Acid gas and metal emission rates during long-lived basalt degassing at Stromboli volcano

The discharge of acid gases and metals from Stromboli is determined from airborne and ground-based filter sampling of particulate matter in the volcanic plume, combined with COSPEC measurements of SO2 fluxes. Smaller particle sizes and high enrichment factors distinguish the most volatile elements (by order: S, Se, Br, Cl, Cd, Bi, In, As, Sb, Sn, F, Au, Pb, Cr, Cu) from those strictly (Fe, Mn, REE, Sc, Sr, Th, Ti, V) or mainly (Al, Ba, Ca, Co, K, Na, U) derived from volcanic ash. Time-averaged volatile fluxes show that Stromboli is a representative are emitter, producing 1-2% of the global volcanic budget of sulfur, halogens and several trace metals, while 15-25% of volcanic emissions of Bi, Cd, Cs, Pb and Sn in southern Italy. Subaerial degassing of its S-Cl-rich shoshonitic magma over the last 2 ky of similar activity may have released as much copper and gold as is encountered in magma-derived high-sulfidation ore deposits.