Chapter 16 - Evolution of the Northern Gulf of Mexico Sedimentary Basin

Abstract

The Gulf of Mexico is a small ocean basin lying between the North American craton and the Yucatan continental block. Crustal extension began in the Late Triassic (ca 225Ma) and continued for some 85 million years into the Early Cretaceous. Asymmetric extension created a broad area of highly attenuated transitional continental crust beneath the central portion of the basin, with thicker crustal blocks and basins floored with more extended crust alternating along the northeastern and western margins. Near the close of crustal extension, thick salt deposits accumulated across most of the basin. This salt was mobilized by subsequent sedimentary loading to create a complex suite of gravity tectonic structures. Most of the salt in the central basin is now allochthonous, forming extensive canopies, sheets, and stocks. Sea floor spreading initiated near the beginning of the Late Jurassic (ca 160Ma) and continued for some 20–25 million years splitting the attenuated crust while the margin began to experience thermal subsidence. By the mid-Cretaceous, thermal subsidence in the northern Gulf of Mexico had created a deep basin floor, flanked by wide continental shelves. The basin contains a succession of Late Jurassic through Holocene strata that is as much as 20km thick. Sediment supply from the North American continent has filled much of the northern Gulf of Mexico basin with prograding shelf-margin and slope sediments.