HR: 09:15h
AN: PP31B-06 INVITED     [Abstracts]
TI: Holocene Paleocirculation from 231Pa/230Th in Sediments from the North Atlantic Ocean
AU: * mcmanus, j
EM: jmcmanus@whoi.edu
AF: whoi, g&g, woods hole, ma 02543 United States
AU: francois, r
EM: rfrancois@whoi.edu
AF: whoi, mc&g, woods hole, ma 02543 United States
AU: francois, r
EM: rfrancois@whoi.edu
AF: ubc, mc&g, vancouver, bc 02543 Canada
AU: major, c
EM: cmajor@whoi.edu
AF: whoi, g&g, woods hole, ma 02543 United States
AU: gherardi, j
EM: jgherardi@whoi.edu
AF: cnrs, lsce, gif-sur-yvette, 02543 France
AU: hoffman, s
EM: shoffman@whoi.edu
AF: whoi, g&g, woods hole, ma 02543 United States
AB: A new record of bulk sedimentary 231Pa/230Th excesses from core GGC5 on the Bermuda Rise has been produced by ICP-MS. The record reveals several aspects of the strength of the meridional overturning circulation during the last ten thousand years. Measurements of uranium, protactinium and thorium in the Holocene section recovered in GGC5 have been resolved at approximately 200-300 years, similar to the response time of excess 231Pa in the water column, and therefore should capture any large departure from modern values in the 231Pa/230Th indicator of paleocirculation. No dramatic increase in ratio or decrease in circulation is indicated by the data, which suggest vigorous overturning in the western basin of the North Atlantic since the end of the Younger Dryas. Instead of large changes in circulation, a series of oscillations punctuates the middle Holocene, indicating a variability of 10-20 percent in the rate of meridional overturning. Specific attention will be paid to millennial events postulated at 8.2 kyr, ~5 kyr, and in the most recent Holocene.
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting