The Neuquén Group is a

group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic iden ...

geologic 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 exp ...

s found in

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 ...

. Rocks in the Neuquén Group fall within the

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

to early

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

stages of the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

Period. It overlies the older

Lohan Cura Formation The Lohan Cura Formation is a geologic formation with outcrops in the Argentine provinces of Río Negro, Neuquén, and Mendoza. It is the second oldest Cretaceous terrestrial formation in the Neuquén Basin. The Lohan Cura Formation unconformab ...

and is itself overlain by the younger

Allen Formation The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous (middle Campanian to early Maastrichtian.Salgado et al., 2007 Dinosaur remains are among the fossils that have been recovered from the forma ...

of the

Malargüe Group The Malargüe Group is a group of geologic formations of the Neuquén Basin of the Mendoza, Neuquén, Río Negro and La Pampa Provinces in northern Patagonia, Argentina. The formations of the Malargüe Group range in age between the middle Campa ...

, separated from both by

unconformities An unconformity is a buried erosion surface, erosional or non-depositional surface separating two Rock (geology), rock masses or Stratum, strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer ...

, dated to 98 and 79 Ma respectively.Leanza et al., 2004, p. 63

Description

Deposits have been located in the

provinces A province is an administrative division within a country or state. The term derives from the ancient Roman , which was the major territorial and administrative unit of the Roman Empire's territorial possessions outside Italy. The term ''provi ...

of Río Negro,

Neuquén Neuquén (; ) is the capital city of the Argentine province of Neuquén and of the Confluencia Department, located in the east of the province. It occupies a strip of land west of the confluence of the Limay and Neuquén rivers which form t ...

, and Mendoza. Although several different types of environments are represented in various sections of the Neuquén Group, the dominant regime is

alluvial Alluvium (, ) is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluvium is also sometimes called alluvial deposit. Alluvium is ...

deposition. Many

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

and other

fossil 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 preserve ...

types have been discovered in these sediments.

Subdivision

There are seven formations within the Neuquén Group. These are divided into three subgroups named after major rivers in the area. In some works, the subgroups themselves are treated as formations and what usually is considered to be the formations as mere members of these. However, particularly in the Río Limay Subgroup, the formations are clearly composed of very distinct rock layers.Sánchez ''et al.'' (2006) Neuquén Group strata, ordered from youngest to oldest * Río Colorado Subgroup (

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

to early Campanian) **

Anacleto Formation The Anacleto Formation is a geologic formation with outcrops in the Argentina, Argentine Patagonian provinces of Mendoza Province, Mendoza, Río Negro Province, Río Negro, and Neuquén Province, Neuquén. It is the youngest formation within the ...

(early Campanian) **

Bajo de la Carpa Formation The Bajo de la Carpa Formation is a geologic formation of the Neuquén Basin that outcrop, crops out in northern Patagonia, in the provinces of Río Negro Province, Río Negro and Neuquén Province, Neuquén, Argentina. It is the oldest of two for ...

(Santonian) *

Río Neuquén Subgroup The Río Neuquén Subgroup is a geological subgroup in the Neuquén Basin, Neuquén Province, Argentina, whose strata date back to the Late Cretaceous. The subgroup, formerly defined as a formation, is the middle unit of the Neuquén Group and co ...

(late Turonian to

Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by ...

) **

Plottier Formation The Plottier Formation is a geologic formation that outcrops in the Argentine Patagonian provinces of Río Negro and Neuquén. It is the younger of two formations belonging to the Río Neuquén Subgroup within the Neuquén Group of the Neuquén ...

(late Coniacian ?to early Santonian) **

Sierra Barrosa Formation The Sierra Barrosa Formation is a geologic formation of the Neuquén Basin in the northern Patagonian provinces of Mendoza Province, Mendoza and Neuquén Province, Neuquén. The formation dates to the Late Cretaceous, Coniacian, middle to late Con ...

(middle Coniacian) ** Los Bastos Formation (early Coniacian) **

Portezuelo Formation The Portezuelo Formation is a geologic formation of Late Cretaceous (Turonian, Late Turonian to Coniacian, Early Coniacian) age, outcropping in the Mendoza Province, Mendoza, Río Negro Province, Río Negro and Neuquén Province, Neuquén provinc ...

(late Turonian to earliest Coniacian) ** Cerro Lisandro Formation (middle Turonian) *

Río Limay Subgroup The Río Limay Subgroup is a geological unit of the Neuquén Group in the Neuquén Basin of Neuquén, Mendoza and Río Negro Provinces, northern Patagonia, Argentina. The strata date back to the Late Cretaceous ( Early Cenomanian to Early Turon ...

(Cenomanian to early

Turonian The Turonian is, in the International Commission on Stratigraphy, ICS' geologic timescale, the second age (geology), age in the Late Cretaceous epoch (geology), Epoch, or a stage (stratigraphy), stage in the Upper Cretaceous series (stratigraphy), ...

) **

Lisandro Formation __NOTOC__ The Lisandro Formation, alternatively known as the Cerro Lisandro Formation, is a Late Cretaceous ( Late Cenomanian to Early Turonian) geologic formation with outcrops in the Neuquén, Río Negro and Mendoza Provinces of Argentina. It ...

(middle to late Turonian) **

Huincul Formation The Huincul Formation is a geologic formation of Late Cretaceous (Cenomanian to Turonian, Early Turonian) age of the Neuquén Basin that outcrops in the Mendoza Province, Mendoza, Rio Negro Province, Río Negro and Neuquén Provinces of northern ...

(late Cenomanian to early Turonian) **

Candeleros Formation The Candeleros Formation is a geologic formation that outcrop, crops out in the Rio Negro Province, Río Negro, Neuquen Province, Neuquén, and Mendoza Province, Mendoza provinces of northern Patagonia, Argentina. It is the oldest formation in the ...

(early Cenomanian) South of

Añelo Añelo is the second category municipality located in the Añelo Department in Neuquén Province, Argentina. Economy The economy of Añelo is based on agriculture. One of the most important crops are grapes as in the near town of San Patricio de ...

, on the road between Lake Los Barreales and the

Neuquén River The Neuquén River () is the second most important river of the province of Neuquén in the Argentine Patagonia, after the Limay River. Rocks of the Neuquén Basin are fossiliferous, and the basin hosts what may become important fields of ...

are views on the successively younger formations, starting with the Lisandro Formation to the northwest of Lake Los Barreales, and finally crossing the Anacleto Formation about down the road near the eastern tip of the lake. The older strata are exposed south of Lake Los Barreales.

References

Bibliography

* * {{DEFAULTSORT:Neuquen Group Geologic formations of Argentina Upper Cretaceous Series of South America Cretaceous Argentina Mapuche language

Description

Subdivision

See also

References

Bibliography