Chemostratigraphy and 40Ar/39Ar geochronology of Ventotene volcano (Pontian Islands, Tyrrhenian Sea): The missing link in the Quaternary potassic magmatism of central Italy

This study provides a new chemostratigraphic and high precision geochronological reconstruction of the Ven totene volcano (Pontian Islands), a pivotal yet understudied site for understanding the Quaternary transition from calc-alkaline to potassic magmatism along the Tyrrhenian margin of Italy. By integrating new 40Ar/39Ar dating, field mapping, and geochemical analysis of bulk rocks and glasses, our study fills a significant gap in the Mediterranean magmatic and tephrostratigraphic framework. Key findings include the dating of the Bagno Vecchio unit (Ponza) at ~1161 ka, which establishes the earliest dated potassic occurrence in the peri- Tyrrhenian area. The temporal evolution of the Ventotene volcanic activity, documented in subaerial expo sures, is constrained between ~620 and 350 ka. The emplacement of the Santo Stefano trachytic lava dome at ~620 ka was followed at ~445 ka by the K-basaltic lava flow sequence of Punta dell’Arco and associated scoria cones, on Ventotene Island. A major transition to highly explosive dynamics is documented in the Cala Battaglia unit (~380-360 ka), characterized by phreatomagmatic pyroclastic current deposits followed by recurrent sub- Plinian to Plinian fall events, phonolitic-trachytic in composition. The Ventotene activity culminated in the ~350 ka Parata Grande caldera-forming eruption, an evolutionary pattern that mirrors other Roman Province vol canoes. By establishing a robust chronostratigraphic and geochemical reference dataset, Ventotene volcano is recognized as a key source area for the Middle Pleistocene tephrostratigraphy of central-southern Italy and central-eastern Mediterranean. Ultimately, this work refines the spatiotemporal framework of Italian potassic volcanism and offers critical data for quantitative petrogenetic modeling and regional volcanic hazard assessment.