摘要
黔东铜仁地区寒武系清虚洞组和娄山关组中分布有多处热液白云岩,其形态包括块状、透镜状、角砾状等。通过露头及薄片观察、流体包裹体温度测定、稀土元素和锶同位素分析,笔者探讨了研究区不同类型热液白云岩的形成机制、热液性质与来源及其与铅锌成矿作用的关系。结果表明:(1)热液白云岩由中粗晶—巨晶鞍状白云石组成,形成温度为96~223℃,平均为155.86℃;盐度为8.28~16.15 wt%Na Cl,平均为12.30wt%Na Cl;具有轻稀土富集和Ce负异常特征,LREE/HREE为16.51,δCe为0.79,87Sr/86Sr为0.708662。(2)块状和透镜状热液白云岩形成于交代作用较完全的环境,角砾状热液白云岩可能形成于水力破裂作用;白云石化流体可能来自包括震旦系碳酸盐岩在内的下伏地层,断层和裂缝为其运移通道。(3)白云石化流体与区域铅锌成矿流体温度、盐度和地球化学特征相近,来源相同或相似;热液白云岩中含有少量成矿物质,应形成于铅锌主成矿期前后。
Multiple outcrops of the hydrothermal dolostone are distributed throughout the Cambrain Qingxudong and Loushanguan Formations in Tongren area,eastern Guizhou Province.The dolostones are generally massive,lenticular and brecciated.Based on investigations in the outcrops and rock slabs,measurement of temperature of fluid inclusions,and REE and Sr isotope analyses,we studied the genesis and fluid property of different types of hydrothermal dolostone and their relationship with the mineralization of Pb-Zn deposits.The results indicate:(1)Hydrothermal dolostone is composed of medium-coarse-crystalline to ultra-coarse-crystalline saddle dolomite crystals.The formation temperature varies from 96 to 223￣￣℃,with an average of 155.86￣￣℃.Salinities is between 8.28 and 16.15 wt%NaCl,with an average of 12.30wt%NaCl.Characterized by REE enrichment and a negative Ce anomaly with the LREE to HREE ratio of 16.51,δCe value of 0.79,and 87 Sr/86 Sr ratio of 0.708662.(2)Massive and lenticular hydrothermal dolostone formed by more complete metasomatism of dolomitized fluid,whereas brecciated hydrothermal dolostone formed by hydrofracturing.Dolomitized fluid may come from the underlying Sinian carbonate strata,with faults and fractures as fluid migration channels.(3)Dolomitized fluid and regional Pb-Zn ore-forming fluid have similar temperature,salinity and geochemical characteristics,and share similar origins.A few metallogenic materials of the hydrothermal dolostone were also formed around the main Pb-Zn metallogenic stage.
作者
李驰
潘文
杜远生
Li Chi;Pan Wen;Du Yuan-Sheng(School of Earth Sciences,China University of Geosciences(Wuhan),Wuhan 430074,Hubei;Geological Brigade 103,Bureau of Geology and Mineral Exploration and Development of Guizhou Province,Tongren 554300,Guizhou)
出处
《古地理学报》
CAS
CSCD
北大核心
2018年第5期869-876,共8页
Journal of Palaeogeography：Chinese Edition
基金
贵州省地质矿产勘查开发局科研项目(编号:黔地矿科合[2016]05号)资助~~
关键词
贵州省
热液白云岩
水力破裂
铅锌矿
Guizhou Province
hydrothermal dolomite
hydraulic fracturing
lead-zinc mine
