Geological evolution of a complex basaltic stratovolcano:

An updated geological evolution model is presented for the composite
basaltic stratovolcano of Mount Etna. It was developed on the
basis of the stratigraphic setting proposed in the new geological map
that was constrained by 40Ar/39Ar age determinations. Unconformitybounded
stratigraphy allows highlighting four main evolutionary
phases of eruptive activity in the Etna region. The Basal Tholeiitic
Supersynthem corresponds to a period, from about 500 to 330 ka, of
scattered fissure-type eruptions occurring initially in the foredeep
basin and then in a subaerial environment. From about 220 ka, an
increase in the eruptive activity built a lava-shield during the Timpe
Supersynthem. The central-type activity occurred at least 110 ka ago
through the Valle del Bove Supersynthem. The earliest volcanic centres
recognized are Tarderia, Rocche and Trifoglietto and later Monte
Cerasa, Giannicola, Salifizio and Cuvigghiuni. During the Stratovolcano
Supersynthem, from about 57 ka ago, the intense eruptive activity
of Ellittico volcano formed a roughly 3600 m-high stratocone that
expanded laterally, filling the Alcantara and Simeto paleovalleys.
Finally, effusive activity of the last 15 ka built the Mongibello volcano.
Its eruptive activity is mainly concentrated in three weakness
zones in which the recurrent magma intrusion generates flank eruptions
down to low altitude. The four main evolutionary phases may
furnish constraints to future models on the origin of Etna volcano
and help unravel the geodynamic puzzle of eastern Sicily.