The formation is most prominently exposed within Talampaya National Park, a UNESCO World Heritage Site within La Rioja Province.

The most common reptiles were proterochampsids (Chanaresuchus, Tropidosuchus, and Gualosuchus), which lived alongside true archosaurs such as Lewisuchus, Lagerpeton, Marasuchus, Gracilisuchus, and Luperosuchus.

[2][3] The Chañares Formation is the lowermost unit of the Agua de la Peña Group, representing the onset of the first syn-rift phase of the Ischigualasto-Villa Unión Basin.

However, Uranium-Lead radiometric dating by Marsicano et al. (2016) later found that a large portion of the formation was deposited in the early Carnian (237–234 Ma), near the start of the Late Triassic.

[7] Nevertheless, the Ladinian-Carnian boundary may still lie within the first few meters of the formation, despite the primary fossiliferous sections being well-supported as early Carnian in age.

As one goes up the section, increasingly finer beds of sandstone and siltstone are interlayered with coarser lenses, corresponding to periodic sheet floods along braided rivers.

Weakly-developed palaeosols can be found within this section, filled with root traces, pebbles and small brown calcareous nodules.

[1] Though fossils are relatively uncommon in the lower fluvial beds of the Chañares Formation, they are taxonomically and taphonomically distinct from those of succeeding layers.

These layers have a high concentration of volcanic ash and debris, ranging from glassy shards at the base to weathered bentonites at the top.

[3] Marsicano et al. (2016) obtained a CA-TIMS U-Pb age of 236.1 ± 0.6 Ma from a siltstone bed immediately below the first major fossil layer within the bluish facies.

[3] Volcanic catastrophes such as lahars, ash falls, or pyroclastic flows[2] are the preferred cause of these rapid mass mortality events.

[4] Fossils found outside concretions are typically from large animals, and were probably buried more slowly (albeit still fairly rapidly) by gradual processes.

[4][1] The largest components of the ecosystem include dicynodonts (namely Dinodontosaurus) and indeterminate carnivorous paracrocodylomorphs, similar to taxa from the underlying Tarjadia AZ.

The upper member is generally similar to the bluish facies in appearance, with wide beds of fine-grained volcaniclastic sediments with a pale grey color.

They belong to a broad range of plants, most abundantly pollen from umkomasiales (a type of seed fern), and in smaller portions from podocarpacean and voltzialean conifers.