The Salado Formation is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

in west

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

and southeastern

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

. It was deposited in the Ochoan

Stage Stage, stages, or staging may refer to: Arts and media Acting * Stage (theatre), a space for the performance of theatrical productions * Theatre, a branch of the performing arts, often referred to as "the stage" * ''The Stage'', a weekly Brit ...

of the

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the s ...

period Period may refer to: Common uses * Period (punctuation) * Era, a length or span of time *Menstruation, commonly referred to as a "period" Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (o ...

Description

The formation consists of up to of

halite Halite ( ), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride ( Na Cl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pi ...

with significant

anhydrite Anhydrite, or anhydrous calcium sulfate, is a mineral with the chemical formula CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with the ...

red beds Red beds (or redbeds) are sedimentary rocks, typically consisting of sandstone, siltstone, and shale, that are predominantly red in color due to the presence of ferric oxides. Frequently, these red-colored sedimentary strata locally contain t ...

, and

polyhalite Polyhalite is an evaporite mineral, a hydrated sulfate of potassium, calcium and magnesium with formula: . Polyhalite crystallizes in the triclinic system, although crystals are very rare. The normal habit is massive to fibrous. It is typica ...

. The formation is found within the Delaware Basin and was deposited after the Capitan Formation, the fossil

reef A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic component, abiotic (non-living) processes such as deposition (geol ...

defining the margins of the Delaware Basin. The Salado Formation lies on the Castile Formation and in turn is overlain by the

Rustler Formation The Rustler Formation is a Formation (geology), geologic formation in Texas. It preserves fossils dating back to the Permian Period (geology), period. See also * List of fossiliferous stratigraphic units in Texas * Paleontology in Texas Refere ...

, and is found almost entirely in the subsurface, with only limited and very poor surface exposures. In locations towards the margins of the Delaware Basin, the Salado Formation is composed mostly of anhydrite and

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate Hydrate, dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk ...

resembling the Castile, and here the contact is placed at a bed of

breccia Breccia ( , ; ) is a rock composed of large angular broken fragments of minerals or Rock (geology), rocks cementation (geology), cemented together by a fine-grained matrix (geology), matrix. The word has its origins in the Italian language ...

thought to represent an

unconformity An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval ...

between the two formations. The Salado Formation, and the underlying Castile Formation, form an

evaporite An evaporite () is a water- soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as oce ...

sequence that formed in a very deep basin (over ) from increasingly saline waters.

History of investigation

The beds belonging to this formation were initially included in the Castile Formation of

George Burr Richardson George Burr Richardson (1872–1949) was an American geologist who participated in extensive field work for the United States Geological Survey (USGS) in Alaska, Pennsylvania, California, Texas, Colorado, and Utah. In Texas, Richardson described ...

. In 1935, Walter B. Lang removed the upper beds of the Castile, which include extensive halite beds in the subsurface, into the Salado Formation.

Footnotes

References

* * * * * {{cite journal , last1=Richardson , first1=G.B. , author-link1=George Burr Richardson , year=1904 , title=Report of a reconnaissance in Trans-Pecos Texas north of the Texas and Pacific Railway , journal=University of Texas, Mineral Survey Bulletin , volume=9 Permian formations of New Mexico Permian formations of Texas