The São Jerônimo da Serra Site, Rio do Rasto Formation (Middle/Upper Permian), Paraná Basin, Brazil: faciological and taphonomic context

Abstract

In this contribution, we present an analysis of the main faciological features of the São Jerônimo da Serra Site, related to the Morro Pelado Member of Rio do Rasto Formation (Middle/Upper Permian), from Paraná State, Brazil, integrated to its taphonomic context. The outcrop, rich in vertebrates and bivalves remains, presents a succession of red siltstones bedded with fine to medium sandstones in which three architectural elements were observed: SF (sheetflood deposits), FF (fine of flood plain) and CS (crevasse). These data, allied to the taphonomic signatures of fossils assigned to eight levels, allowed the identification of three taphofacies. The taphofacies I is characterized by preserved bones in floodplain facies, with different articulation grades and absence of any sign of transport. The taphofacies II is composed by small isolated or fragmented bones and fish scales deposited in terminal splay facies. The taphofacies III is characterized by sandy layers with bivalve shells and fish scales, preserved in crevasse-splay deposits. The obtained data shows that the studied sedimentary succession was generated on a dry trend environment, with sporadic water supply, which conditioned the fossil preservation.