The effects of a Meso-Alpine collision event on the tectono-metamorphic evolution of the Peloritani mountain belt (eastern Sicily, southern Italy)

Abstract

The Peloritani Mountains, in the southern part of the Calabrian Terranes, southern Italy, have been classically interpreted as the product of the Paleogene brittle deformation of the European continental back-stop of the Neotethyan subduction complex. This reconstruction conflicts with the occurrence of an Alpine metamorphic overprint that affected portions of both the Variscan metamorphic units and part of the Mesozoic sedimentary covers of the mountain belt. New field data, integrated with petrographic, micro- and meso-structural analyses and stratigraphic investigation of the syn-tectonic terrigenous covers, well constrain a Paleogene collision event along the Africa–Nubia convergent margin that caused the exhumation of the Alpine metamorphic units of the Peloritani Mountains. The syn-collisional exhumation was associated with shearing along two major Africa-verging crustal thrusts arising from the positive tectonic inversion of the former European palaeomargin. Early tectonic motions occurred within the mountain belts and produced the exhumation of the external portions of the edifice. Later tectonic motions occurred along the sole-thrust of the entire edifice and caused the definitive exhumation of the entire mountain belt. The whole crustal thrusting lasted for a period of c. 10 Ma, during the entire Oligocene. The definitive southwestward emplacement of the Peloritani Mountain Belt onto the Neotethyan accretionary wedge was followed by two Late Oligocene – Early Miocene NW–SE-oriented right lateral shear zones, replacing the previous crustal thrust. These two strike-slip belts are interpreted as the surface expression of the deep-seated suture zone between the colliding Africa and Europe continental crusts.

A Geomorphic Examination of the Calabrian Forearc Translation

“…area in the west (Catalano & D'Argenio, 1982;Lentini et al, 1994), Meso-Cenozoic accretionary wedge chaotic terrains (e.g., Sicilide Unit) and Paleogene terrigenous deposits (e.g., Numidian Flysch) are exposed in the Madonie-Nebrodi Mts. in the middle (Lentini et al, 1994;Roure et al, 1990), and the Europe-affinity Hercynian crystalline basement terranes are exposed to the east in the Peloritani Mts (Ben Avraham et al, 1990;Catalano, Cirrincione, et al, 2018;Lentini et al, 1994Lentini et al, , 2000 Figure 1a). To the south of the PMNPM, progressive emplacement of the accretionary wedge includes several Miocene-to-Pleistocene wedge-top basin sedimentary sequences (Decima & Wezel, 1971;Di Grande & Giandinoto, 2002).…”

Integrated uplift, subsidence, erosion and deposition in a tightly coupled source‐to‐sink system, Pagliara basin, northeastern Sicily, Italy

“…The Peloritani Mountains compose the northeastern tip of Sicily, which is embedded in the actively translating Calabrian Forearc, marking the subduction of Nubian plate beneath Eurasian plate in the central Mediterranean (Amodio Morelli et al., 1976; Dewey et al., 1989; Malinverno & Ryan, 1986) (Figure 1a). The forearc is an orocline made up of crystalline basement with Europe‐affinity (Catalano et al., 2018; Lentini & Vezzani, 1975; Pezzino et al., 2008) that separated from Sardinia ca. 6 Ma (Malinverno, 2012).…”

“…Southeast‐directed translation of the forearc (Figure 1b), presumably by Ionian slab rollback, led to the Sicilian collision and the opening of the Tyrrhenian basin (Boccaletti et al., 1990; Faccenna et al., 2004, 2011; Kastens et al., 1988; Rosenbaum & Lister, 2004). The Peloritani Mountains are underlain by stacked tectonic‐metamorphic units consisting of juxtaposed, top‐to‐bottom, high‐grade and medium‐to‐low‐grade Hercynian European‐affinity crystalline basement (Catalano et al., 2018; Lentini et al., 2000; Lentini & Vezzani, 1975) (Figure 1c,d). This metamorphic backbone is encircled by late Miocene to late Pleistocene sedimentary rocks deposited within basins controlled by normal fault systems, often arranged in an én‐echelon geometry (Lentini et al., 1995; Lentini & Vezzani, 1975).…”

Submagmatic to Solid-State Deformation Microstructures Recorded in Cooling Granitoids during Exhumation of Late-Variscan Crust in North-Eastern Sicily

“…The latter authors proposed indeed that the age of 301 ± 2 Ma was associated with mylonitisation during thrusting of the Aspromonte Unit over the Mandanici Unit. Nevertheless, the contact between the two units is marked by a 30 m-thick cataclastic to mylonitic shear zone that also involves Triassic to Cretaceous greenschist-facies metasediments from the original cover of the Mandanici Unit ( [124]; and references therein), therefore demonstrating the Alpine age of that shear zone. In fact, the age of~300 Ma in the mylonitic augen gneisses cannot be univocally ascribed to a shearing phase, because it corresponds to the age of the thermal peak of the Variscan metamorphism in the CPO, which is recurrently recorded in both sheared and unsheared rocks (e.g., [48,90,125,126]).…”