Stratigraphic range: Early Pleistocene
|Thickness||>100 m (330 ft)|
|Primary||Clay-rich sandstone and silt|
|Region||Bío Bío Region|
|Named for||Caleta Tubul|
|Named by||Egidio Feruglio|
Tubul Formation (Spanish: Formación Tubul) is an Early Pleistocene (formerly described as Middle Pliocene in 1968 and Late Pliocene in 1976) sedimentary formation located in Arauco Province in south–central Chile. Its sediments were deposited in marine conditions. It overlies unconformably the folded sedimentary formations of Ranquil (Miocene–Pliocene), Quiriquina (Late Cretaceous) and the Lebu Group (Paleocene-Eocene).
Mollusc fossils found in the formation derives from soft-bed environments (contrary to rocky coasts). Evidence from the fossil mollusc fauna of the Tubul Formation seem to indicate that local water temperatres were lower in the Pliocene than today. Waters and mollusc faunas of Magallanes Region are modern-day equivalents of Tubul Formation.
- Las Peñas (Tubul Fm) at Fossilworks.org
- García A., Floreal (1968). Ceccioni, Giovanni (ed.). El Terciario de Chile Zona Central (in Spanish). Santiago de Chile: Ediorial Andrés Bello. pp. 25–57.
- Valdovinos, Claudio; Nielsen, Sven N. (2006). "Mollusks of the Tubul Formation (South-Central Chile): Implications for the Early Pleistocene climate of the Southeastern Pacific" (PDF). XI Congreso Geológico Chileno. II. pp. 135–138.
- S. N. Nielson and C. Valdovinos. 2008. Early Pleistocene mollusks of the Tubul Formation, south-central Chile. The Nautilus 122(4):201-216