The Huayquerías Formation () is a

Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...

fossiliferous A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved i ...

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

of the Frontal Cordillera and

Cuyo Basin Cuyo Basin () is a sedimentary basin in Mendoza Province, western Argentina. The Cuyo Basin has a NNW-SSE elongated shape and is limited to the west by the Sierra Pintada System and to the east by the Pampean pericraton. To the north the basin re ...

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

. The formation crops out in the central

Mendoza Province Mendoza (), officially the Province of Mendoza, is a province of Argentina, in the western central part of the country in the Cuyo region. It borders San Juan to the north, La Pampa and Neuquén to the south, San Luis to the east, and the r ...

. The formation, with a maximum thickness of , comprises reddish

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from ''shale'' by its lack of fissility.Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, ...

s with thin beds of

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock co ...

s and

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

s, deposited in a

fluvial A river is a natural stream of fresh water that flows on land or inside caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of its course if it ru ...

, environment. The tuff in the formation is dated to 5.84 ± 0.41 Ma, placing it in the

Huayquerian The Huayquerian () age is a period of geologic time (9.0–6.8 Ma) within the Late Miocene epoch of the Neogene, used more specifically within the SALMA classification. It follows the Chasicoan and precedes the Montehermosan age. Etymology T ...

SALMA, the age named after the formation by Kraglievitch in 1934. The formation has provided fossils of the

procyonid Procyonidae ( ) is a New World family (biology), family of the order (biology), order Carnivora. It includes the Procyon (genus), raccoons, ringtails, cacomistles, coatis, kinkajous, olingos, and olinguitos. Procyonids inhabit a wide range of e ...

'' Cyonasua pascuali'' and the

litoptern Litopterna (from "smooth heel") is an extinct order of South American native ungulates that lived from the Paleocene to the Pleistocene-Holocene around 62.5 million to 12,000 years ago (or possibly as late as 3,500 years ago), and were also pres ...

'' Huayqueriana cristata'', named after the formation.

Description

The Huayqueriás Formation, present in the Frontal Cordillera and the neighboring

, was described in 1934 by Kraglievitch as the basis for the

South American land mammal age The South American land mammal ages (SALMA) establish a geologic timescale for prehistoric South American fauna beginning 64.5 Ma during the Paleocene and continuing through to the Late Pleistocene (0.011 Ma). These periods are referred to as age ...

. The name ''Huayquerías'' means "badlands".Forasiepi et al., 2016, p.1 The formation comprises reddish

s with

mudcrack Mudcracks (also known as mud cracks, desiccation cracks or cracked mud) are sedimentary structures formed as muddy sediment dries and contracts.Jackson, J.A., 1997, ''Glossary of Geology'' (4th ed.), American Geological Institute, Alexandria, VA ...

s, paleoburrows and

ichnofossil A trace fossil, also called an ichnofossil (; ), is a fossil record of biological activity by lifeforms, but not the preserved remains of the organism itself. Trace fossils contrast with body fossils, which are the fossilized remains of part ...

s of

vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

s. Thin

layers of up to thick exist in the formation. An ashfall bed exists at below the contact with the slightly angular

unconformably An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval o ...

Yrigoyen, 1993 overlying

Tunuyán Formation Tunuyán is a city in the west of the provinces of Argentina, province of Mendoza Province, Mendoza, Argentina, located on the western shore of the Tunuyán River, south from the provincial capital Mendoza, Argentina, Mendoza and east of the Chil ...

in a total section of .Garrido et al, 2017, p.51 The

has been dated using ⁴⁰K/⁴⁰Ar analysis to 5.84 ± 0.41 Ma.Marshall et al., 1986

Paleontological significance

The Huayquerías Formation has been used to define the

, 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, extending the temporal range of the

SALMAans until near the Miocene-Pliocene limit. The Huayqueriás Formation has provided fossils of '' Cyonasua pascuali'',Linares, 1981, p.118 and the

'' Huayqueriana cristata'', the latter of which, named after the formation.

References

Bibliography

;Geology * * * ;Paleontology * * {{DEFAULTSORT:Huayquerias Formation Geologic formations of Argentina Montehermosan Messinian Miocene Series of South America Neogene Argentina Mudstone formations of Argentina Tuff formations of Argentina Sandstone formations Fluvial deposits Fossiliferous stratigraphic units of South America Paleontology in Argentina Geology of Mendoza Province

Description

Paleontological significance

See also

References

Bibliography