The Guabirotuba Formation is a late Middle Eocene (Divisaderan in the SALMA classification) geologic formation of the Curitiba Basin in Paraná, Brazil. The formation crops out in and around the city of Curitiba and comprises mudstones and sandstones deposited in a fluvial floodplain environment.
The thick formation has provided several fossil mammals, and indeterminate side-neck turtle fossils, and indeterminate terror bird fossils. A newly described species of Cingulata; 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 Curitiba, the capital of Paraná State.Monteiro Machado, 2012, p.564 The formation is the lowermost sedimentary unit in the Curitiba Basin, a Cenozoic continental rift basin of southeastern Brazil,Sedor et al., 2017, p.39 overlying Cambrian basement comprising gneisses, amphibolites and migmatites of the Atuba Complex and metasediments of the Açungui Group.Da Silva Felipe, 2011, p.12Monteiro Machado, 2012, p.565
Lithologies
The thick Guabirotuba Formation comprises a basal conglomerate,Da Silva Felipe, 2011, p.17 mudstones and sandstones, deposited in a fluvial floodplain environment.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 zircons, abundant epidote, common tourmaline and kyanite and rare rutile 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 to Pliocene, but after the discovery of a mammal 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 Divisaderan South American land mammal 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 Maria Farinha Formation of the Parnaíba Basin and the Itaboraian Itaboraí Formation of the Itaboraí Basin in Rio de Janeiro State, and the younger Tinguirirican Entre-Córregos Formation of the Aiuruoca Basin and the Deseadan Tremembé Formation of the Taubaté Basin.
Fossil content Fossils recovered from the formation include:Guabirotuba Fauna at Fossilworks.org Class Group Fossils Images Notes Mammals Dasypodidae Machlydotherium sp. Meteutatus sp. Parutaetus sp. Utaetus sp. Astegotheriini indet. Parutaetus oliveira Cingulata Proeocoleophorus carlinii Notoungulata Oldfieldthomasiidae indet. Notopithecidae indet. Astrapotheria Astrapotheria indet. Paucituberculata Palaeothentoidea indet. Sparassodonta Nemolestes sp. Theriiformes Argyrolagoidea indet. Birds Phorusrhacidae Phorusrhacidae indet. Sedor et al., 2014, p.807 Reptiles Turtles Pleurodira indet. Wagner Rogério et al., 2012, p.44
See also Abanico Formation, contemporaneous fossiliferous formation of Chile Macarao Formation, contemporaneous formation of Colombia Soncco Formation, contemporaneous fossiliferous formation of Peru
Notes and references Notes
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