HR: 0800h
AN: PP11B-1472    [Abstracts]
TI: Changes in Nutrient Burial, Export Production, and the Sulfur Isotopic Composition of Seawater During the Paleocene Eocene Thermal Maximum
AU: * Faul, K
EM: kfaul@mills.edu
AF: Environmental Sciences, Mills College, 5000 MacArthur Blvd., Oakland, CA 94613 United States
AU: Sayo, J
EM: jsayo@mills.edu
AF: Environmental Sciences, Mills College, 5000 MacArthur Blvd., Oakland, CA 94613 United States
AU: Paytan, A
EM: apaytan@pangea.stanford.edu
AF: Geological and Environmental Sciences, Stanford University, Braun Hall, Stanford, CA 94305 United States
AU: Gray, E
EM: egray@stanford.edu
AF: Geological and Environmental Sciences, Stanford University, Braun Hall, Stanford, CA 94305 United States
AB: We are comparing nutrient burial, using phosphorus (P, micromol P cm^-2 kyr^-1) mass accumulation rates (MARs), to export productivity, using barite (BaSO4, micromol BaSO₄ cm^-2 kyr^-1) MARs, across the Paleocene Eocene Thermal Maximum (PETM) in sediments from the eastern equatorial Pacific (ODP Leg 199 Sites 1221 and 1215), the western equatorial Pacific (ODP Leg 198, Site 1210), and the western equatorial Atlantic (ODP Leg 171B, Site 1051). Reactive phosphorus (the sum of oxide associated, authigenic, and organic P; sequentially extracted from bulk sediment) is used to distinguish the signal of bio-reactive P from detrital P. Barite, correlated with export productivity in the modern ocean, is separated from bulk sediment. The ratio of nutrient burial (phosphorus) to export productivity (barite) may provide an indication of relative organic C burial. Organic C must be efficiently sequestered in the sediments for the proposed PETM global warmth termination by productivity feedback to be effective. We are comparing relative organic C burial rates for sites in both the equatorial Pacific and the equatorial Atlantic. Initial results from ODP Site 1221 in the Pacific indicate that the nutrient burial to export productivity ratio is high before and immediately after the PETM, possibly indicating enhanced relative organic C burial. To better understand the possible relationship of the seawater sulfur isotopic minimum at the time of the PETM to productivity changes, we are measuring S isotopes in marine barite at high resolution. Seawater S isotopic values in marine barite from the PETM section for ODP Leg 199 Site 1221 yield values of ~17 per mil, reflecting the global marine sulfur isotopic value. These preliminary values indicate that minimum sulfur isotopic values occurred before the C isotopic excursion associated with the PETM, and are probably unrelated to short-term productivity and/or relative organic C burial changes occurring during the PETM.
DE: 0488 Sulfur cycling
DE: 4806 Carbon cycling (0428)
DE: 4845 Nutrients and nutrient cycling (0470, 1050)
DE: 4924 Geochemical tracers
DE: 4948 Paleocene/Eocene thermal maximum
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005