EGU2020-10253
https://doi.org/10.5194/egusphere-egu2020-10253
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Primary productivity dynamics in the northeastern Bay of Bengal over the last 26,000 years

Xinquan Zhou1, Stéphanie Duchamp-Alphonse1, Masa Kageyama2, Franck Bassinot2, Luc Beaufort3, and Christophe Colin1
Xinquan Zhou et al.
  • 1Géosciences Paris Sud, CNRS, Université Paris-Saclay, Orsay, France
  • 2Laboratoire des Sciences du Climat et de l'Environnement, CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
  • 3Centre de Recherche et d’Enseignement de Géosciences de l’Environnement, CNRS, IRD, Université Aix-Marseille, Aix-en-Provence, France

Paleo-records of primary productivity (PP) changes from the Arabian Sea (AS) have revealed the major influence of monsoon-wind intensity in controlling productivity variations at different timescales, through mixed-layer dynamics and upwelling activity. Much less is known, however, about past changes in paleo-PP in the Bay of Bengal (BoB).

       In the present study, we have reconstructed PP over the last 26,000 years from a sediment core located on the northeastern (NE-) BoB. Paleo-PP was estimated by a PP empirical equation using the relative abundance of Florisphaera profunda, a deep dwelling coccolithophore that develops in the lower euphotic zone. Our record does not reveal any obvious difference of PP between the Last Glacial Maximum (LGM) and the late Holocene, but strong oscillations characterize the deglaciation. Our NE-BoB record is anti-phased to PP records in the AS, and positively correlated to surface seawater salinity (SSS) changes reconstructed from the same core since the LGM. We propose that the strong correlation to salinity variations reflects the role of salinity-stratification related to monsoon precipitation on PP at both orbital- and millennial-scales. Outputs of a climatic transient simulation (TraCE-21) and runs obtained with the Earth System Model IPSL-CM5 support the above interpretation of a strong control of past PP variations by local hydrological changes in the NE-BoB. Our data also highlight the potential teleconnection of the Atlantic Meridional Overturning Circulation strength and Indian Monsoon intensity during the deglaciation.

How to cite: Zhou, X., Duchamp-Alphonse, S., Kageyama, M., Bassinot, F., Beaufort, L., and Colin, C.: Primary productivity dynamics in the northeastern Bay of Bengal over the last 26,000 years, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10253, https://doi.org/10.5194/egusphere-egu2020-10253, 2020

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