Investigation of the subaerial Ganges-Brahmaputra-Meghna Delta stratigraphy and tectonic using high-resolution multichannel seismics
Final Report Abstract
The general task of the project was to carry out a seismic survey on the river network of Bangladesh to image the subaerial Ganges-Brahmaputra-Meghna Delta by utilizing highresolution, multichannel airgun seismic. This cruise was embedded into the international and multidisciplinary project “BanglaPIRE: Life on a tectonically active delta – convergence of Earthscience and geohazard research in Bangladesh with education and capacity building”. One major aim of the collected data was the identification of promising drill sites, which are a major part of the BanglaPIRE project. Another important goal was the identification of tectonic structures buried by the fast accumulating delta sedimentation. A cruise of three weeks duration was carried out in September 2011 using a small ship normally hosting tourists for cruises into the Sundarbans mangrove forest. Even navigation on the crowded and dynamic river network of Bangladesh was quite challenging, the collection of seismic data worked without major technical problems. During the cruise, a blog was posted on the BanglaPIRE homepage (http://www.banglapire.org/News/seismicsurvey). First results from the cruise are as follows: 1) West of the Shillong Plateau an anticlinal structure was identified, which is interpreted to be the so far unknown western extension of the Dhauki Fault. 2) Along the entire survey along the Jamuna river from the border to India to the junction with the Ganges a prominent reflector could be identified in a depth of 100 – 50 meter below the river level. This reflector is interpreted to represent the Pleistocene land surface, and its topography is probably the result of tectonic deformations. 3) Western extension of subsurface folding related to the Indo-Burman Ranges was imaged for the first time on the Meghna river. These results helped to design the following field work (especially drilling) within the BanglaPIRE project, but gave also a valuable contribution to the understanding of the regional tectonic regime. Last but not least the project showed that it is generally achievable to image the subsurface by collecting multichannel seismic data on small and shallow rivers. Prozessing and interpretation of the data is ongoing work in cooperation with partners in the BanglaPIRE project.
Publications
- (2012), Antecedent morphology and active tectonics in the upper Bengal Delta: Multi-temporal controls on river mobility and sediment preservation, Abstract EP41B-0787 presented at 2012 Fall Meeting, AGU, San Francisco, Calif., 3-7 Dec.
Pickering, J., Goodbred, S. L., Hartzog, T., Spiess, V., Schwenk, T., Palamenghi, L., Steckler, M. S., Seeber, L., Akhter, S. H., Mondal, D., Hossain, S., Petter, A. L., Paola, C.
- (2012), Late Quaternary stratigraphy of an alluvial valley along an active convergence front: Interactions of fluvial processes, tectonic channel steering, and sea level in the eastern Ganges-Brahmaputra-Meghna River delta, Abstract EP41B-0781 presented at 2012 Fall Meeting, AGU, San Francisco, Calif., 3-7 Dec.
Williams, L., Goodbred, S. L., Steckler, M. S., Seeber, L., Spiess, V., Schwenk, T., Palamenghi, L., Akhter, S H., Mondal, D., Hossain, S.
- (2012), Subsurface Deformation in the Gangetic Plain - First results from the BrahmaSeis multichannel seismic survey on Bangladesh Rivers, Abstract T51F-2663 presented at 2012 Fall Meeting, AGU, San Francisco, Calif., 3-7 Dec.
Spiess, V., Schwenk, T., Palamenghi, L., Goodbred, S. L., Steckler, M. S., Seeber, L., Petter, A. L., Akhter, S. H., Mondal, D., Khan, S. R.
