澳大利亚世纪铅锌矿床地质特征和成矿模式  

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

作　　者：秦思婷[1] 田广[2] 吕良冀[2] 杨莎莎[1] 

机构地区：[1]中国地质科学院矿产资源研究所/国土资源部成矿作用与资源评价重点实验室,北京100037 [2]中国地质大学地球科学与资源学院,北京100083

出　　处：《地质通报》2015年第6期1065-1076,共12页Geological Bulletin of China

基　　金：中国地质调查局项目(编号:1212010811029;1212011220911)

摘　　要：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。The Century deposit represents an important new member of the major sediments-hosted Zn-Pb-Ag deposits in the Mount Isa inlier and Mc Arthur 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.

关 键 词：地球化学 矿床地质 同位素 成矿模式 世纪矿床 澳大利亚 

分 类 号：P618.4[天文地球—矿床学]