河南栾川矿集区中鱼库(铅)锌矿床闪锌矿微量元素地球化学特征

GEOCHEMICAL CHARACTERISTICS OF TRACE ELEMENT OF SPHALERITE IN THE ZHONGYUKU(Pb)-Zn DEPOSIT OF THE LUANCHUAN,SOUTHWEST OF CHINA

中鱼库(铅)锌矿床位于豫西栾川Mo-W-Pb-Zn-Ag矿集区内鱼库-赤土店铅锌矿带的北西端。矿体赋存于新元古界栾川群三川组碎屑岩与碳酸盐岩岩性转换部位。矿区内矽卡岩化和角岩化发育。本文在矿床地质特征研究的基础之上,研究闪锌矿微量、稀土元素地球化学特征。结果表明随着流体氧逸度升高和温度降低,早、中和晚三个阶段的闪锌矿ΣREE和LREE/HREE逐渐降低,δEu和δCe负异常逐渐减弱。闪锌矿相对富集Mn、In和Se,亏损Ga、Ge和Tl,指示中鱼库矿床形成于中-高温环境,为与岩浆热液相关的矽卡岩型矿床。通过将中鱼库(铅)锌矿床与国内不同成因类型铅锌矿床的闪锌矿微量元素进行对比,印证了闪锌矿的部分微量元素特征能够有效用于区分铅锌矿床成因类型,这对铅锌矿床的评价和勘探具有一定的指示意义。

Zhongyuku （Pb）-Zn deposit is located in the northwest margin of the Zhongyuku-Chi- tudian metallogenie belt in Luanehuan Mo-W-Pb-Zn-Ag metallogenic concentration area. The ore bodies occur in the lithological conversion zone between elastic rocks and carbonate rocks in the Sanehuan Formation,Neoproterozoic Luanchuan Group. Skarnization and hornfels are well developed in the Zhongyuku deposit. Based on the studies of geological characteristics of the deposit, microscopy fabric of ores and trace and REE elements geochemistry of sphalerite are researched. Results show that the Y.REE values and LREE/HREE ratios of sphalerite decrease gradually from early-to middle-and late-stage with the increase of oxygen fugacity and the decrease of ore-forming temperature,while negative anomalies of δEu and δCe decrease gradually. Sphalerite is relatively enriched in Mn, In and Se, depleted in Ga,Ge and Tl,indicating that the Zhongyuku Pb-Zn deposit is a skarn-type deposit associated with magmatic hydrothermal fluid, formed under medium-high temperature. By comparison of the characteristics of trace elements in the sphalerite with different genetic types of Pb-Zn deposits,it is recognized that some features of trace elements in sphalerite could be useful to distinguish the genetic types of Pb-Zn deposits. Detailed study of trace elements geochemistry of sphalerite in Pb-Zn deposits has remarkable indicative significance in evaluation and exploration of Pb-Zn deposits.