EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

The recovery of the biological pump across the K/Pg boundary in the GSSP of El Kef, Tunisia

Joep van Dijk1,2, Julio Sepúlveda1, Laia Alegret3, Heather Birch4, Timothy Bralower5, Heather Jones5,6, Michael Henehan7, Pincelli Hull8, Mohamed Hedi Negra9, Andy Ridgwell10, Ursula Röhl6, Johan Vellekoop11,12, Thomas Westerhold6, Jessica Whiteside13, and Richard Zeebe14
Joep van Dijk et al.
  • 1Department of Geological Sciences and INSTAAR, University of Colorado Boulder, USA (
  • 2Department of Earth Sciences, Utrecht University, the Netherlands
  • 3Departmento de Ciencias de la Tierra, University of Zaragoza, Spain
  • 4School of Earth Sciences, University of Bristol, Bristol, UK
  • 5Department of Geosciences, Pennsylvania State University, USA
  • 6MARUM - Center for Marine Environmental Sciences, University of Bremen, Germany
  • 7GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany
  • 8Department of Geology & Geophysics, Yale University, USA
  • 9Department of Geology, Faculty of Sciences of Tunis, Tunis El Manar University, Tunisia
  • 10Earth and Planetary Sciences, University of California at Riverside, Riverside, USA
  • 11Department of Chemistry, Analytical, Environmental and Geo- Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
  • 12Department of Geology, KU Leuven, Leuven, Belgium
  • 13Department of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, UK
  • 14Department of Earth Sciences, University of Hawaii at Manoa, Hawaii

The study of Earth’s Big Five mass extinctions provides insight into the resilience of ecosystems to environmental perturbations. Earth’s most recent mass extinction at the Cretaceous/Paleogene boundary (K/Pg) was caused by the impact of an asteroid in the Yucatan peninsula rather than by intense volcanism. Mass extinctions among marine calcareous nannoplankton heavily disrupted the marine food web resulting in a severe weakening of the ocean’s biological pump. The timing and heterogeneous nature of the recovery of the biological pump remain poorly resolved in the neritic zone in the aftermath of the impact. Here, we address the evolution of the biological pump across the K/Pg at the Global Boundary Stratotype Section (GSSP) at El Kef, Tunisia using high-resolution compound-specific carbon isotope records (δ13Cbiomarker) of non-calcareous marine phototrophs from an outer shelf to upper bathyal setting of the southwestern Tethys Ocean. We use δ13Cbiomarker to reconstruct εp, which is a function of the community structure of marine phototrophs, their rate of carbon fixation, and the concentration and isotopic composition of aqueous CO2. We then use our εp record to constrain the recovery of the biological pump in this region while considering the composition of marine phytoplankton, the assemblage and isotopic composition of benthic foraminifera, state-of-the-art physiological models for εp, and carbon cycle simulations using cGENIE. Our results indicate that the recovery of the biological pump in the outer shelf-upper bathyal zone likely outpaced the recovery in the open ocean. This is in agreement with the selective extinctions among phytoplankton at the K/Pg, with most survivors that would later repopulate open-ocean sites being adapted to neritic environments.

How to cite: van Dijk, J., Sepúlveda, J., Alegret, L., Birch, H., Bralower, T., Jones, H., Henehan, M., Hull, P., Hedi Negra, M., Ridgwell, A., Röhl, U., Vellekoop, J., Westerhold, T., Whiteside, J., and Zeebe, R.: The recovery of the biological pump across the K/Pg boundary in the GSSP of El Kef, Tunisia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8200,, 2021.

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