HR: 16:45h
AN: PP52C-04    [PDF]
TI: Comparisons of Radiocarbon Ages of Alkenones With Planktonic Foraminifera and Total Organic Carbon in Oceanic Surface Sediments
AU: * Ohkouchi, N
EM: nohkuchi@jamstec.go.jp
AF: Institute for Frontier Research o n Earth Evolution, 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
AU: Mollenhauer, G
EM: gmollenhauer@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Rd., Woods Hole, MA 02543 United States
AU: Eglinton, T I
EM: teglinton@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Rd., Woods Hole, MA 02543 United States
AB: To further evaluate the fidelity of alkenones as molecular stratigraphic markers, we have measured radiocarbon ages of alkenones as well as coexisting planktonic foraminifera and total organic carbon (TOC) in the surface sediments collected from a range of depositional settings (Gulf of Mexico, Arabian Sea, Indian Ocean, NE Pacific margin, NW Atlantic margin, Bermuda Rise, south Atlantic, etc.). Radiocarbon ages of alkenones are equivalent with those of planktonic foraminifera in sediments from the Arabian Sea, and Indian Ocean. However, at the other sites investigated alkenones are significantly older than those of the corresponding planktonic foraminifera. We ascribe these age differences to sedimentary processes influencing coarse-grained foraminifera and alkenones associated with fine-grained particles. The latter are more susceptible to resuspension, advection and redeposition by oceanic currents. Alkenone ages are, on average, younger than TOC ages at the study locations. The age difference appears to be greatest in coastal sediments, which could be explained by the contribution of old terrigenous organic matter.
DE: 1030 Geochemical cycles (0330)
DE: 1055 Organic geochemistry
DE: 3022 Marine sediments--processes and transport
DE: 4203 Analytical modeling
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting