The Curinga\u2013Girifalco Line in the framework of the tectonic evolution of the remnant Alpine chain in Calabria (southern Italy)

Vincenzo Festa,Marianna Cicala,Fabrizio Tursi

doi:10.1007/s00531-020-01918-5

Vincenzo Festa, Marianna Cicala + Show 1 more

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https://doi.org/10.1007/s00531-020-01918-5

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Abstract

In the peri-Mediterranean metamorphic belts, the tectonic evolution of the Calabria–Peloritani terrane during the dominant compressive tectonics of the Eocene represents one of the most problematic points in palinspastic restorations. A matter of particular debate is its shortening, which could have occurred during the Alpine or the Apennine subduction. In this regard, a crucial joint is provided by the kinematics of one of the most relevant shear zones such as the Curinga–Girifalco Line, cropping out in central Calabria. This shear zone juxtaposed a nearly complete Hercynian crustal section (i.e. the Sila and Serre Unit) onto the remnants of the Castagna Unit. The data in the available literature on ductile kinematics from the south-eastern branch of the Curinga–Girifalco Line indicate a downward movement of the hanging wall. In the present paper we show new, ductile kinematic data and petrographic evidence from outcrops in the north-western and south-eastern branches of the Curinga–Girifalco Line. Our results highlight the coherent kinematics of the Eocene shortening during the Alpine subduction system, followed by (late Eocene?)Oligocene to early Miocene, dominantly ductile extensional reworking, relating to the Apennines subduction system.

Highlights

The Curinga–Girifalco Line (CGL) (Schenk 1980) in the Calabria–Peloritani terrane (Bonardi et al 2001) (Fig. 1, insets top right and left) is characterised by exposures of deep mylonites in the northern Serre Massif (Fig. 1, inset top left)
The tectonic contact is sharp, SSW-dipping, and WNW–ESEstriking, with a dip of c. 35–40° (Fig. 2). It consists of a thick ductile shear zone, which is characterised by mylonites formed at the expense of both the metapelites and the orthogneiss protoliths (Fig. 3c, d)
The transition from mylonites to their protoliths takes place within a few metres, with the boundaries of the ductile shear zone being sub-parallel to the tectonic contact (Fig. 2)

Summary

Introduction

The Curinga–Girifalco Line (CGL) (Schenk 1980) in the Calabria–Peloritani terrane (Bonardi et al 2001) (Fig. 1, insets top right and left) is characterised by exposures of deep mylonites in the northern Serre Massif (Fig. 1, inset top left). The CGL generally dips towards the south and occurs at the base of a nearly complete Hercynian continental crust (i.e. the Sila and Serre Unit), which, in turn, rests above the Castagna Unit (Fig. 1) (Paglionico and Piccarreta 1976, 1978; Schenk 1980; Spiegel 2003; Langone et al 2006; Altenberger et al 2013). This tectonic configuration induced Schenk (1981) to suggest a comparison between the CGL and the Insubric Line, the latter juxtaposing the Ivrea Zone and the Sesia Zone in the western Alps (Fig. 1, inset top right). The Calabria–Peloritani terrane (Bonardi et al 2001), i.e. the ‘calabro-peloritano arc’ sensu to Amodio-Morelli et al (1976), is a nappe stack made by three main groups of tectonic units (Fig. 1, inset top left): (i) the Lower Complex, basically consisting of phyllites and the platform to basinal carbonate rocks of Triassic to middle Miocene age, correlated to lithostratigraphic units cropping out in the Apennines; (ii) the Intermediate Complex, essentially represented by the ophiolite units of Jurassic to Cretaceous Neo-Tethys derivation, recording Eocene high-pressure/low-temperature (HP/LT) metamorphism; (iii) the Upper Complex, made up of continental crust units.

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Conclusion