Nannoconus fragilis and Braarudosphaera africana: two new ca/capeous nannofossil biozones in the Ceará Basin, Brazil

Abstract

Two new calcareous nannofossil biozones are proposed tor the Ceará Basin (Mundaú Subbasin). The top oI the Nannoconus fragilis zone is defined by the extinction level of N. fragilis, which occurred in the Albian. The base of the Braarudosphaera africana zone is characterized by the last occurrence of N. fragilis and its top by the extinction level of B. africana. The latter biozone ranges from the Late Albian to the Early Cenomanian. These two new biozones have been proposed to replace the Nannoconus truitti truilti zone. Although the latter unit has been wide/y used in basins of the Brazilian continental margin. it presents various problems as lar as stratigraphic correlation.