Stratigraphy, composition and provenance of argillaceous marls from the Calcare di Base Formation, Rossano Basin (northeastern Calabria)

The Calcare di Base Formation is a part of the Rossano Basin characterizing the ForelandBasin System of northeastern Calabria. Messinian argillaceous marls from the Calcare di BaseFormation have been studied to characterize the sedimentary evolution of this formation during thepost-orogenic phases of the Calabria–Peloritani Arc. The mineralogical assemblage of the argillaceousmarls is dominated by phyllosilicates (illite, chlorite, illite/smectite mixed layers and traces ofkaolinite), carbonate minerals (calcite, aragonite and dolomite), quartz and traces of feldspars (bothK-feldspars and plagioclase), gypsum and celestine. The palaeoweathering index records changesat the source, reflecting variations in the tectonic regime as shown in the A–CN–K plot, where thestudied samples describe a trend typical of a source area in which active tectonism allows erosion ofall zones within weathering profiles developed on source rocks. The studied samples are derived froman environment in which non-steady-state weathering conditions prevailed. This trend could recorddeformational events that affected the Mediterranean area during the Miocene. The Th/Sc versus Zr/Scratios and Al–Zr–Ti plot suggest that the samples likely record a recycling effect from their basementrocks. The geochemical proxies of these samples suggest a provenance from a mainly felsic source.The Messinian argillaceous marls record that deposition probably occurred in a semi-closed marine environmentmainly subject to hypersalinity with local episodes of meteoric water influx, during a periodcharacterized by persistent dry and warm/arid conditions alternating with relatively wet conditions.