HR: 0830h
AN: PP51C-0937    [PDF]
TI: Quantification of the Changing Sedimentary Architecture of a Continental Margin Sediment Drift as a Result of the Mid Pleistocene Climate Transition (ODP Leg 194)
AU: * Obrochta, S P
EM: obrochta@marine.usf.edu
AF: University of South Florida, 140 7th Ave S, St. Petersburg, FL 33701 United States
AU: Hine, A
EM: hine@marine.usf.edu
AF: University of South Florida, 140 7th Ave S, St. Petersburg, FL 33701 United States
AU: Flower, B
EM: flower@marine.usf.edu
AF: University of South Florida, 140 7th Ave S, St. Petersburg, FL 33701 United States
AU: Hallock, P
EM: pmuller@marine.usf.edu
AF: University of South Florida, 140 7th Ave S, St. Petersburg, FL 33701 United States
AU: Brooks, G
AF: Eckerd College, 4600 54th Ave S, St. Petersbrug, FL 33711 United States
AB: The Marion Plateau (NE Australia margin) possibly provides an ideal setting to study continental margin paleoceanographic history. It is not significantly current scoured and is located at upper continental slope depths, freeing it from the influence of large sediment gravity flows. Atop the plateau, a hemipelagic sediment drift is perched and was drilled on Ocean Drilling Program Leg 194 (Site 1198). The lithologic record and other shipboard-acquired data sets (physical properties, downhole logging), as well as the site-survey seismic data all suggest that cyclicity dominates this sedimentary section, which encompasses the Mid Pleistocene Climate Transition (MPCT). The MPCT contains the transition from a 41 k.y. cycle (ice volume and temperature) to 100 k.y. cycle dominated world. An identical suite of quantitative analyses was conducted on two Pleistocene intervals of Hole 1198A. One interval was deposited prior to the MPCT, while the other was deposited subsequently. Variations in mass accumulation rates (MARs) of each component do not clearly correspond to oxygen isotope excursions, suggesting that processes other than eustatic sea level fluctuations affect sedimentation in this complex environment. Nonetheless, several relationships have been identified. In the 100 k.y. world, terrigenous MARs are highest during sea level trangression, while aragonite, high Mg calcite, and low Mg calcite MARs are highest during sea level highstand. Preliminary results suggest that the highest carbonate MARs occurred during sea level regression or low stand in the 41 k.y. world. Additionally, examination of shipboard color reflectance data indicates suborbital lithologic variability is present and increases during glacial episodes.
DE: 3030 Micropaleontology
DE: 3954 X ray, neutron, and electron spectroscopy and diffraction
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting