MESSINIAN PALEOGEOGRAPHY AND EROSIONAL SURFACES IN ITALY - AN OVERVIEW

The Messinian deposits of Italy display an extreme variability both lateral and vertical, including strong changes in salinity and in sediment accumulation rates. This variability strongly contrasts with the much more uniform nature of both the older (i.e. Tortonian) and younger (i.e. Zanclean) strata. Changes in salinity range from fresh water to hypersaline conditions, leading to evaporite precipitation ("salinity crisis"). The chloride facies it recorded in Calabria, facing the deep Ionian sea, in the central Sicilian Basin and in a single satellite basin of southern Tuscany, fed by the Ligurian Sea. Erosional surfaces are widespread at the southern edge of the Alps, and extend to the subsurface of the Po Basin. Rapidly subsiding, and outward moving foredeeps, deep-seated brine pools uplifted in post-Messinian times, post-tectonic extensional basins provide a different stratigraphic record of the same paleogeographic event, a dramatic drop of sea-level which lasted overall less than one million years. © 1990.