Paleozoic Parana Basin transition from collisional retro-foreland to pericratonic syneclise: Implications on the geodynamic model of Gondwana proto-Andean margin

Providing significant advancements in the knowledge and development of the global plate tectonic theory, the Paran ` a Basin records a long period of sedimentary accumulation with evidence of substantial climatic and biostratigraphic changes throughout most all of the Phanerozoic. Two cycles of sedimentation are identified in the lowermost sequences (Rio Ivai and Paran'a groups), followed by a similar to 50 Ma gap until the deposition of the early Gondwanic cycle (Itarare' Group). The literature suggests that some of those depositional cycles were influenced by episodes of terrane accretion during the amalgamation of the Gondwana Supercontinent. The paleotopography generated by the Ocloyic orogeny (460-430 Ma) likely resulted in flexural subsidence in the lowermost stratigraphic cycles of the Paran'a Basin. In response to dynamic topography, the forebulge probably shifted to a system dominated by long-wavelength propagation developed over a distance of more than 800 km, most likely due to the influence of the subducted oceanic lithosphere of Panthalassa. The presence of Ordovician sources in the pre-Carboniferous sequences supports a provenance of exhumed Famatinian magmatic arc and associated rocks given that Ordovician magmatic activity is not recorded anywhere else in the cratonic regions. Furthermore, important detrital zircon population yielding Cambrian ages, likely derived from Eastern Pampean Range. In additional, the gap between crystallization and depositional ages within the Paran'a Basin supports a model that transitions from a collisional retro-foreland basin to a pericratonic syneclise after the deposition of the Paran'a Group. (AU)