The Chicxulub mega-earthquake: Stratigraphic evidence from the Cretaceous-Paleogene boundary of Colombian Pacific and northeastern Mexico

The Chicxulub impact coincides with the Cretaceous-Paleogene (K-Pg) boundary and is considered the trigger of the last of the “Big Five” mass extinction events in Earth's history. Although geophysical models suggest that the impact released enough energy to produce massive earthquakes affecting vast areas, the evidence is insufficient, and their sedimentological signature is poorly known and illustrated. Here, we show stratigraphic evidence of seismically-induced deformation triggered by the Chicxulub impact in K/Pg sites from Colombia and Mexico, revealing deformation affecting pre-impact, impact-derived, and post-impact deposits. We identify a graded sequence of structures, coinciding with the three zones established for seismites. From top to bottom: 1) the Soupy Zone, characterized by intense ductile deformation. 2) the Rubble Zone, characterized by a mixture of brittle and ductile deformation, and 3) the Segmented Zone, controlled by brittle deformation. Our results indicate that the Chicxulub impact triggered mega-earthquakes (magnitude Mw > 8.5). Estimates derived from projections based on tectonically generated earthquakes suggest that the “Chicxulub mega-earthquake” may have reached a magnitude between Mw ∼9.4 and Mw ∼11.3. Seismically-induced deformation affecting the strata deposited after the Chicxulub impact (hosting the biotic recovery successions, including the interval dominated by fern spores at Gorgonilla), suggests massive seismicity lasting for years. The stratigraphic evidence allows us to better understand the complex geological record of the K/Pg boundary in the Americas and characterize one of the most powerful earthquakes of the Phanerozoic. This knowledge goes beyond Chicxulub and may also be applicable to other mega-earthquakes in the geological record.