The Cretaceous-Paleogene Boundary Unit, Deep-Water Gulf of Mexico: Character, Distribution, and Relation to the Chicxulub Impact

Sanford, Jason C.; Snedden, John W.

Since it was first identified in Italy and Tunisia, the Cretaceous-Paleogene boundary unit has been interpreted to comprise the stratigraphic record of a catastrophic extraterrestrial impact that occurred off of the coast of the Yucatán Peninsula at the end of the Maastrichtian. As petroleum industry interest has investigated deeper objectives in the Gulf of Mexico stratigraphy, well penetrations have revealed a thick (>100-meter) interval that is believed to be the Cretaceous-Paleogene boundary unit. Based on well-log data, the Cretaceous-Paleogene boundary unit in the deep-water Gulf of Mexico is interpreted to consist of a micritic mega-breccia that resulted from catastrophic marine and submarine processes. Mapping on two- and three-dimensional seismic reflection data throughout the Gulf of Mexico reveals a widespread distribution for the unit that thickens substantially (up to ~1000 meters) in areas and is representative of deposition in a submarine environment strongly influenced by allochthonous salt movement. Furthermore, for the first time, correlation of the unit from the deep-water Gulf of Mexico to the Chicxulub crater on two-dimensional seismic reflection data supports a causative link to the impact event. As such, results suggests that the Cretaceous-Paleogene boundary unit in the Gulf of Mexico is the result of catastrophic marine and submarine processes (e.g., extreme seismogenesis, megatsunami generation, massive slope collapse, and mass sediment flow) that occurred as a result of the Chicxulub impact event, drastically altering seafloor topography for subsequent deposition.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013