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 / -37.6; -73.7
Approximate paleocoordinates	40.1°S 64.2°W / -40.1; -64.2
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

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