EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Indian subcontinent hydroclimate and vegetation changes during the last glacial reconstructed by leaf wax stable isotope and pollen analyses on sediments from IODP Site U1446, NW Bay of Bengal

Stefan Lauterbach1,2, Nils Andersen1, Charlotte Clément3,4, Stéphanie Desprat3,4, Coralie Zorzi3,4, Krishnamurthy Anupama5, Srinivasan Prasad5, Dulce Oliveira6,7, Thomas Blanz2, Kaustubh Thirumalai8, Steven C. Clemens9, Philippe Martinez3, and Ralph R. Schneider1,2
Stefan Lauterbach et al.
  • 1Leibniz Laboratory for Radiometric Dating and Stable Isotope Research, Kiel University, 24118 Kiel, Germany (
  • 2Institute of Geosciences, Kiel University, 24118 Kiel, Germany
  • 3Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), UMR 5805 CNRS – Université de Bordeaux – EPHE – OASU, 33615 Pessac, France
  • 4École Pratique des Hautes Études (EPHE), PSL Université Paris, 33615 Pessac, France
  • 5Laboratory of Palynology & Paleoecology, Department of Ecology, French Institute of Pondicherry, 605 001 Puducherry, India
  • 6Instituto Português do Mar e da Atmosfera (IPMA), 1749-077 Lisbon, Portugal
  • 7Centro de Ciências do Mar (CCMAR), Universidade do Algarve, 8005-139 Faro, Portugal
  • 8Department of Geosciences, University of Arizona, Tucson, AZ 85721, United States
  • 9Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, United States

Understanding past variability and forcing mechanisms of the Asian monsoon system is of key importance for better forecasting its behaviour under future global warming scenarios and how this may affect modern societies and economies. So far, knowledge about long-term monsoon variability in mainland Asia is mainly based on proxy records from Chinese speleothems, primarily recording changes of the East Asian Summer Monsoon (EASM). These records have provided evidence for orbital-scale monsoon variability, driven by Northern Hemisphere summer insolation changes, but also for centennial- to millennial-scale reductions in monsoon precipitation. These so-called Weak Monsoon Intervals (WMIs) occurred synchronously to cold intervals in the North Atlantic realm, e.g. during Heinrich Events, pointing at a close hemisphere-scale climatic teleconnection between the North Atlantic and Asia. However, the exact mechanisms that control short-term monsoon variability are still elusive. Moreover, long-term palaeomonsoon proxy records from the core zone of the Indian Summer Monsoon (ISM) are still relatively scarce compared to those from the EASM realm. To identify possible short-term changes in ISM intensity and reconstruct related hydroclimate and vegetation changes on the Indian subcontinent during the interval ~6–74 ka BP, sediments from IODP Site U1446 in the NW Bay of Bengal have been analysed. This site, being located within the reach of the Mahanadi River, is characterized by high riverine input of terrestrial organic matter and thus ideal for high-resolution analyses of pollen content and the stable hydrogen (δD) and carbon (δ13C) isotope composition of n-alkanes from terrestrial plant leaf waxes. Here we present preliminary results of δD and δ13C analyses on odd-numbered long-chain n-alkanes (n-C27 to n-C33,) extracted from the IODP Site U1446 sediments. These indicate several reductions in ISM precipitation during the last glacial, which occurred parallel to cold events in the North Atlantic realm, e.g. during Heinrich events H1, H2, H4, H5 and H6. In combination with pollen and alkenone-based (UK’37) sea surface temperature data from the same sediments, we aim at (1) providing a comprehensive and high-resolution reconstruction of past ISM variability and associated vegetation changes on the Indian subcontinent and (2) understanding the trigger mechanisms of centennial- to millennial-scale WMIs, particularly in relation to changes in Indian Ocean oceanography.

How to cite: Lauterbach, S., Andersen, N., Clément, C., Desprat, S., Zorzi, C., Anupama, K., Prasad, S., Oliveira, D., Blanz, T., Thirumalai, K., Clemens, S. C., Martinez, P., and Schneider, R. R.: Indian subcontinent hydroclimate and vegetation changes during the last glacial reconstructed by leaf wax stable isotope and pollen analyses on sediments from IODP Site U1446, NW Bay of Bengal, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19204,, 2020

This abstract will not be presented.