Mojado Formation

Mojado Formation
Stratigraphic range: Albian PreꞒ Ꞓ O S D C P T J K Pg N
Type	Formation
Underlies	Cowboy Spring Formation
Overlies	U-Bar Formation
Thickness	5,150–7,800 feet (1,570–2,380 m)
Lithology
Primary	Sandstone
Other	Shale, limestone, siltstone
Location
Coordinates	31°30′21″N108°23′14″W / 31.505910°N 108.387181°W / 31.505910; -108.387181
Region	New Mexico
Country	United States
Type section
Named for	Mojado Pass
Named by	R.A. Zeller Jr.
Year defined	1962
Mojado Formation (the United States) Show map of the United States Mojado Formation (New Mexico) Show map of New Mexico

The Mojado Formation is a geologic formation in southwestern New Mexico. It preserves fossils dating back to the early Cretaceous period. ^{[1] [2]}

Description

The formation consists mostly of sandstone and shale, with some limestone, and siltstone. ^[3] It rests conformably on the U-Bar Formation ^[2] and is unconformably overlain by the Cowboy Spring Formation.The total thickness is 5,150–7,800 feet (1,570–2,380 m). ^[4]

Lucas and his coinvestigators assigned the formation to the Bisbee Group and divided it into the Fryingpan Spring, Sarten, Beartooth, and Rattlesnake Ridge members. ^[3]

The Fryingpan Spring Member is interpreted as continental deltaic sedimentation. ^[5] The Sarten Member is fluvial while the Rattlesnake Ridge Member represents a return to shallow marine conditions. ^[6]

Fossils

The formation contains fossil mollusks such as gastropods, ammonites, and pelecypod, ^[2] foraminifera, and scaphopods. These date the formation to the late Albian. ^[4]

History of investigation

The formation name was first used by Zeller in 1962, ^[1] but he did not formally name the formation until 1965. ^[2] In 1998, Lucas and coinvestigators assigned the formation to the Bisbee Group and divided it into the Fryingpan Spring, Sarten, Beartooth, and Rattlesnake Ridge members. ^[3] However, Lawton abandoned the Beartooth Member in 2004. ^[6]

See also

• Earth sciences portal
• Paleontology portal

• List of fossiliferous stratigraphic units in New Mexico
• Paleontology in New Mexico

Footnotes

1. Zeller 1962.
2. Zeller 1965.
3. Lucas & Estep 1998.
4. Zeller & Alper 1965.
5. Hayes 1970.
6. Lawton 2004, pp. 162–163.

References

• Hayes, P.T. (1970). "Cretaceous paleogeography of southeastern Arizona and adjacent areas". U.S. Geological Survey Professional Paper. 658-B: B1 –B42. doi: 10.3133/pp658B .
• Lawton, Timothy F. (2004). "Upper Jurassic and lower Cretaceous strata of southwestern New Mexico and northern Chihuahua, Mexico". In Mack, G.H.; Giles, K.A. (eds.). The geology of New Mexico. A geologic history: New Mexico Geological Society Special Volume 11. pp. 153–168. ISBN   9781585460106.
• Lucas, Spencer G.; Estep, John W. (1998). "Lithostratigraphy and biostratigraphy of the lower-middle Cretaceous Bisbee group, southwestern New Mexico". New Mexico Museum of Natural History and Science Bulletin. 14. Retrieved 5 August 2020.
• Zeller, R.A. Jr. (1962). "Reconnaissance geologic map of southern Animas Mountains [New Mexico]". New Mexico Bureau of Mines and Mineral Resources Geologic Map. 17. Retrieved 5 August 2020.
• Zeller, R.A. Jr. (1965). "Stratigraphy of the Big Hatchet Mountains Area, New Mexico". New Mexico Bureau of Mines and Mineral Resources Memoir. 16. Retrieved 11 October 2021.
• Zeller, R.A. Jr.; Alper, A.M. (1965). "Geology of the Walnut Wells quadrangle, Hidalgo County, New Mexico" (PDF). New Mexico Bureau of Mines and Mineral Resources Bulletin. 84. Retrieved 5 August 2020.