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

西太平洋冲绳海槽烟囱式硫化物矿床分布于琉球弧后扩张盆地、产于尹是名洼陷盆地（深１４００ｍ），其特征与日本黑矿类似。硫化物矿石及烟囱主要有３种化学类型：Ｐｂ－Ｚｎ－Ｂａ型、Ｚｎ－Ｐｂ型和Ｃｕ－Ｚｎ型，三者分别代表温度不断升高的热液体系的早、中、晚３个成矿阶段产物，其中，Ｐｂ－Ｚｎ－Ｂａ矿石及烟囱形成于高ｆｏ２环境和高流速、低温、富Ｐｂ、Ｚｎ、Ｂａ热液体系，Ｃｕ－Ｚｎ矿石及烟囱形成于低流速、高温、富Ｃｕ热液体系，Ｚｎ－Ｐｂ矿石则介于其间。硫化物烟囱显示明显的矿物－化学分带。在Ｐｂ－Ｚｎ－Ｂａ矿石（烟囱），Ｚｎ、Ｃｄ集中于烟囱中央，Ｂａ、Ｆｅ、Ａｓ、Ｓｂ、Ａｇ、Ｐｂ集中于烟囱外带，Ｃｕ则富集于烟囱中外部。在Ｃｕ－Ｚｎ矿石，Ａｓ、Ｓｂ、Ｆｅ、Ａｇ、Ａｕ仍富集于烟囱外带，Ｃｕ、Ｚｎ、Ｐｂ则在烟囱中央富集。依此元素化学分带型式，建立了古代黑矿硫化物矿体分带与硫化物堆积模式。

Chemistry and Zoning for Metal Elements in Massive Sulfide Ores and Sulfide Chimneys from the Central Okinawa Trough, W.Pacific

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.