Early to middle Eocene radiolarian biostratigraphy for the mid-latitude South Atlantic Ocean, Site 356, DSDP LEG 39

Radiolarian assemblages from mid-latitude Site 356, drilled on the Sao Paulo Plateau, Santos Basin, South Atlantic, are studied in this work. A total of 124 radiolarian events from the early to middle Eocene are identified at this site. As a consequence of a lithological change at 218.50 mbsf, a decline in both radiolarian preservation and abundance was noticed. Previous lithological analyses carried out at this site revealed a hiatus from the uppermost middle Eocene to the lowermost Miocene. This hiatus is substantiated by the stratigraphic distribution of radiolarian assemblages. The standard radiolarian zonation for low latitudes is used for the Site 356 cores, and allowed the identification of the zones Podocyrtis (Lampterium) mitra (RP14), Podocyrtis (Podocyrtoges) ampla (RP13), Thyrsocyrtis triacantha (RP12), Dictyoproramongolfieri (RP11) and Theocotyle cryptocephala (RP10), from the middle Eocene, and Phormocyrds striata striata (RP9) from the early Eocene. The biostratigraphic results from the Eocene section at Site 356 in mid-latitude are compared to others from low and mid-latitudes, revealing that the range of some key species present differences relative to the tropics, and similarities to other studies from mid-latitudes.