内蒙古东乌旗阿尔哈达铅-锌-银矿床硫和铅同位素研究

阿尔哈达铅-锌-银矿床是近年来在内蒙古东乌珠穆沁旗境内发现的一处大型铅-锌-银矿床，其产出环境和形成机理为国内外矿床学家所关注。对该矿床代表性岩（矿）石样品进行了硫和铅同位素分析，并对其变化规律和成因意义进行了讨论。研究结果表明，围岩和矿石中硫化物δ³⁴S值变化范围为1.2‰～8.6‰，具有混源硫特征。根据共生硫化物对所确定的温度表明，该矿床的形成可划分为高温和中-低温两个阶段。17件矿石硫化物样品²⁰⁶Pb/²⁰⁴Pb、²⁰⁷Pb/²⁰⁴Pb和²⁰⁸Pb/²⁰⁴Pb比值变化范围分别为18.153~18.431，15.370~15.602和37.653~38.213，其平均值分别为18.271、15.464和37.873；3件围岩硫化物样品²⁰⁶Pb/²⁰⁴Pb、²⁰⁷Pb/²⁰⁴Pb和²⁰⁸Pb/²⁰⁴Pb比值变化范围分别为18.281~18.293，15.470~15.484和37.874~37.909，平均值分别为18.288、15.477和37.893。硫和铅同位素研究结果表明，阿尔哈达铅-锌-银矿床成矿物质分别来自泥盆系火山-沉积岩和印支期花岗岩。

Studies on Sulfur and Lead Isotope of the Arehada Pb-Zn-Ag Deposit, Dong Ujmqin Qi(County), Inner Mongolia

Located at easternmost part of the Early Paleozoic tectono-magmatic belt of the Chaganobo-Aououte-Chaobuleng along the southern edge of the Siberian plate, the newly discovered Arehada deposit is a large scale Pb-Zn deposit occurring in the central eastern Inner Mongolian Autonomous Region.We present 20 new sulfur and lead isotope data of wall rock and orebodies. The sulfur isotope compositions of wall rock are similar to those of orebodies. The δ³⁴S values vary from 1.2‰ to 8.6‰. The sulfur isotope compositions show different sources. The temperatures calculated from sulfide paras show high temperature stage and medium low temperatrue stage. The ²⁰⁶Pb/²⁰⁴Pb,²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb ratios of 17 sulfide samples of orebodies vary in ranges of 18.153-18.431, 15.370-15.602 and 37.653-38.213,with the average values of 18.271,15.464 and 37.873,respectivly. The ²⁰⁶Pb/²⁰⁴Pb,²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb ratios of 3 sulfide samples of wall rock vary in ranges of 18.281-18.293,15.470-15.484 and 37.874-37.909,with the average values of 18.288,15.477 and 37.893, respectively. The lead isotope compositions are similar to those of biotite granite and metasandstone from Chaobuleng skarn iron polymetallic deposit. It indicates that the sources of lead is wall rock and Indosinian granite.