HR: 1340h
AN: S23A-1117    [Abstracts]
TI: Holocene Transgression on the Bengal Shelf and Built up of the Submarine Ganges-Brahmaputra-Meghna Prodelta
AU: * Palamenghi, L
EM: lupala@uni-bremen.de
AF: University of Bremen, Klagenfurter Str., Bremen, 28359, Germany
AU: Bergmann, K
EM: katrin.bergmann@bgr.de
AF: BGR, Stilleweg 2, Hannover, 30655, Germany
AU: Schwenk, T
EM: tschwenk@uni-bremen.de
AF: University of Bremen, Klagenfurter Str., Bremen, 28359, Germany
AU: Reinhard, L
EM: lutz.reinhard@bgr.de
AF: BGR, Stilleweg 2, Hannover, 30655, Germany
AU: Spiess, V
EM: vspiess@uni-bremen.de
AF: University of Bremen, Klagenfurter Str., Bremen, 28359, Germany
AU: Kudrass, H
EM: kudrass@bgr.de
AF: BGR, Stilleweg 2, Hannover, 30655, Germany
AB: The Ganges-Brahmaputra-Meghna Delta is characterized by a low lying and strongly subsiding coastal zone and is therefore very sensitive to sea level variations affecting drainage capacity by enhancing flooding potential during monsoon as well as impact of storm surges on the coast during pre- and post-monsoon. Mean Sea Level changes could additionally alter the balance between the huge sedimentary input delivered by the rivers to the Bengal Shelf and the high subsidence rate due to plate subduction. Predictability of these issues will be studied in an appropriate time scale to detect interaction of coastal development and sea level changes. During the SO-188-2 Expedition to the Bengal Shelf in July 2006 in cooperation between Bremen University and the BGR, Hannover, a detailed seismostratigraphic data set of the sedimentary deposits was acquired and acoustic facies associated with the Holocene sea level variations were determined. The continental shelf offshore the G-B-M Delta have been investigated with high-resolution multichannel seismic, Parasound and bathymetric surveys, ground truthed with a vibrocoring system to analyze the sedimentation and transport processes. The Holocene Transgression could be reconstructed by identification of seismic units, discontinuities and erosive surfaces preserved in the almost unaltered composite sequences. Data suggest that the sea level rise flooded the low-stand deltaic plain from west to east where a wide estuary system developed; relict Ganges delta's distributaries channels are filled with distal sediments rather than eroded. Since the onset of the modern high-stand delta and the formation of the topset-foreset-bottomset submarine system, the prodelta front has been actively prograding. The internal structure of the clinoforms reveals shelf wide episodes of mass depositions identified by transparent units in the Parasound data and internal unconformities in the seismic data. Volumes, distribution and frequency of these units, which might represent a main sediment transport modality of the prodelta system, will be presented together with sedimentological parameters.
DE: 1641 Sea level change (1222, 1225, 4556)
DE: 3002 Continental shelf and slope processes (4219)
DE: 3022 Marine sediments: processes and transport
DE: 3025 Marine seismics (0935, 7294)
SC: Seismology [S]
MN: 2007 Fall Meeting