A new flora from the Rio Bonito Formation (late Asselian) and its implications for the biostratigraphy of the southern Paraná Basin, Brazil

Abstract

The results of this contribution represent the first attempt regarding palynological and paleobotanical records from the municipality of Alfredo Wagner, Santa Catarina State, southern Brazil. The fossils were recovered in the top of the Siderópolis Member, upper portion of the Rio Bonito Formation, Paraná Basin. The palynological assemblage revealed a well-preserved assemblage composed of 28 spores and 24 pollen, mainly dominated by ferns and gymnosperms, correlated with the Vittatina costabilis Zone. Eight taxa are first records for this unit (Granulatisporites varigranifer, Punctatisporites subvaricosus, Gondisporites serrulatus, Didecitriletes sp, Vitreisporites signatus, Alisporites ovatus, Pteruchipollenites indarraensis and Cycadopites cymbatus), and three of them for the basin (P. subvaricosus, Didecitriletes sp. and C. cymbatus). The paleobotanical assemblage is mainly represented by Glossopteris (seven species), ferns (Pecopteris and Sphenopteris) and seeds (Cornucarpus, Cordaicarpus and Samaropsis), corresponding to the Gondwanan “Glossopteris Flora”. Although Cheirophyllum and Cornucarpus would be typical and restricted to the underlying Phyllotheca-Gangamopteris Flora, their presence allows us to correlate the floristic deposits with the basal part of the Glossopteris-Brasilodendron Flora range. In addition, U–Pb zircon CA-TIMS datings obtained in nearby correlated sections allows the macro- and microfloras to be constrained to the latest Asselian age.