ABSTRACT

Studies of an extensive regional grid of multifold seismic data and refraction data in the deep central Gulf of Mexico combined with studies from surrounding regions provide a generalized picture of the geologic framework and tectonic setting of the basin. Various criteria, including seismic reflection data, seismic refraction data, depth-to-basement, gravity, magnetics, distribution of Jurassic salt and sediments, and total tectonic subsidence analysis, provide a basis for characterizing and mapping the distribution of oceanic crust, thin transitional crust, and thick transitional crust or continental crust. This distribution of crust provides constraints for a reconstruction of the Gulf area, which involves closing up, first, oceanic crust and then transitional crust. This reconstruction provides room to accommodate any overlap of South America with Yucatan and supports a counter-clockwise rotation of Yucatan out of the northern Gulf. It is compatible with other published reconstructions that treat Yucatan as a separate block independent of South America, particularly ones that rotate Yucatan out of the Gulf in a counter-clockwise manner. This reconstruction also is compatible with a general model for the early evolution of the Gulf basin that includes 1) a Late Triassic to Middle Jurassic rift stage and formation of transitional crust, culminating with the widespread deposition of evaporites, 2) a brief Late Jurassic period of oceanic crust formation in the deep central Gulf, 3) a Late Jurassic through Early Cretaceous period of cooling and subsidence of the crust and buildup of extensive carbonate platforms surrounding a deep basin, and 4) formation of a widespread middle Cretaceous unconformity (MCU).