Carbonate/evaporitic sedimentation during the Messinian salinity crisis in active accretionary wedge basins of the northern Calabria, southern Italy

Abstract

This work deals with Messinian deposits belonging to the Neogene infill of the Rossano and Belvedere Basins, respectively developed along the fore-arc and the back-arc areas of the north Calabria accretionary wedge. The main goal is to characterize the carbonate and evaporitic sedimentation during the Messinian Salinity Crisis, in the general framework of the basin architecture and the interplay between eustatic vs tectonic controlled sea- level variations. Fieldwork integrated with seismic lines and well logs interpretations led to the revision of the general stratigraphy of the basins and the proposal of a new sequential stratigraphic model driven by cyclic sea- level variations. Each cycle, repeated at least two times during the Messinian Salinity Crisis time frame, begins with a relative sea-level fall responsible for the emplacement of prograding wedges composed of terrigenous and evaporitic deposits that, subsequently, evolve in the deposition of primary basin-fill evaporites. This phase is followed by open marine transgression due to relative sea-level rise that terminates the evaporite formation and predates the development of microbial dominated carbonate platforms associated with shallow-water evapor- ites. Both basins experienced intense tectonic activity during the Messinian, which could be responsible for huge basinward sediments exportation and fast decreasing in the accommodation space. However, this did not sub- stantially influence the development of the systems tracts that, considering the basinal architecture, have been mainly controlled by eustatic sea-level variations. In fact, two major sea-level drops associated with basin re- striction and aridity (cold) conditions seem to have caused the origin of two main evaporitic units as basin-fill evaporites, while consequent sea-level rises and less stressed condition, account for two carbonate units with limited evaporites and terrigenous deposition.