Italy Tectonics and Genesis Part II

By | February 17, 2022

Finally, on the Adriatic side, starting from Urbinate, an eastern area leans against the axial beam, composed of secondary lands from the Trias to the Cretaceous period, which ends, assuming a transversal course, in the Sabina mountains; tectonic bundle of folds and typical carriageways (Spoleto) whose directions, turning first in the meridian direction up to Monte Vettore, tend later, as they proceed towards S., to become NNE.-SSW., thus interrupting the prolongation towards sirocco of the tectonic lines of the axial beam. The folds of this eastern area deviate to the SW. to tighten against a Tivoli-Antrodoco-Monte Vettore line, highlighted by an abnormal contact between the secondary soils and the Miocene, transversal displacement, fracture or carriage surface, of primary importance, which marks not only a tectonic limit but corresponds to a change of facies  of the Apennine Supracretacic which from schistose-limestone (scale, pink limestone, schist to fucoids),  abyssal facies  , to NW, becomes SE. of it compact hippuritic limestone,  cliff facies  , characteristic of the whole southern Apennines.

Beyond this line, starting from Abruzzo, the tectonic alignment of the Apennines resumes the direction from master to sirocco that it had at N., although with a very different structure, complicated by folds and longitudinal dislocations with predominance of the Secondary almost entirely limestone or towards the Tyrrhenian Sea, of the clayey arenaceous Tertiary towards the east.

At the Vallo del Crati begins the block of crystalline schists Calabria-Peloro, of Hercynian structure, which remained completely submerged during the Mesozoic era as evidenced by the superimposed strips of secondary limestone of Monte Paleparto, of M. Coccuzzo (Cosenza), of M. of Tiriolo and other minor ones, remnants of a Mesozoic mantle. The tectonic lines go from NO. to SE. in the Sila and become almost E.-O. in the Serre and the Aspromonte. The Apennine uplift adapts along the Ionic edge of the block, describing an arc from the Gulf of Taranto to the Sicilian Sea and passing from the master-sirocco tectonic direction of the peninsula to the E.-O. of the Caronie and Madonie.

According to MYSTERYAROUND.COM, the orogenic thrust continued vigorously beyond the earliest Miocene so that we now see recent Miocene soils raised in the central Apennines up to 2000 meters; further to S. in the Lepini and Ausoni and in the Irpinia Mountains the hippuritic limestones dominate horizontally by carriageway respectively on the lower Miocene and on the scaly clays. The Apennines thus joined together in a long chain with numerous longitudinal valley furrows that were filled up. Calabria and Sicily still remain a complex of detached islands.

To the east of the main chain, as a distant undulation, rises the Monte Conero of a constitution similar to the Marche Apennines. Further to S. the Gargano is a simple arching of the cretaceous layers of the southern type with Eocene edges. Further to the S. still the vast limestone platform of Puglia stretches with horizontal layers parallel to the Apennines, emerging more slowly than this, as evidenced by its partial coverage of Miocene and Pliocene sediments.

The Miocene ends with a general movement of emergence that gives rise to coastal and lagoon deposits (chalky-sulphurous zone) due in part to a transitory Caspian phase in that Mediterranean that had been forming during the alpine distrophism in place of the Tethys. The Pliocene, on the other hand, marks a transgression or thalassocratic period in which all the inlets, canals and straits remained among the recently uplifted lands are invaded by the sea. Sardinia alone is an exception, because in it, which emerged after the middle Miocene, there is no trace of the Pliocene transgression.

The Quaternary marks a new general uplift where more, where less intense, but always strong, which raises all the coastal Pliocene deposits and thus composes in the current unity all the parts hitherto disjointed. The various Calabrian Pliocene islands come together as a whole; Puglia, Gargano and Conero are joined to the Apennines; the Padano Gulf is reduced and subsequently filled by the Alpine currents. The movement is so intense that the Pliocene is in some cases carried up to over 1000 m. on the sea (Monte dell’Ascensione, 1103 m. near Ascoli); in Calabria the gradual Quaternary rise is marked on the Tyrrhenian side by a fourfold line of terraces; the highest of which has an altitude of 1200 meters.

The alpine diastrophism is accompanied from its beginning by eruptive manifestations. Among the oldest in the Alps are the Euganei dating from the Cretaceous period, the Eocene basalts of Monte Baldo, Veronese and Vicentino, and the Berici. Miocene are the granites and porphyries of Elba and the metaliferous chain, the syenites of Biella and the diorites of Traversella, the granites of S. Fedelino. In Sardinia, trachytes and basalts followed one another from the beginning of the Miocene to the opening of the Quaternary. In Sicily the basalts of the Val di Noto continue until the upper Miocene an activity that began in the Mesozoic in the center of the island. In the Quaternary there is a grandiose revival of volcanism. On the internal side of the Apennines Capraia, Monte Amiata, the volcanoes of Lazio, Campania, Pontic, Aeolian and Ustica.

Italy Tectonics 2