Huayquerías Formation


The Huayquerías Formation is a Late Miocene fossiliferous geological formation of the Frontal Cordillera and Cuyo Basin of Argentina. The formation crops out in the central Mendoza Province.
The formation, with a maximum thickness of, comprises reddish mudstones with thin beds of tuffs and sandstones, deposited in a fluvial, environment. The tuff in the formation is dated to 5.84 ± 0.41 Ma, placing it in the Montehermosan, which is significantly younger than the Huayquerian SALMA, ranging from 9 to 6.8 Ma, the age named after the formation by Kraglievitch in 1934.
The formation has provided fossils of the procyonid Cyonasua pascuali and the litoptern Huayqueriana cristata, named after the formation.

Description

The Huayqueriás Formation, present in the Frontal Cordillera and the neighboring Cuyo Basin, was described in 1934 by Kraglievitch as the basis for the Huayquerian South American land mammal age. The name Huayquerías means "badlands". The formation comprises reddish mudstones with mudcracks, paleoburrows and ichnofossils of vertebrates. Thin sandstone layers of up to thick exist in the formation. An ashfall bed exists at below the contact with the slightly angular unconformably overlying Tunuyán Formation in a total section of. The tuff has been dated using 40K/40Ar analysis to 5.84 ± 0.41 Ma.

Paleontological significance

The Huayquerías Formation has been used to define the Huayquerian South American land mammal age, ranging from 9.0 to 6.8 Ma. However, later analysis of the ashfall bed in the formation, provided a much younger age of 5.84 ± 0.41 Ma, placing the formation in the Montehermosan SALMA. The Huayqueriás Formation has provided fossils of Cyonasua pascuali, and the litoptern Huayqueriana cristata, named after the formation.