山东五莲七宝山铅锌多金属矿床硫化物微量元素分布特征及地质意义

Distribution Characteristics and Geological Significance of Trace Elements of Sulfides in Qibaoshan Pb-Zn Polymetallic Deposit in Wulian,Shandong Province

为探讨五莲七宝山铅锌多金属矿中主要硫化物的微量元素分布特征,对矿床成因类型进行约束,在矿床地质研究的基础上,以不同成矿阶段形成的闪锌矿和方铅矿为研究对象,开展矿相学和矿物LA-ICPMS微量元素组成研究。结合野外地质调查和室内矿相学研究,将五莲七宝山铅锌多金属矿床的成矿过程划分为3个成矿阶段,分别是多金属硫化物+碎裂岩阶段(Ⅰ)、多金属硫化物+石英+白云石阶段(Ⅱ)和石英+白云石阶段(Ⅲ)。LA-ICP-MS分析结果表明,主要硫化物中闪锌矿富集Fe、Co、Mn和Cd元素,贫Ge、Se、Te、Re和Tl元素,方铅矿则主要富集Ag和Cd元素;闪锌矿中Cu、Cd、Fe、Mn、Co和In元素以类质同象的方式赋存在矿物中,偶见方铅矿显微包体,方铅矿中Ag元素以类质同象的形式赋存在矿物中,Cu、Zn和As元素则以显微包体的形式赋存在碳酸盐岩化矿石方铅矿中。闪锌矿微量元素成矿温度研究表明,Ⅰ阶段形成的碎裂—角砾岩化矿石以中温为主,Ⅱ阶段形成的碳酸盐岩化矿石则形成于低温环境。结合矿床地质和微量元素分布特征,认为七宝山铅锌多金属矿床属于与岩浆热液作用相关的中—低温热液脉型矿床。

To examine the distribution characteristics of trace elements within the primary sulfides of the Qibaoshan Pb-Zn polymetallic deposit in Wulian,and to constrain the genetic types of the deposit,this study conducted a detailed analysis of the mineralogy and LA-ICP-MS trace element composition of sphalerite and galena formed during different mineralization stages,building upon the geological investigation of the deposit.Based on comprehensive field investigations and laboratory mineralogical studies,the metallogenic processes of the Qibaoshan Pb-Zn polymetallic deposit can be delineated into three distinct stages:The polymetallic sulfide+cataclastic rock stage(StageⅠ),the polymetallic sulfide+quartz+dolomite stage(StageⅡ),and the quartz+dolomite stage(StageⅢ).LA-ICP-MS analysis indicates that sphalerite is enriched in Fe,Co,Mn,and Cd,but depleted in Ge,Se,Te,Re,and Tl,whereas galena exhibits significant enrichment in Ag and Cd.The elements Cu,Cd,Fe,Mn,Co,and In in sphalerite are primarily present in the form of isomorphous substitutions,while microinclusions within galena are occasionally observed.Silver(Ag)in galena is present in an isomorphic form,whereas copper(Cu),zinc(Zn),and arsenic(As)are found as microinclusions within the carbonated ore galena.An investigation into the metallogenetic temperatures of trace elements in sphalerite indicates that the cataclastic brecciated ore,formed during stageⅠ,predominantly crystallized at medium temperatures.In contrast,the carbonate ore,formed during stageⅡ,primarily crystallized at low temperatures.Based on the geological attributes and trace element distribution of the deposit,the Qibaoshan Pb-Zn polymetallic deposit is classified as a middle-to low-temperature hydrothermal vein-type deposit associated with magmatic hydrothermal processes.