GNGTS 2016 - Atti del 35° Convegno Nazionale

482 GNGTS 2016 S essione 3.1 The Po Plain and the Adriatic sea represents only one microplate separated by the African plate (Finetti et al. , 1987). Based on geophysical constraints these authors have suggested that the Adriatic plate is completely separated from the African one. The first rifting phase may be happened during the Middle-Late Trias with the formation of sea-channels in correspondence to the Ionian sea, but the first geodynamic phase happened during the Middle Jurassic. Between the Late Mesozoic and the Early Paleogene the Adriatic plate margins started to join with the European plate. The compressional movements continued since the Tortonian. At the end of the Oligocene the extensional phase started, leading to the opening of the western Mediterranean, while on the Tyrrhenian margin of the Adriatic plate the Apenninic thrusting began. This deformation was explicated along strike-slip and normal faults in the Ligurian sector, in correspondence to the junction among the Alps and the Apennines, while along the Apenninic belt the subduction of the Adriatic margin started. Results. Well lithostratigraphic data have been analyzed to establish the stratigraphy in correspondence to the Gondola fault system (Gondola 1bis well; Agip, 1970). The well has drilled, in correspondence to a palaeo-structural high, a Mesozoic carbonate succession, ranging in age from the Late Triassic and the Middle-Late Jurassic for an average thickness of 3.4 km. Upper Trias to Lias time interval is characterized by the occurrence of shallow water limestones, indicating the transition from an evaporitic area to a platform area. Shelf sedimentation continued up the Early Jurassic, with the deposition of dolomites. Middle-Late Jurassic was characterized by slope carbonate successions, indicating a relative deepening of depositional environments, with the establishment of slopes on the flanks of the carbonate palaeo-structural high of Gondola. Marly limestones unconformably overlie Late Jurassic slope limestones during the Early Cretaceous, indicating the deposition of Maiolica Formation, pertaining to the Adriatic Basin. Fig. 3 – Seismic line D438.