豫西龙门店银铅矿床铅硫同位素组成对成矿物质来源的示踪

龙门店银铅矿床位于华北克拉通南缘豫西熊耳山地体西段,是近年来新发现的构造蚀变岩型银铅矿床。通过对龙门店银铅矿床铅、硫同位素分析,获得该矿床主成矿阶段铅同位素~(206)Pb/~(204)Pb值为17.660~17.952,~(207)Pb/~(204)Pb值为15.388~15.566,~(208)Pb/~(204)Pb值为37.771~38.380,变化范围均不大,属于正常铅范围;硫同位素组成变化范围为-5.32‰~5.41‰,平均值-0.54‰。综合分析认为,矿石铅以幔源为主,具壳幔混合特征;硫主要来源地幔,并有地壳硫加入,具混合硫特征。铅、硫同位素组成表明,该矿床的成矿物质来源于造山过程中壳幔混合源,以幔源为主。

Tracing indication of lead and sulfur isotope composition for the sources of ore-forming materials in Longmendian Lead-Silver Deposit in western Henan

Longmendian Lead -Silver Deposit is located in the western part of Xiong 'ershan body on the southern margin of North China Craton .It is a tectonic altered rock type Lead -Silver deposit discovered in recent years .In or-der to find out the source of ore-forming materials,the paper studies the lead and sulfur isotopes in the main metallo-genic stages.The results show that the Pb isotope ratio of 206 Pb/204 Pb is 17.660 to 17.952,the ratio of 207 Pb/204 Pb is 15.388 to 15.566,the ratio of 208 Pb/204 Pb is 37.771 to 38.380,and the range of variation is normal without being too large.Sulfur isotopic compositions vary from -5.32 ‰to 5.41 ‰,and the average value is 0.54 ‰.Comprehensive analysis thinks that the lead in the ore comes mainly from the mantle and is characterized by the mixture of mantle and crust;the sulfur comes mainly from the deep mantle and is mixed with crust sulfur .The sulfur and lead isotopic com-positions of the ore deposit indicate that the source of ore-forming minerals is the mixed source from crust and mantle in the process of the orogenic process ,with the mantle as the primary source .