HR: 0800h
AN: H41F-0837    [Abstracts]
TI: A Terminating Channel-Levee System on the Middle Bengal Fan
AU: Bartels, T
EM: bartelst@uni-bremen.de
AF: University of Bremen, Klagenfurter Str, Bremen, 28205, Germany
AU: * Schwenk, T
EM: tschwenk@uni-bremen.de
AF: University of Bremen, Klagenfurter Str, Bremen, 28205, Germany
AU: Keil, H
EM: hanno.keil@uni-bremen.de
AF: University of Bremen, Klagenfurter Str, Bremen, 28205, Germany
AU: Spiess, V
EM: vspiess@uni-bremen.de
AF: University of Bremen, Klagenfurter Str, Bremen, 28205, Germany
AB: The Bay of Bengal is fully covered by the Bengal Fan, the largest submarine fan on Earth. This fan is fed by the Ganges-Brahmaputra river system, which dewaters the Himalaya and transports huge amounts of sediment to the Bengal Basin and Bengal Shelf. From there, the sediments are transported to the deep sea fan by turbidity currents starting in a deeply incised shelf canyon. These turbidity currents build up channel-levee systems being the main architectural features on the Bengal Fan. Therefore the Bengal Fan is ideal to study not only the erosional and climatic history of the Himalayas, but also the structure of channel-levee systems to understand depositional processes on submarine fans in detail. During Cruise SO188-1, carried out in June 2006 with the German Research Vessel Sonne, a terminating channel-levee system on the middle Bengal Fan was studied by collecting multichannel seismic data, Parasound sediment echosounder data and bathymetric data. The aim of the study was to image the changing morphology and architecture of a terminating system and to test the hypothesis if a depositional lobe has developed here. The bathymetric data show that the channel terminates by bifurcating into short distributaries. However, another small channel appears south-east of the bifurcation, and a further small channel is identified to the east. Additionally, the seismic and acoustic data reveal several small completely refilled channels in the study area, which are only partially leveed. These observations indicates that the pattern of the channel-levee systems is here even more complicated than expected and that a succession of erosion and refilling has controlled the deposition. By tracking the channel to the north until its next avulsion point, the channel could be mapped by using the swath sounding system over a distance of 300 nm. This (to our knowledge) unique dataset of a surface channel on the Bengal Fan reveals significant changes of shape and relief of the channel and large variations in terms of sinuosity. Future work should parameterize these variations to try to reconstruct the properties of the turbidity currents which have built this channel-levee system.
DE: 3022 Marine sediments: processes and transport
DE: 3025 Marine seismics (0935, 7294)
DE: 3045 Seafloor morphology, geology, and geophysics
SC: Hydrology [H]
MN: 2007 Fall Meeting