Abstract
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.
Highlights
The version presented here may differ from the published version
We have been able for the first time to recreate model predictions of the thermal flux delivered around the globe by the K-Pg impact in the laboratory
In contrast to previous work that over-simplified the fall-back of high velocity ejecta around the globe in predictions of thermal radiation, our experiments incorporate recent numerical modelling that suggests that the magnitude and duration of the heat flux pulse received by the Earth’s surface would have varied with both distance and direction from Chicxulub
Summary
The version presented here may differ from the published version. If citing, you are advised to consult the published version for pagination, volume/issue and date of publication. An experimental assessment of the ignition of forest fuels by the thermal pulse generated by the Cretaceous-Paleogene impact at Chicxulub. 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. 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. It has been widely held that an extraterrestrial body struck the Earth approximately 65 million years ago (Alvarez et al 1980) forming the ca. 200km wide
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