VOLCANIC ACTIVITY FROM THE NEOGENE TO THE PRESENT EVOLUTION OF THE WESTERN MEDITERRANEAN AREA. A REVIEW

Abstract

The Neogene to Present geodynamic and magmatological evolution of the western Mediterranean area may be summarized as follows: 1) Paleocene to Present volcanic activity in the Massif Central, France, related to the presence of a mantle plume in the Alpine foreland; 2) roughly continuous W-NW subduction of the Adria Plate from the Oligocene under the southern European margin; 3) development of a subduction-related back-arc basin during the Oligocene (Ligurian-Provençal Basin); 4) split of the Sardinia-Corsica Block from the Provençal basement; 5) collapse of the Betic orogen, with rapid exhumation of deep crustal and mantle rocks and development of volcanic activity in SE Spain (~30-2 Ma); 6) subduction-related magmatism in Sardinia (28-15 Ma) and eastern Spain (24-15 Ma); 7) a mid-Miocene ‘leap’ in the subduction system, from the Ligurian-Provençal Basin to the Tyrrhenian Sea, with a shift from Hercynian to Alpine terrane overthrusts; 8) opening of the Tyrrhenian Sea as a back-arc basin; 9) Neogene-Quaternary eastward-moving distensive and compressive tectonic waves and coeval magmatism along the western and southern margins of the Italian peninsula (Tuscan, Roman and Campanian Provinces and Aeolian Islands); 10) volcanic activity in the Betic foreland (Calatrava Province, ~9-1 Ma); 11) Plio-Pleistocene development of rift systems and coeval magmatism in Sardinia, northern and eastern Sicily (Mt. Etna and Hyblean Mts.) and the Strait of Sicily. Intense volcanic activity accompanied the evolution of the last 30 Ma in the western and central Mediterranean, with a wide range of magmatic products which may be grouped into: a) oceanic floor basalts (Ligurian-Provençal Basin and Tyrrhenian bathyal plain with Magnaghi, Vavilov and Marsili seamounts), whose compositions vary from N-MORB to E-MORB and pure low-K calc-alkaline basalts; b) subalkaline series with both tholeiitic and calc-alkaline affinities; c) alkaline products with extreme compositions ranging from mildly alkaline types with sodic affinity to strongly SiO2-undersaturated with both sodic and potassic to ultrapotassic affinity, possibly including also carbonatitic lithotypes. The Sr-Nd-Pb isotopic compositions of these products comprise virtually all the most common worldwide reservoirs and testify to the extremely heterogeneous compositions of the mantle sources of this sector of European lithosphere/ asthenosphere system.