HR: 0800h
AN: PP11B-0560    [Abstracts]
TI: Events at the Paleocene-Eocene Boundary as Recorded in Shelf Sediments From the Californian Margin
AU: * John, C M
EM: cjohn@es.ucsc.edu
AF: Department of Earth Sciences, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AU: Bohati, S
EM: sbohaty@es.ucsc.edu
AF: Department of Earth Sciences, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AU: Zachos, J C
EM: jzachos@es.ucsc.edu
AF: Department of Earth Sciences, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AU: Brinkhuis, H
EM: H.Brinkhuis@bio.uu.nl
AF: Laboratory of Palaeobotany and Palynology, Department of Palaeoecology, Utrecht University, Budapestlaan 4, Utrecht, CD 3584 Netherlands
AU: Sluijs, A
EM: A.Sluijs@bio.uu.nl
AF: Laboratory of Palaeobotany and Palynology, Department of Palaeoecology, Utrecht University, Budapestlaan 4, Utrecht, CD 3584 Netherlands
AU: Gibbs, S
EM: sgibbs@geosc.psu.edu
AF: Department of Geosciences, Pennsylvania State University, Deike Building, University Park, PA 16802 United States
AU: Bralower, T
EM: bralower@geosc.psu.edu
AF: Department of Geosciences, Pennsylvania State University, Deike Building, University Park, PA 16802 United States
AU: McDougall-Reid, K
EM: kris@usgs.gov
AF: Flagstaff Science Center, U. S. Geological Survey, 2255 N. Gemini Dr., Flagstaff, AZ 86001 United States
AB: The Paleocene-Eocene Thermal Maximum (PETM) is characterized by rapid global warming, as much as 8 degrees C, and a transient 3 per mil negative excursion in carbon isotopes (CIE) that has been observed in marine and terrestrial records worldwide. The magnitude of the CIE is best explained by the rapid transfer of a large mass of methane from gas hydrate reservoirs to the atmosphere. The rise in temperature associated with the addition of this greenhouse gas appears to have also altered global humidity and precipitation patterns, a feature which is best expressed in near shore depositional facies. While extensively studied in deep-sea sediments, the PETM has been comparatively less investigated in near-shore, shallow-marine records. This is particularly true for the Californian margin, where complications linked to syn-sedimentary and post depositional tectonic have so far limited paleoceanographic works on Paleocene-Eocene sedimentary records. Continental shelves are, however, a potentially important archive of the PETM event as they are proximal to rivers and are the principal sink for terrigenous sediments. The coastal marine ecosystems are also particularly sensitive to changes in local salinity and nutrient fluxes brought about by changing runoff. Here, we present data from several marine sections (claystones and siltstones) now exposed in the mountains of central and southern California and comprised of sediments deposited across the Paleocene-Eocene boundary. Sedimentation at these locations resulted from the interplay between tectonic, paleoceanographic, and climatic processes. The main objective of our study is to explore the relative timing between the CIE, possible changes in continental weathering, productivity and paleoceanography, and changes in regional climate (such as increased or decreased precipitation). The results obtained thus far indicate that 1) the CIE is recorded on the Western North American shelf, though its onset is truncated due to complex regional eustatic tectono-sedimentary patterns, 2) the magnitude of the isotopic excursion is similar to that in the deep-sea, 3) the excursion interval is expanded due to higher sedimentation rates, and 4) kaolinite to smectite ratios indicate a more complex relationship between continental weathering and climate than has been recorded on the U.S. East coast or on the southern margin of the Tethys.
DE: 4806 Carbon cycling
DE: 4267 Paleoceanography
DE: 3022 Marine sediments--processes and transport
DE: 1040 Isotopic composition/chemistry
DE: 1050 Marine geochemistry (4835, 4850)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting