Mojado Formation | |
---|---|
Stratigraphic range: Albian
| |
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″N 108°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 |
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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]
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]
The formation contains fossil mollusks such as gastropods, ammonites, and pelecypod,[2] foraminifera, and scaphopods. These date the formation to the late Albian.[4]
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]