贵州牛角塘铅锌矿区大亮锌矿闪锌矿微量元素地球化学特征及其地质意义

The geochemical characteristics of trace elements contained in sphalerite from Daliang zinc mine in Niujiaotang lead-zinc ore field in Guizhou Province and its geological significance

大亮锌矿是贵州牛角塘铅锌矿田的重要组成部分,目前所开采的对象为近年来在“陡倾斜带”中新发现的矿体,其地质学研究还十分薄弱。采用ICP-MS技术对该矿闪锌矿单矿物进行了微量元素测试,以揭示该矿的成矿作用,结果表明:闪锌矿中Ni、Ga、Ge、Pb、Cd、Tl等较为富集,而Mn、Fe、As、Ag、Sb、Co、Se等较为亏损。闪锌矿矿石为Cd、Ga、Ge富集但Fe质量分数较低(平均为0.27%)的浅色闪锌矿,且具有较低的In/Ge、In/Ga比值(平均为0.02和0.05),这些特征指示其成矿温度较低。分析闪锌矿微量元素特征、Fe-Tl、Fe-Co、lnGa-lnIn关系图以及Ag-(Ga+Ge)-(In+Se+Te)三端元图可知,大亮锌矿与MVT型铅锌矿极为相似,明显区别于矽卡岩型铅锌矿和SEDEX+VMS型铅锌矿。因此认为大亮锌矿为低温热液矿床,且属于MVT型铅锌矿,其与牛角塘矿区的缓倾斜层状矿体为同一成矿作用在不同成矿空间的产物。

The Daliang zinc mine is an important deposit in Niujiaotang lead-zinc ore field.The mining object is the ore body discovered within the"steep dip zone"in recent years,where little geological research work has been done.In this study,ICP-MS technology was employed to test trace elements contained in sphalerite mineral from Daliang zinc deposit in order to reveal the mineralization of this mine.The results show that the trace elements such as Ni,Ga,Ge,Pb,Cd,Tl were enriched,while the others like Mn,Fe,As,Ag,Sb,Co,Se were quite deficit in the sphalerite ore from Daliang zinc deposit.The sphalerite mineral mainly exhibited light yellow,enriched in elements like Cd,Ga and Ge,but contained low Fe(averaged 0.27%)with low ratio of In/Ga and In/Ge(averaged 0.02 and 0.05 respectively),which indicated the low metallogenetic temperature.From analysis of the characteristics of trace elements and figure Fe vs.Tl,figure Fe vs.Co,figure lnGa vs.lnIn and the ternary diagram Ag vs.(Ga+Ge)vs.(In+Se+Te)of sphalerite,the results show that Daliang zinc deposit was quite similar to Mississippi Valley-Type(MVT)lead-zinc deposit but quite different from skarn type lead-zinc deposit and sedimentary exhalative deposits and volcanogenic massive sulfide deposits(SEDEX+VMS).Therefore,Daliang zinc deposit was mineralized at a low temperature in the same way of mineralization as the gently inclined and bedded ore body in Niujiaotang ore field but in different formation spaces.It is classified as MVT lead-zinc deposit.