Claudia Cannatelli

Quantitative model for magma degassing and ground deformation (bradyseism) at Campi Flegrei, Italy: Implications for future eruptions

Campi Flegrei (Phlegrean Fields) is an active volcanic center near Naples, Italy. Numerous eruptions have occurred here during the Quaternary, and repeated episodes of slow vertical ground movement (bradyseism) have been documented since Roman times. Here, we present a quantitative model that relates deformation episodes to magma degassing and fracturing at the brittle-ductile transition in a magmatic-hydrothermal environment. The model is consistent with fi eld and laboratory observations and predicts that uplift between 1982 and 1984 was associated with crystallization of ~0.83 km 3 of H 2 O-saturated magma at 6 km depth. During crystallization, ~6.2 ◊ 10 10 kg of H 2 O and 7.5 ◊ 10 8 kg of CO 2 exsolved from the magma and generated ~7 ◊ 10 15 J of mechanical (PΔV) energy to drive the observed uplift. For comparison, ~10 17 J of thermal energy was released during the 18 May 1980 lateral blast at Mount St. Helens.

Detection of liquid H2O in vapor bubbles in reheated melt inclusions: Implications for magmatic fluid composition and volatile budgets of magmas?

Abstract Fluids exsolved from mafic melts are thought to be dominantly CO2-H2O ± S fluids. Curiously, although CO2 vapor occurs in bubbles of mafic melt inclusions (MI) at room temperature (T), the expected accompanying vapor and liquid H2O have not been found. We reheated olivine-hosted MI from Mt. Somma-Vesuvius, Italy, and quenched the MI to a bubble-bearing glassy state. Using Raman spectroscopy, we show that the volatiles exsolved after quenching include liquid H2O at room T and vapor H2O at 150 °C. We hypothesize that H2O initially present in the MI bubbles was lost to adjacent glass during local, sub-micrometer-scale devitrification prior to sample collection. During MI heating experiments, the H2O is redissolved into the vapor in the bubble, where it remains after quenching, at least on the relatively short time scales of our observations. These results indicate that (1) a significant amount of H2O may be stored in the vapor bubble of bubble-bearing MI and (2) the composition of magmatic fluids directly exsolving from mafic melts at Mt. Somma-Vesuvius may contain up to 29 wt% H2O.

Contrasting sediment melt and fluid signatures for magma components in the Aeolian Arc: Implications for numerical modeling of subduction systems

The complex geodynamic evolution of Aeolian Arc in the southern Tyrrhenian Sea resulted in melts with some of the most pronounced along the arc geochemical variation in incompatible trace elements and radiogenic isotopes worldwide, likely reflecting variations in arc magma source components. Here we elucidate the effects of subducted components on magma sources along different sections of the Aeolian Arc by evaluating systematics of elements depleted in the upper mantle but enriched in the subducting slab, focusing on a new set of B, Be, As, and Li measurements. Based on our new results, we suggest that both hydrous fluids and silicate melts were involved in element transport from the subducting slab to the mantle wedge. Hydrous fluids strongly influence the chemical composition of lavas in the central arc (Salina) while a melt component from subducted sediments probably plays a key role in metasomatic reactions in the mantle wedge below the peripheral islands (Stromboli). We also noted similarities in subducting components between the Aeolian Archipelago, the Phlegrean Fields, and other volcanic arcs/arc segments around the world (e.g., Sunda, Cascades, Mexican Volcanic Belt). We suggest that the presence of melt components in all these locations resulted from an increase in the mantle wedge temperature by inflow of hot asthenospheric material from tears/windows in the slab or from around the edges of the sinking slab.

The distribution of Pb, Cu and Zn in topsoil of the Campanian Region, Italy

In this paper we present a comparison of statistical and spatial distributions between Pb, Cu and Zn concentration data and clr-transformed data of 3669 topsoil samples from the Campanian Region. Results show that both approaches, the classical univariate analysis and the compositional data analysis, are necessary to understand the real structure of the data and shed light on different aspects. In particular, the spatial distributions of concentration (‘raw’) data and clr-transformed data of the three elements differ completely. Raw data essentially represent a high anthropogenic impact, requiring an additional human health risk assessment for the three investigated elements. The information obtained by the clr-coefficient maps reveals the geogenic contribution to the element distribution. To better constrain the degree of contamination due to these potentially toxic elements and their impact on human health, we present an RGB composite map of Pb, Cu and Zn. This map unravels potential sources of contamination and locates the areas where concentrations exceed thresholds established by the Italian legislation.