High-diversity European palaeoflora favoured by early Pliocene warmth: New chronological constraints from the Ca′ Viettone section, NW Italy

We present new chronological constraints for a reference European palaeoflora based on integrated stratigraphic, palaeobotanical, palaeomagnetic and micropalaeontological analysis carried out on the Pliocene section of Ca′ Viettone, northwestern Italy. This site is characterized by rich fossil plant records of high taxonomic diversity, good preservation, and varied taphonomic mode. Palaeofloral analysis shows that the Ca′ Viettone assemblage reflects a chronologically delimited and distinguishable stage of vegetation development in northern Italy (called Ca′ Viettone Florenkomplex). Palaeomagnetic analyses show a dominant normal polarity that, however, seems to be the result of a remagnetization process due to secondary oxidation. Layers with no evidence of oxidation have registered a reverse polarity, which likely represents the original magnetization of the sediments. These results, in combination with biochronological indications, suggest that deposition of the succession preceded the Gilbert-Gauss reversal and took place during the final part of the Gilbert chron. This confirms a late Zanclean age for the rich Ca′ Viettone palaeoflora and allows us to propose this locality both as reference for a regional Florenkomplex and as a representative example of terrestrial vegetation in Europe during the early Pliocene warm interval.