How were salt domes formed beneath the Gulf of Mexico?

Salt domes beneath the Gulf of Mexico formed through a process driven by the gravitational instability of buried salt deposits.1

The process began when the Gulf of Mexico basin formed as the Yucatán Peninsula separated from the continent, leading to the precipitation of thick salt layers on the basin floor due to evaporation. Over time, these salt deposits were buried by denser sedimentary strata, such as sandstone. Because salt is a relatively plastic material with a lower density than the overlying rock, it became gravitationally unstable.21

Under the influence of pressure and temperature at depth, the salt began to flow upward, initially forming rounded "salt pillows" and eventually breaking through the overlying layers to create plug-shaped salt domes. As the salt moved, it deformed the surrounding strata, often creating faults and rim synclines. This upward growth has continued alongside the deposition of additional sediments, with some domes reaching the surface, such as the Sigsbee Knolls.1345