Late Pliocene volcaniclastic products from southern Apennines: distal witness of early explosive volcanism in the central Tyrrhenian sea.

Two volcaniclastic successions intercalated in Pliocene basinal clays from the Southern Apennines have been analysed to determine their provenance and their relationship with the geodynamic evolution of the Western Mediterranean. The studied deposits are exclusively made up of ashy pyroclasts, dominated by fresh acidic to intermediate glass, mostly in the form of shards, pumice fragments and groundmass fragments with vitrophyric texture. Crystals include PI, Opx, Cpx, Hbl and rare Bt. Sedimentological features suggest that the volcanic material accumulated near the basin margin by primary fallout processes and was later remobilized by density currents. 40Ar-39Ar geochronology allowed dating of one succession at 2.24 +/- 0.06 Ma, corresponding to the Late Pliocene. Composition of the volcaniclastic material is typical of a transitional high-K calc-alkaline series. The age and chemical composition constrain the provenance of the volcaniclastic rocks from the Southern Tyrrhenian domain. Here, volcanic centres were active during Pliocene time, approximately at the northern end of a volcanic arc formed before the opening of the southernmost part of the sea. This paper shows that a detailed study of volcaniclastic products from the southern Apennines and Calabria can be very useful in collecting new pieces of information on the eruption history of the southern Tyrrhenian domain, since they record additional data not available from the study of exposed volcanic edifices.