湖南宝山铜多金属矿床流体包裹体特征及氢氧同位素地球化学的初步研究

发布时间：2018-02-26 18:23

  本文关键词： 流体包裹体 流体演化 铜多金属矿床 湖南宝山　出处：《岩石学报》2017年03期 　论文类型：期刊论文

【摘要】：宝山矿床处于NE向钦杭成矿带与EW向南岭成矿带的结合部位,是湘南地区最大的铜多金属矿床,成矿斑岩主要为花岗闪长斑岩,其中铜钼矿体主要分布于花岗质岩体与碳酸盐岩接触带的矽卡岩中,铅锌矿体则分布于断裂破碎带和石炭系的层间裂隙带中。本文以宝山铜多金属矿床为研究对象,在详细野外调查的基础上,系统开展了镜下观察、流体包裹体显微测温、激光拉曼分析以及H-O同位素分析,进而对宝山矿床的成矿流体演化进行了初步研究,获得了如下认识:(1)该矿床成矿演化过程可分为矽卡岩阶段、退化蚀变阶段、金属硫化物阶段及萤石-方解石脉阶段;(2)包裹体类型以富液相包裹体为主,成矿流体主要为H_2O-NaCl体系,含少量的CO_2,偶见含子晶包裹体;(3)矽卡岩阶段流体包裹体均一温度分布在430~550℃,主要集中在550℃以上,盐度范围为13.4%~21.98%NaC leqv;退化蚀变阶段的均一温度范围为211.8~395℃,在260~320℃和360~395℃出现两个峰值,盐度范围为3.71%~19.53%NaCleqv,该阶段围压由静岩压力向静水压力转变;金属硫化物阶段均一温度分布于156.7~323.1℃,主要为190~240℃,盐度范围为3.71%~19.84%NaC leqv;萤石-方解石脉阶段中的包裹体均一温度为100~266.5℃,主要集中于145~180℃,盐度分布在0.71%~18.3%NaC leqv。宝山矿床成矿压力介于23.8~169.9Mpa之间,利用静岩压力-静水压力梯度可得宝山矿床成矿深度约为2.25~6.29km,主要为4~6km;(4)退化蚀变阶段流体的37‰~7.47‰之间,δD_(H_2O)值介于3. 64‰;金属硫化物阶段和萤石-方解石脉阶段的δ~(18)O_(H_2O)值为-70‰~-δ~(18)O_(H_2O)值介于0.33‰~5.28‰之间,表明有大量的大气降水混入。因此,成矿流体从早阶段到晚阶段,由岩浆热液演变为大气降水,流体混合作用可能是矿质沉淀的主要机制。宝山铜多金属矿床是早期高温中高盐度流体向低温低盐度流体演化过程中形成的。
[Abstract]:Baoshan deposit, which is the largest copper polymetallic deposit in southern Hunan, is located in the combination of NE Xiang Qinhang metallogenic belt and EW Nanling metallogenic belt. The ore-forming porphyry is mainly granodiorite porphyry. The copper-molybdenum ore body is mainly distributed in skarn in the contact zone between granitic and carbonate rocks, while the lead-zinc ore body is distributed in the fracture zone and the interlayer fissure zone of Carboniferous. In this paper, the Baoshan copper polymetallic deposit is taken as the research object. On the basis of detailed field investigation, the microscopic temperature measurement of fluid inclusions, laser Raman analysis and H-O isotope analysis have been carried out systematically, and the evolution of ore-forming fluids in Baoshan deposit has been preliminarily studied. The ore-forming evolution of the deposit can be divided into skarn stage, degenerative alteration stage, metal sulphide stage and fluorite-calcite vein stage. The inclusions are mainly liquid-rich inclusions, and the ore-forming fluids are mainly H _ 2O-NaCl systems. The homogeneous temperature of fluid inclusions in skarn stage is 430 ~ 550 鈩，

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