Shallow-water polymetallic sulfide deposits in the Aeolian island arc

Back-arc basins represent the best-known present-day sites of ongoing massive sulfide deposition in subduction-related tectonic settings. Here we present results obtained from shallow-water sea-floor sampling of barium-rich zinc and lead sulfides genetically analogous to Kuroko-type black ore on an active island arc. The samples come from a newly discovered, hydrothermally active depression on the submerged volcanic edifice of Panarea in the Aeolian island arc (Tyrrhenian Sea). Hydrothermal activity in the area is represented by extensive gas venting associated with white sea-floor aprons of sulfate and iron oxide precipitates. A series of barite-rich sediment samples containing galena, sphalerite, and pyrite was recovered 40 cm below the sea bed at a water depth of 80 m. The deposits represent a unique example of massive-sulfide deposition in an active island arc not yet affected by strong extensional tectonics and reveal that, in this environment, the formation of Kuroko-type black-ore sulfides can take place at shallow water depths.