Geochronology of Pleistocene marine terraces and regional tectonics in the Tyrrhenian coast of South Calabria, Italy

Abstract

At least twelve orders of marine terraces (named Terrace I to XII in this paper) are identified along the Tyrrhenian coast, from the Capo Vaticano Promontory to the Messina Strait, in southern Calabria (Italy). The shoreline of the highest terrace (Terrace I) reaches 1350 m in altitude around Aspromonte. On the basis of geomorphological and biostratigraphical correlation and uranium-series dating, all marine terraces are ascribed to an emergence in Pleistocene times: - terraces I and II are assigned to interglacial high sea levels around 1000÷1200 ka; terrace IV probably to the oxygen isotope Stage 25 (~950 ka); terrace VII is related presumably to Stage 9 (or to Stage 11) (~300÷400 ka); terrace X with Strombus bubonius-beanng sediments and the uranium-series age of 121±7 ka of Cladocora is ascribed to Stage 5e (~125 ka) corresponding to the last interglacial peak (Eutyrrhenian transgression). Altitude changes in elevated shorelines and fault movements show disuniform and differential tectonic phases in Pleistocene. Doming uplift manifested by warping (wavelength: ~50 km) prevailed in the Early Pleistocene (~1200÷900 ka), probably originating from an upper mantle diapiric intrusion into the crust, contemporary with an extensional normal faulting that started in Pliocene. Three local uplifting centres are identified: Monte Poro, Le Serre, and Aspromonte. In particular, around Aspromonte local gravitational faulting is superimposed onto normal faulting and is simultaneous with rapid doming uplift (the maximum rate being 3.8 m/ka). The gravitational features imply brittle collapses on slopes of the rapidly up-domed upper crust. A generalized regional uplift (0.9÷1.1 m/ka) has been dominant since Middle-Late Pleistocene (~300 ka), suggesting arc-wide crustal deformations in the Calabrian ridge, accompanied by gentle warping. At the Capo Vaticano Promontory the marked doming uplift continued, as shown by the Eutyrrhenian shoreline varying in elevation from 50 m at Vibo Valentia Marina to 120 m at Capo Vaticano. There are no geomorphological evidence of active normal faults after the Middle Pleistocene, even if severe earthquakes have interested southern Calabria in historical times.