Abstract

An integrated biostratigraphic study based on calcareous nannofossils and foraminifera was performed on 3 upper Pliocene terrigenous sections sampled in the S. Arcangelo piggy-back basin (section of Torrente Racanello, section of Torrente Sauro, section of San Giorgio Lucano). In spite of low Discoaster abundance, pre-Pliocene and Pliocene organic reworking and inorganic content, the new quantitative analyses on calcareous nannofossils allowed to recognize a succession of events according to the scheme proposed by Rio et alii (1990): disappearances of D. tamalis, D. pentaradiatus and D. brouweri, acme of D. triradiatus in the upper part of D. brouweri Zone, base of the last acme of D. pentaradiatus, high abundance of "small" Gephyrocapsa near the extinction of D. brouweri. Therefore, the biostratigraphic scheme of Rio et alii (1990) serves to recognize the biozonal interval in the terrigenous deposits, as well as in the pelagic sediments. Moreover, the integrated biostratigraphy allowed to recognize, in the same terrigenous sections, also several planktonic and benthic foraminifera events according to the schemes of Spaak (1993) and Colangolo & Sartoni (1979): appearance of Neogloboquadrina atlantica left and Bulimina marginata, above the disappearance of D. pentaradiatus; disappearance of N. atlantica left; appearance of Globorotalia truncatulinoides truncatulinoides, Sphaeroidinella dehiscens, Globorotalia tosaensis, and Globorotalia inflata near the acme event of Discoaster triradiatus; appearance of Bulimina elegans marginata in the Dictyococcites productus Zone. The correlation between calcareous nannofossils and foraminifera events allowed a reliable and detailed age determination for these terrigenous sediments.

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