Ranquil Formation
| Ranquil Formation Stratigraphic range: Miocene–Pliocene | |
|---|---|
| Type | Geological formation |
| Underlies | Tubul Formation |
| Overlies | Eocene sedimentary formations |
| Lithology | |
| Primary | Conglomerate with clay and silt matrix, breccia, sandstone, siltstone, mudstone |
| Other | Conglomerate with sand matrix |
| Location | |
| Region | Bío Bío Region |
| Country | Chile |
| Type section | |
| Named for | Caleta Ranquil |
| Named by | Juan Tavera |
Ranquil Formation (Spanish: Formación Ranquil) is a Miocene and Pliocene sedimentary formation located in Arauco Province in south–central Chile, including outcrops in Mocha Island. The formation has its greatest thicknesses in the south-west, where its sediments were largely deposited in marine conditions. It overlies unconformably various sedimentary formations dated to the Eocene.[1] The formation is part of the fill of Arauco Basin which is a sedimentary basin that extends south of Concepción.[2]
The formation has been subdivided into five units, with the lowermost being made up of sandstone and shale, and the second lowest one being made up of a conglomerate. The middle unit is made up of mudrock and massive sandstone. At some places the middle unit is overlain by a unit made up of sandstone with thin layers of conglomerate and sandstone that has been bioturbated. The uppermost unit include a breccia and the so-called Huenteguapi sandstone.[2]
The formation was first defined in 1942 by Juan Tavera.[1]
See also
References
- 1 2 García A., Floreal (1968). Ceccioni, Giovanni, ed. El Terciario de Chile Zona Central (in Spanish). Santiago de Chile: Ediorial Andrés Bello. p. 25–57.
- 1 2 Le Roux, J.P.; Nielsen, Sven N.; Kemnitz, Helga; Henriquez, Álvaro (2008). "A Pliocene mega-tsunami deposit and associated features in the Ranquil Formation, southern Chile" (PDF). Sedimentary Geology 203 (1): 164–180. Retrieved 11 April 2016.