The stratigraphic puzzle of the permo-mesozoic southwestern Gondwana: The Paraná Basin record in geotectonic and palaeoclimatic context

The compilation of stratigraphic, sedimentologic, paleontologic and geochronological data allows the proposal of a regional stratigraphic framework for the Late Permian to Lower Cretaceous succession of the Paraná Basin. Each unit is characterized in terms of sedimentological and stratigraphic characteristics, ages (fossils and radiometric dating) and regional correlation, allowing the construction of an integrated stratigraphic chart. The Permo-Mesozoic sedimentary succession is mostly characterized by fluvial and/or aeolian systems that can be subdivided into eight distinct depositional sequences limited by unconformities of tectonic origin. These sequences correspond to the following stratigraphic units: Rio do Rasto, Buena Vista, Sanga do Cabral, Santa-Maria-Caturrita, Piramboia, Guará, Pedreira and Serra Geral. The Paraná Basin sedimentary record is marked by a very complex tectono-stratigraphic evolution, characterized by sedimentary units accumulating in different depocenters and with a highly fragmented preservation, reflecting regional tectonic events of Gondwana. Despite the incomplete record, a general evolutionary scenario can be reconstructed where the paleoclimates and wind regimes of western Gondwana are inferred. The Middle to Late Permian is characterized by a progressive aridization, evidenced by the presence of distributive fluvial systems (Rio do Rasto Formation) overlain by extensive aeolian dune deposits (Buena Vista Formation). The Triassic Period (Sanga do Cabral, Santa Maria and Caturrita formations) is marked by an essentially fluvial sedimentation indicative of relatively wetter climate conditions, with a well-marked peak of humidity in the Carnian Age. The Jurassic Period is characterized by fluvio-aeolian systems of the Piramboia Formation, Guará Formation and Pedreira Sandstone, indicating a semi-arid setting. The Lower Cretaceous (Valanginian-Hauterivian) is characterized by the development of an extensive paleoerg (Botucatu Formation) denoting hyperarid climatic conditions, which later switches to wetter conditions during the volcanic events of the Serra Geral Group. Despite these climatic variations during the Permo-Mesozoic, the wind regime from Permian to Lower Cretaceous remained dominated by westerly winds in the mid-latitudes and monsoonal winds in the mid-to-low latitudes of Gondwana.