AN INVESTIGATION OF PALEO-WILDFIRES DURING THE CRETACEOUS-PALEOGENE (K-PG) BOUNDARY AT EL KEF, TUNISIA

Gross, Michael

Undergraduate Honors Thesis

AN INVESTIGATION OF PALEO-WILDFIRES DURING THE CRETACEOUS-PALEOGENE (K-PG) BOUNDARY AT EL KEF, TUNISIA Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/undergraduate_honors_theses/p5547r75x

Abstract

The causes and consequences of the Cretaceous-Paleogene mass extinction have long been a source of contention. Several models predict that enough thermal radiation from the bolide impact was produced to ignite wildfires at least regionally and possibly on a global scale, raising average temperatures by up to ~10°C, and releasing large amounts of CO₂ and CO. However, the role of regional versus global wildfire events as an environmental stressor, as well as the sources of the fire (land vegetation vs. hydrocarbon reservoirs) and its expression in terrestrial and marine archives, remains controversial. Typically, wildfires are preserved in the geologic record by features such as charcoal and soot deposition. Additionally, molecular fossils (biomarkers) like polycyclic aromatic hydrocarbons (PAHs) and long-chain n-alkanes preserved in marine sedimentary sequences can be diagnostic of biomass burning (including sources and temperature of combustion) and terrestrial input to the marine realm, respectively. Using Gas Chromatography- Mass Spectrometry, we investigated the abundance of these biomarkers in the K/Pg global stratotype and section point (GSSP) of El Kef, Tunisia. Our results indicate the occurrence of a spike in PAH concentration and vegetation proxies for a few thousand years immediately above the K/Pg boundary. These results are like those found in the marine section of Caravaca, Spain and demonstrate that wildfires and enhanced terrestrial input following the K/Pg may have been more widespread features of this event than previously recognized. Finally, a dominance of 4–5 ringed PAHs is consistent with moderate-high intensity.

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