Steady-state volcanic activity implies equilibrium between the rate of magma replenishment and eruption of compositionally homogeneous magmas, lasting for tens to thousands of years in an open conduit system. The Present-day activity of Stromboli volcano (Aeolian Islands, Southern Italy) has long been recognised as typical of a steady-state volcano, with a shallow magmatic reservoir (highly porphyritic or hp-magma) continuously refilled by more mafic magma (with low phenocryst content or lp-magma) at a constant rate and accompanied by mixing, crystallisation and eruption. Our aim is to clarify the timescale and dynamics of the plumbing system at the establishment of the Present-day steady-state activity (<1.2 ka) to pinpoint the onset of the steady-state regime. We investigated the Post-Pizzo (PP) pyroclastic sequence (∼1.7-1.5 ka) and one of the Early Paroxysms (EP) of the Present-day activity, focusing on the clinopyroxene population. Whole rock and clinopyroxene compositional variation among the PP and EP magmas is consistent with the time progression of the Stromboli system towards more mafic and lower 87 Sr/ 86 Sr compositions, pointing to the chemical and isotopic signature of the Present-day activity. Clinopyroxenes from both PP and EP record a complex history with compositional zoning that reflects growth in three different melt domains: a high-Mg# proto-lp recharging magma, a low-Mg# proto-hp resident magma, and a transient intermediate-Mg# magma. These are the result of complex turbulent flow fields and mixing regimes produced by repeated injections of the proto-lp magma in the shallow proto-hp magma reservoir. During the PP period the magmatic system was already able to regain the pre-input proto-hp composition, gradually changing toward a less evolved signature after the injection(s) of the more mafic proto-lp magma, owing to efficient (days to a few years) stirring and melt homogenisation (i.e., homogenisation time < residence time).Based upon Fe-Mg diffusion in clinopyroxene the total residence time during PP and EP periods, from the arrival of the mafic magma in the shallow system until the eruption, ranges from 1 to ∼50 years. Longer residence times (up to 150 years) have been recorded in the initial phase of the PP sequence, possibly testifying to the transition from a closed-to the open-conduit, steady-state regime of the Present-day activity. Some clinopyroxenes from the PP recorded the mafic triggering event of the feeding proto-lp magma occurring within few months to a few days before eruption. Remarkably, other clinopyroxene portions crystallised and captured the rapid timescales (a few days) of the on-going mixing and homogenisation process between the proto-lp and the proto-hp magmas leading to the eruption. The modelling of clinopyroxene zoning events at Stromboli provides evidence for growth and storage in three different melt domains, and sets robust constraints on their residence time from lp-magma recharge(s) to eruption, along with the timescales of melt homogenisation and triggerin...

The radiogenic isotopic compositions of inorganic heavy elements such as Sr, Nd, and Pb of the food chain may constitute a reliable geographic fingerprint, their isotopic ratios being inherited by the geological substratum of the territory of production. The Sr isotope composition of geomaterials (i.e., rocks and soils) is largely variable, and it depends upon the age of the rocks and their nature (e.g., genesis, composition). In this study we developed a high-precision analytical procedure for determining Sr isotopes in wines at comparable uncertainty levels of geological data. With the aim of verifying the possibility of using Sr isotope in wine as a reliable tracer for geographic provenance, we performed Sr isotope analyses of 45 bottled wines from four different geographical localities of the Italian peninsula. Their Sr isotope composition has been compared with that of rocks from the substrata (i.e., rocks) of their vineyards. In addition wines from the same winemaker but different vintage years have been analyzed to verify the constancy with time of the (87)Sr/(86)Sr. Sr isotope compositions have been determined by solid source thermal ionization mass spectrometry following purification of Sr in a clean laboratory. (87)Sr/(86)Sr of the analyzed wines is correlated with the isotopic values of the geological substratum of the vineyards, showing little or no variation within the same vineyard and among different vintages. Large (87)Sr/(86)Sr variation is observed among wines from the different geographical areas, reinforcing the link with the geological substratum of the production territory. This makes Sr isotopes a robust geochemical tool for tracing the geographic authenticity and provenance of wine.

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Constraining the timescales of pre-eruptive magmatic processes in active volcanic systems is paramount to understand magma chamber dynamics and the triggers for volcanic eruptions. Temporal information of magmatic processes is locked within the chemical zoning profiles of crystals but can be accessed by means of elemental diffusion chronometry. Mineral compositional zoning testifies to the occurrence of substantial temperature differences within magma chambers, which often bias the estimated timescales in the case of multi-stage zoned minerals. Here we propose a new Non-Isothermal Diffusion Incremental Step model to take into account the non-isothermal nature of pre-eruptive processes, deconstructing the main core-rim diffusion profiles of multi-zoned crystals into different isothermal steps. The Non-Isothermal Diffusion Incremental Step model represents a significant improvement in the reconstruction of crystal lifetime histories. Unravelling stepwise timescales at contrasting temperatures provides a novel approach to constraining pre-eruptive magmatic processes and greatly increases our understanding of magma chamber dynamics.