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raising the possibility of changing magmatic conditions. Here we decipher the origin and mechanisms of the second eruption from the composition and volatile (H 2 O, CO 2 , S, Cl) content of olivine-hosted melt inclusions in explosive products from its south flank vents. Our results demonstrate that powerful lava fountains and ash columns at the eruption onset were sustained by closed system ascent of a batch of primitive, volatile-rich (!4 wt %) basaltic magma that rose from !10 km depth below sea level (bsl) and suddenly extruded through 2001 fractures maintained opened by eastward flank spreading. This magma, the most primitive for 240 years, probably represents the alkali-rich parental end-member responsible for Etna lavas' evolution since the early 1970s. Few of it was directly extruded at the eruption onset, but its input likely pressurized the shallow plumbing system several weeks before the eruption. This latter was subsequently fed by the extrusion and degassing of larger amounts of the same, but slightly more evolved, magma that were ponding at 6-4 km bsl, in agreement with seismic data and with the lack of preeruptive SO 2 accumulation above the initial depth of sulphur exsolution ($3 km bsl). We find that while ponding, this magma was flushed and dehydrated by a CO 2 -rich gas phase of deeper derivation, a process that may commonly affect the plumbing system of Etna and other alkali basaltic volcanoes.

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[1] Paroxysms at Stromboli are the most violent manifestations of the persistent activity and are related to the emission of small volumes (10 3 -10 5 m 3 ) of nearly aphyric HKbasaltic pumices. They offer the exceptional opportunity to detail the mixingcrystallization-degassing processes that occur in a steady state basaltic arc volcano. We present mineralogy, major, volatile, and trace element geochemistry of olivine-hosted melt inclusions of these pumices. In all the paroxysms, melt inclusions hosted in olivines Fo 88 -91 have recorded the parental melts rich in CaO (up to 14.5 wt %) but low in FeO (6-7 wt %). They demonstrate recurrent variations in the K 2 O content (1.6-1.3 wt %) and S/Cl ratios (1.2-0.8) of the melts that entered the deep system. Dynamic magma mixing between melts slightly distinct by their degree of evolution, rapid crystallization, and entrapment of gas-oversaturated melts during decompression are indicated by (1) the high density of irregular, clear melt inclusions, and embayments in homogeneous olivines (Fo 87±0.5 -Fo 83±0.5 ), (2) the variable ratio between melt and gas bubble, and (3) the variability of melt inclusion compositions in both major (CaO/Al 2 O 3 = 1-0.59) and volatile (3.4-1.8 wt % H 2 O, 1582-1017 ppm CO 2 ) elements. FeO-rich melt inclusions in patchy, reversely zoned olivines also demonstrate interactions between ascending melt blobs and inherited olivine crystals. We propose a model involving a vertically extended dike-like system, where magmas progress and differentiate. On the basis of olivine growth rate calculations the volatile-rich magma blobs may ascend within few hours to few tenths of hours. Finally, we propose that sulfur degassing is possibly initiated during the early stage of magma differentiation.

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Red Pompeian paintings, very famous for their deep intensity, are currently suffering from darkening. The origins of this darkening degradation are not clearly identified yet and remain a major issue for curators. In the specific case of cinnabar (HgS)-based red pigment, a photoinduced conversion into black metacinnabar is usually suspected. This work is focused on the blackening of red cinnabar paintings coated on a sparry calcite mortar. Different samples exhibiting different levels of degradation were selected upon visual observations and analyzed by synchrotron-based microanalytical techniques. Atomic and molecular compositions of the different debased regions revealed two possible degradation mechanisms. On one hand, micro X-ray fluorescence elemental maps show peculiar distributions of chlorine and sulfur. On the other hand, X-ray absorption spectroscopy performed at both Cl and S K-edges confirms the presence of characteristic degradation products: (i) Hg-Cl compounds (e.g., corderoite, calomel, and terlinguaite), which may result from the reaction with exogenous NaCl, in gray areas; (ii) gypsum, produced by the calcite sulfation, in black coatings. Metacinnabar is never detected. Finally, a cross section was analyzed to map the in-depth alteration gradient. Reduced and oxidized sulfur distributions reveal that the sulfated black coating consists of a approximately 5-mum-thick layer covering intact cinnabar.