摘要
In-situ LA-ICP-MS and S isotopes of pyrite from the Baoshan Cu polymetallic deposit were conducted to investigate the ore-forming process and the enrichment mechanism of elements.Three generations of pyrite (Py Ⅰ,Py Ⅱ,and Py Ⅲ) in the skarn-type ores and pyrite in the carbonate-hosted sulfide ores from central,western,and northern(C_Py,W_Py,and N_Py) mining districts are selected for comparison.Compared with Py Ⅰ and Py Ⅲ,the contents of most elements in Py Ⅱ are apparently higher.The As and Se contents are high within a wide range and are decoupled in the growth band of the C_Py.The highest As,Se,and Pb contents were found in W_Py and N_Py.These results indicate the drastic changes in the temperature and fluid mixing during the mineralization.The occurrence of fluctuation and change in temperature and f(O_(2)) was triggered by intermittent pulses of magmatic-hydrothermal fluids,mixing with meteoric water,and water-rock interactions.The sulfur isotopes of all species of pyrite indicated the magmatic source.The change in the f(O_(2)) conditions caused slight differences in the sulfur isotope compositions.Consequently,a metallogenic model was proposed to explain the ore-forming processes.
对宝山铜多金属矿床中的黄铁矿进行原位LA-ICP-MS和硫同位素研究,以探讨矿床的成矿过程和元素富集机制。选取矽卡岩型矿石中的3个世代黄铁矿(Py I、Py Ⅱ和Py Ⅲ)以及中部、西部和北部(C_Py、W_Py和N_Py)矿区赋存在碳酸盐岩中的硫化物矿石里的黄铁矿为研究对象进行比较。与Py I和Py Ⅲ相比,Py Ⅱ中大多数元素的含量明显较高。C_Py中砷和硒的含量很高且变化范围大,这两种元素在C_Py的生长带中呈解耦趋势。W_Py和N_Py中具有最高的砷、硒和铅含量。这些结果表明,成矿过程中伴随着温度的剧烈变化以及流体混合作用。岩浆热液间歇脉冲、流体混合作用以及水-岩相互作用导致温度和f(O_(2))波动以及变化。黄铁矿的硫同位素暗示硫主要为岩浆来源。f(O_2)条件的变化是导致各类黄铁矿中硫同位素组成轻微差异的主要原因。最后,提出成矿模式以阐明宝山成矿过程。
基金
funded by the National Key Research and Development Program of China (Nos. 2018YFC0603904, 2018YFC0603901)。
