Angostura Formation, Ecuador

For other uses, see Angostura Formation.

The Angostura Formation is a Late Miocene (Mayoan to Montehermosan in the SALMA classification) geologic formation of the Borbón Basin in northwestern Ecuador.^[1]

Angostura Formation
Stratigraphic range: Late Miocene (Mayoan-Montehermosan) ~11.6–5.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Santiago Group
Underlies	Onzole Formation
Overlies	Viche Formation
Thickness	150 m (490 ft)
Lithology
Primary	Sandstone
Other	Conglomerate
Location
Coordinates	1.0°N 79.6°W / 1.0; -79.6
Approximate paleocoordinates	0.6°N 78.0°W / 0.6; -78.0
Region	Esmeraldas Province
Country	Ecuador
Extent	Borbón Basin
Angostura Formation, Ecuador (Ecuador)

Description

The coarse sandstones and beds of conglomerates, about 150 metres (490 ft) in thickness. The formation is resistant to erosion and is largely barren, but at a few places there are lenses or interbeds filled with finely preserved fossils. The formation overlies the Viche Formation, and is overlain by the lower Onzole Formation. The Angostura Formation is time-equivalent with the fossiliferous Gatún Formation of Panama.^[1]

Fossil content

The formation has provided bivalve and gastropod fossils.^[1]

See also

• List of fossiliferous stratigraphic units in Ecuador