138-2 Environmental Stabilization in the First 300,000 Years After the K-Pg Mass Extinction

Session: The Cretaceous-Paleogene (K-Pg) Boundary Interval: From Large-Scale Geological Events to Mass Extinction Mechanisms

Presenting Author:

Authors:

Abstract:

The loss of ~76% of species during the Cretaceous-Paleogene (K-Pg) mass extinction had lasting impacts on both local ecosystems and global biogeochemical cycling during the rebound of life on Earth (Birch et al., 2021; D’Hondt, 2005; Witts et al., 2018). The immediate climatic aftermath of the bolide impact has been extensively studied (Alvarez et al., 1980; Artemieva and Morgan, 2009; Brugger et al., 2017), and the long-term evolutionary rebound has been characterized globally (Bralower et al., 2020; D’Hondt, 2005), but biotic stabilization might occur between these extremes, on the order of 10s to 100s kyrs. Petrographic and geochemical analysis of the first 300,000 years after the K-Pg boundary is used here to characterize how shallow marine environments along the Gulf Coast evolved in the intermediate-scale aftermath of the extinction at sites ~1000 km from the impact site at Trim Cane Creek, MS (TCC). Shallow marine sections at TCC are situated in the global context of K-Pg sections worldwide using δ13C analysis from bulk sediment geochemistry. Sedimentological analysis of thin sections from each unique lithology within the measured sections characterizes how changes in depositional environment may have contributed to observed faunal and geochemical stabilization post-impact. Finally, comparison between these environmental indicators of short-term recovery can be correlated with existing biostratigraphic analyses of ammonites, dinoflagellates, and nannofossils previously conducted in the Gulf Coastal Plain in the latest Cretaceous (Larina et al., 2016) and earliest Paleogene (Dastas et al., 2014), along with high-resolution- foraminiferal turnover points (Sosa‐Montes De Oca et al., 2024). Preliminary results suggest that shifts in sediment sourcing across the time interval may be correlated with abundance of fossil material, though the relationship between geochemical stabilization and changes in faunal diversity is more ambiguous.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-4906

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