Huincul Formation
Encyclopedia
The Huincul Formation is a geologic formation
that outcrop
s in Río Negro
and Neuquén
provinces of Argentina
. It is the second formation in the Río Limay Subgroup, the oldest subgroup within the Neuquén Group
. Formerly that subgroup was treated as a formation, and the Huincul Formation was known as the Huincul Member.
The type locality of the Huincul Formation is near the town of Plaza Huincul
in Neuquén province. This formation conformably
overlies the Candeleros Formation
, and it is in turn overlain by the Lisandro Formation.
The Huincul Formation is thought to represent an arid environment with ephemeral or seasonal stream
s. In some areas, it is up to 250 meters thick. It is mainly composed of green and yellow sandstone
s and can easily be differentiated from the overlying Lisandro Formation, which is red in color. The Candeleros Formation, underlying the Huincul, is composed of darker sediments, making all three formations easily distinguishable.
Period: Late Cretaceous
Faunal stage
: late Cenomanian
Absolute Age
: ~97 to ~94 mya
Fossil
bones are rarely found in the Huincul Formation. However, remains of the largest land animal known, Argentinosaurus huinculensis, were found in the Huincul Formation, and this species is named after it. One of the largest predators known, Mapusaurus
, has also been recovered from a bonebed in this formation.
Animal fossils found in the Huincul Formation include:
Geologic formation
A formation or geological formation is the fundamental unit of lithostratigraphy. A formation consists of a certain number of rock strata that have a comparable lithology, facies or other similar properties...
that outcrop
Outcrop
An 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 superficial deposits are covered by a mantle of soil and vegetation and cannot be...
s in Río Negro
Río Negro Province
Río Negro is a province of Argentina, located at the northern edge of Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean.Its capital is Viedma...
and Neuquén
Neuquén Province
Neuquén is a province of Argentina, located in the west of the country, at the northern end of Patagonia. It borders Mendoza Province to the north, Rio Negro Province to the southeast, and Chile to the west...
provinces of Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. It is the second formation in the Río Limay Subgroup, the oldest subgroup within the Neuquén Group
Neuquén Group
The Neuquén Group is a group of geologic formations found in Argentina. Rocks in the Neuquén Group fall within the Cenomanian to early Campanian stages of the Late Cretaceous Period, about 100 million to 80 million years in age...
. Formerly that subgroup was treated as a formation, and the Huincul Formation was known as the Huincul Member.
The type locality of the Huincul Formation is near the town of Plaza Huincul
Plaza Huincul
Plaza Huincul is a village and municipality in Neuquén Province in southwestern Argentina.-References:...
in Neuquén province. This formation conformably
Unconformity
An unconformity is a buried erosion 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 of time before deposition of the younger, but the term is used to describe...
overlies the Candeleros Formation
Candeleros Formation
The Candeleros Formation is a geologic formation that outcrops in Río Negro, Neuquén, and Mendoza provinces of Argentina. It is the oldest formation in the Neuquén Group and belongs to the Rio Limay Subgroup...
, and it is in turn overlain by the Lisandro Formation.
The Huincul Formation is thought to represent an arid environment with ephemeral or seasonal stream
Stream
A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...
s. In some areas, it is up to 250 meters thick. It is mainly composed of green and yellow sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
s and can easily be differentiated from the overlying Lisandro Formation, which is red in color. The Candeleros Formation, underlying the Huincul, is composed of darker sediments, making all three formations easily distinguishable.
Age
Era: MesozoicMesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
Period: Late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
Faunal stage
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
: late Cenomanian
Cenomanian
The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...
Absolute Age
Geochronology
Geochronology is the science of determining the age of rocks, fossils, and sediments, within a certain degree of uncertainty inherent to the method used. A variety of dating methods are used by geologists to achieve this, and schemes of classification and terminology have been proposed...
: ~97 to ~94 mya
Paleontology
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
bones are rarely found in the Huincul Formation. However, remains of the largest land animal known, Argentinosaurus huinculensis, were found in the Huincul Formation, and this species is named after it. One of the largest predators known, Mapusaurus
Mapusaurus
Mapusaurus was a giant carnosaurian dinosaur from the early Late Cretaceous of what is now Argentina. It was similar in size to its close relative Giganotosaurus, with the largest known individuals estimated as over in length and weighing approximately...
, has also been recovered from a bonebed in this formation.
Animal fossils found in the Huincul Formation include:
- several titanosaurian sauropods (including ArgentinosaurusArgentinosaurusArgentinosaurus is a genus of titanosaur sauropod dinosaur first discovered by Guillermo Heredia in Argentina. The generic name refers to the country in which it was discovered...
) - a rebbachisaurid sauropod (CathartesauraCathartesauraCathartesaura is a genus of rebbachisaurid sauropod dinosaur hailing from the Late Cretaceous strata of the Huincul Formation located in the "La Buitrera" locality, Río Negro Province, Argentina. The fossil remains, described by Gallina and Apesteguía in 2005, consist of a partial skeleton...
) - a carcharodontosaurid theropod (MapusaurusMapusaurusMapusaurus was a giant carnosaurian dinosaur from the early Late Cretaceous of what is now Argentina. It was similar in size to its close relative Giganotosaurus, with the largest known individuals estimated as over in length and weighing approximately...
) - abelisauroid theropods (including IlokelesiaIlokelesiaIlokelesia is a primitive abelisaur found in 1991, preserved in the layers of the earliest Late Cretaceous of the Río Limay Formation, Neuquén Group, located near Plaza Huincul, Neuquén Province, Argentina. The specimen, consisting of very fragmentary elements of the skull, the axial and the...
) - several ornithopodOrnithopodOrnithopods or members of the clade Ornithopoda are a group of ornithischian dinosaurs that started out as small, bipedal running grazers, and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world, and dominated the North American...
s