煎茶岭硫化镍矿床的铂族元素地球化学特征及其意义

Geochemical characteristics of Platinum group elements of the sulfide nickel ores and related rocks in Jianchaling, Lueyang county, Shannxi province, China and their implication for genesis

采用ICP-MS分析方法对煎茶岭硫化镍矿床岩石及矿石的铂族元素地球化学研究表明,煎茶岭矿床蛇纹岩的Cu/Pd值低于原生地幔岩浆的Cu/Pd值,说明岩浆熔离作用较弱,其Au/Pd值反映存在后期变质热液成矿作用镍矿石的Pd/Ir比值变化较小,指示其多数矿石属于岩浆型,尽管岩浆活动弱,但以岩浆成矿作用为主。该硫化镍矿床的铂族元素特征参数(Pt/(Pt+Pd)、(Pt+Pd)/(Ru+Ir+Os)、Pd/Ir及Cu/(Ni+Cu)等)具有过渡特征,这与其处于过渡的构造环境、特殊的岩浆性质和复杂的成矿作用有关煎茶岭镍矿床成矿过程中有壳源物质的混染,整体上岩、矿石铂族元素含量较低,这与其岩浆熔离作用弱。

The Platinum-group elements (PGE) geochemistry of rocks and copper-nickel sulfide ores from Jianchaling deposit is systemically studied by ICP-MS testing method. The Cu/Pd ratio of serpentinite is lower than that of original mantle magma, indicating that magmatic liquation is weak, and the Au/Pd ratio of the serpentinite reflects the post-magmatic emplacement metamorphic hydrothermal minealization is also responsible for the formation of the copper-nickel sulfide deposit. The Pd/Ir ratio of ores changes in a small range, showing the ores belong to magma-type, although magmatic action is relatively weak in the ore field, but the magma ore-forming process play an important role in the formation of copper-nikel sulfide ores. The Platinum-group elements characteristic parameter for the sulfide nickel deposit have transition feature, which is corresponding to transition tectonic setting of the minerlization, special magma composition, and complicated metallogenesis. The substances of the crustal source have contaminated during ore-forming process, the content of PGE for the rocks and ores are low. On the whole, this can be ascribed to weak magmatic liquation and undeveloped PGE mineralization.