La Colonia Formation
The La Colonia Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.
| La Colonia Formation | |
|---|---|
| Stratigraphic range: Campanian-Maastrichtian ~ | |
An outcrop of the La Colonia Formation on the Somún Curá plateau that is the type locality of Chubutinectes. Photographed in 2009. | |
| Type | Geological formation |
| Sub-units | Lower, Middle and Upper members |
| Underlies | El Buitre & Sarmiento Formations |
| Overlies | Cerro Barcino & Paso del Sapo Formations |
| Thickness | Up to 210–240 m (690–790 ft) Thinning to 17 m (56 ft) around Telsen |
| Lithology | |
| Primary | Siltstone |
| Other | Sandstone, claystone, conglomerate |
| Location | |
| Coordinates | 43.0°S 67.5°W |
| Approximate paleocoordinates | 45.7°S 53.8°W |
| Region | Chubut Province |
| Country | Argentina |
| Extent | Cañadón Asfalto Basin |
| Type section | |
| Named for | Sierra La Colonia |
La Colonia Formation (Argentina) | |
Originally thought to be Campanian (c.73-72 million years ago) in age or earlier, studies of underlying formations have made a Maastrichtian (70–66 million years ago) age more likely.
It is divided up into three distinct facies, the first is up to 16 metres (52 ft) thick and consists of conglomerate, the second is by far the thickest at over 100 metres (330 ft), consists of siltstone and claystone, with interbeds of claystone/shale and sandstone, the third is less than 10 metres (33 ft) thick and consists of clay, and probably represents a nearshore marine environment.