Chemical and minero-petrographic features of Plio-Pleistocene fine-grained sediments in Calabria, southern Italy

The composition of Plio-Pleistocene fine-grained sedimentsfrom different areas of Calabria (southern Italy), have been studiedto unravel the interplay of provenance. The use of multivariate statisticalmethods (e.g., PCA) based on biplot, allows for the discriminationof different groups of sediments. The general chemical compositionof the fine-grained samples reflects the mineralogicalvariation observed in the sediments, which are composed of phyllosilicates,quartz, calcite, dolomite and feldspars. The I-S mixedlayers, 10 Å-minerals (illite and micas) are the most abundant phyllosilicates,chlorite and kaolinite are present in variable amounts,and smectite and chlorite/smectite mixed layers are presents in traceamounts. These chemical and mineralogical variations are also confirmedby SEM analysis, which also demonstrates that phyllosilicatesare characterized by open and folded structures with generationof neoformed clay minerals. Provenance proxies and elementratios testify greater input of felsic source rocks, with lack of amarked mafic-ultramafic detritus input for all studied sediments,and the minero-petrographical features of the studied fine-grainedsediments. These chemical and mineralogical variations are alsoconfirmed by SEM analysis showing abundant phyllosilicate mineralsfor Groups 1 (Crotone Basin) and 2 (Crati Graben) and high contentof quartz and feldspars grains for Group 4 (Catanzaro Graben)samples, probably due to abundant siliciclastic input coming fromplutonic-metamorphic source and associated Mesozoic to Miocenesedimentary sources (Sila and Serre Massifs), and abundant calcium-carbonate phases mainly related to the presence of planktoniccalcareous microfossils (Globigerina and coccoliths) for Groups 3(southern Ionian coast) and 5 (southern Tyrrhenian coast).Furthermore, paleogeographic reconstructions characterized byre-establishment of open-marine conditions in the Mediterraneanfollowing the Messinian salinity crisis at the beginning of thePliocene, play an important role. A progressive increase in the connectivityof Mediterranean sub-basins with the Atlantic (e.g., subbasinsat the south of the Catanzaro Strait, characterized by normalwater supply) and Paratethys (e.g., sub-basins at the north of theCatanzaro Strait, characterized by freshwater supply) can be envisagedduring the Neogene period; this paleogeographic reconstructionmay also explain the different composition among the studiedsamples.