青海东莫扎抓铅锌矿床硫化物特征及成因意义

Characteristics of Sulfide Minerals in Dongmozhazhua Lead-zinc Deposit,Qinghai Province,and Their Genetic Significance

青海东莫扎抓矿床是新探明的一个大型铅锌矿床。通过大量矿石光薄片观察、等离子质谱、电子探针分析,对其矿石矿物进行系统研究。结果表明:矿石矿物发育一套中温热液矿物组合;围岩蚀变具有中温蚀变特点;硫化物的硫同位素具有MVT型块状硫化物的特征。综合研究认为,东莫扎抓铅锌矿至少可分为3期成矿:在海相白云岩沉积阶段存在闪锌矿、黄铁矿等金属硫化物的热液喷流沉积成矿;在弧后前陆盆地构造环境中发育有MVT型铅锌矿床成矿;在后期构造运动热液作用下,之前形成的铅锌矿可能会发生热液叠加改造。因此,东莫扎抓具有多期次多阶段叠加成矿的特点。

The Dongmozhazhua ore deposit is a new large-size lead-zinc deposit in the south of Qinghai Province.Based on a considerable number of polished ore sections as well as massive spectrum and electron microprobe analyses,the systematic study on ore minerals is finished.The results show that the ore mineral is intermediate-temperature hydrothermal mineral association.Wall rock alteration is intermediate-temperature alteration.Sulfide isotope has the characteristic of the sulfides isotope in massive sulfide deposit.Combining the study results,it is believed that Dongmozhazhua lead-zinc deposit has experienced three stages mineralization.In the stage of marine dolomite sedimentation,there exist hydrothermal sedimentation-exhalation mineralization of sphalerite,pyrite and else metal sulfides.The structure environment of the back（front） arc basin is characterized by development of massive sulfide lead-zinc deposits.In the late tectonic activity and hydrothermal process,the lead-zinc deposit maybe occur hydrothermal superimposition and reformation.Therefore,the Dongmozhazhua lead-zinc deposit has characteristics of the multi-stage and superimposed metallization.