Sarmiento Formation
| Sarmiento Formation | |
|---|---|
| Stratigraphic range: Bartonian-Burdigalian (Casamayoran-Colhuehuapian) ~ | |
| Sub-units | Colhué Huapí Member, Gran Barranca Member, Puesto Almendra Member, Rosado Member, Trelew Member, and Vera Member |
| Underlies | Chenque Formation Gaiman Formation |
| Overlies | Koluel Kaike Formation (Río Chico Group) |
| Thickness | 319 metres |
| Lithology | |
| Primary | Sandstone, mudstone |
| Other | Limestone |
| Location | |
| Country | Argentina |
| Extent | Golfo San Jorge Basin |
| Type section | |
| Named for | Sarmiento, Chubut |
| Region | Chubut Province |
| Country | Argentina |
| Thickness at type section | 319 metres (1,047 ft) (tuffs) |
Location of the Sarmiento Formation within Argentina | |
The Sarmiento Formation (Spanish: Formación Sarmiento), in older literature described as the Casamayor Formation, is a geological formation in Chubut Province, Argentina, in central Patagonia, which spans around 30 million years from the mid-Eocene to the early Miocene. It predominantly consists of pyroclastic deposits, which were deposited in a semi-arid environment. It is divided up into a number of members. The diverse fauna of the Sarmiento Formation, including a variety of birds, crocodilians, turtles and snakes, also includes many mammals such as South American native ungulates (notoungulates, litopterns, astrapotheres) as well as armadillos, and caviomorph rodents.