GNGTS 2013 - Atti del 32° Convegno Nazionale

A-A’, AA-AA’, B-B’); iii) the Conselve-Pomposa fault dips 70° to 87° to ENE or NE (sections B-B’, CC-CC’, C-C’, D-D’, E-E’). In addition, faults cutting only Mesozoic horizons, dipping at high angle to ENE/NE or to WSW/SW (sections AA-AA’, CC-CC’, C-C’, D-D’, E-E’), and an high angle reverse fault dipping at high angle to SW (section E-E’), probably associated to the Apennines activity, are observed. The throw of the Upper Triassic base and the Pliocene base along the main segments of the SVFS depicted in the depth-converted sections is also measured (Tab. 2). The data obtained through the fault mapping and depth conversion were used to perform a map of the depth of the Pliocene base along the SVFS. The collected data were merged with available data provided by ENI in the whole Veneto plain gaining a broader regional view (Fig. 3). This map shows a general deepening towards the S, clearly related to the Apennines subduction and the subsequent flexuring of the north Adriatic (Fantoni et al ., 2002). In addition, a different behaviour in the deepening of the Pliocene base is observed crossing the SVFS. The LBE block, to the west of the SVFS, shows a regular slope starting from 0 m near the reliefs and reaching about 2800 m of depth near the Apennines thrust front (about 2.8 km of deepening in 90 km; dip ~3% = 1.7°). The Veneto-Friuli foredeep, to the east of the SVFS, shows a gentle slope in its northern part close to the reliefs and the Eastern Southern Alps thrust front (about 0.6 km of deepening in 60 km; dip ~1% = 0.6°), followed by a steeper slope in the southern part (about 1.4 km of deepening in 40 km; dip ~3% = 1.7°) similar to the LBE block slope. These results are in accordance with the dip of the Apennines monocline (1.5°) calculated by Cuffaro et al. (2009). Tab. 2 – Throw of the base of Dolomia Principale (Upper Triassic base) and the Upper Messinian Unconformity (Pliocene base) measured in the depth-converted sections and related to the Conselve-Pomposa and Schio-Vicenza faults and the Travettore-Codevigo fault. The throw marked by * in AA’ section is inferred using the Upper- Middle Miocene throw. Conselve-Pomposa fault + Schio-Vicenza fault Travettore-Codevigo fault Section X (Km) Upper Triassic Base throw (m) Pliocene Base throw (m) X (Km) Upper Triassic Base throw (m) Pliocene Base throw (m) E-E’ 14 60 70 - - - D-D’ 31 50 10 - - - C-C’ 37 200 30 - - - CC-CC’ 52 550 320 - - - B-B’ 61 240 260 33 190 60 AA-AA’ - - - 50 150 170 A-A’ 112 430 430(*) 71 1070 200 Discussion and conclusions. The throw analysis of the Upper Triassic base and the Pliocene base (Tab. 2) allows to elucidate the role of the fault system in the accommodation of the two main deformational events of the foredeep, i.e. the Mesozoic extensional phase and the Cenozoic flexural phase. A clear separation between the cumulative throw of the two horizons is depicted. The Upper Triassic base throw is usually greater than the Pliocene base throw and their separation increases towards the N (from 170 m near Adria to 870 m near Vicenza), with a main supplying of the Travettore-Codevigo fault. Therefore, the SVFS, or some segments of the fault system, seems to be active during the Mesozoic when the extension was controlled by synsedimentary normal faults (Masetti and Bianchin, 1987). Such control is clearly detected in the northernmost sections crossing the eastern margin of the Jurassic Trento Platform-Plateau and it is testified by the abrupt increasing thickness of the Mesozoic units across the high-angle 190 GNGTS 2013 S essione 1.2