Irati Formation

Irati Formation
Stratigraphic range: Early Permian
~278.4–270 Ma
The Irati Formation belongs to the Gondwana I megasequence
TypeGeological formation
Unit ofPassa Dois Group
UnderliesSerra Alta Formation (Paraná Basin)
Teresina Formation (Pelotas Basin)
OverliesPalermo Formation
Area1,000,000 km2 (390,000 sq mi)
Thicknessup to 80 m (260 ft)
Lithology
PrimaryBlack shale
OtherSandstone
Location
Coordinates25°30′S 50°42′W / 25.5°S 50.7°W / -25.5; -50.7
RegionParaná & Pelotas Basins
Goiás, Mato Grosso do Sul, Mato Grosso, São Paulo, Paraná, Santa Catarina, Rio Grande do Sul
Country Brazil
Type section
Named byWhite
Year defined1908
Approximate paleocoordinates45°48′S 29°42′W / 45.8°S 29.7°W / -45.8; -29.7

The Paraná Basin in South America

Irati Formation is the name of a geological formation of the Paraná Basin in Brazil. It has previously been dated as Late Permian using palynomorphs, but is now dated as Early Permian using zircon ages obtained from bentonite layers. The base of the formation has been dated at 278.4 ± 2.2 Ma.[1][2] Exposures of the Irati Formation are to be found in the South (Geopark of Paleorrota), southeastern Brazil and in the states of Goiás, Mato Grosso, São Paulo, Paraná, Santa Catarina, Rio Grande do Sul and Mato Grosso do Sul.[1] The formation is part of the Passa Dios Group, underlying the Serra Alta Formation and overlying the Palermo Formation. The formation has been deposited in a restricted marine environment.[3] The Irati Formation, with a maximum thickness of 80 metres (260 ft), was defined and named by White in 1908.[4]

Fossil content

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Reptiles

Reptiles of the Irati Formation
Genus Species Location Stratigraphic position Material Notes Image
Brazilosaurus B. sanpauloensis A mesosaurid mesosaur
Mesosaurus M. tenuidiens A mesosaurid mesosaur
Stereosternum S. tumidum A mesosaurid mesosaur

Fish

Fish of the Irati Formation
Genus Species Location Stratigraphic position Material Notes Images
Amelacanthus A. sp. A ctenacanthid shark
Fairchildodus[5] F. rioclarensis A petalodont
Iratiacanthus I. santamariaensis A sphenacanthid shark
Itapyrodus I. punctatus A petalodont
Orodus O. ipeunaensis A orodontid shark
Sphenacanthus S. sanpauloensis A sphenacanthid shark
Taquaralodus T. albuquequei A diplodoselachid shark
Xenacanthus X. pricei A Xenacanthid shark

Crustaceans

Sauropods of the Irati Formation
Genus Species Location Stratigraphic position Material Notes Images
Iraticaris I. damiani
Myelontordoxylon M. camposii
Permocaris P. purperae
Pittinucaris P. wuerdigae

See also

References

  1. ^ a b Da Costa, 2015, p.28
  2. ^ Ventura Santos et al., 2006
  3. ^ Diduch, 2011, p.21
  4. ^ Da Costa, 2015, p.12
  5. ^ Chahud, A. (2023). "Holocephali from the Irati Formation (Paraná Basin), Brazil: Origin, paleogeographical and paleoenvironmental considerations". Estudios Geológicos. 79 (2). e155. doi:10.3989/egeol.44987.632. S2CID 261376731.

Bibliography