T259 Dynamics of Earth’s Climate System and Biogeochemical Cycles in Deep Time

Wednesday, 12 October 2022
1:30 PM - 5:30 PM
506

WILDFIRE INTENSITY AND FREQUENCY ACROSS THE CRETACEOUS-PALEOGENE BOUNDARY SECTION FROM EL KEF, TUNISIA

Paper number: T259-14
Program: Technical Sessions
Time: 4:35 PM – 4:50 PM

Authors

Abstract

66 million years ago, at the Cretaceous-Paleogene (K/Pg) boundary, a ~12 km-wide asteroid struck near Chicxulub, Mexico causing Earth’s most recent mass extinction. Because of its geological abruptness, the K/Pg boundary is a valuable analog for current and future trends in climate change. Paleoenvironmental reconstructions suggest the occurrence of widespread wildfires in the immediate aftermath of the impact, which could have injected enough CO2 into the atmosphere to raise Earth’s temperature by several °C. However, questions remain about the intensity and frequency of wildfires before, during, and after the K/Pg boundary, as well as the sources of biomass burning, largely due to the limited number of continuous and expanded sedimentary sequences covering vast parts of the latest Cretaceous and the earliest Paleogene.

Our study provides a reconstruction of wildfire intensity and frequency and its impact on the terrestrial realm across the K/Pg boundary as recorded in expanded, high-resolution sedimentary sequences from the K/Pg Global Boundary Stratotype Section and Point (GSSP) at El Kef, Tunisia. Sediment cores from the El Kef Coring Program represent an outer-neritic to upper-bathyal environment (200-300 m) of the Tethys Ocean covering ~200 kyr of the latest Cretaceous and ~1.5 myr of the early Paleogene. Due to its proximity to the continental margin, this region captures environmental and ecological perturbations from the adjacent land at higher temporal resolution than continental sequences. Thus, our record provides a unique opportunity to study fire dynamics during the latest Cretaceous, across the K/Pg boundary, and during the long-term “recovery phase” in the Danian. We will present results on wildfire intensity and frequency using pyrogenic polycyclic aromatic hydrocarbons (PAHs) produced by the incomplete combustion of biomass, in addition to evidence for the perturbation of the terrestrial realm based on plant-derived biomarkers. We will compare our results against records from other regions and discuss fire dynamics in a post-impact world.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-383729

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