It is the oldest formation in the Neuquén Group and belongs to the Rio Limay Subgroup.

The sediments of the latter are of lighter greenish and yellow colors and the fused boundary between the Candeleros and Huincul formations is easily recognizable.

Overall, the formation represents a part of the ancient Kokorkom desert with braided river system, made up mostly of sandstones and conglomerates.

[1][3] The Candeleros Formation has a very diverse fossil fauna, including fish, frogs, mammals, rhynchocephalians, snakes, turtles, notosuchians, pterosaurs, and abundant dinosaurs including rebbachisaurid and titanosaurian sauropods and diverse theropods, and the enigmatic armored Jakapil.

Ichnofossils found in the formation include those assigned to Sousaichnum monettae, Limayichnus major, Bressaniichnus patagonicus, Deferraiichnum mapuchense, and Picunichnus benedettoi.