HR: 12:05h
AN: PP31D-08    [PDF]
TI: Comparative Molecular Biomarker Assessment of Phytoplankton Paleo-productivity for the last 160 kyr off Cap Blanc, N.W. Africa
AU: * Zhao, M
EM: Meixun.Zhao@Dartmouth.edu
AF: Dartmouth College, Dept. of Earth Sciences 6105 Fairchild Center, Hanover, NH 03755 United States
AU: Mercer, J
EM:
AF: Dartmouth College, Dept. of Earth Sciences 6105 Fairchild Center, Hanover, NH 03755 United States
AU: Higginson, M J
EM:
AF: University of Massachusetts at Dartmouth, Center for Marine Science and Technology, New Bedford, MA 02744 United States
AU: Eglinton, G
EM:
AF: Dartmouth College, Dept. of Earth Sciences 6105 Fairchild Center, Hanover, NH 03755 United States
AB: High-resolution molecular data for chlorins, alkenones, dinosterol, long chain diols and n-alkanes/n-alkanols, and for TOC and opal from ODP Site 658 (20$^{o}$45'N, 18$^{o}$35'W; 2,263 m water depth) are compared to evaluate paleo-productivity changes for this upwelling site over the last two glacial/interglacial cycles. The content of chlorins is used as a total phytoplankton productivity proxy, while the contents of opal, dinosterol, alkenones and diols are used as productivity proxies for diatoms, dinoflagellates, haptophyceae and eustigmatophytes, respectively. Five high total productivity intervals (HPI) are identified: two at the glacial/interglacial transition boundaries of 132-122 ka and 15-8 ka, two within the warmer periods of MIS3 (50-30 ka) and the late Holocene (4-0 ka), and only one within the glacial period of MIS 4 (67-60 ka). Productivity was the lowest during both the penultimate glacial maximum of MIS 6 (150-140 ka) and the last glacial maximum (22-18 ka), as revealed by both the total phytoplankton and individual phytoplankton productivity indicators. However, during the transitions from lower to higher productivity of the Termination II HPI, the algal productivity increases started with diatoms and eustigmatophytes, followed by dinoflagellates, and then haptophyceae. This type of sequence operating over hundreds to thousands of years is provisionally termed $<$ETH$>$chrono-eco-successionŒ. Such sequences are discussed in context of the changing amounts and nature of nutrient inputs contributed by the various regional sources, including eolian dusts, river influxes, ocean currents and upwelling water masses.
DE: 1055 Organic geochemistry
DE: 4267 Paleoceanography
DE: 4279 Upwelling and convergences
DE: 4806 Carbon cycling
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting