HR: 1340h
AN: OS33B-0587    [Abstracts]
TI: Sediment Accumulation Rates of Late Quaternary Deposits in San Pedro Basin, the Gulf of Santa Catalina, and San Diego Trough, Offshore Southern California
AU: * Normark, W R
EM: wnormark@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025 United States
AU: McGann, M
EM: mmcgann@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025 United States
AU: Ray, S
EM: rsliter@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025 United States
AB: A multiyear program of seismic-reflection profiling and sediment coring has focused on understanding the history of late Quaternary sedimentation within the inner basins of the California Borderland. The objective of this study has been to develop a high-resolution seismic stratigraphy primarily for the Last Glacial Maximum and the Holocene that can be used to understand depositional processes, sediment budgets, and deformation within the basins. The Santa Barbara and Santa Monica Basins in the northern Borderland are closed basins and both were cored during the Ocean Drilling Program (ODP) in support of paleoclimatic studies. In contrast, the inner basins in the southern Borderland that are the focus of this report are open-ended basins that have not been the subject of scientific drilling. We present the preliminary results of sediment coring at 21 sites in San Pedro Basin, the Gulf of Santa Catalina, and San Diego Trough. Initial estimates of sediment-accumulation rates for these basins are based on 48 previously unpublished radiocarbon dates. During the Holocene, average sediment-accumulation rates are generally less than 0.5 m/ky on the basin floors where turbidite deposition locally continued at reduced rates from those of the OIS 2-lowstand interval. This rate is nearly an order of magnitude less than was documented for the Holocene by ODP coring at Site 1015 in Santa Monica Basin reflecting, in part, the loss of sediment in the non-closed basins. Background hemipelagic rates range from 0.01 to 0.1 m/ky, with the lowest rates on mid-basin highs, e.g., Lasuen Knoll. More dating is currently underway for some of the core sites to determine the rate of change in sediment accumulation during the Holocene.
DE: 4299 General or miscellaneous
DE: 3022 Marine sediments--processes and transport
DE: 3099 General or miscellaneous
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting