The Louann Salt is a widespread evaporite

Evaporite

Evaporite is a name for a water-soluble mineral sediment that result from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporate deposits, marine which can also be described as ocean deposits, and non-marine which are found in standing bodies of...

 formation that formed in the Gulf of Mexico

Gulf of Mexico

The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...

 during the Callovian

Callovian

In the geologic timescale, the Callovian is an age or stage in the Middle Jurassic, lasting between 164.7 ± 4.0 Ma and 161.2 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the Oxfordian....

 in the mid Jurassic

Jurassic

The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

. The Louann formed in a rift

Rift

In geology, a rift or chasm is a place where the Earth's crust and lithosphere are being pulled apart and is an example of extensional tectonics....

 as the South American

South American Plate

The South American Plate is a continental tectonic plate which includes the continent of South America and also a sizeable region of the Atlantic Ocean seabed extending eastward to the Mid-Atlantic Ridge....

 and North American Plate

North American Plate

The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, Bahamas, and parts of Siberia, Japan and Iceland. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust...

s separated, from an embayment of the Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

. The Louann underlies much of the northern Gulf coast from Texas

Texas

Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...

 to the Florida

Florida

Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

 panhandle and extends beneath large areas of the Gulf coastal plain of Mississippi

Mississippi

Mississippi is a U.S. state located in the Southern United States. Jackson is the state capital and largest city. The name of the state derives from the Mississippi River, which flows along its western boundary, whose name comes from the Ojibwe word misi-ziibi...

, Louisiana

Louisiana

Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...

 and Texas.

The Campeche Salt or Isthmaian Salt is the contemporaneous salt layer that developed on the south margin of the Gulf rift. It extends from Campeche

Campeche

Campeche is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Located in Southeast Mexico, it is bordered by the states of Yucatán to the north east, Quintana Roo to the east, and Tabasco to the south west...

, Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 north along the west margin of the Campeche Bank

Campeche Bank

Campeche Bank is part of the Gulf of Mexico and extends from the Yucatan Straits in the east to the Tabasco-Campeche Basin in the west.Among the reefs with islets on Campeche Bank are Cayos Arcas in the southwest and Arrecife Alacran in the north....

 north of the Yucatan Peninsula

Yucatán Peninsula

The Yucatán Peninsula, in southeastern Mexico, separates the Caribbean Sea from the Gulf of Mexico, with the northern coastline on the Yucatán Channel...

.

The Orca Basin

Orca Basin

The Orca Basin is a mid-slope, silled, mini-basin in the northern Gulf of Mexico some 300 km southwest of the Mississippi River mouth on the Louisiana continental slope. It is unique amongst the mini-basins in this area, in containing a large brine pool of anoxic salt brine...

 is a distinctive brine pool

Brine pool

Brine pools are large areas of brine on the ocean basin. These pools are bodies of water that have a salinity three to five times greater than the surrounding ocean. For deep-sea brine pools, the source of the salt is the dissolution of large salt deposits through salt tectonics...

 on the Louisiana continental shelf

Continental shelf

The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...

.

One of the many salt dome

Salt dome

A salt dome is a type of structural dome formed when a thick bed of evaporite minerals found at depth intrudes vertically into surrounding rock strata, forming a diapir....

s derived from the Louann was the site of the Spindletop

Spindletop

Spindletop is a salt dome oil field located in the southern portion of Beaumont, Texas in the United States. The Spindletop dome was derived from the Louann Salt evaporite layer of the Jurassic geologic period. On January 10, 1901, a well at Spindletop struck oil . The new oil field soon produced...

 oil

Petroleum

Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...

 strike near Beaumont, Texas

Beaumont, Texas

Beaumont is a city in and county seat of Jefferson County, Texas, United States, within the Beaumont–Port Arthur Metropolitan Statistical Area. The city's population was 118,296 at the 2010 census. With Port Arthur and Orange, it forms the Golden Triangle, a major industrial area on the...

in 1901.