Mineral Component, Texture and Forming Conditions of Hydrothermal Chimney on the East Pacific Rise 9°-10°N
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摘要: 为研究东太平洋海隆9°~10°N热液活动特征, 采用成因矿物学方法, 通过矿相显微镜、扫描电镜、X射线衍射分析以及电子探针等手段, 对烟囱体矿物成分、结构和地球化学特征进行了研究.该区烟囱体硫化物矿物有3种矿物组合: (1) 硬石膏+白铁矿+黄铁矿; (2) 黄铁矿+闪锌矿+黄铜矿; (3) 黄铜矿+斑铜矿+蓝辉铜矿+铜蓝.成矿热液流体温度经历了低-高-低的变化, 最高温度可达到400℃以上.该热液烟囱为典型的“黑烟囱”类型, 早期硬石膏沉淀形成烟囱体的框架, 后期的金属硫化物在烟囱体内表面沉淀, 由烟囱壁向内形成了硬石膏-黄铁矿、多金属硫化物和黄铜矿及次生铜矿物的矿物分带.Abstract: To characterize the hydrothermal processes of East Pacific rise at 9°-10°N, sulfide mineral compositions, textural and geochemical features of chimney ores were studied using ore microscope, scanning electron microscope, X-ray diffraction analysis, and electron microprobe techniques.Resultsshow that there are three mineral assemblages for the hydrothermal chimney ores, namely: (1) anhydrite + marcasite + pyrite, (2) pyrite + sphalerite + chalcopyrite, and (3) chalcopyrite + bornite + digenite + covellite. Mineral assemblages, zonational features, and geochemical characteristics of the ore minerals indicate that ore fluid temperature changed from low to high then to low with a maximum temperature up to 400 ℃. The chimney is a typical black smoker. The initial structure of the chimney was formed by the precipitation of anhydrites, and later the sulfides began to precipitate in the inner wall.
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Key words:
- hydrothermal processes /
- black smoker /
- mineral assemblage /
- exsolution texture /
- ore fluid
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图 1 东太平洋海隆9°~10°N热液烟囱采样位置图(据Haymon et al., 1991)
Fig. 1. Location map of hydrothermal chimney at EPR 9°-10°N
图 2 东太平洋海隆9°~10°N热液烟囱体矿物的带状分布
Fig. 2. Mineral zonation of hydrothermal chimney at EPR 9°-10°N
图 3 东太平洋海隆9°~10°N热液烟囱体矿物结构显微照片
Fig. 3. Microphotograph of hydrothermal chimney minerals at EPR 9°-10°N
图 4 东太平洋海隆9°~10°N热液烟囱矿物生成顺序
Fig. 4. Paragenetic sequence for hydrothermal chimney minerals at EPR 9°-10°N
表 1 东太平洋海隆9°~10°N热液烟囱矿物电子探针分析结果(%)
Table 1. Result of electron microprobe analyses of hydrothermal chimney minerals at EPR 9°-10°N
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