heinrich event 1 (H1). Iceberg migration to the subtropics likely created an isolated environment involving turbulent mixing, upwelled water, and nutrient-rich meltwater, supporting diatom productivity in an otherwise oligotrophic setting. In addition, the occurrence of mode water eddies likely brought silica-rich waters of Southern Ocean origin to the euphotic zone. The persistence of lower-salinity surface water beyond the last ice rafting suggests continued injection of fresh water by cold-core rings and advection around the subtropical gyre. These results indicate that opal productivity may have biased estimates of meridional overturning based on 231Pa/230Th ratios in Bermuda Rise sediments during H1.
Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 24 (2009): PA4101, doi:10.1029/2008PA001729.
Showing items related by title, author, creator and subject.
Magnell, Bruce Arthur (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1973-06)Many hypotheses have been advanced to explain the formation of mixed layers in the ocean; the salt finger type of double-diffusive convection, in particular, has received much attention. Because of their uniquely ordered ...
Identification of organic matter sources in sulfidic late Holocene Antarctic fjord sediments from fossil rDNA sequence analysis Coolen, Marco J. L.; Volkman, John K.; Abbas, Ben; Muyzer, Gerard; Schouten, Stefan; Sinninghe Damste, Jaap S. (American Geophysical Union, 2007-05-09)The 18S ribosomal DNA (rDNA) isolated from sulfidic Holocene sediments and particulate organic matter in the water column of the stratified Small Meromictic Basin (SMB) in Ellis Fjord (eastern Antarctica) was analyzed to ...
Results of research on surface waves of the western North Atlantic. I. Investigation of bottom pressure fluctuations and surface waves. II. Results of sea surface roughness determinations in the vicinity of Woods Hole, Mass., and Bermuda Seiwell, Harry Richard (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1948-08)Part I: It is to be expected that in the future, measurements of pressure fluctuations beneath the ocean surface will provide basic data for solution of many practical problems on the state of the sea. As a result of the ...