Neogene and pleistocene volcaniclastites of the Apennines (Italy).

Abstract

Numerous volcaniclastic deposits are found interbedded in several Neogene-Pleistocene units of the Apennines. They are mostly the result of volcanic activity that was contemporaneous with sedimentation and they thus have a specific geodynamic significance. These volcaniclastites are indicative of periods of intense volcanic activity (e.g. Aquitanian-Burdigalian-Langhian), alternating with periods of lesser activity (e.g. post-evaporitic Messinian). Periods of increased volcanic activity must be attributed to important tectonic phases in the Mediterranean area. Moreover, a migration of volcaniclastic products towards the external zones of the Apennines can be observed. The composition of the pyroclastites suggests an origin from calc-alkaline magmas that were generated in volcanic arcs probably developed on continental crust. No comprehensive hypothesis on the location of the Neogene-Pleistocene effusive centres has been put forward up to now. Nevertheless, some areas, such as the Po Plain and the Tyrrhenian zone, are particularly suspicious in this respect.