Southeastern Atlantic Leg 40 Calcareous Nannofossils

This report deals with the study of the calcareous nannofossil content of the six southeastern Atlantic Sites 360 to 365 drilled during DSDP Leg 40 (Figure 1). Calcareous nannofossils were recovered from all sites; they range in age from Lower Cretaceous (Aptian) to Quaternary and represent an almost complete sequence of the biostratigraphic units for this time interval. All the stratigraphic stages, except for part of the Turonian and the Cenomanian, are represented in the sedimentary record of the investigated sites. The light microscope was used to examine the 1329 smear slides of the cores sampled. Use of the scanning electron microscope was only made to check the structure of some problematic lower Eocene nannofossils from Site 361 and to illustrate some upper Cretaceous forms. Of the three authors, F. Proto Decima studied Sites 361, 362, 362A, 363, and 365, F. Medizza Site 364, and L. Todesco Site 360. Discussions and conclusions on biostratigraphic and taxonomic problems were worked out jointly. Table 1 lists in alphabetical order the nannofossil genera and species considered in this report.