The lacustrine ecosystem of the Bajo de Veliz Formation: A wet spot at the Carboniferous-Permian boundary in westernmost Gondwana

During the Carboniferous-Permian transition in the westernmost part of Gondwana, the environment became drier and more seasonal than the preceding humid estuarine and fluvial habitats of the Middle Pennsylvanian of central western Argentina. The Gzhelian-Asselian Pallero Member of the Bajo de Veliz Formation, located to the east of the Paganzo Basin, represents an ecosystem preserved in lake deposits. This unit comprises lacustrine facies, and the fossil flora and fauna contained therein represent a wet refuge developed within a regionally semi-arid context. The flora is assigned to the Gangamopteris Biozone and includes specimens of lycophytes, equisetaleans, cordaitaleans, coniferophytes, and glossopterids that grew around the lake shoreline. Winged insects, arachnids, large eurypterids, and traces of fishes comprise terrestrial and aquatic fauna. This ecosystem is considered a wet spot similar to those that characterize the global paleoclimatic shift in low paleolatitudes. •The Gzhelian-Asselian lacustrine strata of the Bajo de Veliz Fm. are analyzed.•It is representative of the late Pennsylvanian climatic shift at high latitudes.•The paleolake supported both terrestrial and aquatic life.•The ecosystem established in drier regional conditions provided a wet refuge.