• Campi Flegrei
• experimental petrology
• phase equilibria
• Pre-eruptive conditions

The Campi Flegrei caldera (CFc; Orsi et al., 1996) is located in the Campania region and it is part of the Phlegrean Volcanic District (PVD), which includes the volcanic islands of Ischia and Procida (Orsi et al., 2004). The Campi Flegrei (CF) magmatic system, one of the largest known volcanic areas on Earth, is still active as testified by the Monte Nuovo eruption occurred in the 1538 A.D. (Di Vito et al., 1987), the recent bradyseismic episodes of 1969–1972, 1982–1984 and the 2000 to present, which resulted in a net uplift of 3.5 m in and around the town of Pozzuoli (Barberi et al., 1984, 1991; Orsi et al., 1999; Chiodini et al., 2012), and the ongoing intense fumarolic and hot spring activity. The caldera is densely inhabited by more than 1.5 million people, making the volcanic risk in the area one of the highest in the world (Orsi et al. 2004).
This PhD project is based on an experimental petrology study of different mafic to intermediate compositions of Phlegrean magmas (trachybasalt, shoshonite, latite) in order to define the phase stability fields and the pre-eruptive conditions of such magmas in terms of pressure, temperature and composition of both solid and fluid phases, and the processes that can lead to generate critical masses of evolved magmas capable of erupting explosively. Three eruptions were studied: the trachybasalt Fiumicello eruption of Procida (75-60 ka, Fedele et al., 2012), the shoshonite Minopoli 1 eruption (11.1 - 10.3 ka, Di Vito et al. 1999) and the latite Fondo Riccio eruption (10.3 - 9.5 ka, Di Vito et al. 1999), which compositions are rather rare and unusual in the CF contest, mainly characterized by most evolved compositions. Both natural and experimental products from the three eruptions were investigated. The experimental work was developed at the laboratories of the CNRS-ISTO in Orléans (France), using internal heating autoclaves (IHPV). Crystallization experiments were carried out for the study of phase equilibria, while preliminary investigations of the effects of variable rates of decompression on magma crystallization were performed on the shoshonite Minopoli sample, with the objective of evaluating the possible role of decompression crystallization. The phase equilibria experiments were conducted in parallel on the three compositions, exploring a wide temperature range between 850 and 1060 °C, and under different fluid conditions (XHO2fluid 0.4 - 1 mol), oxygen fugacity (fO2) ~ NNO 0.5 ±0.5 and total pressure (1 - 2 kbar). Based on 119 experimental runs, isobaric and polythermal diagrams T–XH₂Ofluid were constructed one at each of the investigated pressure values investigated, for the three compositions considered. The microanalysis of the experimental products and the comparison with data on natural samples finally allowed to define the pre-eruptive conditions of the magmas involved in the eruptions here investigated. The data produced allowed us to reach a more detailed understanding of the deep CF magmatic system (8-10 km) and of the role of possible magmatic reservoirs at more superficial levels, as suggested by geophysical and geochemical data (Cecchetti et al. 2001; Pappalardo et al. 2002; Marianelli et al. 2006; Piochi et al. 2005; Zollo et al., 2008; Di Renzo et al. 2011).