Late Pleistocene sea-level changes and vertical movements between Formia and Minturno, central Italy

The Tyrrhenian coast of southern Lazio, central Italy, is one of the most representative coastal segment of the Italian peninsula from a morphotectonic viewpoint. Many markers of Late Quaternary sea-level changes have been surveyed In this area (Ozer et al., 1987; Antonioli, 1991; De Pippo et al., 2007). The whole south-facing arched coastal plain is relatively narrow being immediately bordered at its back by an impressive mountain ridge (Aurunci Mts) made of Mesozoic-Cenozoic carbonate rocks and terrigenous units. The coastal belt ranges from the sea level to about 30 m a.s.l. and is geologically constituted of several Quaternary units, partly cropping out in the inner portion of the study area, and by a Holocene sequence known only by well logs. A new geological survey associated to detailed measures of sea-level markers has been carried out along the Gaeta Bay coastline, from Vindicio plain to Monte di Scauri promontory (respectively to the west and the east of Formia town) and at Monte d'Argento in the Minturno plain. In the Vindicio area, a carbonate clastic deposit, never reported before in the maps of this sector, has been found at about 17 m a.s.l.: petrographic analysis of thin sections of these sediments suggested a deposition in an intertidal littoral environment as beachrock deposits. Different cementation facies indicated an early cementation in a littoral environment followed by supratidal main cementation. 230Th/234U isotopic analysis revealed a Late Pleistocene (pre-Tyrrhenian) age. It can be assumed that the area of Vindicio underwent a remarkable tectonic uplift in Quaternary times. At Monte di Scauri and Monte d'Argento sites fossil notches, lithodome holes, beach deposits, and other geomorphological markers are well exposed and locally displaced by faults. Data there collected allowed us to complete the framework of the morphotectonic evolution following the uplift occurred in the Late Pleistocene and indicated that the area was subject to a significant tectonic activity also during the Tyrrhenian up to the MIS 5.1.