太平洋三海区热液烟囱物的氧同位素特征及形成温度

Oxygen Isotope Feature and Formation Temperature of Hydrothermal Chimney Materials in Three Sea Areas of the Pacific Ocean

使用氧同位素方法 ,测试了西太平洋马里亚纳岛弧、马里亚纳海槽、冲绳海槽和东太平洋加拉帕戈斯裂谷的海底热液烟囱和硫化物全岩样品。结果表明 :马里亚纳岛弧上的埃斯梅拉尔达破火山口的热液硫化物的形成温度最高 (达 2 75℃ ) ,而成为高温产物的代表 ;冲绳海槽和加拉帕戈斯裂谷烟囱 ,表现为中高温类型 ,其氧同位素温度在 1 5 0℃左右 ;马里亚纳海槽以蛋白石为主要矿物的烟囱物 ,则显示出典型的低温热液类型 ,少量黄铁矿砂试样则表现出中温类型特征。但上述区域大都不同程度地存在有闪锌矿、黄铁矿、黄铜矿等中高温热液矿物 ,说明研究区除马里亚纳海槽明显有中低温热液活动类型外 。

The oxygen isotype method was used to test the hydrothermal chimney and sulfide samples collected from the Mariana Island Arc, the Mariana Trough, the Okinawa Trough and the Galapagos Rift. It is shown from the test results that the hydrothermal sulfide sampled from the Esmeralda caldera of the Mariana Island Arc is the representative of high temperature products with a formation temperature of 275 ℃;the hydrothermal chimney meterials sampled from the Okinawa Trough and the Galapagos Rift are of moderate high temperature type with an oxygen isotope temperature of 150 ℃; and the hydrothermal chimney materials sampled from the Mariana Trough have main component of opal and show features of low temperature hydrothermal type, but a few pyrite samples show features of moderate temperature hydrothermal type. However, there are more or less moderate high temperature hydrothermal minerals such as sphalerite, pyrite and chalkopyrite in the above areas, which indicates that expcept in the Mariana Trough, where there are obvious moderate low temperature hydrothermal activities, there are moderate high temperature hydrothermal activities in the above study areas.