Irati Formation is the name of a

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

Paraná Basin The Paraná Basin ( pt, Bacia do Paraná, es, Cuenca del Paraná) is a large cratonic sedimentary basin situated in the central-eastern part of South America. About 75% of its areal distribution occurs in Brazil, from Mato Grosso to Rio Grande ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

. It has previously been dated as

Late Permian Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...

using palynomorphs, but is now dated as

Early Permian 01 or '01 may refer to: * The year 2001, or any year ending with 01 * The month of January * 1 (number) Music * 01'' (Richard Müller album), 2001 * ''01'' (Son of Dave album), 2000 * ''01'' (Urban Zakapa album), 2011 * ''O1'' (Hiroyuki Sawano ...

using

zircon Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of th ...

ages obtained from

bentonite Bentonite () is an absorbent swelling clay consisting mostly of montmorillonite (a type of smectite) which can either be Na-montmorillonite or Ca-montmorillonite. Na-montmorillonite has a considerably greater swelling capacity than Ca-m ...

layers. The base of the formation has been dated at 278.4 ± 2.2 Ma.Da Costa, 2015, p.28Ventura Santos et al., 2006 Exposures of the Irati Formation are to be found in the South ( Geopark of Paleorrota), southeastern

and in the states of

Goiás Goiás () is a Brazilian state located in the Center-West region. Goiás borders the Federal District and the states of (from north clockwise) Tocantins, Bahia, Minas Gerais, Mato Grosso do Sul and Mato Grosso. The state capital is Goiânia. ...

Mato Grosso Mato Grosso ( – lit. "Thick Bush") is one of the states of Brazil, the third largest by area, located in the Central-West region. The state has 1.66% of the Brazilian population and is responsible for 1.9% of the Brazilian GDP. Neighborin ...

São Paulo São Paulo (, ; Portuguese for 'Saint Paul') is the most populous city in Brazil, and is the capital of the state of São Paulo, the most populous and wealthiest Brazilian state, located in the country's Southeast Region. Listed by the Ga ...

, Paraná, Santa Catarina, Rio Grande do Sul and

Mato Grosso do Sul Mato Grosso do Sul () is one of the Midwestern states of Brazil. Neighboring Brazilian states are (from north clockwise) Mato Grosso, Goiás, Minas Gerais, São Paulo and Paraná. It also borders the countries of Paraguay, to the southwest, a ...

. The formation is part of the

Passa Dios Group Passa may refer to: People * Chiara Passa (born 1973), Italian visual artist * Frank Passa (1916–2001), American luthier * François Jaubert de Passa (1785-1856), French engineer and politician Places * Passa, Pyrénées-Orientales, France * ...

, underlying the

Serra Alta Formation Serra (Latin for "saw") may refer to: People * Serra (footballer) (born 1961), Portuguese footballer * Serra (surname) * Serra (given name) Cities, towns, municipalities Brazil * Serra, Espírito Santo, a city in the Greater Vitória area *Amp ...

and overlying the Palermo Formation. The formation has been deposited in a

restricted marine Restricted may refer to: *R rating (disambiguation), list of subjects where "R" stands for "Restricted" *18 rating, media rating designation sometimes called "Restricted" *Restricted (country club), historical use of the term in country clubs in t ...

environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...

.Diduch, 2011, p.21 The Irati Formation, with a maximum thickness of , was defined and named by

White White is the lightness, lightest color and is achromatic (having no hue). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully diffuse reflection, reflect and scattering, scatter all the ...

in 1908.Da Costa, 2015, p.12

Fossil content

The formation is particularly famous for the occurrences of the

mesosaur Mesosaurs ("middle lizards") were a group of small aquatic reptiles that lived during the early Permian period, roughly 299 to 270 million years ago. Mesosaurs were the first known aquatic reptiles, having apparently returned to an aquatic lif ...

s '' Mesosaurus tenuidiens'',Irati
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 and '' Stereosternum tumidum''. Other fossils found in the formation are '' Myelontordoxylon camposii'',Diduch, 2011, p.24 and

crustacea Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...

ns of the genera '' Paulocaris'', '' Pygaspis'', '' Liocaris'', and '' Clarkecaris''.Diduch, 2011, p.23 It is considered time equivalent to the

Whitehill Formation The Whitehill Formation, alternatively written as White Hill Formation and formerly known as White Band or Whitehill or White Hill Member, is a regional Early Permian (Artinskian to Kungurian, dating to around 282 to 275 Ma) geologic formation b ...

of the

Ecca Group The Ecca Group is the second of the main subdivisions of the Karoo Supergroup of geological strata in southern Africa. It mainly follows conformably after the Dwyka Group in some sections, but in some localities overlying unconformably over much ...

of the

Karoo Supergroup The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a pe ...

of southern

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

and the Mangrullo Formation of

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

.Piñeiro et al., 2012, p.299

References

Bibliography

* * * * {{cite LSA , last=Ventura Santos , first=Roberto , last2=Souza , first2=Paulo A. , last3=Souza de Alvarenga , first3=Carlos José , last4=Luiz Dantas , first4=Elton , last5=Martins Pimentel , first5=Marcio , last6=Gouveia de Oliveira , first6=Claudinei , last7=Medeiros de Araújo , first7=Laury , year=2006 , title=Shrimp U–Pb zircon dating and palynology of bentonitic layers from the Permian Irati Formation, Paraná Basin, Brazil , url= , journal=

Gondwana Research ''Gondwana Research'' is a peer-reviewed scientific journal with an "all earth science" scope and an emphasis on the origin and evolution of continents. It is part of the Elsevier Elsevier () is a Dutch academic publishing company speciali ...

, volume=9 , pages=456–463 , accessdate=2017-08-03 Geologic formations of Brazil Formations Permian System of South America Cisuralian Series Permian Brazil Shale formations Sandstone formations Oil shale formations Oil shale in Brazil Permian southern paleotemperate deposits Formations Formations Formations Formations Formations Formations Formations

Fossil content

See also

References

Bibliography