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A New Model for the Mesozoic Tectonostratigraphic Evolution of the Gulf of Mexico Basin: New Plate Tectonic and Sediment Routing Reconstructions


The Gulf of Mexico (GoM) Mesozoic history can be subdivided into a series of four tectonostratigraphic phases, reflecting both long-term tectonic evolution of the basin and shorter-term eustatic and climatic processes influencing sedimentation. The four phases that cover the post-Pennsylvanian to end Cretaceous section (300 ma to 66 ma) are: 1) Post Quachita-Appalachian Successor Basin-fill; 2) Early Mesozoic Rifting; 3) Middle Mesozoic Drift and Cooling; and 4) Late Mesozoic Local Tectonic and Crustal Heating. These Mesozoic tectonostratigraphic phases naturally reflect plate tectonic forces that controlled source terrane exposure and sediment routing, subsidence, accommodation, and even marine water entry to the nascent basin to form the Louann Salt.

Our new tectonostratigraphic model is based upon updated plate tectonic reconstructions, new detrital zircon geochronology from deep wells, and analysis of seismic reflection data in Mexico and the USA. Newly developed concepts depart from conventional GoM thinking both in timing and kinematics. This evidence suggests the early Mesozoic South Georgia/Newark rift system does not extend into Texas/Louisiana and much of the pre-salt Triassic Eagle Mills deposition occurred in a successor basin overlying deformed Quachita-Marathon strata. Pre-salt deposition in northern Yucatán forms a seaward dipping wedge of continental deposition derived from erosion of exposed Yucatán basement. The pre-salt section of the Yucatán and Campeche province is probably younger than the Eagle Mills, as accommodation was probably not available until the Jurassic when the Mayan block had rotated sufficiently to create space between the Yucatán shelf and North America. The interpreted younger age plus its location away from higher heat flow continental crust are both more favorable conditions for improved reservoir quality.

The Middle Mesozoic Drift and Cooling Phase is dominated by marine carbonates, evolving from ramp microbalites to platform margin reef systems. These prominent reef systems were quite effective at limiting siliciclastic bypass to the basin.

The subsequent Late Mesozoic Local Tectonic and Crustal Heating Phase, by contrast, shows the first major entry of siliciclastics into the northern GoM basin in the Ceno-Turonian, with the deepwater Tuscaloosa sandstone. Local silled basins enriched source rocks in the Eagle Ford and its equivalent in Mexico, the Agua Nueva.

The end-Mesozoic Chicxulub impact event (KPg) greatly modified the land- and seascape of the basin, paving the way for the long-lived source to sink transport systems routing sediment from the Laramide orogenic belt into the deep Gulf Basin in the early Paleogene. The KPg breccia also forms the most important producing unit in Mexico, at Cantarell and adjacent fields.