Cretaceous–Paleogene boundary exposed: Campeche Escarpment, Gulf of Mexico

Abstract

We present the first multibeam bathymetric maps of the Campeche Escarpment, a Mesozoic carbonate platform in the Gulf of Mexico, which represents the closest Cretaceous–Paleogene (K-Pg) boundary outcrops to the Chicxulub impact structure. The impact of an extraterrestrial-body ~ 65 million years ago on top of this platform is implicated in the end of the Cretaceous mass extinction and caused the largest debris flow yet described on Earth, which is found across the floor of the Gulf of Mexico and the Caribbean Sea. The location of the K-Pg boundary has been identified in the escarpment face by combining the new multibeam data with existing information from boreholes. The boundary is represented by an abrupt change in gradient on the escarpment face. The morphology of the escarpment combined with seismic data reveals that a significant amount of material is missing from the face, which failed catastrophically due to seismic shaking produced by the impact. The escarpment face is inferred to be an important source for the extensive debris flows triggered by the impact, whose deposits are found throughout much of the Gulf of Mexico.