New insights into the ∼ 74 ka Toba eruption from sulfur isotopes of polar ice cores

• Published in: Climate of the Past
• Main Authors: L. Crick, A. Burke, W. Hutchison, M. Kohno, K. A. Moore, J. Savarino, E. A. Doyle, S. Mahony, S. Kipfstuhl, J. W. B. Rae, R. C. J. Steele, R. S. J. Sparks, E. W. Wolff
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2021
• Subjects: Environmental pollution; TD172-193.5; Environmental protection; TD169-171.8; Environmental sciences; GE1-350; Antarctic; Dronning Maud Land; Greenland; Antarc*; Greenland ice cores; ice core
• Online Access: https://doi.org/10.5194/cp-17-2119-2021; https://doaj.org/article/9ac58b208bf146c287f641e070c9a41e

The ∼74 ka Toba eruption was one of the largest volcanic events of the Quaternary. There is much interest in determining the impact of such a large event, particularly on the climate and hominid populations at the time. Although the Toba eruption has been identified in both land and marine archives as the Youngest Toba Tuff, its precise place in the ice core record is ambiguous. Several volcanic sulfate signals have been identified in both Antarctic and Greenland ice cores and span the Toba eruption <math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msup><mi/><mn mathvariant="normal">40</mn></msup><mi mathvariant="normal">Ar</mi><msup><mo>/</mo><mn mathvariant="normal">39</mn></msup><mi mathvariant="normal">Ar</mi></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="49pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="581fb8b0d6f0045e486f57fce7236dcc"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cp-17-2119-2021-ie00001.svg" width="49pt" height="15pt" src="cp-17-2119-2021-ie00001.png"/></svg:svg> age uncertainty. Here, we measure sulfur isotope compositions in Antarctic ice samples from the Dome C (EDC) and Dronning Maud Land (EDML) ice cores at high temporal resolution across 11 of these potential Toba sulfate peaks to identify candidates with sulfur mass-independent fractionation (S-MIF), indicative of an eruption whose plume reached altitudes at or above the stratospheric ozone layer. Using this method, we identify several candidate sulfate peaks that contain stratospheric sulfur. We further narrow down potential candidates based on the isotope signatures by identifying sulfate peaks that are due to a volcanic event at tropical latitudes. In one of these sulfate peaks at 73.67 ka, we find the largest ever reported magnitude of S-MIF in volcanic sulfate ...