Post Reply 
 
Thread Rating:
  • 88 Votes - 2.84 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Holocene fluctuations in Arctic sea-ice cover: dinocyst-based reconstructions for the
09-23-2010, 08:14 AM
Post: #1
Holocene fluctuations in Arctic sea-ice cover: dinocyst-based reconstructions for the
H/T The Hockey Schtick

Canadian Journal of Earth Sciences, 45: 1377-1397

Authors: J.L. McKay, A. de Vernal, C. Hillaire-Marcel, C. Not, L. Polyak, and D. Darby

Abstract: Cores from site HLY0501-05 on the Alaskan margin in the eastern Chukchi Sea were analyzed for their geochemical (organic carbon, d13Corg, Corg/N, and CaCO3) and palynological (dinocyst, pollen, and spores) content to document oceanographic changes during the Holocene. The chronology of the cores was established from 210Pb dating of near- surface sediments and 14C dating of bivalve shells. The sediments span the last 9000 years, possibly more, but with a gap between the base of the trigger core and top of the piston core. Sedimentation rates are very high (*156 cm/ka), allowing analyses with a decadal to centennial resolution. The data suggest a shift from a dominantly terrigenous to marine input from the early to late Holocene. Dinocyst assemblages are characterized by relatively high concentrations (600–7200 cysts/cm3) and high species diversity, allowing the use of the modern analogue technique for the reconstruction of sea-ice cover, summer temperature, and salinity. Results indicate a decrease in sea-ice cover and a corresponding, albeit much smaller, increase in summer sea-surface temperature over the past 9000 years. Superimposed on these long-term trends are millennial-scale fluctuations characterized by periods of low sea-ice and high sea-surface temperature and salinity that appear quasi-cyclic with a frequency of about one every 2500–3000 years. The results of this study clearly show that sea-ice cover in the western Arctic Ocean has varied throughout the Holocene. More importantly, there have been times when sea-ice cover was less extensive than at the end of the 20th century.

THE PDF LINK TO THE PAPER

It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
Visit this user's website Find all posts by this user Give Reputation to this user
Quote this message in a reply
Post Reply 




User(s) browsing this thread: 1 Guest(s)