Organic matter from the Chicxulub crater exacerbated the K-Pg impact winter.
File(s)Lyons-accepted_PNAS_2020.pdf (381.85 KB)
Accepted version
Author(s)
Type
Journal Article
Abstract
An asteroid impact in the Yucatán Peninsula set off a sequence of events that led to the Cretaceous-Paleogene (K-Pg) mass extinction of 76% species, including the nonavian dinosaurs. The impact hit a carbonate platform and released sulfate aerosols and dust into Earth's upper atmosphere, which cooled and darkened the planet-a scenario known as an impact winter. Organic burn markers are observed in K-Pg boundary records globally, but their source is debated. If some were derived from sedimentary carbon, and not solely wildfires, it implies soot from the target rock also contributed to the impact winter. Characteristics of polycyclic aromatic hydrocarbons (PAHs) in the Chicxulub crater sediments and at two deep ocean sites indicate a fossil carbon source that experienced rapid heating, consistent with organic matter ejected during the formation of the crater. Furthermore, PAH size distributions proximal and distal to the crater indicate the ejected carbon was dispersed globally by atmospheric processes. Molecular and charcoal evidence indicates wildfires were also present but more delayed and protracted and likely played a less acute role in biotic extinctions than previously suggested. Based on stratigraphy near the crater, between 7.5 × 1014 and 2.5 × 1015 g of black carbon was released from the target and ejected into the atmosphere, where it circulated the globe within a few hours. This carbon, together with sulfate aerosols and dust, initiated an impact winter and global darkening that curtailed photosynthesis and is widely considered to have caused the K-Pg mass extinction.
Date Issued
2020-09-28
Online Publication Date
2021-03-28T00:01:16Z
Date Acceptance
2020-09-01
ISSN
0027-8424
Publisher
National Academy of Sciences
Start Page
25327
End Page
25334
Journal / Book Title
Proceedings of the National Academy of Sciences of USA
Volume
117
Issue
41
Copyright Statement
© 2020 Published under the PNAS license https://www.pnas.org/site/aboutpnas/licenses.xhtml.
Sponsor
Natural Environment Research Council (NERC)
Identifier
https://www.pnas.org/content/early/2020/09/22/2004596117/tab-article-info
https://www.ncbi.nlm.nih.gov/pubmed/32989138
2004596117
Grant Number
NE/P005217/1
Subjects
Chicxulub impact crater
Cretaceous–Paleogene
impact winter
polycyclic aromatic hydrocarbons
wildfires
Chicxulub impact crater
Cretaceous–Paleogene
impact winter
polycyclic aromatic hydrocarbons
wildfires
Publication Status
Published
Country
United States
Date Publish Online
2020-09-28