HR: 0830h
AN: PP51B-0922    [PDF]
TI: Northwestern Subarctic Pacific Paleoproductivity Fluctuations : a Strong Link With Climate Variability During the Early-Mid-Neogene.
AU: * Jaccard, S L
EM: jaccard@erdw.ethz.ch
AF: ETH Zurich, Sonneggstr. 5, Zurich, CH-8092 Switzerland
AU: Haug, G H
EM: haug@gfz-potsdam.de
AF: GFZ Potsdam, Telegrafenberg, Potsdam, 14473 Germany
AU: Sigman, D M
EM: sigman@princeton.edu
AF: Princeton University, Guyot Hall M52, Princeton, NJ 08544 United States
AU: Pedersen, T F
EM: tfp@uvic.ca
AF: University of Victoria, School of Earth and Ocean Sciences. Petch Building 168 3800 Finnerty Road, Victoria, BC V8P 5C2 Canada
AB: Deep-sea records of biogenic opal accumulation and bulk sediment as well as diatom-bound $^{15}$N/$^{14}$N indicate that the subarctic North Pacific underwent drastic productivity fluctuations closely related to major climatic transitions in the late Cenozoic. In the northwestern Subarctic Pacific (ODP sites 882/883) warm intervals are characterized by massive biogenic opal deposition and relatively low nitrate utilization. On the other hand, cold periods show reduced opal export production together with more complete nitrate consumption. Once high-opal, nutrient-rich environments developed in the mid-Cenozoic, there is evidence that the greatest polar overturning actually occurred during somewhat warmer intervals in the late Oligocene, and during the Middle Miocene climatic optimum. In these intervals, higher opal content and lower sedimentary $\delta^{15}$N seem to indicate a correlation between warm climate and enhanced surface-water nutrient concentrations. The correlation between global temperature and biogenic opal accumulation is also documented across the abrupt 2.7 Myr transition from Pliocene warmth towards widespread Northern Hemisphere Glaciation, as well as across subsequent glacial/interglacial transitions. This consistent pattern over different time scales suggests that climate has been affected by the tendency for polar overturning during warm intervals and polar stratification during cold periods. Reduced stratification would have represented a leak in the biological pump, releasing deep-sequestered carbon dioxide back into the atmosphere.
DE: 0330 Geochemical cycles
DE: 4207 Arctic and Antarctic oceanography
DE: 4267 Paleoceanography
DE: 4845 Nutrients and nutrient cycling
DE: 4870 Stable isotopes
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting