Upper Messinian siliciclastic rocks in southeastern Calabria (southern Italy): palaeotectonic and eustatic implications for the evolution of the central Mediterranean region

Abstract

The Messinian stratigraphy of eastern Calabria (southern Italy) is characterised by a threefold subdivision: (1) a pelite section with local limestone and gypsum, deposited in a restricted-marine environment, is unconformably, or disconformably, overlain by (2) coarse-grained alluvial conglomerate, which is in turn locally overlain by (3) a thin and discontinuous ribbon-shaped sedimentary body of sandstone and pelite, commonly displaying a shallow-marine to continental progradational trend. The basal unconformity/disconformity, coarse grain-size, and abrupt compositional-sedimentological change of unit 2 with respect to unit 1 can be explained as a response to tectonic instability and out-of-sequence thrusting in the Calabrian orogenic wedge, possibly induced by isostatic back-tilting of the wedge following the desiccation of the Mediterranean Sea. This mechanism could explain widespread late Messinian thrusting and syntectonic sedimentation along the Apenninic–Maghrebian orogenic belt. The uppermost Messinian continental to shallow-marine siliciclastic deposits of unit 3 crop out today at elevations of up to 300 m. Similar, age-equivalent sedimentary deposits can be traced along the Apennines and the Sicilian Maghrebides, thus, indicating that the Mediterranean area was flooded before deposition of the Trubi Formation, the base of which is traditionally regarded as marking the reestablishment of marine conditions in the Mediterranean region.