Transition From Late‐Miocene Syn‐Orogenic Extension to Plio‐Pleistocene Corinth Rifting in the Southern Hellenides, Northern Peloponnese, Greece

This study investigates the Late Miocene to Pliocene transition from contractional to extensional tectonics in the upper plate of the Western Aegean retreating subduction system focusing on the Northern Peloponnese area, Greece. A new 3D tectonic model based on field data and cross‐sections clarifies the relationship between Corinth Rift (CR) normal faulting and inherited structures of the Hellenides belt. The tectonic history is divided into five stages: (a) Late Oligocene to Early Miocene ductile high‐pressure, low‐temperature metamorphism of the Phyllite‐Quartzite (PQ) Unit in the Hellenic subduction channel, synchronous with emplacement of overlying Hellenides nappes, (b) syn‐orogenic ductile exhumation of the PQ Unit at the subduction interface below the Cretan detachment (24–14 Ma), (c) Late Miocene underplating and vertical exhumation of the PQ Unit accommodated by thinning of the Hellenides nappe stack on low‐angle normal faults (LANFs) rooting into the Cretan detachment, followed by (d) NW‐SE‐trending high‐angle normal faulting, and (e) initiation of Corinth rifting by N‐S extension at 4–3.5 Ma. New results show that the LANFs all pre‐date Corinth rifting, forming above and around the NNW‐SSE‐trending, N‐plunging PQ dome, so that their strike varies from E‐W in the north to NE‐SW further south. Alluvial sediments deposited above E‐W‐striking LANFs are crosscut by early high‐angle CR faults. The northern termination of the PQ dome partially controls the location and segmentation of the CR. The transition from regional contraction to extension is attributed to changes in subduction dynamics at 8–5 Ma and to the SW propagation of the North Anatolian fault. Plain Language Summary Extensional rifted margins often develop over areas that were affected by an inherited polyphase tectonic history. Inherited structures can be reactivated and influence the geometry of the active rift system. In this work, the inherited structural framework of the Southern Hellenides belt in Greece and its effect on younger Corinth rifting are investigated. The various structures (detachments, brittle low‐angle and high‐angle normal faults) observed in Northern Peloponnese are described and used to build a structural model that documents the 3D relationships between Corinth Rift structures and pre‐rift structures. A chronology of the different tectonic events that affected the Northern Peloponnese is proposed. Key Points The Hellenides fold and thrust belt is thinned by Late