Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Harvey, M. C. Articles by Montanari, A. GeoRef GeoRef Citation

Combustion of fossil organic matter at the Cretaceous-Paleogene (K-P) boundary

¹ Department of Geological Sciences, Indiana University, 1001, East 10th Street, Bloomington, Indiana 47405-1405, USA
² Department of Geology, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
³ Coldigioco Geological Observatory, Frontale, Apiro I-62020, Italy

Recognition of elevated concentrations of aciniform soot in Cretaceous-Paleogene (K-P) boundary sediments worldwide led to the hypothesis that global-scale forest wildfires could have been generated by the K-P boundary bolide impact and might have contributed directly to the extinction event. The wildfires are estimated to have injected 10¹³ t of CO₂ into the atmosphere, resulting in an interval of greenhouse warming. Yet minimal amounts of charred plant remains and abundant noncharred material occur in various K-P boundary locations across North America. This refutes the inference that wildfires occurred on a global scale, and requires an alternative explanation for the aciniform soot. Here we describe significant concentrations of carbon cenospheres in K-P boundary sediments from New Zealand, Denmark, and Canada. Carbon cenospheres are thought to derive solely from incomplete combustion of pulverized coal or fuel-oil droplets, which suggests that the impact may have combusted organic-rich target crust. The Chicxulub impact crater is located adjacent to the Cantarell oil reservoir, one of the most productive oil fields on Earth. This indicates that abundance of organic carbon in the Chicxulub target crust was likely to have been above global mean values. But even if we discount Chicxulub's organic-rich locality, the global mean crustal abundance for fossil organic matter is more than adequate to account for observed concentrations of both carbon cenospheres and aciniform soot, therefore making the global wildfire hypothesis unnecessary.

Key Words: Cretaceous-Paleogene • Cretaceous-Tertiary boundary • extinction • fire • impacts • soot • aciniform • ash • K-T • anthropogenic pollutants • kerogen