ABSTRACT The interaction of fluvial, lacustrine, and eolian processes in endorheic basins can result in highly complex depositional architecture and stratigraphic patterns. This complexity results from multi-scale, nonperiodic sedimentary processes occurring over large depositional areas typical of low-gradient, internally drained basins influenced by local and regional climatic and tectonic events. The middle to late Permian Rio do Rasto Formation, which covers a considerable area of the Paraná Basin in southern Brazil, presents extensive lateral and vertical exposures that allow detailed sedimentological and stratigraphic analyses as well as paleoflow reconstructions. In this field-based study, 21 lithofacies were recognized and grouped into eight facies associations grouped into four subsystems. The overall depositional evolution recognized along the composite section shows progradational cycles associated with the accumulation of distributive fluvial systems, characterized by lacustrine deposits at the base and fluvial, overbank, and eolian deposits at the top. In each superimposed progradational cycle, fluvial processes increasingly dominate over lacustrine processes. Individual analyses of paleocurrents and depositional architecture of the fluvial deposits suggest that fluvial channels drained multiple catchments that also had pronounced discharge variability, with very complex depositional patterns. In addition, analyses of modern processes and Quaternary deposits in Lake Eyre, central Australia, and Lake Chad, central northwestern Africa, were key to understanding the depositional complexity compared to endorheic basins. Thus, the stratigraphic framework of the Rio do Rasto Formation in the study area elucidates the evolution of coalescent distributive fluvial systems that accumulated in a broad endorheic basin that was strongly influenced by various climatic regimes.
Manna et al. (Fri,) studied this question.