Ichnology and sedimentological aspects of the Floriano Formation (Miocene of the Resende Basin), southeast of Brazil

Abstract

Many previous studies identified depositional systems for the Resende Basin using sedimentological and petrographic techniques. However, the lack of ichnological research leaves a gap in our understanding of paleoenvironment and paleoecology of this basin. Therefore, this study reports the first occurrence of trace fossils in the Floriano Formation (Miocene) and suggests more refined paleoenvironmental interpretations for this unit. We only observed ichnofossils in an outcrop on the RJ-161 road in Resende Municipality, Rio de Janeiro State. The deposit represents a floodplain overlayed by a crevasse splay, both sedimented in a meandering fluvial context. Trace fossils of terraphilic organisms – represented by Taenidium isp., Planolites isp. and Arenicolites isp. – were found in the fine-grained sediments of the outcrop. This ichnocoenosis is composed of feeding (fodinichnia), locomotion (repichnia) and/or habitation (domichinia) structures produced by worm-like invertebrates. The ichnotaxonomic assemblage consists of the first record of Scoyenia ichnofacies for a typical meandering fluvial system in Brazil. Keywords: continental ichnology, sedimentology, ichnofacies, paleoenvironment.