Volcanic events in the Eastern part of the Adriatic foreland (Northern Marchean Italy)

Proceedings of the 1'I R.C.A.N.S. Congress, Lisboa, October 1992

In the Late Miocene sequence of the Pesaro-Gabicce cliff (external Marchean basin) two volcanoclastic events of regional relevance have been discovered. The first important volcano-tectonic event occurred during the TortonianlMessinian boundary ( SchlierlEuxinic-Pelites Fms). It is characterized by volcano-derivated deposits, mainly constituted by the abundance of biotite, sanidine, andesine with smalleramounts of augite. The clayey minerals are mainly dominated by crystalline smectite accompanied by minor amounts of illite-smectite, illite, chlorite and vermiculite. Piroclastic flow horizons intercalated within the turbiditic sequenceofthe S. Donato Fm (Upper Messinian) characterize the second volcanoclastic event of the sedimentary succession of the eastern Adriatic foreland basin. This event is connected with explosive acid volcanic activity (rhyolithic composition) probably located in the North Adriatic Foredeep. Such volcanic events are probably correlated with similar lithologies outcropping in the Atlantic and Mediterranean areas (see Betic Cordillera). The presence of global volcanic events offers new data on the geodynamic evolution of the sedimentary basins during Neogene.