The Guabirotuba Formation is a late Middle Eocene (

Divisaderan The Divisaderan age is a South American land mammal age, covering a period of geologic time (42.0–36.0 Ma) within the Middle and Late Eocene epochs of the Paleogene. It follows the Mustersan age and is followed by the Tinguirirican age.

in the SALMA classification) geologic

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondary ...

of the

Curitiba Basin Curitiba () is the capital and largest city in the state of Paraná in Brazil. The city's population was 1,948,626 , making it the eighth most populous city in Brazil and the largest in Brazil's South Region. The Curitiba Metropolitan area c ...

in Paraná,

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 ...

. The formation crops out in and around the city of

Curitiba Curitiba () is the capital and largest city in the state of Paraná in Brazil. The city's population was 1,948,626 , making it the eighth most populous city in Brazil and the largest in Brazil's South Region. The Curitiba Metropolitan area c ...

and comprises mudstones 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 deposited in a

fluvial 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 fluv ...

floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...

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 ...

. The thick formation has provided several fossil mammals, and indeterminate side-neck turtle fossils, and indeterminate

terror bird Phorusrhacids, colloquially known as terror birds, are an extinct clade of large carnivorous flightless birds that were one of the largest species of apex predators in South America during the Cenozoic era; their conventionally accepted tempo ...

fossils. A newly described species of

Cingulata Cingulata, part of the superorder Xenarthra, is an order of armored New World placental mammals. Dasypodids and chlamyphorids, the armadillos, are the only surviving families in the order. Two groups of cingulates much larger than extant arma ...

; '' Proeocoleophorus carlinii'' was also found in the formation.

Description

The Guabirotuba Formation was first described by and in 1962. The geologists named the formation after , a neighborhood of

, the capital of

Paraná State Paraná, Paranã or Parana may refer to: Geology *Paraná Basin, a sedimentary basin in South America Places In Argentina *Paraná, Entre Ríos, a city * Paraná Department, a part of Entre Ríos Province * Paraná, Buenos Aires, a settlement ...

.Monteiro Machado, 2012, p.564 The formation is the lowermost sedimentary unit in the

, a Cenozoic continental

rift basin In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-grabe ...

of southeastern Brazil,Sedor et al., 2017, p.39 overlying

Cambrian The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ag ...

basement A basement or cellar is one or more Storey, floors of a building that are completely or partly below the storey, ground floor. It generally is used as a utility space for a building, where such items as the Furnace (house heating), furnace, ...

comprising

gneiss Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures a ...

es,

amphibolite Amphibolite () is a metamorphic rock that contains amphibole, especially hornblende and actinolite, as well as plagioclase feldspar, but with little or no quartz. It is typically dark-colored and dense, with a weakly foliated or schistose (flak ...

s and

migmatite Migmatite is a composite rock found in medium and high-grade metamorphic environments, commonly within Precambrian cratonic blocks. It consists of two or more constituents often layered repetitively: one layer is an older metamorphic rock th ...

s of the Atuba Complex and metasediments of the Açungui Group.Da Silva Felipe, 2011, p.12Monteiro Machado, 2012, p.565

Lithologies

Paraná River Floodplain, Northern Argentina

The thick Guabirotuba Formation comprises a basal conglomerate,Da Silva Felipe, 2011, p.17 mudstones and

s, deposited in a

.Monteiro Machado, 2012, p.566 The sediments of the formation contain between 0.24 and 2.61% heavy minerals.Monteiro Machado, 2012, p.567 Heavy mineral analysis on the very abundant

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 ...

s, abundant

epidote Epidote is a calcium aluminium iron sorosilicate mineral. Description Well developed crystals of epidote, Ca2Al2(Fe3+;Al)(SiO4)(Si2O7)O(OH), crystallizing in the monoclinic system, are of frequent occurrence: they are commonly prismatic in hab ...

, common

tourmaline Tourmaline ( ) is a crystalline silicate mineral group in which boron is compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is a gemstone and can be found in a wide variety of colors. ...

and

kyanite Kyanite is a typically blue aluminosilicate mineral, found in aluminium-rich metamorphic pegmatites and sedimentary rock. It is the high pressure polymorph of andalusite and sillimanite, and the presence of kyanite in metamorphic rocks generally ...

and rare

rutile Rutile is an oxide mineral composed of titanium dioxide (TiO2), the most common natural form of TiO2. Rarer polymorphs of TiO2 are known, including anatase, akaogiite, and brookite. Rutile has one of the highest refractive indices at visible wa ...

has provided insight in the paleocurrents of the fluvial environment, with predominant flow directions towards the northwest and east-northeast.Monteiro Machado, 2012, p.570

Age

The age of the formation has been a matter of debate, with early descriptions assigning the formation to the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58mammal fauna described by Sedor et al. in 2017, the age of the formation has been defined as late Middle Eocene, or "Barrancan", which is a sub-age of the

South American land mammal age The South American land mammal ages (SALMA) establish a geologic timescale for prehistoric South American fauna beginning 64.5 Ma during the Paleocene and continuing through to the Late Pleistocene (0.011 Ma). These periods are referred to as age ...

, ranging from approximately 42 to 39 Ma.Bellosi & Krause, 2014, p.31Woodburne et al., 2014, p.7

Paleontological significance

The Guabirotuba Formation is one of few formations in Brazil providing Paleogene mammal faunas, between the older

Tiupampan The Tiupampan ( es, Tiupampense) age is a period of geologic time (64.5–62.5 Ma) within the Paleocene epoch of the Paleogene used more specifically with South American land mammal ages (SALMA). It is the oldest SALMA age and precedes the Peligr ...

Maria Farinha Formation of the Parnaíba Basin and the

Itaboraian The Itaboraian ( pt, Itaboraiense) age is a period within the Early Eocene geologic time (53.0–50.0 Ma) epoch of the Paleogene, used more specifically with South American land mammal ages (SALMA). It follows the Riochican and precedes the Cas ...

Itaboraí Formation The Itaboraí Formation ( pt, Formação Itaboraí) is a highly fossiliferous geologic formation and LagerstätteKellner & Campos, 1999, p.399 of the Itaboraí Basin in Rio de Janeiro, southeastern Brazil. The formation reaching a thickness ...

of the

Itaboraí Basin Itaboraí (, ) is a city in the state of Rio de Janeiro in Brazil, that belongs to the Rio de Janeiro metropolitan area. It was founded in 1672. In 2020, it had a population of 242,543. Location Culturally, its closest municipalities are São ...

Rio de Janeiro State Rio de Janeiro () is one of the 27 federative units of Brazil. It has the second largest economy of Brazil, with the largest being that of the state of São Paulo. The state, which has 8.2% of the Brazilian population, is responsible for 9.2% of ...

, and the younger

Tinguirirican The Tinguirirican ( es, Tinguiririquense) age is a period of geologic time (36.0–29.0 Ma) within the Late Eocene and Early Oligocene epochs of the Paleogene, used more specifically within the SALMA classification in South America. It follows th ...

Entre-Córregos Formation of the Aiuruoca Basin and the

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 ...

Tremembé Formation Tremembé is a municipality in the state of São Paulo in Brazil. It is part of the Metropolitan Region of Vale do Paraíba e Litoral Norte. The population is 47,714 (2020 est.) in an area of 191.09 km². The elevation is 560 m. A shr ...

of the

Taubaté Basin Taubaté is a medium-sized city in the State of São Paulo, in southeastern Brazil. Location Its strategic location between the two most important Brazilian cities (São Paulo away, and Rio de Janeiro away), connected to both by the Presiden ...

Fossil content

Fossils recovered from the formation include:Guabirotuba Fauna
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

Notes and references

Notes

References

Bibliography

* * * * * * * {{cite LSA , last=Woodburne , first=M.O. , last2=Goin , first2=F.J. , last3=Bond , first3=M. , last4=Carlini , first4=A.A. , last5=Gelfo , first5=J.N. , last6=López , first6=G.M. , last7=Iglesias , first7=A. , last8=Zimicz , first8=A.N. , year=2013 , title=Paleogene Land Mammal Faunas of South America; a Response to Global Climatic Changes and Indigenous Floral Diversity , url=https://www.researchgate.net/publication/257591980_Paleogene_Land_Mammal_Faunas_of_South_America_a_Response_to_Global_Climatic_Changes_and_Indigenous_Floral_Diversity , journal=

Journal of Mammalian Evolution The ''Journal of Mammalian Evolution'' is the official journal of the Society for the Study of Mammalian Evolution. The journal is peer-reviewed Bi-monthly is a multidisciplinary forum devoted to studies on the comparative morphology, molecular ...

, volume=21 , pages=1–73 , accessdate=2019-02-15 Geologic formations of Brazil Eocene Series of South America Paleogene Brazil Bartonian Stage Divisaderan Mudstone formations Sandstone formations Conglomerate formations Fluvial deposits Fossiliferous stratigraphic units of South America Paleontology in Brazil Formations Tupi–Guarani languages

Description

Lithologies

Age

Paleontological significance

Fossil content

See also

Notes and references

Notes

References

Bibliography