Fullerenes in the Cretaceous-Tertiary Boundary

Fullerenes C60 and C70 were found in the thin clay seams of nine worldwide locations of the geologic boundary between the Cretaceous and Tertiary periods. These clays are also rich in soot. One hypothesis suggests that the fullerenes were synthesized in global wildfires that followed the meteorite impact 65 Ma ago. An alternative hypothesis suggests that the fullerenes predate the formation of the solar system because they contain isotopically anomalous helium in their carbon cages.