Markers of the last interglacial sea-level high stand along the coast of Italy: Tectonic implications

Abstract

A compilation of the Marine Isotope Substage (MIS) 5.5 high stand (∼125 Ka) sites spanning the coastline of Italy allows a picture of the vertical displacement pattern affecting the Central Mediterranean coasts since the Late Pleistocene to be drawn. For each of the 246 listed sites, the accurate elevation of the high stand is defined through well-known markers. Coupled with a refined age assessment locally supported by new radiometric dating, these markers provide robust constraints on deformation. Significant alongshore differences in site elevation between +175 and −125 m a.s.l. resulted from the interplay of regional and local tectonic processes, including faulting and volcanic deformation. Whereas most of Sardinia's coasts and the northern Tyrrhenian Sea coasts are tectonically stable, the central Tyrrhenian Sea coasts display stable promontories, subsiding plains, and localized centres of weak uplift. Subsidence of the plains is related to extensional faulting locally enhanced by volcano-tectonic collapse, and weak uplift arising from magmatic processes. Rapid uplift of southern Calabria, northeast Sicily and the Jonian sea coasts probably reflects the extent of deep crustal delamination. The central Adriatic Sea shows weak thrust-related uplift, but foreland flexure in northern Adriatic and possibly southwestern Sicily results in locally intense regional subsidence. The rapidly uplifting regions are well correlated with the sectors of higher seismic release and surface horizontal motion documented by geodetic velocities. In this light, the MIS 5.5 marker indicates with a relatively high spatial resolution the vertical component of tectonic displacement and provides insight into the long-term tectonic processes of the Central Mediterranean orogen.