Irati Formation

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title: "Irati Formation" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["geologic-formations-of-brazil", "paraná-basin", "permian-system-of-south-america", "cisuralian-series", "permian-brazil", "shale-formations", "sandstone-formations", "oil-shale-formations", "oil-shale-in-brazil", "permian-southern-paleotemperate-deposits", "geography-of-goiás", "geography-of-mato-grosso", "geography-of-mato-grosso-do-sul", "geography-of-paraná-(state)", "geography-of-rio-grande-do-sul", "geography-of-santa-catarina-(state)", "geography-of-são-paulo-(state)"] description: "Geologic formation in Brazil" topic_path: "philosophy" source: "https://en.wikipedia.org/wiki/Irati_Formation" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Geologic formation in Brazil ::

::data[format=table title="Infobox rockunit"]

Field	Value
name	Irati Formation
period	Early Permian
age	Early Permian
~
image	Parana Basin simplified stratigraphic chart.png
caption	The Irati Formation belongs to the Gondwana I megasequence
type	Geological formation
prilithology	Black shale
otherlithology	Sandstone
unitof	Passa Dois Group
underlies	Serra Alta Formation (Paraná Basin)
Teresina Formation (Pelotas Basin)
overlies	Palermo Formation
thickness	up to 80 m
area	1000000 km2
map	South America satellite plane Bacia do Parana.jpg
map_caption	The Paraná Basin in South America
coordinates
region	Paraná & Pelotas Basins
Goiás, Mato Grosso do Sul, Mato Grosso, São Paulo, Paraná, Santa Catarina, Rio Grande do Sul
country	Brazil
namedby	White
year_ts	1908
paleocoordinates_ts
::

| name = Irati Formation | period = Early Permian | age = Early Permian ~ | image = Parana Basin simplified stratigraphic chart.png | imagesize = | caption = The Irati Formation belongs to the Gondwana I megasequence | type = Geological formation | prilithology = Black shale | otherlithology = Sandstone | unitof = Passa Dois Group | subunits = | underlies = Serra Alta Formation (Paraná Basin) Teresina Formation (Pelotas Basin) | overlies = Palermo Formation | thickness = up to 80 m | area = 1000000 km2 | map = South America satellite plane Bacia do Parana.jpg | map_caption = The Paraná Basin in South America | location = | coordinates = | region = Paraná & Pelotas Basins Goiás, Mato Grosso do Sul, Mato Grosso, São Paulo, Paraná, Santa Catarina, Rio Grande do Sul | country = Brazil | extent = | namedfor = | namedby = White | year_ts = 1908 | location_ts = | coordinates_ts = | paleocoordinates_ts = | region_ts = | country_ts = | thickness_ts = 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. 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. The Irati Formation, with a maximum thickness of 80 m, was defined and named by White in 1908.

Fossil content

Reptiles

::data[format=table]

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

Fish

::data[format=table]

Fish of the Irati Formation	Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Amelacanthus	A. sp.				A ctenacanthid shark
Fairchildodus	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

::data[format=table]

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

References

Bibliography

References

1. Da Costa, 2015, p.28
2. Ventura Santos et al., 2006
3. 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]] [[depositional environment
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.

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