澳大利亚世纪铅锌矿床地质特征和成矿模式

澳大利亚世纪（Century）铅锌矿床赋存于中元古代劳恩希尔组页岩和粉砂岩中。矿化主要为细粒闪锌矿，其次为方铅矿和黄铁矿。大部分硫化物（80%~90%）在黑色页岩单元中以易碎的交代层状出现，被富菱铁矿粉砂岩层隔开。矿化具有2个大尺度的变化趋势，在白蚁圈断层由北东至南西，Zn品位显著降低，由南东至北西，Zn品位略有降低。层状闪锌矿主要有2种结构，多孔闪锌矿的焦沥青含量较高，无孔闪锌矿焦沥青含量较低。S同位素研究显示，整个成矿流体系统是一个封闭的储层，重S在变形与成矿事件中进一步富集。世纪矿床由变形作用驱使流体迁移到异常高压（压实作用下的）页岩层位时，页岩容矿的矿化作用形成。较热的富含金属的流体和较深盆地的卤水，使得有机质迅速成熟，最终导致硫酸盐的还原和贱金属的沉淀。

Geological characteristics and metallogenic model of the Century Pb-Zn deposit,Australia

The Century deposit represents an important new member of the major sediments-hosted Zn-Pb-Ag deposits in the Mount Isa inlier and McArthur basin. The deposit is hosted in shales and siltstones of the Mesoproterozoic Lawn Hill Formation. Mineralization comprises fine-grained sphalerite with minor galena and pyrite. Most sulfides (80%-90%) occur as delicate brittle lamellae in black shale units, separated by siderite-rich siltstone horizon. The mineralization shows two large-scale trend，a striking decline in grade from northeast to southwest away from the Termite Range fault，and a more subtle decline in grade from southeast to northwest. Two principal textural varieties of stratabound sphalerite are recognized: "porous," which has a high pyrobitumen content, and "nonporous," which has a relatively low pyrobitumen content. The sulfur isotope suggests that the whole fluid system was a large closed system reservoir, with progressive enrichment of heavy sulfur during the deformation and mineralization process. The Century deposit seems to represent an example of shale-hosted mineralization formed during deformation-driven migration of fluids into an over-pressure/under-compacted shale sequence. The influx of relatively hot metal-bearing deep basin brines resulted in the rapid maturation of organic material, which ultimately led to sulfate reduction and base metal precipitation.