The Beclabito Formation is a late Jurassic

sedimentary Sedimentary rocks are types of rock (geology), rock that are formed by the accumulation or deposition of mineral or organic matter, organic particles at Earth#Surface, Earth's surface, followed by cementation (geology), cementation. Sedimentati ...

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 ...

, found in northwestern

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

and northeastern Arizona.

Description

The formation is composed mostly of thinly bedded sandstone,

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...

, and

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...

which is reddish-orange to reddish-brown in color. The sandstone is very fine to medium grained and displays ripple crossbedding, trough crossbedding, and horizontal

laminations Lamination is the technique/process of manufacturing a Raw material, material in multiple layers, so that the composite material achieves improved strength of materials, strength, stability, sound insulation, visual appearance, appearance, or ...

. The siltstones are reddish-brown and show wavy laminations. The formation is thick. The formation

conformably Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology. In general, strata are primarily igne ...

overlies the

Todilto Formation The Todilto Formation is a geologic formation in northern New Mexico and southeastern Colorado. It preserves fossils dating back to the Callovian stage of the middle Jurassic period. Description The formation consists of evaporites. It is di ...

and conformably underlies the

Bluff Formation The Bluff Formation is a geological formation found in the Four Corners area. It was deposited in the late Jurassic Period (geology), Period. Description The Bluff Formation consists of massive wind-deposited (Aeolian processes, eolian) sandston ...

. The formation is interpreted as having been deposited in a marginal marine or coastal sabkha environment.

Investigative history

The formation was first named by S.M. Condon and H.C. Huffman, Jr., as the Beclabito Member of the

Wanakah Formation The Summerville Formation is a geological Formation (geology), formation in New Mexico, Colorado, and Utah of the Southwestern United States. It dates back to the Oxfordian (stage), Oxfordian stage (stratigraphy), stage of the Late Jurassic.Wilcox ...

. The beds making up the formation were previously assigned to the Summerville Formation on the basis of similar lithology and stratigraphic position, and on the similarity of the Curtis Formation that underlies the Summerville Formation to the Todilto Formation that underlies the Beclabito beds, but the correlation is questionable. Steven M. Cather concurred with reassigning the beds from the Summerville to the Beclabito, which he also proposed raising to formation rank. Cather pointed out that the Curtis appears to be younger than the Todilto, calling into question the correlation between the overlying Summerville and Beclabito beds, and that there are significant lithological differences between the Summerville and the Beclabito.

References

{{Reflist Jurassic Arizona Jurassic formations of New Mexico Oxfordian Stage Jurassic System of North America