Geochemical evidence for combustion of hydrocarbons during the K-T impact event.

It has been proposed that extensive wildfires occurred after the Cretaceous-Tertiary (K-I) impact event. An abundance of soot and pyrosynthetic polycyclic aromatic hydrocarbons (pPAH5) in marine K-T boundary impact rocks (BIRs) have been considered support for this hypothesis. However, nonmarine K-T BIRs, from across North America. contain only rare occurrences of charcoal yet abundant noncharred plant remains. pPAH5 and soot can be formed from a variety of sources, including partial combustion of vegetation and hydrocarbons whereby modern pPAH signatures are traceable to their source. We present results from multiple nonmarine K-T boundary sites from North America and reveal that the K-T BIRs have a pPAH signature consistent with the combustion of hydrocarbons and not living plant biomass. providing further evidence against K-T wildfires and compelling evidence that a significant volume of hydrocarbons was combusted during the K-T impact event. [ABSTRACT FROM AUTHOR]