Distribution and Seismic Characteristics of the Cretaceous-Paleogene Boundary Layer in the Gulf of Mexico, USA, and Mexico Deepwater

Abstract

Catastrophic slope failures, major sediment reworking, and global mass extinctions have been previously tied to the Cretaceous-Paleogene (K-Pg) bolide impact on the Yucatan Peninsula. An event bed corresponding to this cataclysm forms a well-defined horizon in the Gulf of Mexico subsurface, easily distinguishable in cores and on regional seismic surveys. Utilizing seismic data and well picks from the Gulf Basin Depositional Project database, we present for the first time, basin-wide maps of the distribution and thickness of this event bed across the Gulf of Mexico. Previous mapping efforts were restricted to the Northern Gulf of Mexico, but new available seismic data from offshore Mexico has facilitated this basin-scale analysis. We also document common seismic facies, including onlap surfaces, truncation surfaces, and slumps associated with slope failure along the Florida and Campeche Scarps. Well penetrations in Mexico and the USA indicate that carbonate breccia forms the majority of the K-Pg Boundary layer in areas proximal to carbonate shelfs; this breccia is recrystallized, fractured, and forms an impermeable layer that acts as a trap and reservoir for hydrocarbons, as demonstrated in the Cantarell Field of Mexico. The K-Pg Boundary layer truncates older Cretaceous units in some areas, and is an onlap surface for most Paleogene/Neogene units across the Gulf, creating the potential for stratigraphic entrapment. Bathymetric lows were filled by impact layer, smoothing over seafloor features; this process may have contributed to the wide distribution of the subsequent Paleogene-age Wilcox sands, as previously suggested for the Northern GOM.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016