HR: 0800h
AN: PP11B-0562    [Abstracts]
TI: Tracers of Productivity across the PETM, Walvis Ridge, ODP Sites 1262 and 1263
AU: Quartini, J C
EM: joequartini@hotmail.com
AF: Earth Sciences, Univeristy of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AU: * Chun, C O
EM: cchun@ucsc.edu
AF: Ocean Sciences/Institute of Marine Sciences, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AU: Delaney, M L
EM: delaney@ucsc.edu
AF: Ocean Sciences/Institute of Marine Sciences, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AU: Zachos, J C
EM: jzachos@earthsci.ucsc.edu
AF: Earth Sciences, Univeristy of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AB: The rapid and extreme global warming across the Paleocene-Eocene Thermal Maximum (PETM) is unmatched in Earth's history. We are using sedimentary phosphorus concentrations and geochemistry, along with barium and trace metals, to reconstruct nutrient burial, primary productivity, and paleoredox state across a depth transect for Walvis Ridge. We have chosen Ocean Drilling Program (ODP) Sites 1262 (4755 m water depth) and 1263 (2717 m water depth) at a sample resolution of $\sim$ 1-2 kyr for 5 Ma centered at 55 Ma. We are characterizing the nutrient burial history during the PETM by recording the associated short-term changes in ocean chemistry and circulation. We have measured Ba excess, a good indicator of export productivity in marine sediments underlying oxic conditions, for Site 1262 samples. Ba excess concentrations range between $\sim$ 2-5 umol Ba/g prior to the warming event and decrease to zero at the boundary (140.04 mcd). Ba excess gradually recovers but does not greatly exceed pre-event concentrations ($\sim$ 2-5 umol Ba/g). Uranium and manganese enrichment factors (EF) were determined during this event for Site 1262. U ranges from 0.9 -1.1 relative to crustal averages pre-event, 0.7- 0.8 during the event, and 0.9 -1.1 after the rapid warming. Uranium data shows consistent recovery with calcium carbonate deposition over a depth range $\sim$ 0.5m. Mn EF values range between 3.7 -8.6 prior to the event, suggesting an oxygenated depositional environment. At the boundary, Mn EF values drop to 1.3, then gradually return to pre-event values with a peak at 139.76 mcd of 13.2. We will compare our geochemical results with Site 1263 data.
DE: 4267 Paleoceanography
DE: 1050 Marine geochemistry (4835, 4850)
DE: 1615 Biogeochemical processes (4805)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting