The late Messinian Lago-Mare episode in the central Italy: a regional review.

During the Messinian Lago-Mare episode, in the central Mediterranean area, compression- and extension-related basins developed as a consequence of the post-Tortonian evolution of the Tyrrhenian-Apennines system. In particular, in the frontal Apennine zone, which was affected by compressional tectonics, a foreland basin system developed, originating: thrust-top basins (such as Le Vicenne Basin), a foredeep basin (Pescosansonesco-Roccacaramanico) and a foreland basin (Roccamorice-S. Valentino in Abruzzo Citeriore) (fig. 1). Meanwhile, the Tyrrhenian area was affected by a strong subsidence rate with sedimentary basins developed in a syn-rift stage (Tyrrhenian Basin east of the R. Selli lineament, Garigliano plain, Tolfa-Blera Basin and Tuscan late Messinian basins). All these sedimentary basins were characterized by different subsidence rates and sedimentary processes, depending on both the tectonic and the subsiding regime they underwent. We examined foreland, foredeep, thrust-top, extension-related basins, and the results of the Mondragone 1 well in Tyrrhenian Basin.This regional review on the late Messinian Lago-Mare deposits in central Italy shows that the Tyrrhenian rifting process, the accretion of the Apennine thrust belt as well as the increase in subsidence rate in the foreland domain occurred synchronously. The total subsidence rates computed in the area of the Tyrrhenian Basin, which, during the Messinian Lago-Mare episode, was affected by rifting, evidence a different behaviour between the northern and the southern Tyrrhenian (Fig. 2). North of the Tiber delta, the Messinian post-evaporitic sedimentary basins show a mean total subsidence rate of 1 mm/a (Volterra, Val di Fine and Tolfa-Blera basins), whereas in the Garigliano plain the subsidence was at least 4 mm/a. This difference in the syn-rift subsidence could be explained with the segmentation model of the Tyrrhenian –Apennines system along a NNE-SSW lithosphere discontinuity (Cipollari et al., 1999), from Ancona to the Tyrrhenian Basin.