Holocene stratigraphy of the lower Ganges-Brahmaputra river delta in Bangladesh

Research Article

Abstract

Major part of the Holocene Ganges-Brahmaputra delta occupies the southern and southwestern part of Bangladesh with a smaller part extending beyond the international boundary in the west. Five facies assemblages are documented in the lower deltaic plain in five different depositional environments: levee or levee complex, bil or depression, abandoned meander belt, interdistributary plain and estuarine plain. The thickness of the Holocene sediments ranges from 30 m to 70 m in the deltaic plain, usually floored by the Pleistocene stiff clays, with the exception of the abandoned meander belt deposit where Holocene channel sand deposited directly on the Pleistocene sand. Radiocarbon dates indicate that low-rate sedimentation has occurred in the northern part, where 4-6 m thick sediments were deposited since the mid-Holocene, whereas 10-30 mthick sediments were deposited in the southern part during the same span of time. In addition, significant coastal subsidence (3 mm/a on average), added by sea-level rise (1.5 mm/a, conservative rate) occurs in the study area, which serves as a negative factor in degrading the coastal plain of Bangladesh in the future, while taking into consideration the weaker sedimentation in the area.

Keywords

levee bil/depression abandoned meander belt interdistributary plain estuarine plain Holocene sediment thickness 

References

  1. Alam M, Alam M M, Curray J R, et al (2003). An overview of the sedimentary geology of the Bengal Basin in relation to the regional tectonic framework and basin-fill history. Sedimentary Geology, 155(3–4): 179–209CrossRefGoogle Scholar
  2. Banerjee M, Sen P K (1987). Paleobiology in understanding the change of sea level and coast line in Bengal Basin during Holocene period. Indian Journal of Earth Sciences, 14: 307–320Google Scholar
  3. Banerjee M, Sen P K (1988). Paleobiology and environment of deposition of Holocene sediments of the Bengal basin, India. The Palaeoenvironment of East Asia from the mid-Tertiary, Proceedings of the 2nd Conference. Hong Kong: Centre of Asian Studies, University of Hong Kong, 703–731Google Scholar
  4. Blanchon P, Shaw J (1995). Reef drowning during the last deglaciation: Evidence for catastrophic sea-level rise and ice-sheet collapse. Geology, 23: 4–8CrossRefGoogle Scholar
  5. Curray JR, Emmel F J, Moore D G, et al (1982). Structure, tectonics and geological history of the northestern Indian Ocean. In: Naim A E M, Stehli F G, eds. The Ocean Basins and Margins. The Indian Ocean, vol 6. New York: Plenum, 399–450Google Scholar
  6. Fairbanks R G (1989). A 17 000-year glacio-eustatic sea level record: influence of glacial melting rates on the Younger Dryas event and deep-ocean circulation. Nature, 342: 637–642CrossRefGoogle Scholar
  7. Goodbred S L, Kuehl S A (1999). Holocene and modern sediment budgets for the Ganges-Brahmaputra river system: Evidence for highstand dispersal to floodplain, shelf, and deep-sea depocenters. Geology, 27(6): 559–562CrossRefGoogle Scholar
  8. Goodbred S L, Kuehl S A (2000). Late Quaternary evolution of the Ganges-Brahmaputra River delta: Significance of high sediment discharge and tectonic processes on margin sequence development. Sedimentary Geology, 133: 227–248CrossRefGoogle Scholar
  9. Khan S R, Kudrass H R (1999). Holocene sedimentation of the lower Ganges-Brahmaputra river delta, Bangladesh. SONNE-SO126 cruise Final Report, Federal Institute for Geosciences and Natural Resources, Stilleweg 2, 30655, Hanover, GermanyGoogle Scholar
  10. Milliman J D, Syvitski J P M (1992). Geomorphic/tectonic control of sediment discharge to the ocean: The Importance of small mountainous rivers. Journal of Geology, 100: 525–544CrossRefGoogle Scholar
  11. Umitsu M (1987). Late Quaternary sedimentary environment and landform evolution in the Bengal lowland. Geographical Review of Japan, 60: 164–178Google Scholar
  12. Umitsu M (1993). Late Quaternary sedimentary environments and landforms in the Ganges delta. Sedimentary Geology, 83: 177–186CrossRefGoogle Scholar
  13. Weber M E, Wiedicke M H, Kudrass H R, et al (1997). Active growth of the Bengal fan during sea-level rise and highstand. Geology, 25: 315–318CrossRefGoogle Scholar

Copyright information

© Higher Education Press and Springer-Verlag GmbH 2008

Authors and Affiliations

  1. 1.Geological Survey of Bangladesh 153 Pioneer RoadSegunbagichaDhakaBangladesh
  2. 2.Department of Geology and MiningUniversity of BangladeshRajshahiBangladesh

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