Cretaceous calcareous nannofossils from Pelotas Basin, Brazil: Biostratigraphic and paleoecological inferences

Biostratigraphic and paleoecological inferences are made on the distribution of calcareous nannofossils in three wells drilled in the Pelotas Basin, southern Brazil. The succession is composed mainly of siliciclastic rocks sampled by cutting and short core intervals. Eleven biozones were recognized, comprised the late Albian and the Maastrichtian. The frequency and relative abundance of some Cretaceous calcareous nannofossils species suggest a prevalence of warm-water conditions, with cooling events during the late Turonian, late Turonian/early Coniacian, late Coniacian and late Santonian/early Campanian.

► The studied calcareous nannofossils present an upper Albian–Maastrichtian age.
► Paleoecologic analyses revealed the prevalence of warm-water in this section.
► Cooling events were noted in the Turonian, Coniacian, Santonian and Campanian.