Tracking the subduction signature within dismantled collisional orogens: evidence from Punta delle Rocchette, SW Tuscany (Northern Apennines, Italy)

Recognizing subduction-related signatures in collisional orogens that have been subsequently dismantled by post-contractional tectonics remains a key challenge. In the Northern Apennines, continental units derived from the Adria margin preserve important, but still incompletely constrained, records of these processes. Here we present new structural and thermobarometric data from the Pseudoverrucano Unit exposed at Punta delle Rocchette, south of the Gulf of Follonica (Tyrrhenian coast, central-northern Italy). The unit records a polyphase tectonic evolution. The D1 phase developed during underthrusting and accretion along a west-dipping subduction interface under low-blueschist-facies peak conditions (270–310°C and 0.70–0.81 GPa), providing the first direct evidence of subduction-related metamorphism in this unit. The D2 phase marks the onset and evolution of syncontractional exhumation within an orogenic wedge, whereas the D3 phase and subsequent high-angle normal faulting document late- to post-collisional extensional reworking. Overall, the Pseudoverrucano Unit preserves a coherent record of subduction, accretion and exhumation comparable to other Alpine-type orogens in the Mediterranean, despite significant tectonic dismantling of the wedge. These results constrain the evolution of continental subduction systems from underthrusting to exhumation and highlight Punta delle Rocchette as a robust analogue for collisional mountain belts worldwide.