The classical Late Piacenzian Monte Falcone–Rio Crevalese section (Northern Italy): palynological evidence and biomagnetostratigraphic constraints for climatic cyclicity and local mollusc extinctions

Abstract

The Monte Falcone–Rio Crevalese section (Northern Italy) crosses the uppermost part of the Piacenzian sandy silts of Pareto (Bull. Soc. Geol. France 22 (1865) 210) and the Monte Padova–Castell’Arquato calcarenite. Previous ecobiostratigraphic studies recorded that the disappearance of both the Terebridae and the majority of Conidae, about 10 m below the lowest Castell’Arquato calcarenitic body, was not due to edaphic factors. Taking into account the biostratigraphic constraints, we put forward the working hypothesis that this event is correlatable with the beginning of the Glacial Pliocene which approximates the Gauss-Matuyama boundary. The analysis of the pollen record fully confirms that the disappearance of the warm-water molluscs was correlated with an important cooling phase. Moreover, an almost complete climatic cycle is recorded in the silty sand beds between the two calcarenitic bodies of Castell’Arquato (Rio Crevalese section). The paleomagnetic data and the biostratigraphic constraints make it possible to date the base of Monte Padova–Castell’Arquato calcarenite at around 2.7 Ma and correlate the cooling, recorded by pollen analysis just below this, with the oxygen isotopic stage 110.