HR: 17:45h
AN: PP52C-08    [PDF]
TI: Influence of Multiple Sources and Processes on Continental Slope Sedimentation: New Climate Records off Martha's Vineyard (0-12 ka)
AU: * Giosan, L
EM: lgiosan@whoi.edu
AF: Woods Hole Oceanographic Institution, Department of Geology and Geophysics, Woods Hole Road, Woods Hole, MA 02543 United States
AU: Keigwin, L D
EM: lkeigwin@whoi.edu
AF: Woods Hole Oceanographic Institution, Department of Geology and Geophysics, Woods Hole Road, Woods Hole, MA 02543 United States
AU: Mollenhauer, G
EM: gmollenhauer@whoi.edu
AF: Woods Hole Oceanographic Institution, Department of Marine Chemistry and Geochemistry, Woods Hole Road, Woods Hole, MA 02543 United States
AB: Physical oceanographic conditions of the New England margin are among the most studied in the Atlantic. Deployment of a continuous profiler off Martha's Vineyard in 2001 (Station W) and planned augmentation with additional profilers, fixed moorings, and regular hydrographic cruises in 2004 will increase our knowledge of this region to an unprecedented level of detail. Paleoceanography of the region on the other hand is poorly characterized; few cores exist because the region has been considered to be strongly affected by mass sediment transport phenomena. We piggy-backed a cruise to Station W in 2002 and collected 3.5 kHz echosounder profiles and two cores at 1600 m and 3100 m water depth. Echosounder data show that contourite deposition is common on the slope to a depth of at least 4000 m and that continuous deposition of contourites is likely to extend over several glacial cycles. Preliminary results show that sedimentation rates are between 10 and 30 cm/kyr. In the deeper core, we recovered a relatively thick brick-red layer, probably corresponding to the Younger Dryas, containing ice-rafted material originating from the Permo-Carboniferous red sandstones in the St. Lawrence estuary. Alkenone-based temperature records for the two cores show similar trends, but significant differences in SST might reflect local conditions in the slope waters. Oxygen isotopic composition of the planktonic foram N. pachyderma (right) measured at a coarse resolution show several maxima and minima. Detrital sand, mostly quartz, is persistently present in cores, with higher percentages in the shallower core, suggesting that transfer from the shelf should be considered in addition to ice-rafting. Indicators of current intensity/eddy kinetic energy, such as sortable silt and silt clay ratio, along with sand content, show significant sub-orbital changes.
DE: 3022 Marine sediments--processes and transport
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting