Lebu Group

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
Region Bío Bío Region
Country Chile
Type section
Named for Lebu

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]

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

  1. ↑ What was previously known as Caleta Viel Formation is now considered to be the roof Millongue Formation.[2]

References

  1. 1 2 3 García A., Floreal (1968). "Estratigrafía del Terciario de Chile Central". In Ceccioni, Giovanni. El Terciario de Chile Zona Central (in Spanish). Santiago de Chile: Ediorial Andrés Bello.
  2. ↑ 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.
  3. ↑ 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.
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