Marine terraces in the Tyrrhenian Sea margin of the Southern Apennines (Italy): new constraints on differential vertical motions from dated paleoshorelines

The Neogene to Quaternary southern Apennines mountain belt is flanked to the SW by the Tyrrhenian Sea back-arc basin, which was formed since late Miocene times. Extensional tectonics related to back-arc basin formation affected the Tyrrhenian margin of the southern Apennines since the Quaternary with formation of a series of horst and graben structures. Huge amounts of existing surface, subsurface and offshore data indicate that subsidence on the order of thousands of metres affected the grabens, and remarkable flights of marine terraces are indicative of Quaternary uplift of the horst blocks. The highest and older marine terraces, Early Pleistocene in age, occur up to several hundreds of metres above the sea level.

A huge number of former studies have provided fundamental data on both the outcropping (raised) and buried paleoshorelines and littoral deposits, the chronological framework for the identified relative sea level fluctuations mostly rests on local-scale relative chronology reconstructions constrained by dating that are still quite rare and sparse.

Detail-scale geomorphological-geological mapping, integrated with Quaternary stratigraphy, aimed at the recognition, characterisation and dating of raised marine terraces and paleoshorelines (tidal notches, platform inner edges) has been carried out in several key areas of the southern Apennines Tyrrhenian Sea margin, from Campania, in the North, to northern Calabria, in the South. The field surveys have been carried out both in rocky coasts (where continental deposits cover and sometimes hide the paleoshorelines) and in the two main alluvial-coastal basins, namely the Campania and Sele River plains. The new geochronological data constrain the ages of several late Middle Pleistocene to Late Pleistocene sea level markers, allowing a better definition of the vertical motions in each study area. Overall, the time-space distribution of the vertical motions on the regional scale is better reconstructed, along with the framework of the Quaternary surface uplift of the southwestern slope of the southern Apennines mountain belt.