A well exposed ductile shear zone (Montalto shear zone- MSZ) in the Aspromonte area (southern Calabria-Italy) shows structural features depicting a complex deformational evolution, overprinting, in a multistage non-coaxial regime, previously Variscan (Aspromonte Unit) and Alpine (Madonna di Polsi Unit) prograde metamorphic evolution (Pezzino et al., 1990; Fazio et al., 2010, 2016). During this retrograde evolutionary stages, which allows the superimposition of these two units, the upper one (i.e., Aspromonte Unit), locally characterized by the presence of granitoid rocks, developed complex mesoscopic to microscopic structural features such as mylonitic foliations with occurrence of spectacular asymmetric winged objects, intrafoliar folds and curvilinear up to sheath folds. The unraveling of this sequential evolution is not always straightforward because visible structures can be potentially ascribed to different causes: i) are they the effect of a single deformational episode which evolves through time (i.e., invariant stress field orientation)?; ii) or rather they can be associated to different deformational episodes implying a change of principal stress orientation? This aspect is crucial for a correct interpretation of the tectono-metamorphic evolution of the orogenic system. In this view, overprinting relationships and progressive development of folds from the study area provided some clues, which suggest an alternative deformational sequence, by proposing the activity of flow perturbation folds developed during a single Oligo-Miocene evolutionary stage rather than the occurrence of

Reconstruction of sequential pattern deformation within the multistage evolution of the Montalto Shear Zone (Aspromonte Massif – Calabria).

Fazio E.
;
Ortolano G.;Visalli R.;Cirrincione R.;Pezzino A.
Supervision
2017

Abstract

A well exposed ductile shear zone (Montalto shear zone- MSZ) in the Aspromonte area (southern Calabria-Italy) shows structural features depicting a complex deformational evolution, overprinting, in a multistage non-coaxial regime, previously Variscan (Aspromonte Unit) and Alpine (Madonna di Polsi Unit) prograde metamorphic evolution (Pezzino et al., 1990; Fazio et al., 2010, 2016). During this retrograde evolutionary stages, which allows the superimposition of these two units, the upper one (i.e., Aspromonte Unit), locally characterized by the presence of granitoid rocks, developed complex mesoscopic to microscopic structural features such as mylonitic foliations with occurrence of spectacular asymmetric winged objects, intrafoliar folds and curvilinear up to sheath folds. The unraveling of this sequential evolution is not always straightforward because visible structures can be potentially ascribed to different causes: i) are they the effect of a single deformational episode which evolves through time (i.e., invariant stress field orientation)?; ii) or rather they can be associated to different deformational episodes implying a change of principal stress orientation? This aspect is crucial for a correct interpretation of the tectono-metamorphic evolution of the orogenic system. In this view, overprinting relationships and progressive development of folds from the study area provided some clues, which suggest an alternative deformational sequence, by proposing the activity of flow perturbation folds developed during a single Oligo-Miocene evolutionary stage rather than the occurrence of
mylonites, flow perturbation folds, deformation history.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.11769/319701
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