贵州筲箕湾铅锌矿床硫化物中Tl-Cd-Ga富集机制及地质意义

筲箕湾铅锌矿床位于黔西北铅锌成矿区中部,为该区铅锌矿床中的又一典型代表,其金属资源量（Pb＋Zn）超过20万t。本文利用电感耦合等离子体质谱（ICP-MS）分析了不同类型矿石中原生矿石硫化物（黄铁矿、闪锌矿和方铅矿）中分散元素含量,结果显示除Cd含量较高外,Ga、In、Se、Tl和Re的富集程度均较低。不同分散元素在硫化物中表现出不同的富集规律,表现为Ga含量在闪锌矿中最高,黄铁矿次之,方铅矿最低;方铅矿中Tl含量高于闪锌矿,黄铁矿最低;Cd在闪锌矿中含量最高,方铅矿次之,黄铁矿最低;从黄铁矿→方铅矿→闪锌矿In含量依次升高;Re含量表现出在闪锌矿中最高,黄铁矿次之,方铅矿最低;Se富集程度从黄铁矿→方铅矿→闪锌矿依次升高。Ga、In和Re在不同颜色闪锌矿中富集程度相似,而Se、Cd和Tl则相对富集在棕色闪锌矿中。统计发现闪锌矿中Zn含量与Cd、Ga含量不呈类质同象的负相关特征,而其中的Fe含量与Cd、Ga含量间表现出曲线相关或负相关特征,暗示Cd、Ga可能是通过替代先进入闪锌矿中的Fe而占据其晶格,这可能是一种新的机制。闪锌矿Ga、Cd、In含量及Ga/In、Zn/Cd比值等参数,指示筲箕湾铅锌矿床形成于中-高温条件,其矿床成因类型与沉积-改造型相似。

Enrichment Mechanisms and Implications of Tl-Cd-Ga in Sulfides of Shaojiwan Pb-Zn Deposit,Guizhou Province,China

Located in the middle of NW Guizhou Pb-Zn metallogenetic province,Shaojiwan Pb-Zn deposit is a typical representative Pb-Zn deposits in the region,whose metal resources(Pb+Zn) are more than 0.2 Mt.In this study,the dispersed elements contents in different types of ore sulfides(pyrite,sphalerite,and galena) were analyzed by using the methods of Inductively Coupled Plasma Mass Spectrum(ICP-MS).The results show that content of Cd is higher than those of Ga,In,Se,Tl and Re,and they have different concentration characteristics in sulfides.The concentration of Ga is according to the decreasing order of the sphalerite and pyrite,followed by galena;the concentration of Tl in sphalerite is higher than that in galena,followed by that in pyrite;the concentration of Cd in sphalerite is higher than that in the party lead mine,followed by that in pyrite;the concentration of In increases according to the order of pyrite→ galena→ sphalerite in turn;the concentration of Re is higher in sphalerite than that in pyrite,followed by that in galena;the concentration of Se increases according to the order of pyrite→ galena→sphalerite in turn.the concentration of Ga,In and Re conent is similiar in spalerites with different colors,but he concentration of Se,Cd and Tl are relatively abandent in brown sphalerite.The statistics show that the Zn content in the sphalerite is not allomerism and not negatively correlated with those of Cd and Ga.The Fe content shows negative correlation with Cd and Ga contents,suggesting that Cd and Ga may occupy the lattices of sphalerite by replacing the Fe,which may be a new mechanism.The contents of Ga,Cd and In and the ratios of Ga/In and Zn/Cd in the sphalerite indicate that Shaojiwan Pb-Zn deposits formed under middle-high temperature conditions,and the metallogenetic deposit might be diplogenetic-regenerated.