Sedimentary evolution in a migrating foredeep basin : geometry and facies analysis of the massive sandy bodies of the Cellino Formation (Lower Pliocene Periadriatic foredeep, Central Italy)

The sedimentary evolution of the Lower Pliocene Periadriatic Foredeep in Central Italy is described on the basis of integrated facies analysis of the numerous turbidite massive sandy bodies (megabeds) and correlations of well log-field data, which give new perspectives on the effects of the basin migration. The basin evolution shows four major morphological changes during the Lower Pliocene. In a first phase, the basin was fed From the south, as testified by coarse clastic, turbiditic sediments coming from the Maiella Massif. Subsequently (second stage) its Southern feeding system was switched off by the uplift of a structural high (Cigno structural high) and the basin received turbidite fill from northern source areas. Basin-wide, very thick (2 to 22 m) megabeds are the result of aggradation of high efficiency, large-volume turbidites that can be interpreted as deposited from sustained (long-lived) currents flowing in a confined basin. The foredeep migration towards the south-east, common in the entire Periadriatic foredeep, caused, in the third phase, a reactivation of the sedimentation with megabeds thinning southward in the northern uplifting area, followed by megabeds prograding and aggrading into a new depocenter located to the south. In the final stage, the increasing uplift of the northern part of the basin, due to thrusts active in the north-western area, gave rise to its deep erosion, above a relevant unconformity, development of channels filled by sands in the inner fan and progradation of the outer fan southward. It is hoped that this study can be applied to other migrating basins of the Periadriatic Foredeep.