Following this renewed explorative interest, the need for a stratigraphic framework aimed to support well correlations and geological modelling became of greatest importance.
Planktonic components are rare within foraminiferal assemblages.
Though the assemblages are often poorly diversified, calcareous nannofossils prove an effective tool, at least in identifying some biostratigraphic horizons of regional value. The Rio et al. A sector displaying a relatively complete section was identified southward. The top of the Early Pliocene has been approximated to the top of MNN14-15, since G. puncticulata is generally missing. On the contrary, the LO of Sphenolithus spp.