Microfossil biostratigraphy and stage-stratotypes of the Cretaceous

Abstract

Correlation of the most recent Cretaceous zonations based on calcareous nannoplankton, planktonic foraminifera and calpionellids allows more precise determination of the relative position of some Cretaceous stage-stratotypes in the standard chronostratigraphical scale. In particular, those of the Santonian, Campanian and Maastrichtian stratotypes seem to be very limited in time-span. It is possible to overcome these limitations and to some extent also the problems concerning their recognition and traceability by a pragmatic extension of the type-sections and by the introduction of auxiliary hypostratotypes in the type areas. However, it is concluded that designation of one or more independent reference sections for Upper Cretaceous stages is a preferable alternative which should receive more attention. In this way also a more useful section could be proposed for the Cenomanian, Turonian and Coniacian stages.