Soot in Cretaceous-Paleogene boundary clays worldwide: is it really derived from fossil fuel beds close to Chicxulub?

High soot contents have been reported in Cretaceous-Paleogene boundary (KPB) clays worldwide. One of the interpretations suggests this material comes from combustion of fossil fuels such as crude oil, coal or oil shales near the Chicxulub impact site. Combustion was triggered by the KPB impactor. In this Note, I show that the estimated mass of crude oil (or fossil hydrocarbons in general) burned (ca. 10 17 –10 19 g), based on the average amount of soot (0.0022–0.012 g cm −2 ) or elemental carbon (0.011 g cm −2 ) found at the marine KPB sites, contradicts the fossil hydrocarbons hypothesis.