Ricerc@Sapienza

Zannone is a very important island, located in the Neogene-Quaternary extensional domain of the Tyrrhenian back-arc basin, as it is the unique spot where the Paleozoic (?) crystalline basement is hypotesized to be exposed in central Apennines. The exposure of such hypothetical basement in the Zannone Island is very problematic as it implies very large normal displacements (> 3 km) along surrounding faults. No such displacements are known along faults close to Zannone Island.

Deformation in the upper crust is heterogeneous and mostly localized along brittle faults. Faults and fault rocks may be weak compared to surrounding host rocks and are likely to accommodate repeated slip episodes due to structural reactivation during commonly fluid-assisted faulting events. Thrust fault reactivation by subsequent normal faulting has been commonly documented in orogenic wedges, where extensional tectonics often follows contraction.

The inner Apennines (Italy) are characterized by scattered outcrops of continent‐derived orogenic metamorphic units exposed along the Tyrrhenian coast from northern to southern Apennines. At least since the 1970s, some peculiar rocks exposed on Zannone Island (central Italy) have been described as the only Paleozoic‐Triassic metamorphic complex linking those exposed in the northern—with those