Mojado Formation
Geologic formation in New Mexico, US
From Wikipedia, the free encyclopedia
The Mojado Formation is a geologic formation in southwestern New Mexico. It preserves fossils dating back to the early Cretaceous period.[1][2]
| Mojado Formation | |
|---|---|
| Stratigraphic range: | |
| 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 | 31.505910°N 108.387181°W |
| 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)  Mojado Formation (New Mexico) | |
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]
