Chemistry and Zoning for Metal Elements in Massive Sulfide Ores and Sulfide Chimneys from the Central Okinawa Trough, W.Pacific
西太平洋冲绳海槽烟囱硫化物矿床矿石化学特征与分带型式

Massive sulfide ores in the central Okinawa trough is located in back arc spreading basin rifted on the continental crust and occur in Izena depression with 1400m depth. The geology and mineralogy of the sulfide ores are very similar to that of Kuroko deposits in Japan, suggesting that they probably are modern analogue of Kuroko type deposits. Based on mineralogy and chemistry of sulfide ores, three type ores have been recognized, i.e., Pb Zn Ba, Zn Pb and Cu Zn ores. They could be products of earlier, middle and later mineralization stages in a thermal intensifying hydrothermal system , respectively. The mineral association and ore chemistry indicate that Pb Zn Ba ore and sulfide chimney resulted from a hydrothermal system with high f o 2, high discharging rate and high concentration of Pb, Zn and Ba, while Cu Zn ore and sulfide chimney resulted from a hydrothermal fluid with high temperature, low flow rate and rich in Cu.The sulfide chimneys show clear mineral chemical zoning. In Pb Zn Ba ores, Zn and Cd concentrate in center of the chimney, whereas Ba, Fe, As, Sb, Ag, Pb are rich in outer parts of the chimneys. In Cu Zn ore, the outer parts of chimneys show enrichment in As, Sb, Fe, Ag and Au, while center shows enrichment of Cu, Zn and Pb. A new model on chemical zoning and deposition processes of sulfide have been established based on the metal element pattern in sulfide chimneys.