Genesis, chronology and tectonics of the Quaternary marine terraces of the Tyrrhenian coast of northern Calabria (Italy). Their correlation with climatic variations

Abstract

Five orders of marine terraces have been identified along the Tyrrhenian coast of Northem Calabria (Italy) between Noce-Castrocucco and Lao riverso The terraced portion of the coast is markedly different from the portion uphill that displays a mature continental morphology with few poorly preserved terraces whose marine origin is not evidenced.

The 1st-order terrace is the most extensive (up to >3 km wide) and has been correlated with the clay sedimentation of Emilian age. The corresponding shoreline (inner edge of the terrace) is clearly indicated by beach deposits, Lithodomus holes, etc. A new genetic model is proposed for this terrace: i.e., the extensive wave-cut platform would have formed because of the cumulative effect of repeated transgressions each of which having reached an elevation greater than the preceding one owing to a long-Iasting subsidence period. The complete emergence of the terrace would have occurred at the end of Lower Pleistocene due to the combined action of the uplift of the region, and the regression because of glacio-eustatic changes of sea levaI.

The chronological reconstruction of the sequence of terraces based on the morphological evidence was controIled with U-series age measurements on Cladocora from the 4th-order terrace. It was also compared with oxygen isotope palaeoclimatic curves and high sea stands corresponding to interglacial peaks. Variation in the elevation of each order of terraces has provided information concerning the differences in uplift that occurred along the coast during Middle and Upper Pleistocene.

The results of this study suggest that a marine terrace cannot be regarded as a simple "marine form", but must be thought of as the result of the complex interaction between climatic variations, sea level changes, and coastal vertical movements.