A seismically induced onshore surge deposit at the KPg boundary, North Dakota

Robert A DePalma, Jan Smit, David A Burnham, Klaudia Kuiper, Phillip L Manning, Anton Oleinik, Peter Larson, Florentin J Maurrasse, Johannes Vellekoop, Mark A Richards, Loren Gurche, Walter Alvarez

Onderzoeksoutput: Articlepeer review

52 Citaten (Scopus)
33 Downloads (Pure)


The most immediate effects of the terminal-Cretaceous Chicxulub impact, essential to understanding the global-scale environmental and biotic collapses that mark the Cretaceous–Paleogene extinction, are poorly resolved despite extensive previous work. Here, we help to resolve this by describing a rapidly emplaced, high-energy onshore surge deposit from the terrestrial Hell Creek Formation in Montana. Associated ejecta and a cap of iridium-rich impactite reveal that its emplacement coincided with the Chicxulub event. Acipenseriform fish, densely packed in the deposit, contain ejecta spherules in their gills and were buried by an inland-directed surge that inundated a deeply incised river channel before accretion of the fine-grained impactite. Although this deposit displays all of the physical characteristics of a tsunami runup, the timing (<1 hour postimpact) is instead consistent with the arrival of strong seismic waves from the magnitude M w ∼10 to 11 earthquake generated by the Chicxulub impact, identifying a seismically coupled seiche inundation as the likely cause. Our findings present high-resolution chronology of the immediate aftereffects of the Chicxulub impact event in the Western Interior, and report an impact-triggered onshore mix of marine and terrestrial sedimentation—potentially a significant advancement for eventually resolving both the complex dynamics of debris ejection and the full nature and extent of biotic disruptions that took place in the first moments postimpact.

Originele taal-2English
Pagina's (van-tot)8190–8199
Aantal pagina's10
TijdschriftProceedings of the National Academy of Sciences of the United States of America
Nummer van het tijdschrift17
StatusPublished - 23 apr 2019


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