An experimental assessment of the ignition of forest fuels by the thermal pulse generated by the cretaceous–palaeogene impact at chicxulub
Journal of the Geological Society
This is the author accepted manuscript. The final version is available from Geological Society via http://dx.doi.org/10.1144/jgs2014-082.
© The Geological Society of London A large extraterrestrial body hit the Yucatán Peninsula at the end of the Cretaceous period. Models suggest that a substantial amount of thermal radiation was delivered to the Earth’s surface by the impact, leading to the suggestion that it was capable of igniting extensive wildfires and contributed to the end-Cretaceous extinctions. We have reproduced in the laboratory the most intense impact-induced heat fluxes estimated to have reached different points on the Earth’s surface using a fire propagation apparatus and investigated the ignition potential of forest fuels. The experiments indicate that dry litter can ignite, but live fuels typically do not, suggesting that any ignition caused by impact-induced thermal radiation would have been strongly regional dependent. The intense, but short-lived, pulse downrange and at proximal and intermediate distances from the impact is insufficient to ignite live fuel. However, the less intense but longer-lasting thermal pulse at distal locations may have ignited areas of live fuels. Because plants and ecosystems are generally resistant to single localized fire events, we conclude that any fires ignited by impact-induced thermal radiation cannot be directly responsible for plant extinctions, implying that heat stress is only part of the end-Cretaceous story.
Please note C.M.B. and R.M.H. contributed equally to this paper. We thank R, Spicer, G. Upchurch and V. Vajda for their useful reviews that assisted us in improving this paper. C.M.B. acknowledges funding from a Marie Curie Career Integration Grant (PyroMap PCIG10-GA-2011-303610) and a European Research Council Starter Grant ERC-2013-StG-335891-ECOFLAM and the University of Exeter. J.V.M. acknowledges funding from the Leverhulme Trust. G.R. and R.M.H. acknowledge EPSRC Doctoral Prize funding from Imperial College London. T.G. acknowledges funding from the Lise Meitner Program of the Austrian Science Fund (FWF). We also acknowledge the influence of E. Pierazzo, who passed away during the early phases of this research, whose drive to ‘bridge the gap’ between geologists, modellers and experimentalists influenced the conception of this research.
This is an open access article available at http://jgs.lyellcollection.org/content/172/2/175.full .
Vol. 172, pp. 175 - 185