新疆乌拉根铅锌矿矿床地球化学特征及成因讨论

Geochemical Characteristics and Genetic Discussion of Xinjiang Wulagen Lead-zinc Ore Deposit

为确定乌拉根铅锌矿床形成机制,对矿区不同类型岩石中的铅锌矿石进行了地球化学特征对比研究。结果显示,稀土元素数据表明不同类型的铅锌矿石的物质来源不同;铅同位素^(206 )Pb/^(204 )Pb,^(207)Pb/^(204)Pb,^(208)Pb/^(204)Pb比值分别为18.326～8.641 3,15.402～15.645 4,38.029～38.750 7,说明成矿物质主要来自造山带的上地壳;δ^(34)S为-26.09×10^(-3)～+14.6×10^(-3),硫同位素主要是来自经由细菌产生的硫化物和热解产生的有机硫;δ^(13)C_(V·PDB)(10^(-3))为4.2～-7.7,δ^(18 )O_(V·SMOW)(10^(-3))为20.9～31.9,显示成矿作用期间有外来流体活动特点;流体盐度为3.55%～13.07%,流体包裹体数据表明乌拉根铅锌矿的流体特征为低温中高盐度的热卤水。结合地质特征,认为乌拉根铅锌矿是一个早期以海底沉积成因为主,晚期以MVT成因为主的复合叠加性矿床。

To determine the formation mechanism ofWulagen lead-zinc ore deposit,the author carries out comparative study for the geochemical characteristics of the different rocks in the mining area.The results shown that,rare earth element data indicates different types of lead-zinc ore have different material source;The specific value of lead isotope 206 Pb/204 Pb,207 Pb/204 Pb and 208 Pb/204 Pb is 18.326~8.641 3,15.402~15.645 4 and 38.029~38.750 7,which means the ore-forming matters are from the upper crust of the orogenic belt;δ34 S is 26.09×10^-3^+14.6×10^-3,the sulfur isotope is mainly from the sulfide generated from the bacteria and the organic sulfur generated by pyrolysis;δ13 C V·PDB(10^-3)is 4.2^-7.7,δ18 O V·SMOW(10^-3)is 20.9~31.9,which shows that there's extraneous fluid activity features during the period of mineralization;The salinity of the fluid is 3.55%~13.07%,the fluid inclusion data shows that the fluid characteristic of the Wulagen lead-zinc ore is hot brine with high salinity in low temperature.Combining with geologic feature,it is thought that Wulagen lead-zinc ore is a composite additive ore deposit which is mainly formed by bottom deposit in the early stage,while the main reason in the late stage is MVT.