Pollen record and magnetostratigraphy of the Middle-Late Pliocene lacustrine sequence in the Tiberino basin, (central Italy)

The lowermost deposits of the Tiberino basin in Umbria are made of a continuous succession of deep lake clays, which were sampled in two outcrops for pollen and paleomagnetic analyses. The former sampling evidenced a gradual climatic deterioration followed by warmer/cooler fluctuations while the latter provided the magnetostratigraphic framework extending from the late Gauss chron to shortly after the Reunion sub-chron. The validity of the paleomagnetic analyses was based on good rock magnetic properties yielding a very stable magnetization related to the uniform clay lithology. Consequently the Tiberino basin sections were correlated to one another and to the sequence of the Upper Valdarno basin, about one hundred km to the North, also in agreement with their pollen contents. Pollen changes of both Tiberino and Upper Valdarno basins suggest climate conditions correlatable with those recorded at the global scale during the Middle and Late Pliocene.