Paleogeographic evolution of the southern Paraná Basin during the Late Permian and its relation to the Gondwanides

Abstract

The end of the Permian marks an important change in the depositional context of the southwestern Gondwanan continent. These changes are related to the last invasion of the Panthalassa Ocean, and the posterior oceanic retreat and emplacement of desertic conditions. This paper provides a detailed paleogeographic evolution of the southern portion of the Paraná Basin, supported by facies descriptions, stratigraphic analysis, and U-Pb-Hf detrital zircon analysis (LA-ICP-MS). The studied interval records a large regression that was composed of three forced-regression pulses related to important facies shifts ascribed to the outer ramp, inner ramp, and arid continental systems. Provenance zircon UPb analysis in the inner ramp and continental arid climate deposits indicates that the main sediment source was the Brasiliano basement and the Gondwanides mountain ridge, situated to the west and south. The abrupt paleogeographic change related to the evolution of a system dominated by inner ramp to arid continental facies is compatible with the tectonic reorganization of the Paraná Basin close to the Permo-Triassic limit. Here we present a paleogeographic evolution model which adds new elements to better understand the great transgressive-regressive event that occurred in southwestern Gondwana during the late Permian.