INVESTIGATION Of THE VOLCANOGENIC MASSIVE SULFIDE DEPOSITS BASED ON THE MINOR ELEMENT CONTENTS OF ORES

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1. Compared with the Kuroko deposit, the Besshi-type massive sulfide deposits are rich in Sn, Co, Se and To. Sn contents are especially high in the Shimokawa deposit in the Hidaka belt which explains the high average Sn content of the Besshi-type deposits. No Se-enriched minerals are present in the ores and Se/S ratios of sulfide minerals are generally higher in the Besshi-type deposits than Kuroko deposits. Higher Te contents are reflected in the rare occurrence of tellurian tennantite in the Besshi-type deposits.2. Sulfide mineralogy, minor element contents and sulfur isotope ratios of ores are different between sediment-covered and sediment-starved present sea-floor hydrothermal deposits. The sulfide deposits are chemically and mineralogically different corresponding to the crustal evolution in the back-arc basin and volcanic rift zone in the continent. It is likely that the Hitachi deposit in the Abukuma belt and Yanahara deposit in the Maizuru belt were formed on the continental sea floor in the spreading back-arc basin or continental rift zone.3. The Nanokawa deposit in the Chichibu belt was covered by manganese-rich hydrothermal siliceous sediment The manganiferous siliceous schists associated with sulfide deposits and basic schists in the Sambagawa belt are probably derived from the siliceous sediments of hydrothermal origin.4. The FeS contents are remarkably higher in sphalerites included in pyrites than those occurring in interstices of pyrite grains in the Tsuchikura deposit. Post depositional sea-floor metamorphism and diagenesis probably correspond to the sulfidation of ores as like in the present sea-floor sulfide deposits.5. The metallogeny of the Besshi-type volcanogenic massive sulfide deposits are deeply related with the evolution of the Japanese island arc.