Continental input on shelfal deposits unveiled by integration of ichnology, sedimentology, and taphonomy: A case study in givetian beds of the Paraná basin, Brazil

Abstract The Devonian succession in Parana Basin encompasses marine deposits bearing fossils representative of the Malvinokaffric Realm, corroborated by sedimentological and ichnological data. Although the trace fossil assemblage preserved in these beds is archetypal of fully marine conditions, signs of environmental stressing conditions can be observed locally in the Givetian beds. This study aims to provide an integrated ichnological, sedimentological, and taphonomic analysis to test the hypothesis of a continental influence in the shallow marine environmental settings that sheltered the Malvinokaffric Realm in the Parana Basin during the Lower Givetian. The integration among seven lithofacies, nine ichnofabrics, and three taphofacies allowed identifying a continental influence associated with salinity variations in a prograding section of an early highstand systems tract, above the maximum flooding surface (Kacak Evet). The stress apparently caused by salinity fluctuations, as indicated by the ichnological signatures, and the high organic input in the Itaytyba outcrop succession may be related to freshwater flows that were reworked by longshore currents. The results presented herein support the hypothesis that continental influxes along shoreline fed by rivers locally generated shoreline progradation and affected the Parana Basin shelfal settings during the Lower Givetian. It contributed to reducing the benthic diversity in the Malvinokaffric Realm, as normally expressed in the basal intervals of Devonian beds from Parana Basin.