High pressure experiments on kinetic and rheological properties of primitive alkaline magmas: constraints on deep magmatic processes at the Campi Flegrei Volcanic District

Defining the timescales of magma storage and ascent beneath active volcanoes is a fundamental tool in volcanological investigation of the last decade to constrain pre-eruptive magmatic processes and magma chamber dynamics, since it is able to provide the basis for volcanic hazard assessment. This Ph.D. project focuses on the investigation of the deep portion of the Campi Flegrei Volcanic District plumbing system (crustal-mantle boundary; ~25 km of depth), in correspondence of which the presence of a possible crystallization zone has been hypothesized on the basis of melt inclusion studies, seismic data interpretations, gravimetric and petrological modelling and experimental data. The Campi Flegrei Volcanic District, which includes the Campi Flegrei and the islands of Ischia and Procida, represents one of the most active volcanic areas in the Mediterranean region and one of the most dangerous volcanic complexes on Earth owing to the intense urbanization of the area. Many petrological, geochemical and geophysical surveys were carried out in the Campania Active Volcanic Area that have helped to define the main architecture and the development of the sub-volcanic system. Nevertheless, the dynamic processes that operate during the earliest, deepest differentiation steps of primitive magmas that fed all Campi Flegrei eruptions are yet poorly constrained. The knowledge of the dynamics and residence and ascent timescales of magma at deep levels, indeed, may be the key to understand the triggering mechanisms of volcanic eruptions, and are essential for understanding the rates at which magmas are supplied to volcanic complexes. In this thesis, the investigation of the kinetic and rheological properties of a K-basaltic magma at Moho depth, together with the partitioning of trace elements between crystal and melts, has allowed to fill some gaps relative to the knowledge of the deep portion of the Campi Flegrei Volcanic District plumbing system, providing magma residence time and ascent timescales, and models for deep magmatic differentiation processes.