HR: 0830h
AN: PP51C-0941    [PDF]
TI: Changes in Benthic Foraminiferal Assemblages and Total Organic Carbon in Sediments at ODP Site 1058, Blake Outer Ridge During Marine Isotope Stages 11-12
AU: * Poli, M
EM: mpoli@emich.edu
AF: Eastern Michigan University, 205 Strong Hall, Ypsilanti, MI 48197
AU: Orscheln, N
EM: nell_orscheln@yahoo.com
AF: Oregon State University, 104 Ocean Administration Building, Corvallis, OR 97331-5503
AU: Thunell, R
EM: Thunell@geol.sc.edu
AF: University of South Carolina, 700 Sumter Street, Columbia, SC 29208
AU: Meyers, P
EM: pameyers@umich.edu
AF: The University of Michigan, 3514 CC Little Building, Ann Arbor, MI 48109-1063
AU: Arnaboldi, M
EM: marna@umich.edu
AF: The University of Michigan, 3514 CC Little Building, Ann Arbor, MI 48109-1063
AB: Marine isotope stages 11-12 (approximately 480 to 362 ka) comprise the most extreme climatic and hydrologic changes of the Late Pleistocene. During MIS 12, sea level was about 140m below present, and the production of NADW was severely reduced. In contrast, MIS 11 was probably the warmest and longest interglacial of the last 500 kyrs, characterized by sea level possibly 20m higher than today and a maximum in NADW production. In the western North Atlantic, the switch from one mode of circulation to the other appears to have been paralleled by a 3-4§C change in bottom-water temperatures. We have examined benthic foraminiferal assemblages and organic carbon content in sediments from ODP Site 1058 (Blake Outer Ridge, 3000m water depth), spanning the MIS 11-12 time interval. Stable isotope data indicate that during MIS 11 Site 1058 was bathed by NADW, and by a water mass of southern origin during MIS 12. The organic carbon record is characterized by elevated values in the early part of MIS 11 and at the end of MIS 11. Benthic foraminiferal assemblages in these intervals show increased abundances of Bulimina, Uvigerina and Melonis, taxa usually indicative of stressed environments. The overall benthic foraminiferal record shows changes in relative abundances of the different taxa that are not related simply to glacial-interglacial changes. Instead, a more complex variability is evident, driven most probably by the interplay of different environmental factors, including changes in current strength and food supply, downslope transport, and lateral advection of material reworked from shallower areas.
DE: 3030 Micropaleontology
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting