Anacleto Formation

Anacleto Formation Stratigraphic range: Late Campanian
Type	Geological formation
Unit of	Neuquén Group
Underlies	Allen Formation
Overlies	Bajo de la Carpa Formation
Location
Country	Argentina

The Anacleto Formation is a geologic formation with outcroppings in the Argentine Patagonian provinces of Mendoza, Río Negro, and Neuquén. It is the youngest formation within the Neuquén Group and belongs to the Río Colorado Subgroup. Formerly that subgroup was treated as a formation, and the Anacleto Formation was known as the Anacleto Member.

The type locality of this formation lies 40 kilometers west of the city of Neuquén. At its base, the Anacleto Formation conformably overlies the Bajo de la Carpa Formation, also of the Río Colorado Subgroup, and it is in turn unconformably overlain by the Allen Formation of the younger Malargüe Group.

The Anacleto Formation varies between 60 and 90 meters thick, and consists mainly of claystones and mudstones, purple and dark red in color, of fluvial origin. Geodes are often found scattered throughout this formation.

Era: Mesozoic
Period: Late Cretaceous
Faunal stage: early Campanian
Absolute Age: ~83 to ~78 mya

Nests of dinosaur eggs, many with preserved embryos inside, have been discovered in large quantities at the famous Auca Mahuevo locality, and have been attributed to titanosaurs.

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