Sediment transport by tropical cyclones recorded in a submarine canyon off Bangladesh
- 230 Downloads
Frequent cyclones originating in the Bay of Bengal landfall on the delta coast of the Ganges and Brahmaputra rivers. The cyclones are well recorded in the sediments of a canyon that is deeply incised into the shelf offshore Bangladesh. The large mud supply by the two rivers forms temporary deposits on the innermost shelf, where they are mobilized by waves and currents during the passage of cyclones. The resulting, highly concentrated fine sand-silt-clay suspension is moved by wind-induced currents and eventually plunges into the shelf canyon. These gravity flows are deposited as graded beds on the broad canyon floor. In a 362-cm-long section of a dated sediment core covering the period from 2006 to 1985, nearly all 59 graded beds can be correlated with 42 cyclones observed in that period. The threefold decrease in the sedimentation rate of the last decade compared to the period from 1994 to 1954 is due to the decreased number and power of cyclones. Compared to the sediment transfer by cyclones, the input by local sediment slumps, tidal currents, and monsoonal floods is small. Thus, cyclones dominate the mobilization and distribution of sediment on the Bangladesh shelf. This sediment dispersal mechanism is probably also typical for other shelf areas crossed by tropical cyclones.
BM acknowledges the support by the German Science Foundation (DFG), the German Federal Environmental Foundation (DBU), and the German Academic Exchange Service (DAAD). IM was supported by CARIMA/BMBF. WZ is supported by the research program “Marine, Coastal and Polar Systems” (PACES II) of the Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren e.V. Grain-size analyses were performed by BM at LIAG/Hannover. U. Röhl at MARUM/Bremen did the RFA scan. 137Cs concentrations were determined by the Bundesamt für Seeschifffahrt und Hydrographie/Hamburg. A former shorter version of the manuscript benefited from the comments of P. Puig, Institut de Ciencies del Mar, Barcelona/Spain, and J. P. Walsh, East Carolina, Greenville/USA. The present manuscript greatly profited from the suggestions of B. Flemming, Senckenberg am Meer, Wilhelmshaven/Germany, and two anonymous reviewers.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Allison MA (1998) Historical changes in the Ganges-Brahmaputra Delta front. J Coast Res 14:1269–1275Google Scholar
- Bonnin J, Heussner S, Calafat A, Fabres J, Palanques A, Durrieu de Madron X, Canals M, Puig P, Avril J, Delsaut N (2008) Comparison of horizontal and downward particle fluxes across canyons of the Gulf of Lions (NW Mediterranean): meteorological and hydrodynamical forcing. Cont Shelf Res 28:1957–1970CrossRefGoogle Scholar
- French KL, Hein CJ, Haghipour N, Wacker L, Kudrass HR, Eglington TI, Galy V (2018) Millennial soil retention of terrestrial organic matter deposited in the Bengal Fan. Nature. Scientific Reports 8: 11997| DOI: https://doi.org/10.1038/s41598-018-30091-8
- Keen TR, Slingerland RL (1993) Four storm-event beds and the tropical cyclones that produced them; a numerical hindcast. J Sediment Res 63:218–232Google Scholar
- Kuehl SA, Allison M-A, Goodbred SL, Kudrass H (2005) The Ganges-Brahmaputra Delta In: Giosan L, Bhattacharya JP (Eds) River deltas–concepts, models, and examples. SEPM Spec Publ 83, pp 413–434Google Scholar
- Machalett B (2011) Past atmospheric circulation patterns and Aeolian dust dynamics recorded in Eurasian loess: utilizing high-resolution particle size analysis and amino acid geochronology. Mensch & Buch Verlag, Berlin 120 ppGoogle Scholar
- Machalett B (2017) WEBINAR: particle size characterization by laser diffraction analysis in geoscience and soil science - background, analyses, application, and interpretation. Beckman Coulter Life Sciences, Particle Size Research Letters 1Google Scholar
- Machalett B, Oches EA, Frechen M, Zöller L, Hambach U, Mavlyanova NG, Markovic SB, Endlicher W (2008) Aeolian dust dynamics in central Asia during the Pleistocene: driven by the long-term migration, seasonality, and permanency of the Asiatic polar front. Geochem Geophys Geosyst 9:Q08Q09. https://doi.org/10.1029/2007GC001938 CrossRefGoogle Scholar
- Mairs HL, Koch SP, Gordon RB, Cuellar R (1992) The storm current response of Gulf of Mexico hurricanes. In: OnePetro (Eds) Offshore technology conference, 4–7 May 1992, Houston TX, OTC 6833, pp 235–241Google Scholar
- Open University (1989) Ocean circulation, 1st edn. Pergamon Press, OxfordGoogle Scholar
- Palanques A, Puig P, Durrieu de Madron X, Sanchez-Vidal A, Pasqual C, Martín J, Calafat A, Heussner S, Canals M (2012) Sediment transport to the deep canyons and open-slope of the western Gulf of Lions during the 2006 intense cascading and open-sea convection period. Prog Oceanogr 106:1–15CrossRefGoogle Scholar
- Parsons JD, Friedrichs CT, Traykovski PA, Mohrig D, Imran J, Syvitski JPM, Parker G, Puig P, Buttles JL, García MH (2009) The mechanics of marine sediment gravity flows. In: Nittrouer CA, Austin JA, Field ME, Kravitz JH, Syvitski JPM, Wiberg PL (eds) Continental margin sedimentation: from sediment transport to sequence stratigraphy. IAS Spec Publ, vol 37, pp 275–337Google Scholar
- Ulses C, Estournel C, Puig P, Durrieu de Madron X, Marsaleix P (2008) Dense shelf water cascading in the northwestern Mediterranean during the cold winter 2005: quantification of the export through the Gulf of Lion and the Catalan margin. Geophys Res Lett 35:L07610. https://doi.org/10.1029/2008GL033257 CrossRefGoogle Scholar