Chapter 15 Depositional Evolution of the Gulf of Mexico Sedimentary Basin

Abstract

Abstract The Gulf of Mexico is a small ocean basin lying between the North American plate and the Yucatan block. Following initiation in the Middle Jurassic, sea-floor spreading continued approximately 25 Myr. Spreading was asymmetric, creating a broad area of attenuated transitional continental crust beneath the northern basin. Initially, widespread, thick salt deposits accumulated across much of the basin; mobilization of this salt by subsequent sedimentary loading has created a complex suite of gravity tectonic structures. Most salt is now allochthonous, forming extensive stocks and canopies. By the end of the Mesozoic, thermal subsidence had created a deep basin floor, flanked by continental shelves. The resultant basin contains a succession of Late Jurassic through Holocene strata that is as much as 20 km thick. Sediment supply from the North American continent has filled nearly one-half of the basin since its inception, primarily by offlap of the northern and northwestern margins. Depositional history can be generalized in seven phases: (1) Middle-Late Jurassic evaporite and carbonate deposition in a broad, shallow, restricted to open marine basin. (2) Latest Jurassic-Early Cretaceous sand-rich clastic progradation from the northern margins. (3) Late-Early Cretaceous development of a rimmed carbonate shelf. (4) Late Cretaceous mixed clastic and carbonate aggradation of the continental margins. (5) Resurgent Paleogene clastic progradation and filling centered in the NW basin. (6) Miocene progradation and basin filling centered in the central and NE Gulf. (7) Late Neogene climatically and eustatically influenced progradation along the central Gulf margin. In contrast to the broad, progradational sediment wedge of the northern Gulf, the Florida margin is a primarily aggradational carbonate platform.