SHALLOW-WATER POLYMETALLIC SULFIDE DEPOSITS IN THE AEOLIAN ISLAND-ARC

Back-are basins represent the best-known present-day sites of ongoing massive sulfide deposition in subduction-related tectonic settings, He re we present results obtained from shallow-water sea-floor sampling o f barium-rich zinc and lead sulfides genetically analogous to Kuroko-t ype black ore on an active island are. The samples come from a newly d iscovered, hydrothermally active depression on the submerged volcanic edifice of Panarea in the Aeolian island are (Tyrrhenian Sea). Hydroth ermal activity in the area is represented by extensive gas venting ass ociated with white sea-floor aprons of sulfate and iron oxide precipit ates. A series of barite-rich sediment samples containing galena, spha lerite, and pyrite was recovered 40 cm below the sea bed at a water de pth of 80 m. The deposits represent a unique example of massive-sulfid e deposition in an active island are not yet affected by strong extens ional tectonics and reveal that, in this environment, the formation of Kuroko-type black-ore sulfides can take place at shallow water depths .