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.

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.