New constraints on the Middle-Late Pleistocene Campi Flegrei explosive activity and Mediterranean tephrostratigraphy (∼160 ka and 110-90 ka)

The Campi Flegrei (CF) caldera, in southern Italy, is the source of some of the most powerful Late Pleistocene eruptions of the European sub -continent (e.g., Campanian Ignimbrite, Neapolitan Yellow Tuff eruptions). Although the CF caldera has been continuously and intensively investigated for decades, relatively little is known regarding its earliest volcanic activity. In this work, integrating existing and new tephrostratigraphic data, we provide a comprehensive and updated framework for the CF volcanic activity which has occurred at -160 ka and between -110 ka and -90 ka. The new tephrostratigraphic, geochemical (EMPA + LA-ICP-MS), chronological ( 40 Ar/ 39 Ar dating) and grain -size distribution data relate to CF tephra deposits preserved in mid -proximal (Campanian Plain), distal (Tyrrhenian Sea) and ultra -distal (Lower Danube area) sedimentary archives. Our results allowed us to recognize the presence of at least 13 CF eruptions covering the investigated time frame, with 12 eruptions occurring between 110 and 90 ka. Our high -resolution stratigraphic and chronological investigation also allowed us to recognize that the Triflisco/C-22 tephra, previously considered as a single marker layer, can be actually separated into three different events, sourced from within the CF area in the short time interval of -9390 ka, suggesting a more complex and intense volcanic history than previously thought. Moreover, a Bayesian age -depth model, constrained by previous and new high precision 40 Ar/ 39 Ar ages, has led to a reliable estimate of the ages of those undated CF eruptions. Overall, the updated framework on the stratigraphy, chronology, dispersion, and geochemistry of the CF tephra of -160 ka and between 110 ka and 90 ka consolidates the notion that the Middle -Late Pleistocene activity in theCF area represents a significant stage of its volcanic evolution, characterised by intense and frequent explosive eruptions.