The Eurydesma-Lyonia fauna of the Capivarí marine beds, Late Paleozoic, Itararé Group, northeast of the Paraná Basin, Brazil

Abstract

A 2-m-thick silty shale bed within the Taciba Formation, Itararé Group, Paraná Basin, State of São Paulo, southeastern Brazil, records marine sedimentation in a siliciclastic-dominated, low energy, shelfal setting during a short-lived deglacial event. Within this bed, which is located 100-150 m below the base of the early Permian, post-glacial, overlying Tatui Formation, remains of shelly marine benthos (Capivari assemblage) are disperse, and representing the highest phylum-level diversity so far identified within a given fossil-bearing horizon in the uppermost portion of the Itararé Group. The marine assemblage is dominated by rhynchonelliform brachiopods, with subordinated occurrences of bivalves, gastropods and crinoids. Shells of brachiopods (Lyonia rochacamposi, Rhynchopora grossopunctata, Biconve-xiella sp., Quinquenella rionegrensis), bivalves (Phestia tepuelensis, Streblopteria aff. lagunensis, Limipecten capivariensis, Praeundulomya cf. subelongata), and gastropods [Woolnoughia (Mourlonia)? sp., Peruvispira sp.] were identified. Crinoid columns were assigned to øPentaridica sp. Biconvexiella and Peruvispira are probably new species. The overwhelming majority of brachiopods belongs to B. sp. followed by R. grossopunctata. Particularly noteworthy is the record of L. rochacamposi that are also present in the uppermost part of the Taciba Formation in southern Brazil. Quinquenella, Phestia, Limipecten, and Praeundulomya are also recorded in fine to very fine sandstones/siltstones with hummocky cross-stratification and intercalated mudstones of the Taciba Formation, Teixeira Soares region, State of Paraná. Hence, the Capivari marine fauna correlates, but is not necessarily strict synchronous, with those of the upper part of the Taciba Formation from the southern Brazil, and Sauce Grande-Colorado(Argentina), Huab (Hardap shale of the Dwyka Group), Aranos area (Namibia), southwest Africa, and the Carnarvon (Western Australia) basins. This correlation suggests a latest Asselian-earliest Sakmarian age for the fauna. Data indicate that the Capivari fossil-bearing marine beds record a short-lived deglacial event and the first occurrence of members of the Eurydesma-Lyonia fauna in the northeastern part of the Paraná Basin, Brazil. [FAPESP 13/25317-7; CNPq 302903/12-3].