EGU2020-4
https://doi.org/10.5194/egusphere-egu2020-4
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Where is the Toba eruption in the Vostok ice core? Clues from tephra, O and S isotopes

Joel Savarino1, Elsa Gautier1, Nicolas Caillon1, Emmanuelle Albalat2, Francis Albarède2, Shohei Hattori4, Jean-Robert Petit1, and Vladimir Lipenkov3
Joel Savarino et al.
  • 1Institut des Géosciences de l'Environnement, Grenoble, France (joel.savarino@cnrs.fr)
  • 2Ecole Normale Supérieure de Lyon, Lyon, France
  • 3Arctic and Antarctic Research Institute, St. Petersburg, Russia
  • 4Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Japan

The ca. 74 ka BP ‘‘super-eruption’’ of Toba volcano in Sumatra is the largest known Quaternary eruption. It expelled an estimated of 2800 km3 of dense rock equivalent, creating a caldera of 100 x 30 km. The eruption is estimated to have been 3500 greater than the Tambora eruption that created the “year without summer” in 1816 in Europe (Oppenheimer, 2002). However, the consequences of this “mega-eruption” on the climate and human evolution that could be expected for such eruption are still debated and uncertain. There is no evidence that this eruption has triggered any catastrophic climate change such as a “nuclear winter”. One of such lack of evidence lies in the ice.

In the ice core community, this eruption still remains a mystery. Indeed, the estimated size of the eruption should have left a gigantic mark in the ice, at least in the form of a huge sulfuric acid layer but none of the ice records covering this period show any such singularity. The sulfate record seems so common that it is in fact difficult to allocate a specific sulfate peak to this event.

In an effort to synchronize the Vostok ice core and the EPICA Dome C core, (Svensson et al., 2013) have identified three possible sulfuric acid layers for the Toba eruption in the Vostok ice core. In order to see if one of such event could have been the Toba eruption, we have performed the sulfur  & oxygen isotope analysis of these three sulfuric acid layers in the hope that it could reveal some particularity. The sulfur results show that 1- all these three events have injected their products in the stratosphere and 2- the sulfur isotopic compositions of these three events share a common array, array that is in lines with other stratospheric eruptions, however one of the three acid layers shows an extremely and unusual weak oxygen anomaly, potentially indicating a major eruption. In order to remove the last doubts about the existence or not of one or a series of eruptions related to TOBA, the geochemical analysis of volcanic glasses trapped in the ice will be performed and presented.

How to cite: Savarino, J., Gautier, E., Caillon, N., Albalat, E., Albarède, F., Hattori, S., Petit, J.-R., and Lipenkov, V.: Where is the Toba eruption in the Vostok ice core? Clues from tephra, O and S isotopes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4, https://doi.org/10.5194/egusphere-egu2020-4, 2019

Comments on the presentation

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Presentation version 1 – uploaded on 16 Apr 2020
  • CC1: Comment on EGU2020-4, Anders Svensson, 05 May 2020

    Dear Joel, Elsa and all,

    Very nice presentation. Glad to know that it is still a possibility that some of the bipolar eruptions at around 74 ka are Toba candidates. But you are right that the peaks are really not that extraordinary from an ice core perspective. Only in GISP2 the T1 peak is very signifcant. Looking forward to the continuation of the story.

    Best regards, Anders

    • AC1: Reply to CC1, Joel Savarino, 05 May 2020

      Thanks Anders for your comment

      yes indeed, the Toba in ice core remains a mistery. Where is it? Since I posted my presentation
      I got new results from Italian colleagues on the geochemistry of the volcanic shards found in these layers
      and none of them show a geochemical composition close to the Toba volcanic ashes. I can't show the
      data yet as the Italians are not co authors of this presentation but these data will be published
      in the paper I'm preparing.

      Best