Soot has been discovered by Wolbach et al. at the Cretaceous-Tertiary boundary in various geographic locations, supporting the theory that worldwide wildfires were ignited by the impact of a giant meteorite which caused the mass extinction 65 million years ago. This project examines a deep sea core sample from the North Central Pacific Ocean for evidence of soot. Soot discovery at this site, the only deep ocean site to be studied, supports the theory that soot distribution from the fires was worldwide.
In another project, samples from the suevite breccia of the Kara Ust-Kara craters in Russia (unrelated to the KT impact) were examined for' soot to find evidence of fires triggered by a different impact. After demineralization to remove the minerals in the rock, reduced carbon was found in both the core and crater samples. Oxidation in dichromate solution removed the organic carbon (kerogen) form the samples. Analysis of the post-oxidation residues under a scanning electron microscope confirmed the presence of soot in both the core and crater samples.
Kufner '94, Gregory S., "Ignition and Environmental Effects of Wildfires as Related to Giant Impacts" (1994). Honors Projects. Paper 17.