| Seca Formation | |
| Type: | Geological formation |
| Age: | Late Eocene (Divisaderan-Tinguirirican) ~ |
| Period: | Priabonian |
| Prilithology: | Shale |
| Region: | Santa Elena Province |
| Coordinates: | -2.3°N -80.8°W |
| Paleocoordinates: | -4.8°N -73.8°W |
| Unitof: | Ancón Group |
| Underlies: | Punta Ancón Formation |
| Overlies: | Socorro Formation |
| Extent: | Progreso Basin |
The Seca Formation is a Late Eocene (Divisaderan to Tinguirirican in the SALMA classification) geologic formation of the Progreso Basin in southwestern Ecuador. The shales of the formation have provided fossils of the marine snake Pterosphenus sheppardi.[1]
The Seca Formation, part of the Ancón Group, conformably overlies the Socorro Formation and is overlain by the Punta Ancón Formation. The Seca Formation comprises grey to greenish shales deposited in a marine platform with submarine fans environment.[2] The formation is a reservoir rock,[3] and potential source rock,[4] in the oil-rich Progreso Basin.