Tracking metal evolution in arc magmas: Insights from the active volcano of La Fossa, Italy

The mineralization potential of arc magmas depends, among other factors, on the timing sulfide melt saturation relative to magma differentiation and exsolution a magmatic fluid phase. In fossil mineralized or barren systems, understanding evolution metals along path is often hindered by late processes hydrothermal alteration. To better understand process metal “caught in act” crustal reservoirs, we analyzed sulfides inclusions found within eruptive products from active volcano, La Fossa (Vulcano Island, Italy), for basalt rhyolite compositional spectrum. We that, case sulfide-undersaturated volatile-rich basalts, are scarcely subtracted degassing during ascent shallow reservoirs reach highest abundances intermediate (250 ppm Cu). At has 34–66 wt% Cu, leading dramatic decrease chalcophile dissolved silicate melt. After fractionation only 0.2–0.3 solid assemblage, exsolved monosulfide solution (pyrrhotite) containing <3 Cu. Metals that do not partition (Pb, Zn) increase their concentrations until they sequestered Cl-rich aqueous phase at rhyolitic stage. absolute Cu-normalized similar accessories rocks associated with world-class porphyry Cu systems. Our results demonstrate mechanisms governing inferred stage environments can be also tracked an using as snapshots evolution. Arc volcanoes thus viewed ideal analogues when studying these crucial formation deposits.