Uncovering the Middle-Late Pleistocene Slip History of Garigliano Graben Faults and Its Impact on the Construction and Collapse of the Roccamonfina Volcano, Italy

The Roccamonfina volcano, located in the Garigliano Graben, is the most long-lived volcano along the Tyrrhenian margin of the southern Apennines, with activity through the Middle–Late Pleistocene. The lack of estimates about the timing and extent of graben-bounding fault activity hinders a thorough reconstruction of its evolution. In this study, we have conducted a comprehensive investigation into the magmatic dykes hosted within the carbonate rocks of the nearby Mt Cesima ridge. Combining new geochronologic data with borehole and topographic data, we provide quantitative estimates of displacements along graben bounding faults. Our results suggest that the volcanic activity was regulated by tectonic extension rates, marking the shift from early regional fissure swarms to climax in tectonic extension producing the uplift of the graben-bounding carbonate reliefs, potentially inducing the gravitational collapse of the main stratocone. The extensional tectonic activity decreased over time, which resulted in the decline of volcanic activity. The results of this study allow us to shed light on the timing of the fault activity controlling the shift from rift-like monogenetic fields to the formation of localised central volcanoes. Hence, the framework reconstructed here helps to understand the onset and establishment of the volcanism in the Campania plain, whose early stage is concealed under the volcaniclastic cover.