Type Geological formation Country Chile | Thickness ca. 3,000 m Underlies Farellones Formation | |
Regions O'Higgins Region, Santiago Metropolitan Region, Valparaíso Region | ||
Abanico Formation (Spanish: Formación Abanico) is a 3 km thick sedimentary formation exposed in the Andes of Central Chile. The rocks of the formation sedimented in a timespan from the Eocene to the Miocene. Abanico Formation's contact with the Miocene Farellones Formation that overlies it has been the subject of differing interpretations since the 1960s.
The sediments accumulated in the Abanico Extensional Basin within a context of the Andean orogeny. The basin had a north-south elongated shape that spanned the latitudes of 29–38° S. Tectonic inversion from 21 to 16 million years ago made the basin collapse and the sediments to be incorporated to the Andean cordillera. The northern part of the basin inverted before the southern part. Parts of the formation are known to have experienced Prehnite-pumpellyite facies metamorphism.
The Tinguiririca fauna is known from the fossils found in the Abanico Formation near Tinguiririca River.