The mass extinction event at the Cretaceous/Palaeogene boundary 65.5 Myr ago has been widely attributed to the Chicxulub impact1, 2, but the mechanisms of extinction remain debated1, 3, 4, 5, 6. In the oceans, near-surface planktonic foraminifera suffered severe declines, in contrast to the relatively high survival rates of bottom-dwelling benthic foraminifera7. The vapour produced by an impact into Chicxulub’s target rocks, which include sulphate-rich anhydrite, could have led to global acid rain, which can explain the pattern of oceanic extinctions4, 5. However, it has been suggested that most of the sulphur in the target rocks would have been released as sulphur dioxide and would have stayed in the stratosphere for a long time6. Here we show, from impact experiments into anhydrite at velocities exceeding 10 km s−1, that sulphur trioxide dominates over sulphur dioxide in the resulting vapour cloud. Our experiments suggest that the Chicxulub impact released a huge quantity of sulphur trioxide into the atmosphere, where it would have rapidly combined with water vapour to form sulphuric acid aerosol particles. We also find, using a theoretical model of aerosol coagulation following the Chicxulub impact, that larger silicate particles ejected during the impact efficiently scavenge sulphuric acid aerosol particles and deliver the sulphuric acid to the surface within a few days. The rapid surface deposition of sulphuric acid would cause severe ocean acidification and account for preferential extinction of planktonic over benthic foraminifera.
At a glance
- Extraterrestrial cause for the Cretaceous–Tertiary extinction. Science 208, 1085–1108 (1980). , , &
- The Chicxulub asteroid impact and mass extinction at the Cretaceous–Paleogene boundary. Science 327, 1214–1218 (2010). et al.
- Global fire at the Cretaceous–Tertiary boundary. Nature 334, 665–669 (1988). et al.
- Impact winter at the Cretaceous/Tertiary extinctions: Results of a Chicxulub asteroid impact model. Earth Plant. Sci. Lett. 128, 719–725 (1994). , , &
- Chicxulub and climate: Radiative perturbations of impact-produced S-bearing gases. Astrobiology 3, 99–118 (2003). , &
- Surface-water acidification and extinction at the Cretaceous–Tertiary boundary. Geology 22, 983–986 (1994). et al.
- Geochemical constraints on source region of Cretaceous/Tertiary impact glasses. Nature 353, 839–842 (1991). et al.
- Acid-neutralizing scenario after the Cretaceous–Tertiary impact event. Geology 31, 489–492 (2003). &
- Indication of global deforestation at the Cretaceous– Tertiary boundary by New Zealand Fern Spike. Science 294, 1700–1702 (2001). et al.
- Energy, volatile production and climate effects of the Chicxulub Cretaceous/Tertiary impact. J. Geophys. Res. 102, 21645–21664 (1997). , , &
- Sulfur chemistry in laser-simulated impact vapor clouds: Implications for the K/T impact event. Earth Planet. Sci. Lett. 218, 347–361 (2004). et al.
- Impact experiments with a new technique for acceleration of projectiles to velocities higher than Earth’s escape velocity of 11.2 km/s. J. Geophys. Res. 115, E04003 (2010). et al.
- Direct measurements of impact devolatilization of calcite using a laser gun. Geophys. Res. Lett. 35, L13202 (2008). et al.
- Flyer acceleration by high-power laser and impact experiments at velocities higher than 10 km/s. 847–850 (American Institute of Physics, 2012). et al. in Proc. Shock Compression of Condensed Matter—2011 (eds Elert, M. L., Buttler, W. T., Borg, J. P., Jordan, J. L. & Vogler, T. J.)
- Direct measurement of chemical composition of SOx in impact vapor using a laser gun. 851–854 (American Institute of Physics, 2012). et al. in Proc. Shock Compression of Condensed Matter—2011 (eds Elert, M. L., Buttler, W. T., Borg, J. P., Jordan, J. L. & Vogler, T. J.)
- Shock vaporization of anhydrite and global effects of the K/T bolide. Earth Plant. Sci. Lett. 156, 125–140 (1998). &
- The nature of the K/T impactor. A 54Cr reappraisal. Earth Plant. Sci. Lett. 241, 780–788 (2006). , &
- Shock wave equations of state of chondritic meteorites. 115–118 (American Institute of Physics, 1998). & in Proc. Shock Compression of Condensed Matter—1997 (eds Schmidt, S. C., Dandekar, D. P. & Forbes, J. W.)
- Degassing of sedimentary rocks due to Chicxulub impact: Hydrocode and physical simulations. Geol. Soc. Am. Special Paper 307, 125–139 (1996). et al.
- Environmental perturbations caused by the impacts of asteroids and comets. Rev. Geophys. 35, 41–78 (1997). et al.
- Impact dust not the cause of the Cretaceous–Tertiary mass extinction. Geology 30, 99–102 (2002).
- Hydrocode simulations of the Chicxulub impact event and the production of climatically active gases. J. Geophys. Res. 103, 28606–28625 (1998). , &
- The global stratigraphy of the Cretaceous–Tertiary boundary impact ejecta. Annu. Rev. Earth Planet. Sci. 27, 75–113 (1999).
- 1998). & Atmospheric Chemistry and Physics: From Air Pollution to Climate Change (Wiley, (
- End-Cretaceous marine mass extinction not caused by productivity collapse. Proc. Natl Acad. Sci. USA 109, 728–732 (2012). , &
- The Cretaceous-Tertiary extinction: A lethal mechanism involving anhydrite target rocks. Geochim. Cosmochim. Acta. 56, 3603–3606 (1992).
- Terrestrial acidification at the K/T boundary. 181–197 (Springer, (2003). & in High-Pressure Shock Compression of Solids V (eds Davison, L., Horie, Y. & Sekine, T.)
- Lithium isotope history of Cenozoic seawater: Changes in silicate weathering and reverse weathering. Science 335, 818–823 (2012). &
- Silicate weathering rates decoupled from the 87Sr/86Sr ratio of the dissolved load during Himalayan erosion. Chem. Geol. 201, 119–139 (2003). et al.
- Cretaceous–Tertiary profile, rhythmic deposition, and geomagnetic polarity reversals of marine sediments near Bjala, Bulgaria. Geol. Soc. Am. Special Paper 356, 213–229 (2002). et al.
- Supplementary Information (489 KB)