Messinian salinity crisis and its paleogeographical implications

Abstract

During the Late Messinian (uppermost Miocene) the region that is now Italy was occupied by a lake or system of lakes similar to those of the Paratethys existing to the east. Lacustrine deposits are known, not only in Italy, but extending southward through Sicily into the northern part of Tunisia. These strata contain faunas tyoical of a hyposaline environment. The lakes generally exhibit shallow-water characteristics and follow the structural trends of the “geosynclinal” development of Italy during the Late Miocene. We conclude that the water level ofthe hyposaline lake system was conspicuously lower than the general level of the World Ocean system. We support the point of view that the western Mediterranean was in a state of partial desiccation. In the area studied, the sharp contact between Miocene and Pliocene deposits points to a sudden change from a region of shallow lakes or subaerial erosion to the deposition of deep-water sediments. The sudden appearance of d deep-water environment is explained if the Pliocene transgression is considered to be a consequence of the re-establishment of communications with the open sea.