HR: 16:15h
AN: PP52C-02 INVITED     [PDF]
TI: Radiocarbon ages of marine biomarkers and co-occurring foraminifera: evidence for differential particle transport on continental margins
AU: * Mollenhauer, G
EM: gmollenhauer@whoi.edu
AF: Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Fye Laboratory, MS#4, Woods Hole, MA 02543-1543 United States
AU: Eglinton, T I
EM: teglinton@whoi.edu
AF: Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Fye Laboratory, MS#4, Woods Hole, MA 02543-1543 United States
AU: Hayes, J M
EM: jhayes@whoi.edu
AF: National Ocean Science AMS Facility, Woods Hole Oceanographic Institution, McLean Laboratory, MS#8, Woods Hole, MA 02543-1539 United States
AU: Kienast, M
EM: mkienast@whoi.edu
AF: Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Fye Laboratory, MS#4, Woods Hole, MA 02543-1543 United States
AU: Lamy, F
EM: frankl@uni-bremen.de
AF: Fachbereich Geowissenschaften, Universitaet Bremen, Klagenfurter Str., Bremen, 28357 Germany
AU: Meggers, H
EM: meggers@uni-bremen.de
AF: Fachbereich Geowissenschaften, Universitaet Bremen, Klagenfurter Str., Bremen, 28357 Germany
AU: Schneider, R R
EM: rschneid@uni-bremen.de
AF: Fachbereich Geowissenschaften, Universitaet Bremen, Klagenfurter Str., Bremen, 28357 Germany
AB: Continental margins, with their typically high accumulation rates, are prime locations for high temporal resolution studies of past climate. One key assumption is that the sediments in these locations reflect past conditions in overlying ocean waters, and that co-occurring sediment constituents are coeval. We will present evidence based on radiocarbon dating of various sediment constituents from several continental margin sites that these assumptions are often not valid due to current-induced sorting of fine-grained and coarse-grained sediments. Marine organic biomarkers, which are often also used as proxies for past ocean conditions, can be up to several thousand years older than co-occurring foraminifera, which in turn provide age control in most paleoceanographic studies. The age offsets between the organic compounds and the coarse-grained foraminifera appear to be site-dependent and, at the same time, relatively constant over time at a given site. The offsets seem to be caused by a combination of resuspension, often caused by bottom currents, and preferential preservation of protected and refractory compounds. This observation has important implications for our understanding of sedimentary records, the paleoclimatic signals preserved in them, and organic carbon burial.
DE: 1055 Organic geochemistry
DE: 3022 Marine sediments--processes and transport
DE: 4267 Paleoceanography
DE: 4806 Carbon cycling
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting