Lebu Group

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 youngers to oldest these are: Millongue Formation,^{[note 1]} Trihueco Formation, Boca Lebu Formation and Curanilahue Formation.^[1]

Eocene Millongue Formation is made up of shale and siltstone of both marine and continental deposition. Its topis made up of 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

^ ^a ^b ^c 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.

[note_1-3] What was previously known as Caleta Viel Formation is now considered to be the roof Millongue Formation.^[2]

[Garcia1968-1] 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.

[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.

[Becerraetal2013-4] 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.

[1]

[note 1]

[3]

[2]