Atarque Sandstone
The Atarque Sandstone is a geologic formation in New Mexico. It preserves fossils dating back to the late Cretaceous period.[1]
| Atarque Sandstone Stratigraphic range: late Cretaceous | |
|---|---|
| Type | Formation |
| Underlies | Moreno Hill Formation |
| Overlies | Rio Salado Tongue, Mancos Shale |
| Thickness | 100 feet (30 m) |
| Lithology | |
| Primary | Sandstone |
| Other | Shale |
| Location | |
| Coordinates | 35.131797°N 108.651864°W |
| Region | New Mexico |
| Country | United States |
| Type section | |
| Named for | Atarque settlement |
| Named by | W.S. Pike, Jr. |
| Year defined | 1947 |
  Atarque Sandstone (the United States)  Atarque Sandstone (New Mexico) | |
Description
The formation consists of very fine to fine buff fossiliferous sandstone with a maximum thickness of 100 feet (30 m). The beds are flat, massive and have low-angle crossbedding. The formation intertongues with the underlying Rio Salado Tongue of the Mancos Shale and is overlain by either the Carthage Member of the Tres Hermanos Formation or the Moreno Hill Formation. It was deposited during the early to middle Turonian Age of the late Cretaceous.[2]
The formation is interpreted as a coastal barrier sandstone deposited by a regression of the Western Interior Seaway to the northeast.[2]
Fossils
The formation contains fossil pelecypods and plesiosaur vertebra.[3] It also contains fossils of the ammonite Spathites rioensis characteristic of the middle Turonian.[4]
History of investigation
The unit was first defined as the Atarque Member of the Mesaverde Formation by W.S. Pike in 1947. Pike assigned the lowermost 127 feet (39 m) of the Mesaverde in the San Juan Basin to the unit.[1] S.C. Hook and coinvestigators revised the Cretaceous stratigraphy of the San Juan and Zuni basins in 1983 and assigned both Pike's Atarque Member and beds in the Zuni Basin assigned to the lower Gallup Sandstone to the Tres Hermanos Formation. The Atarque Member was redefined as the lower sandstone beds of the Tres Hermanos Formation.[2] Simultaneously, M.W. McLellan and coinvestigators raised the Atarque to formation rank as the Atarque Sandstone in the Salt Lake coal field of west-central New Mexico.[3]
Footnotes
References
- Cobban, W.A. (1988). "The Late Cretaceous ammonite Spathites Kummel and Decker in New Mexico and Trans-Pecos Texas" (PDF). New Mexico Bureau of Mines and Mineral Resources Bulletin. 114: 5–21. Retrieved 10 September 2020.
- Hook, S.C.; Molenaar, C.M.; Cobban, W.A. (1983). "Stratigraphy and revision of nomenclature of upper Cenomanian to Turonian (Upper Cretaceous) rocks of west-central New Mexico" (PDF). New Mexico Bureau of Mines and Mineral Resources Circular. 185: 7–28. Retrieved 2 August 2020.
- McLellan, M.W.; Haschke, L.R.; Robinson, L.N.; Carter, M.D.; Medlin, A.L. (1983). "Middle Turonian and younger Cretaceous rocks, northern Salt Lake coal field, Cibola and Catron Counties, New Mexico" (PDF). New Mexico Bureau of Mines and Mineral Resources Circular. 185: 41–47. Retrieved 2 August 2020.
- Pike, W.S., Jr. (1947). "Intertonguing marine and nonmarine Upper Cretaceous deposits of New Mexico, Arizona, and southwestern Colorado". Geological Society of America Memoir. Geological Society of America Memoirs. 24: 1–115. doi:10.1130/MEM24-p1. ISBN 9780813710242. Retrieved 2 August 2020.