GNGTS 2016 - Atti del 35° Convegno Nazionale

GNGTS 2016 S essione 3.2 529 Senonian. The stratigraphic data have suggested that the neritic sedimentation on the platform continued with a certain regularity after the Turonian emersion evidenced by the A unconformity (stratigraphic unit 1a), so the platform was newly submerged during the Early Senonian. Outcrop and well data for the southern Murge sector have shown that the platform, while vertically aggraded in correspondence to the unit 1A, supplied a slope area characterized by rock fall processes. These processes have been evidenced by carbonate breccias including clasts of platform. These breccia have been described by Pieri and Laviano (1989) in outcrop in the Ostuni area (Calcare di Caranna) and recognized offshore at the Picchio well, located in correspondence to the Monopoli town (Aiello, 1992). During the Campanian the evolution of the platform-basin system was interrupted by an abrupt rise of the sea level, evidenced by the progradation of the Scaglia calcarea formation on the neritic limestones (Unit 2 overlying the unit 1) and resulting in a flooding of some sectors of the platform (B unconformity). At the same time, the occurrence of neritic and marginal carbonates (upper part of the Unit 1a) in the inner parts of the Apulian platform demonstrated that the drowning was not completed. Paleocene-Eocene. The carbonate platforms of southern Apennines were characterized by a general hiatus of the sedimentation during the Paleocene-Eocene (D’Argenio et al. , 1973). Neritic limestones of shelf domains with Nummulitids and Alveolinas, Eocene in age, crop out in the eastern Gargano Promontory, unconformably overlying the pelagic sediments of the Scaglia calcarea (Martinis and Pavan, 1967). These Eocene limestones, namely the Calcare di Peschici Formation have been found offshore the southern Murge, at the Picchio well, located in an embayment of the shelf margin. The same succession has been drilled by several wells located in the northern Gargano offshore. Amain unconformity occurs in correspondence with the Paleocene-Eocene hiatus observed in the shelf (C unconformity). It has been recognized on seismic profiles and tied by well data in the South-Adriatic Basin. The Cretaceous-Paleocene Scaglia limestones are truncated upwards and directly overlain by Late Oligocene clastic sequence of south Adriatic foredeep. The stratigraphic gap related with this unconformity represents a time interval ranging between 10 and 30 My. Due to its regional extension (platform-basin) the C unconformity probably corresponds to an episode of regional emersion and may be related with the Paleogene phase of uplift and erosion of southern Apenninic carbonate platforms. The eustatic control does not account by alone a so prolonged event and a tectonic control should be inferred. In particular, the unconformity may result from an uplift episode linked to a bulge linked to the effect of the orogenic deformation of the internal Dinarides-Hellenides. Oligocene-Miocene. The stratigraphic architecture of Late Oligocene formations in the platform-basin system records another main variation in the dispersal pattern of sediments. In the Salento area the shelf sedimentation is characterized again by margin and reef facies (Unit 4a), directly overlying Late Senonian limestones. Due to the formation of the southern Adriatic foredeep, the subsidence of the South Adriatic Basin was strongly accelerated and the previous carbonate environment, exposed during the Eocene, was converted in a siliciclastic environment. The age of the first clastic sediments in the foredeep is Late Oligocene. During same time a phase of erosional retreatment along the eastern margin of the Mesozoic platform took place. The seismic profiles perpendicular to the shoreline show chaotic reflections at the base of the slope, interstratified in the Oligo-Miocene basinal sequence. These sedimentary bodies, having a fan-shaped geometry may be interpreted as alternating carbon ate re-sediments and siliciclastic turbidites. The greater frequency of carbonate turbidites in proximity to the shelf margin is a further prove of a phase of retreatment which took place during the Early Tertiary. Due to the emplacement of the Dinaric-Hellenic foredeep the basinal depositional environments evolve towards a hybrid carbonate-siliciclastic system (Dolan, 1989), in which