Lebu Group
Lebu Group is stratigraphic unit of Arauco Basin in south-central Chile. The group consists of a sequence of four formations, of both marine and nonmarine origin, deposited between the Early Paleocene and Middle Eocene.[1]
Lebu Group | |
---|---|
Stratigraphic range: Paleocene–Eocene | |
Type | Stratigraphic group |
Sub-units | Millongue Formation Trihueco Formation Boca Lebu Formation Curanilahue Formation |
Underlies | Ranquil Formation |
Overlies | Quiriquina Formation |
Lithology | |
Primary | Shale, sandstone, siltstone, mudstone |
Other | Coal |
Location | |
Coordinates | 37.6°S 73.7°W |
Approximate paleocoordinates | 40.1°S 64.2°W |
Region | Bío Bío Region |
Country | Chile |
Extent | Arauco Basin |
Type section | |
Named for | Lebu |
Lebu Group (Chile) |
Description
The group is made up of four formations, from youngest to oldest these are: Millongue Formation,[note 1] Trihueco Formation, Boca Lebu Formation and Curanilahue Formation.[1]
The Eocene Millongue Formation is composed of shale and siltstone of both marine and continental origin. Its top is marked by an unconformity, the so-called “main unconformity” of Arauco Basin, which is thought to have formed by erosion during a period of tectonic inversion.[1][3]
Notes
- What was previously known as Caleta Viel Formation is now considered to be the roof Millongue Formation.[2]
References
- García A., Floreal (1968). "Estratigrafía del Terciario de Chile Central". In Ceccioni, Giovanni (ed.). El Terciario de Chile Zona Central (in Spanish). Santiago de Chile: Ediorial Andrés Bello.
- Palma-Heldt, S.; Quinzio, L.A.; Bonilla, R.; Cisterna, K. (2009). Implicancias estratigráficas del primer registro de Notofagadites en el Paleógeno de la Cuenca de Arauco, Región del Bío-Bío, Chile (PDF). XII Congreso Geológico Chileno (in Spanish). Santiago, Chile.
- Becerra, Juan; Contreras-Reyes, Eduardo; Arriagada, César (2013). "Seismic structure and tectonics of the southern Arauco Basin, south-central Chile (~ 38°S)". Tectonophysics. 592: 53–66. Bibcode:2013Tectp.592...53B. doi:10.1016/j.tecto.2013.02.012.
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