The formation, with a maximum thickness of 300 metres (980 ft), comprises tuffs and sandstones with minor siltstones, marls and limestones, deposited in a fluvial, deltaic and shallow to deep lacustrine environment in small basins separated by faults.

The formation has provided many fossils of mammals, reptiles, among others the snake Waincophis australis, and the largest terror bird Kelenken guillermoi.

[1] 40Ar/39Ar analysis on amphibole crystals, collected from fresh pumice clasts, revealed an age of 14.86 ± 0.13 Ma for the middle section of the Collón Curá Formation in the Gastre Sub-basin of the Cañadón Asfalto Basin.

[1] In its type locality, the Collón Curá Formation is characterized by homogeneous greyish-yellow well-consolidated massive vitrocrystalline tuffs without visible sedimentary structures, but with calcareous concretions.

[1] Around the Río Chico in the Cañadón Asfalto Basin, the formation is about 300 metres (980 ft) thick and comprises siltstones, sandstones, marls and limestones.

[13] The mammal fauna of the Collón Curá Formation led researchers to establish the Colloncuran age in the SALMA classification, ranging from 15.5 to 13.8 Ma.

Sister taxa of these caviids first appeared in the Colloncuran; Guiomys unica and Microcardiodon williensis, found in the Collón Curá Formation.

[15] In alternative classification proposed in 2012 by Pérez and Pol, Guiomys is considered an optional early caviid, pushing back the lineage to the Colloncuran.