Peloritani Continental Crust composition (Southern Italy): geological and petrochemical evidence

This paper reconstructs the State of the Art on the Peloritani Crust (Southern Italy). It illustrates the geometry, the real extension, petrographic and geochemical compositions and the tectono-metamorphic evolution of its terrains, with special regard to the crystalline basements, focusing on the most important stages of their evolution. In the Southern Sector of the Calabria-Peloritani Arc, the Peloritani Belt (PB) exhibits a complex structure, characterised by an Alpine continental crust stack of tectono-stratigraphic units, with Africa-ward vergence, involving both Variscan, or older, crystalline rocks and Mesozoic-Cenozoic deposits (AMODIO-MORELLI et alii, 1976; BONARDI et alii, 1976a, 1996, 2001; MESSINA et alii, 1996a). The PB tectonic setting consists of seven Alpine units, which are, geometrically, from bottom to top, and geographically, from south to north: the Longi-Taormina, Fondachelli, Alì, Mandanici, Piraino, Mela and Aspromonte Units. They are bounded by Alpine meter-thick, low-temperature cataclastic to mylonitic shear zones (MESSINA, 1998a, b, 2002; MESSINA et alii, 2003). A new structural scheme has been delineated, illustrating the geometrical relationships among the seven recognised tectono-stratigraphic units of the Peloritani Crust. Field relationships are also demonstrated through a 1:300.000 scale Geological sketch map of the Peloritani Belt, with a geological cross section from Acquedolci to Messina, illustrating the State of the Art, in addition to three geological transects (S. Lucia del Mela-Pizzo Croce, Piraino-Vetriolo, Guidomandri-Gaggi) which, together, exhibit the geometry of the seven PB Alpine units and the most representative post-orogenic cover (Stilo-Capo d’Orlando Formation; BONARDI et alii, 1980, 2000). The S. Lucia del Mela-Pizzo Croce, Piraino-Vetriolo, Guidomandri-Gaggi geological cross sections reconstruct portions of a lower to medium-upper Variscan continental crust and portions of a superficial Mesozoic-Cenozoic crust. Representative rock samples, selected in the transects, have been assembled in the four compositional clusters: Quartz-Feldspar-(QFT), Phyllosilicate-(PHYT), Amphibolite-(AMPT) and Carbonate-(CART) rich Types. Petrographic features, which document the tectonic and metamorphicrelationships among the Alpine Peloritani units, indicate that the crystalline rocks, as a whole, consist of Variscan very-low to high grade metamorphics, with locally Pre- or Eo-Variscan relics and Late-Variscan plutonites. Basements and covers exhibit Alpine cataclastic effects, and some of them also a metamorphic overprint. Geochemical data show that, in spite of different genesis and evolutional histories of the representative samples, each cluster shows a restricted compositional range, marked by distinctive Major, Trace and Rare Earth Element values. The Peloritani Belt undoubtedly shows different evolutional histories for each tectonic unit. Consequently, it is made up of genetically unrelated Alpine tectono-stratigraphic units, originated from different paleogeographic domains and also from different crustal levels of the Variscan Chain.