Burned organic matter in Chicxulub impact

A study finds that burned organic matter in sediments ejected from the Chicxulub impact crater may have contributed significantly to the mass extinction at the end of the Cretaceous Period, 66 million years ago. Geologic records of the impact of an asteroid in the Yucatán Peninsula that likely initiated the end-Cretaceous extinction include markers of burned organic matter, the source of which was previously unclear. Shelby L. Lyons and colleagues analyzed three sedimentary sequences from the impact event to characterize the sources and potential implications of the burn markers, which are composed of polycyclic aromatic hydrocarbons (PAHs). PAH chemical signatures suggest that the initial release of black carbon came from a fossil source rather than from global wildfires and had experienced rapid heating, consistent with rock material ejected during the asteroid impact. The authors estimate that between 7.5 x 1014 and 2.5 x 1015 g of black carbon was ejected from the crater and dispersed in the atmosphere immediately following the impact. Charcoal was also present in the samples, indicating that wildfires following the impact were likely delayed and protracted relative to the formation of black carbon burn markers and that the wildfires' contribution to the impact winter and subsequent extinction may have been smaller than thought. According to the authors, the black carbon in the atmosphere, which rapidly circled the globe, likely combined with dust and sulfate aerosols to darken the planet and initiate an impact winter and a mass extinction event.

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Article #20-04596: "Organic matter from the Chicxulub crater exacerbated the K-Pg impact winter," by Shelby L. Lyons et al.

MEDIA CONTACT: Shelby L. Lyons, Pennsylvania State University, University Park, PA; e-mail: shelby.l.lyons@gmail.com

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