HR: 1340h
AN: PP13A-0601    [Abstracts]
TI: Primary Productivity Changes in the subtropical western North Atlantic During Marine Isotope Stages 11-12: Inferences from Benthic Foraminifera
AU: * Poli, M
EM: mpoli@emich.edu
AF: Eastern Michigan University, Geography and Geology Dept. 221 Strong Hall, Ypsilanti, MI 48197 United States
AU: Meyers, P A
EM: pameyers@umich.edu
AF: The University of Michigan, Department of Geological Sciences 3514 CC Little Building, Ann Arbor, MI 48109-1063 United States
AU: Thunell, R
EM: thunell@geol.sc.edu
AF: Univeristy of South Carolina, Department of Geological Sciences 700 Sumter Street, Columbia, SC 29208 United States
AB: The time interval referred to as Marine Isotope Stage 11 (MIS 11, ~423 to 362 ka) is characterized by a configuration of earth's orbit similar to that of the Holocene, and is therefore a good analog for our current interglacial. 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 contrast, during MIS 12, sea level was about 140m below present, and the production of NADW was severely reduced. We have examined benthic foraminiferal assemblages in sediments from ODP Site 1058 (Blake Outer Ridge, 3000m water depth), and Site 1063 (Bermuda Rise, 4584m water depth) spanning the MIS 11-12 time interval at a time resolution of 500 to 3000 years. At both sites the glacial-interglacial transition is accompanied by changes in faunal composition; however, bottom environmental conditions appear to have undergone the most dramatic change at Site 1058. Here, infaunal taxa indicative of organic carbon-rich sediments dominate during glacial MIS 12, and are replaced during MIS 11 by epifaunal species indicative of oligotrophic environments. The beginning of the MIS 12 and MIS 10 glaciation is characterized by large, rapid increases in the relative and absolute abundances of {\it Epistominella exigua} both at Site 1058 and Site 1063. In the modern ocean, this species inhabits seasonally deposited aggregates of phytodetritus produced during spring plankton blooms, thus suggesting an increase in surface ocean primary productivity at these times.
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
DE: 3030 Micropaleontology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting