Based on sedimentologic and paleontological characteristics present in the sedimentary record of the Calingasta-Uspallata and Paganzo basins, a model of paleoclimatic evolution for the Late Paleozoic of central west Argentina is proposed. Additional evidence is also provided by data from other basins of southern (San Rafael and Tepuel basins) and northern (Tarija basin) west Argentina. Five paleoclimatic stages have been defined:

Paleoclimatic stage I (Tournalism-Visean, Early Carboniferous) is characterized by temperature and humid preglacial conditions as evidencedin the El Ratón and Malimán formations (Calingasta-Uspallata basin). Plant remains of Archeosigillaria and Lepidodendropsis zone are present in both units.

The paleoclimatic stage II (Namurian-Early Westphalian, Middle Carboniferous) comprises widespread glacial deposits including glaciomarine sequence in the westernmost basins (Calingasta-Uspallata, western Paganzo, San Rafael and Tepuel) and terrestrial tillites and glaciolacustrine fine clastics in some areas of the Paganzo basin. Fossils of the Levipustula fauna are distinctive in the glaciomarine deposits of this stage and in the overlying postglacial fine clastics of the basal portion of stage III (substage IIIa)

The paleoclimatic stage III, of Middle Carboniferous (Late Westphalian) age, corresponds to postglacial transgressions that flooded the previously glaciated shelves in the Calingasta-Uspallata and Tepuel basins, terminal glaciolacustrine deposits (substage IIIa), indicate of the demise of glacial conditions, and coal measures of fluvial affinity in the Paganzo basin (substage IIIb). Probably this postglacial stage was characterized by high humidity and moderate temperatures. This stage is paleobiologi defined by a floral assemblage known as NBG (Nothorhacopteris, Botrychiopsis and Ginkgophyllum).

The paleoclimatic stage IV (Late Carboniferous (Stephanian)-Early Permian) corresponds to a time-interval characterized by seasonally dry climates and a progressive amelioration in humidity. Clear evidence of these climatic conditions is present in several localities in the Paganzo basin. The first Astherothecae and Glossopteris leaves are found.

Finally, paleoclimatic stage V (Middle-Late? Permian) is dominated by red-beds, thick eolian sequences and saline lake facies deposited under arid to semi-arid conditions. Coeval volcanism derived from the west is expressed by interbedded tuffs and agglomerates (Calingasta-Uspallata, Paganzo and San Rafael basins).