Syn-orogenic extension in the Peloritani Alpine Thrust Belt (NE Sicily, Italy): Evidence from the Alì Unit

Abstract

Structural and petrological analyses on the Alì Unit, in the Peloritani Thrust Belt, document the first evidence for Alpine exhumation associated with syn-orogenic extension in this part of the Calabria-Peloritani Arc. The Alì Unit displays ductile structures occurred during three Alpine deformation phases (D a1 , D a2 , D a3 ). D a1 and D a3 developed in a contractional context, whereas D a2 was generated in an extensional regime. The present-day tectonic contact between the Alì Unit and the overlying Mandanici Unit is interpreted as a low-angle extensional detachment responsible for the metamorphic break between the two units. Structural overprinting relationships indicate that the development of D a2 structures and related tectonic exhumation occurred during syn-convergence extension, and were followed by further nappe stacking in the Peloritani Belt.

The south-western side of the Calabrian Arc (Peloritani Mountains): Geological, structural and AMS evidence for passive clockwise rotations

“…During the late Oligocene, crystalline (Bonardi et al, 1984(Bonardi et al, , 1992Messina et al, 1990Messina et al, , 1992Messina et al, , 1996Platt and Compagnoni, 1990) and covers (Atzori, 1968;Ferla and Azzaro, 1978;Somma et al, 2005) locally underwent Alpine metamorphism. During the Aquitanian, the Peloritani terrains, partly exhumed by syn-convergence extension (Somma et al, 2005), underwent a further shortening which gave rise to the present PTB and the main deformation of the Meso-Cenozoic covers. Burdigalian wedge-top basin deposits of the Stilo-Capo d'Orlando Fm.…”

Tectonic evolution of the Sicilian Thrust System (central Mediterranean)

“…This could sug gest that the ex hu ma tion of southern Calabria was ac com mo dated by sev eral tec tonic pulses from 45 to 28.6 Ma, with sig nif i cant ki ne matic changes in this in ter val. In the Pelo ritan Moun tains of Sic ily, the tec tonic evo lu tion of the Cala bride Com plex is sim i lar but both ki nematic di rec tions and ages for suc ces sive steps are poorly constrained (Somma et al, 2005).…”

Sedimentary evolution of the Mesozoic continental redbeds using geochemical and mineralogical tools: the case of Upper Triassic to Lowermost Jurassic Monte di Gioiosa mudrocks (Sicily, southern Italy)

“…Bonardi et al 2001). The Alì unit consists of a Paleozoic arenaceous-conglomeratic basement covered by a Lower Jurassic-Cretaceous sequence, affected by a very lowgrade metamorphic overprint Pezzino 1991, 1994;Somma et al 2005). The Fondachelli unit is characterized by a Paleozoic sequence (phyllites, metarenites, quartzites, metalimestones and minor metabasites) with a Variscan, low-P, polyphase and monofacial metamorphism, typical of chlorite zone of greenschist facies, covered by a Mesozoic calcareous deposits (Messina et al 2004).…”