The end of the Lago-Mare time in the SE Valdelsa Basin (Central Italy): interference between local tectonism and regional sea-level rise.

A multi-disciplinary study has been carried out on a Late Neogene succession exposed in the SE portion of the Valdelsa Basin (Strolla Creek, Central Italy). Th e succession consists of upper Tortonian-Messinian sediments, unconformably overlain by uppermost Messinian-Pliocene deposits, accumulated in alluvial, lacustrine and marine environments. Previous studies on this succession hypothesized a sudden marine fl ooding of the upper Messinian Lago-Mare realm in the earliest Zanclean in apparent agreement with the Mio-Pliocene transition recorded elsewhere in the Mediterrranean Basin. Data from this study suggest a more complex stratigraphy recording a local depositional evolution possibly driven by interference between uplift, relief denudation and eustacy. Th e sediments encompassing the Mio-Pliocene transition have been included into the Borro Strolla synthem, furtherly subdivided into three sub-synthems. Th e Borro Strolla synthem has been dated as uppermost Messinian-earliest Zanclean based on the integration of physical stratigraphy, facies analysis and biochronology of non-marine fossil assemblages in part documented for the fi rst time. Th e occurrence in the lower Borro Strolla Synthem of the gerbil Debruijnimys sp. and the murid Stephanomys aff . S. donnezani (Depéret, 1890) with Pliocene affi nity represents the most important novelty in the composition of a mammal fauna otherwise similar to other Italian late Messinian sites. Th e co-occurrence of terrestrial molluscs from the same sediments gives further biochronologic constrains supporting the calibration of the Borro Strolla synthem to the latest Messinianearliest Zanclean. Th e Borro Strolla stratigraphic section then is discussed in the framework of local to regional events which marked the transition from the Messinian to Pliocene.