Geology and geochemistry of the Jianchaling hydrothermal nickel deposit: T-pH-fO(2)-fS(2) conditions and nickel precipitation mechanism
Geology and geochemistry of the Jianchaling hydrothermal nickel deposit: T-pH-fO(2)-fS(2) conditions and nickel precipitation mechanism
复制标题
尖茶岭热液镍矿地质与地球化学：T≤pH≤fO2≤fS2条件及镍沉淀机制
DOI：
10.1016/j.oregeorev.2017.10.005
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发表时间：
2017
影响因子：
3.3
通讯作者：
Zhu Yongfeng
中科院分区：
文献类型：
--
作者：
Jiang Jiuyang;Zhu Yongfeng
煎茶岭镍存款产于中国陕西碧口地体中，沿着花岗斑岩与碳酸盐超镁铁岩（碳酸盐蛇纹岩、滑石-碳酸盐岩和碳酸盐岩）之间的边界。碳酸盐超镁铁岩在热液作用下形成了蛇纹石-磁铁矿、蛇纹石-菱镁矿-磁铁矿和菱镁矿-滑石-石英-黄铁矿-紫石英-菱镁矿-黄铜矿组合.碳酸盐超镁铁岩中与菱镁矿共生的含镍硫化物、晚生磁铁矿。与蛇纹岩相比，滑石碳酸盐岩中Ni、Co、Cu、Mn、Pb富集。磁铁矿中NiO含量随蛇纹岩碳酸盐化程度的增加而降低，说明磁铁矿中的Ni在流体中富集，对煎茶岭镍存款的形成有贡献。硫化物从流体中沉淀出来，logfO 2值在−34.5到−31.8之间变化，logfS 2值在−10.3到−9.2之间变化。蛇纹石向菱镁矿-滑石-石英组合转化引发的高pH和HS−活动促进了含镍硫化物的沉淀，最终形成煎茶岭热液镍存款。
The Jianchaling nickel deposit in the Bikou Terrane (Shaanxi Province, China) occurs along the boundaries between granite porphyry and carbonated ultramafic rocks (carbonated serpentinite, talc–carbonate rocks, and listwaenite). Serpentine– magnetite, serpentine– magnesite– magnetite, and magnesite– talc– quartz– pyrite– violarite– millerite– chalcopyrite assemblage formed in carbonated ultramafic rocks during hydrothermal activities. Ni-bearing sulphides, coexisting with magnesite, postdated magnetite in carbonated ultramafic rocks. Compared with serpentinite, Ni, Co, Cu, Mn, and Pb concentrate in talc–carbonate rocks. The fact that the NiO contents of magnetite decrease with progressive carbonation of serpentinite suggests that Ni from magnetite concentrated in fluid and contributed to the formation of the Jianchaling nickel deposit. Sulphides precipitated from fluid with logfO2value varying from −34.5 to −31.8 and logfS2value varying from −10.3 to −9.2. High pH and HS−activities triggered by transformation of serpentine into magnesite–talc–quartz assemblage promoted precipitation of Ni-bearing sulphides, and finally formed the Jianchaling hydrothermal nickel deposit.