The Malargüe 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 ide ...

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 of 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 ...

of the Mendoza,

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 ...

, Río Negro and

La Pampa Province La Pampa () is a sparsely populated province of Argentina, located in the Pampas in the center of the country. Neighboring provinces are from the north clockwise San Luis, Córdoba, Buenos Aires, Río Negro, Neuquén and Mendoza. History In 1 ...

s in northern

Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and ...

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, t ...

. The formations of the Malargüe Group range in age between the middle

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. Campani ...

Deseadan The Deseadan ( es, Deseadense) age is a period of geologic time (29.0–21.0 Ma) within the Oligocene epoch of the Paleogene to the Early Miocene epoch of the Neogene, used more specifically within the SALMA classification of South America. It fol ...

, an

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but ...

age of the SALMA classification, straddling the

Cretaceous–Paleogene boundary The Cretaceous–Paleogene (K–Pg) boundary, formerly known as the Cretaceous–Tertiary (K–T) boundary, is a geological signature, usually a thin band of rock containing much more iridium than other bands. The K–Pg boundary marks the end ...

, about 79 million to 30 million years in age. The group overlies the older Neuquén Group, separated by an unconformity dated to 79 Ma.Leanza et al., 2004, p.63 The rocks of the Malargüe Group comprise both marine and continental deposits which are over 400 m (1312 ft) thick in total.

Subdivision

The Malargüe Group is subdivided into: * Agua de la Piedra Formation (

) - white-grayish

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 ...

s and tobaceous

paleosol In the geosciences, paleosol (''palaeosol'' in Great Britain and Australia) is an ancient soil that formed in the past. The precise definition of the term in geology and paleontology is slightly different from its use in soil science. In geol ...

sAgua de la Piedra Formation
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cre ...

.org * Roca Formation (Maastrichtian to Danian) - coastal mudstones and sandstonesRoca Formation
at

.org *

Jagüel Formation The Jagüel Formation is a geological formation, located in Patagonia, Argentina. It underlies the Roca Formation and overlies the Allen Formation. All of these formations belong to the Malargüe Group. Its name was coined by Windhausen in 1914 ...

(middle Maastrichtian to Danian) - shallow marine mudstonesJagüel Formation
at

.org *

Loncoche Formation Loncoche (Mapudungun for "head of an important person") is a city and commune in Cautín Province in the Araucanía Region, southern Chile. It is located near the border to Los Ríos Region and the city of Lanco. Loncoche is a major centre ...

(late Campanian to early Maastrichtian) - terrestrial conglomerates and

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, delta plain sandstones and

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms wh ...

sLoncoche Formation
at

.org *

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 formati ...

(middle Campanian to early

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interv ...

) - eolian

s and

fluvio In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or flu ...

lacustrine A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

mudstones and

Fossil content

Fossils of

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

plesiosaurs The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared ...

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 ('' Euclastes'',''Euclastes''
at

.org '' Mendozachelys wichmanni''),De la Fuente et al., 2017 '' Paleoanculosa sp.'',Previtera & González Riga, 2008

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% ...

,Gónzalez Riga, 1999

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s ('' cf. Andrewsornis sp.'') and

mammals Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fu ...

have been recovered from the strata that make up the Malargüe Group.Weishampel et al., 2004 ;Mammals of the Agua de la Piedra Formation '' Archaeohyrax suniensis'', '' Argyrohyrax proavus'', '' Asmodeus petrasnerus'', '' Fieratherium sorex'', ''

Gualta cuyana ''Gualta'' is an extinct genus of leontiniid notoungulates. It lived during the Late Oligocene of what is now Argentina. Description This genus is known from numerous fossil remains including an almost complete skull, several vertebrae, numero ...

'', '' Hegetotheriopsis sulcatus'', '' Mendozahippus fierensis'', '' Meteutatus aff. lagenaformis'', ''

Proborhyaena gigantea ''Proborhyaena'' is an extinct genus of proborhyaenid sparassodont that lived during the Oligocene of what is now South America. It is considered to be the largest of the sparassodonts. Description This animal was very large in size, with the s ...

'', '' Prohegetotherium malalhuense'', '' P. schiaffinoi'', '' P. cf. sculptum'', '' Propachyrucos cf. smithwoodwardi'', '' ?Prozaedyus aff. impressus'', '' Pyrotherium romeroi'', '' Stenotatus aff. ornatus'', '' Trachytherus cf. spegazzinianus'', '' cf. Archaeotypotherium sp.'', '' Pharsophorus sp.'', '' Proadinotherium sp.'', '' Progaleopithecus sp.'', '' cf. Prosotherium sp.'', Acaremyidae indet., Glyptodontidae indet., Interatheriidae indet., Litopterna indet., ?Megalonychidae indet., Notohippidae indet., Toxodontidae indet.Quebrada Fiera
at

.orgCerdeño & Reguero, 2015Seoane & Cerdeño, 2014Cerdeño & Vera, 2014

References

Bibliography

;Cretaceous * * * * * ;Paleogene * * * * * {{DEFAULTSORT:Malargue Group Geologic formations of Argentina Upper Cretaceous Series of South America Paleocene Series of South America Oligocene Series of South America Sandstone formations Mudstone formations Conglomerate formations Limestone formations Tuff formations Fluvial deposits Deltaic deposits Lacustrine deposits Aeolian deposits Shallow marine deposits Geology of La Pampa Province Geology of Mendoza Province Geology of Neuquén Province Geology of Río Negro Province

Subdivision

Fossil content

See also

References

Bibliography