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    • Keywords


      Bay of Bengal; sediment core; calcium carbonate; dilution; detrital; biogenic; turbidite; Ganges–Brahmaputra.

    • Abstract


      Down-core variations of granulometric, geochemical and mineral magnetism of a 70-cm long sediment core retrieved from the eastern Bay of Bengal abyssal region were studied to understand sedimentation pattern and sediment provenance during the last ∼12 kyr BP. Based on down-core physical and elemental variations, three units were identified: unit 3 (70–43 cm) is a ∼30 cm thick clayey silt organic carbon-rich (0.5–0.92%) turbidite probably delivered by the Brahmaputra River during the late Quaternary period. Units 2 (43–24 cm) and 1 (24–0 cm) represent enhanced and reduced supply of coarse-grained detrital sediments from the Ganges River during early and late Holocene period, respectively. Increased terrigenous supply dilutes calcium carbonate (CaCO3) and biogenic elements (P, Ba and Cu) in units 3 and 2. On the contrary, a reduction in detrital input enhances CaCO3 and biogenic elements in unit 1. Lithogenic elements (Ti, Al, K and Rb) and shale-normalized REE patterns in all three units suggest terrigenous source. The shift in provenance from the Brahmaputra to the Ganges derived sediments is evident by a sharp increase in sediment grain size, increased concentration and grain size assemblages of magnetic minerals, lithogenic elements concentration and $La_{n}/Yb_{n}$ ratio. This study highlights terrigenous dilution on biogenic sedimentation in the eastern Bay of Bengal sediments.

    • Author Affiliations


      C Prakash Babu1 J N Pattan1 K Dutta2 N Basavaiah3 G V Ravi Prasad2 D K Ray2 P Govil4

      1. National Institute of Oceanography (CSIR), Dona Paula 403 004, Goa, India.
      2. AMS Radiocarbon Laboratory, Institute of Physics, Bhubaneswar 751 005, Orissa, India.
      3. Indian Institute of Geomagnetism, Kalamboli, New Panvel, Navi Mumbai 410 218, India.
      4. National Centre for Antarctic and Ocean Research, Headland Sada, Vasco 403 804, Goa, India.
    • Dates

  • Journal of Earth System Science | News

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      Posted on July 25, 2019

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