Why is the Gulf of Mexico so rich in fossil fuel deposits?

Despite the continuous exploration, the Gulf of Mexico still has enormous quantities of oil and gas deposits.

From around 335 million years ago until 200 million years ago, all land on Earth was concentrated on a single continent known as Pangea and surrounded by a vast ocean. Then, the massive continent was split as a result of a 6,000-kilometer fracture into two smaller supercontinents (Laurasia and Gondwana) from which the current continents of Earth emerged. 

A section of the large fracture that split Pangea apart subsequently expanded and stretched to create a large depression that would eventually become what we now know as the Gulf of Mexico basin. About 150 million years ago, the basin deepened due to lateral spreading and was periodically filled with water (initially from the Pacific Ocean and later from the Atlantic Ocean). The re-filling cycles resulted in the formation of vast salt deposits with thicknesses of up to 4 kilometers. Those deposits, among other things, were crucial for the basin to host vast amounts of fossil fuels.

The erosion processes that took place in the mainland transported massive amounts of debris into the Gulf of Mexico to create seafloor deposits that overly the salt formations. About 100-120 million years ago, a steep landmass developed in the eastern part of the basin after sediment deposition on a crystal block. That landmass would eventually evolve into the Florida peninsula.

According to recent studies conducted via seismic imaging, a technique for determining the characteristics of the underground rock formations from seismic data, there are still vast quantities of fossil fuels in the basin despite its exploration for over 60 years. In fact, the basin consists of multiple petroleum systems and stacked reservoirs.

There are 2 main reasons that the Gulf contains those amounts of gas and oil:

1. The salt deposits that govern how fossil fuel basins shape. In particular, salt is a more deformable rock compared to other sedimentary formations and it may readily create more space and room for the collection of fossil fuels. It also acts as a preservative for gas and oil since it moderates heat around the deposits. In fact, salt formations that surround oil and gas prevented people from detecting them via previously-used techniques.

2. The constant supply of coarse-grained and fine-grained sediments mainly through erosion processes that take place on the land of North America (sediments are mostly carried away via rivers).

Nonetheless, the deposits that exist in the salt rock "blanket" are not easily accessible. Reaching and extracting them is not an easy task but some believe it is our best change regarding power generation from fossil fuels. New methods of exploration constantly evolve and the process may be facilitated in the future.

Findings on the Gulf of Mexico fossil fuel reservoirs were recently published in the American Association of Petroleum Geologists Bulletin.

A video explaining the development of the Gulf of Mexico basin can be found below.