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      https://www.ias.ac.in/article/fulltext/jess/122/04/1141-1152

    • Keywords

       

      Ganga Plain; monsoonal rainfall; isotopic ratio; C3–C4 plants; late Quaternary; soil carbonate.

    • Abstract

       

      Present study aims at reconstructing the paleomonsoonal rainfall, paleovegetation and provenance change during the late Quaternary. Towards this, Bhognipur core, collected from the southern Ganga Plain, have been sampled for soil carbonate (SC) and soil. The 𝛿18O values of SC (𝛿18OSC) range from −7.6 to −4.9‰. The variations in 𝛿18OSC values suggest that during the late Quaternary, the monsoon intensified during MIS 3 and MIS 1 and the maximum lowering of rainfall intensity is observed during MIS 2. The 𝛿13C value of SC (𝛿13CSC), organic matter dispersed in the soil (𝛿13CSOM) and occluded in the carbonate nodules (𝛿13CNOM) ranges from −4.1 to +1.4‰, −25.6 to −16.3‰, and −27.7 to −25.0‰, respectively, implies mixed C3$–$C4 vegetation over the Ganga Plain. Variations in 𝛿13CSOM and 𝛿13CNOM values at same depth imply preservation problem of pristine organic matter signature. Therefore, it is important to assess the preservation of residual organic matter before using it for paleovegetational reconstruction. The monsoon-vegetation relationship indicates that relative abundances of C3$–$C4 vegetation were mainly driven by variations in monsoonal rainfall intensity. Using 87Sr/86Sr in SC, we show that the Himalayan river was supplying sediments in the southern part of the Ganga Plain during MIS 3.

    • Author Affiliations

       

      Shailesh Agrawal1 2 Prasanta Sanyal3 Melinda K Bera3 Jitendra K Dash4 Srinivasan Balakrishnan4

      1. Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur 721 302, India.
      2. Wadia Institute of Himalayan Geology, Dehradun 248 001, India.
      3. Department of Earth Sciences, Indian Institute of Science Education and Research, Kolkata, Nadia 741 252, India.
      4. Department of Earth Sciences, Pondicherry University, Pondicherry 605 014, India.
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  • Journal of Earth System Science | News

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