Glacigenic strata associated with the proto-Precordillera were deposited in the Calingasta-Uspallata and Río Blanco back-arc basins and the Paganzo foreland basin in west-central Argentina during the early Pennsylvanian (upper Namurian; Bashkirian). These basins were formed due to tectonic loading and later postcollisional extension in a convergent-margin setting along the western margin of Gondwana during the Chañic and Río Blanco tectonic events. Uplift of the proto-Precordillera fold-and-thrust belt during the latest Visean–earliest Namurian (Serpukhovian) resulted in the development of a widespread unconformity that formed the pre glacial basin floors. During the Namurian, alpine glaciers carved deep valleys into the upland, and...