HR: 09:15h
AN: OS51A-06    [PDF]
TI: Emplacement and Modification of the Autumn 2000 Po River Flood Deposit
AU: * Wheatcroft, R A
EM: raw@coas.oregonstate.edu
AF: Oregon State University, College of Oceanic and Atmospheric Sciences, Corvallis, OR 97331 United States
AU: Lewis, R
EM: rlewis@coas.oregonstate.edu
AF: Oregon State University, College of Oceanic and Atmospheric Sciences, Corvallis, OR 97331 United States
AU: Hunt, L
EM: lhunt@coas.oregonstate.edu
AF: Oregon State University, College of Oceanic and Atmospheric Sciences, Corvallis, OR 97331 United States
AU: Stevens, A
EM: astevens@coas.oregonstate.edu
AF: Oregon State University, College of Oceanic and Atmospheric Sciences, Corvallis, OR 97331 United States
AB: During October - November 2000, flooding by the Po River (northern Italy) created a flood deposit on the adjacent prodelta (10 to 30-m water depth) of the Adriatic Sea. An event-response cruise in December 2000 and six additional cruises during the ensuing 30 months have yielded a rich data set pertaining to the initial distribution and properties of the flood bed and its subsequent physical and biological modification. In contrast to previously documented flood deposits (e.g., Eel River, northern California) the deposit was located immediately adjacent to the river's mouths, exhibited clear proximal-distal indicators and had sharp thickness gradients. In addition, wide variation in bed thickness (up to 40 cm) and a diversity of physical sedimentary structures suggest that multiple emplacement processes (e.g., gravity-driven transport, and suspension fall-out) may have operated during the creation of the flood deposit. The flood deposit is evolving in a variety of ways. First, a rich subsurface stratigraphy with unique marker beds has permitted quantitative estimates of erosion and deposition. On most portions of the margin, there is little evidence of net erosion, but much evidence of physical reworking. Bed consolidation is also being quantified using digital x-radiographs and compared to results from a micro-resistivity profiler. Lastly, bioturbation structures have increased in abundance and depth within the deposit, such that in some areas of the margin the flood deposit, despite being many centimeters thick, is almost completely obliterated.
DE: 3020 Littoral processes
DE: 3022 Marine sediments--processes and transport
DE: 4219 Continental shelf processes
DE: 4804 Benthic processes/benthos
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting