| Tralcán Formation | |
| Type: | Geological formation |
| Period: | Rhaetian |
| Age: | Rhaetian |
| Otherlithology: | Shale |
| Namedfor: | Tralcán |
| Namedby: | Aguirre & Levi |
| Year Ts: | 1964 |
| Region: | Los Ríos Region |
| Coordinates: | -39.8°N -72.5°W |
| Underlies: | Quaternary glacial deposits |
| Overlies: | Trafún Metamorphic Complex |
| Thickness: | >800m (2,600feet) |
Tralcán Formation (Spanish; Castilian: Formación Tralcán) is a sedimentary formation of Triassic age in Los Ríos Region in south–central Chile. It overlies unconformably the Trafún Metamorphic Complex. Tralcán Formation and nearby Panguipulli Formation form possibly the remnants of an ancient lake and river system. The formation is named after Mount Tralcán on the western edge of Riñihue Lake.[1]
The Tralcán Formation was first defined by Aguirre and Levi in 1964, based on the outcrop at Tralcán. The more than 800m (2,600feet)[1] thick formation comprises reddish-grey conglomerates with a sandy matrix and intercalated reddish shales. The shales of the formation contain abundant fossil flora. Fossils of Cladophlebistenia oeshi have helped to redefine the age of the formation, that was formerly considered Late Jurassic (Kimmeridgian to Tithonian), to the Rhaetian of the Triassic.[2]
The following genera of fossil flora have been identified in the formation:[1]