The Lohan Cura Formation is a

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 ...

with

outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. Features Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficia ...

s in the

Argentine Argentines (mistakenly translated Argentineans in the past; in Spanish ( masculine) or ( feminine)) are people identified with the country of Argentina. This connection may be residential, legal, historical or cultural. For most Argentines ...

provinces of Río Negro,

Neuquén Neuquén (; arn, Nehuenken) 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 rive ...

, and Mendoza. It is the second oldest

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

terrestrial formation in the

Neuquén Basin Neuquén Basin ( es, Cuenca Neuquina) is a sedimentary basin covering most of Neuquén Province in Argentina. The basin originated in the Jurassic and developed through alternating continental and marine conditions well into the Tertiary. The ba ...

. The Lohan Cura Formation

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 ...

overlies the terrestrial

La Amarga Formation The La Amarga Formation is a geologic formation with outcrops in the Argentine provinces of Río Negro, Neuquén, and Mendoza. It is the oldest Cretaceous terrestrial formation in the Neuquén Basin. The type locality is La Amarga Arroyo a ...

. In some places it also overlies the older marine Agrio and Bajada Colorada Formations of the

Mendoza Group Mendoza may refer to: Places Argentina * Greater Mendoza, the name given to the large urban conurbation around the city of Mendoza * Mendoza, Argentina, the capital of the province of Mendoza * Mendoza Department, subdivision of the Mendoza Provi ...

through the same Middle Miranican unconformity. It is in turn overlain by the

Candeleros Formation The Candeleros Formation (formerly known as the Candeleros Member of the "Río Limay Formation") is a geologic formation that crops out in the Río Negro, Neuquén, and Mendoza provinces of northern Patagonia, Argentina. It is the oldest formati ...

of the Neuquén Group, separated by the Main Miranican unconformity. The Lohan Cura correlates with the Rayoso Formation in some areas.Leanza et al., 2004, p.66

Subdivision

The Lohan Cura Formation contains two

members Member may refer to: * Military jury, referred to as "Members" in military jargon * Element (mathematics), an object that belongs to a mathematical set * In object-oriented programming, a member of a class ** Field (computer science), entries in ...

of roughly equal thickness. The lowermost member, Puesto Quiroga Member is approximately thick. The lowest sediments in this unit are conglomerates, overlain by

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

s and

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, ...

s. The upper two-thirds of the member consists mainly of

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...

s. The Cullín Grande Member is the upper member within the formation, about thick, which contains numerous

s displaying evidence of stream channels. Near the top of the sequence, siltstones and

claystone Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone, slate, and shale. Most of the particles of which the stone is composed are less than and are too sm ...

s become dominant.

Fossil content

Numerous

tetrapod Tetrapods (; ) are four-limb (anatomy), limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant taxon, extant and extinct amphibians, sauropsids (reptiles, including dinosaurs and therefore birds) and synapsids (p ...

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 preserved ...

s have been recovered from the Cullín Grande Member of the Lohan Cura, including: * several

turtle Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked ...

s (including 2 species of ''

Prochelidella ''Prochelidella'' is an extinct genus of Early to Late Cretaceous chelid turtles from the Bajo Barreal, Candeleros, Cerro Barcino and Portezuelo Formations of the Cañadón Asfalto, Golfo San Jorge and Neuquén Basins in Patagonia, Argentin ...

'') * rebbachisaurid

sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their ...

s (including '' Agustinia'' and ''

Comahuesaurus ''Comahuesaurus'' (meaning "Comahue lizard") is a genus of sauropod dinosaur of the family Rebbachisauridae. It was found in the Lohan Cura Formation, in Argentina and lived during the Early Cretaceous, Aptian to Albian. The type species is ''C. ...

'') * ''

Ligabuesaurus ''Ligabuesaurus'' is a genus of somphospondylan sauropod dinosaur from the Early Cretaceous that lived in what is now Argentina. The type species, ''Ligabuesaurus leanzai'', was described by Jose Bonaparte, Gonzalez Riga, and Sebastián Apeste ...

'' The rebbachisaurid ''

Rayososaurus ''Rayososaurus'' is a genus of plant-eating sauropod dinosaur of the superfamily Diplodocoidea. It was found in the Candeleros Formation, but was named ''Rayososaurus'' after the Rayoso Member, which later has been elevated to the older Rayoso Fo ...

'' comes from the correlating Rayoso Formation in this same area.

Subdivision

Fossil content

See also

References

Bibliography

Further reading