The Devonian of the Paraná Basin, Brazil: Sequence stratigraphy, paleogeography, and SW Gondwana interregional correlations

Abstract

The Devonian Period is characterized by an overall mean sea-level higher than is observed today. This pattern is recognized in several basins worldwide and permitted, for example, the flooding of the Rheic ocean through SW Gondwana's cratonic domain. Nonetheless, this flooding was not purely eustatic. The Ordovician-Devonian geodynamic Famatinian episode also played its role. This tectonic-eustatic interplay favored shallow-marine deposition recorded in several SW Gondwana basins, such as the Paraná Basin in Brazil. Even so, the evolution of the Paraná Basin through the Devonian and the factors responsible for the accommodation space remain speculative, which leads to bias regarding the correlation of transgressive-regressive events in SW Gondwana. This work aims, by integrating outcrop and subsurface data, to provide a basin-scale stratigraphic framework and a paleogeographical reconstruction of the Ponta Grossa (Early Devonian) and São Domingos formations (Middle to Late Devonian) of the Paraná Basin. It also correlates the studied interval with adjacent basins to identify the impact of tectonic and eustatic processes on the evolution of SW Gondwana tectono-sedimentary cycles. We identified two 2nd order Transgressive-Regressive sequences that correspond to the lithostratigraphic occurrence of Ponta Grossa and São Domingos formations, respectively, and whose maximum transgressive and regressive surfaces and high-hierarchy unconformities are traceable through adjacent basins. The Ponta Grossa-São Domingos boundary also delineates an important tectonic event associated with far-field stresses probably caused by Precordilleran orogeny related phenomena. The Ponta Grossa and São Domingos formations share several similarities with coeval strata in SW Gondwana basins, indicating that they can be extrapolated and correlated to contemporaneous processes of interregional scale. The first, namely Precordilleran I (Early Devonian) was dominated by tectonics and encompasses the Ponta Grossa and Las Pavas composite sequence set. The second, Precordilleran II (Middle to Late Devonian), was mostly eustatic and encompasses São Domingos and Aguarave composite sequence sets. Both intervals are part of the Famatinian geodynamic cycle.