STRATIGRAPHIC EVIDENCE OF AN ASTEROID IMPACT, MEGA-EARTHQUAKES, AND TSUNAMIS IN JUST ONE BED: THE K-PG BOUNDARY IN COLOMBIA, MEXICO, AND THE UNITED STATES

The impact of the Chicxulub asteroid, in what is now the Yucatan Peninsula, Mexico, ~66 Ma ago, coincides with the Cretaceous-Paleogene boundary (the K/Pg boundary). The environmental consequences of this collision are the most likely cause for the last of the “Big Five” extinction events in the Phanerozoic. The processes triggered by the impact imply the release of energy enough to induce mega-earthquakes and tsunamis during the creation of a 180-200 km diameter crater, expelling vast quantities of dust, gases, and ejecta materials. The simultaneous occurrence of these geologic processes allows us to hypothesize that the sedimentary record of the strata associated with the Chicxulub impact (here called the K-Pg bed -KPGB-) should include a complex but clearly defined stratigraphy. In this way, the KPGB should record the timing of the sequence of events depending on geographic position and local paleoenvironmental conditions. To test this, we have studied the KPGB at several locations in Colombia, NE Mexico, and the southern United States. These sites were located at different paleodistances relative to the crater and recorded sedimentation in diverse paleoenvironments, from coastal to deep-marine. Combining stratigraphic and sedimentological analysis and geographic information systems, here we present the detailed study of the KPGB, reconstructing the aftermath of this planetary event. The information is displayed graphically, using storymaps in multilingual versions (English, Spanish, Mandarin, French, and Italian). In all the sections studied, it is possible to identify evidence of in situ liquefaction and soft-sediment deformation before, during, and after the fall of the ejecta, proving intense seismic activity for weeks to months. The evidence can be related to the Chicxulub mega-earthquake and its aftershocks. On the other hand, tsunami waves are only evident in the shallow sections. This information allows us to understand the complex stratigraphic record of the KPGB, the paleogeography, and the direct connection between asteroid impacts and resultant seismicity.