Reconstructing the sedimentation history of the Bengal Delta Plain by means of geochemical and stable isotopic data |
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| Institution: | 1. Institute of Mineralogy and Geochemistry, Karlsruhe Institute of Technology (KIT), D-76131 Karlsruhe, Germany;2. KTH – International Groundwater Arsenic Research Group, Royal Institute of Technology (KTH), Teknikringen 76, SE-100 44 Stockholm, Sweden;3. Institute of Biology for Engineers and Biotechnology of Waste Water Treatment, Karlsruhe Institute of Technology (KIT), Am Fasanengarten, D-76131 Karlsruhe, Germany;4. Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona, Spain;5. Department of Chemistry, University of Kalyani, Nadia 741235, West Bengal, India;1. Cz N. Assas, La géologie appliquée, 7, avenue de Toulon, 13006 Marseille, France;2. Muséum national d’histoire naturelle, département Histoire de la Terre, 8, rue Buffon, CP38, 75005 Paris cedex 05, France;3. CNRS UMR 5243 Géosciences Montpellier, Université Montpellier 2, place Eugène-Bataillon, 34095 Montpellier cedex 05, France;1. Biology Department, Memorial University of Newfoundland, St. John''s, NL, Canada A1B 3X9;2. Department of Ocean Sciences, Memorial University of Newfoundland, St. John''s, NL, Canada A1C 5S7;1. State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian 361102, China;2. Ocean Sciences Department, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA;3. Lawrence Livermore National Laboratory, Livermore, CA 94550, USA;4. Department of Earth Sciences, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada;5. CSIC, Instituto de Investigaciones Marinas (IIM), Eduardo Cabello 6, 36208 Vigo, Spain;6. Monterey Bay Aquarium Research Institute, Moss Landing, CA 95039, USA;1. School of Environment, Earth and Ecosystem Sciences, The Open University, Walton Hall, Milton Keynes, MK76AA, United Kingdom;2. National Environmental Isotope Facility, British Geological Survey, NG12 566, Nottingham, United Kingdom;3. School of Biosciences, University of Nottingham, LE12 5RD, Loughborough, United Kingdom;4. CSIR-National Institute of Oceanography, Dona Paula, 403004, Goa, India;1. University of South Alabama, Mobile, AL, USA;2. Dauphin Island Sea Lab, Dauphin Island, AL, USA;3. University of Tuebingen, Tuebingen 72074, Germany;4. University of Johannesburg, Auckland Park 2006, South Africa;5. Akita University, Tegata Gakuen machi 010-8502, Japan;6. Yale University, New Haven, CT, USA |
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| Abstract: | The purpose of this study is to examine the sedimentation history of the central floodplain area of the Bengal Delta Plain in West Bengal, India. Sediments from two boreholes were analyzed regarding lithology, geochemistry and the stable isotopic composition of embedded organic matter. Different lithofacies were distinguished that reflect frequent changes in the prevailing sedimentary depositional environment of the study area. The lowest facies comprises poorly sorted fluvial sediments composed of fine gravel to clay pointing at high transport energy and intense relocation processes. This facies is considered to belong to an early Holocene lowstand systems tract that followed the last glacial maximum. Fine to medium sands above it mark a gradual change towards a transgressive systems tract. Upwards increasing proportions of silt and the stable isotopic composition of embedded organic matter both indicate a gradual change from fluvial channel infill sediments towards more estuarine and marine influenced deposits. Youngest sediments are composed of clayey and silty overbank deposits of the Hooghly River that have formed a vast low-relief delta-floodplain. Close to the surface, small concretions of secondary Mn-oxides and Fe-(oxyhydr)oxides occur and mark the fluctuation range of the unsaturated zone. These concretions are accompanied by relatively high contents of trace elements such as Zn, Ni, Cu, and As. To sum up, the outcomes of this study provide new insights into the complex sedimentation history of the barely investigated central floodplain area of West Bengal. |
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