Advances in the biostratigraphy of the Agrio Formation (Lower Cretaceous) of the Neuquen Basin, Argentina: ammonites, palynomorphs, and calcareous nannofossils

Detailed stratigraphic logging and systematic studies on late Valanginian-e arly Barremian ammonites from the Agrio Formation of the Neuquen Basin of w est-central Argentina, have provided a detailed local ammonite zonation. He re we combine the ammonite data with an initial study of calcareous nannofo ssils and palynomorphs from two sections to produce a provisional integrate d biostratigraphy for the Agrio Formation. While the palynomorphs are essen tially of local value only, especially the continental forms, the nannofoss ils and the ammonites allow some correlations to be made with the European Mediterranean 'standard' sequences. (C) 1999 Elsevier Science B.V. All righ ts reserved.