都龙锡锌矿床绿泥石特征及其成矿意义

Characteristics of chlorites from Dulong Sn-Zn deposit and their metallogenic implications

都龙锡锌超大型矿床是中国第三大锡石硫化物矿床,其中的绿泥石化相当普遍,并与矿化关系密切。本文在岩矿鉴定基础上,利用电子探针对绿泥石进行了微区化学成分研究。研究结果表明,该矿床绿泥石为富铁种属的假鳞绿泥石、鲕绿泥石、蠕绿泥石(铁绿泥石)及铁镁绿泥石,指示形成于还原环境;绿泥石为泥质岩或铁镁质岩受热液交代蚀变的产物,绿泥石结构的离子置换主要体现为Fe对Mg的置换,反映其形成与含铁建造有关;绿泥石的形成温度为231～304℃,平均为269℃,属于中-低温范围。绿泥石的形成机制主要表现为溶蚀-结晶、溶蚀-迁移-沉淀结晶2种。绿泥石可能与锡成矿同期形成,其与矿石矿物的生成关系表明,燕山期岩浆活动对都龙矿床的叠加改造作用显著。

The Dulong superlarge Sn-Zn deposit is the third largest cassiterite sulfide deposit in China. Chlorite is one of the main hydrothermal alteration minerals genetically related to tin mineralization in this ore deposit. By means of microscopic and electron microprobe analysis,the user investigated chemical composition and texture of the chlorite and concluded that chlorites in the Dulong Sn-Zn deposit have the following characteristics：① they are mainly Fe-rich chlorites composed of pseudothuringite,chamosite,prochlorite and brunsvigite,indicating a reducing environment during their user; ② they were produced by hydrothermal alteration of pelitic or mafic rocks,and the phenomenon that Fe-Mg substitution dominates the octahedral substitution suggests that their formation had to do with the iron-rich formation; ③ they were formed at temperatures of 231～304 ℃ （averagely 269 ℃）,in the range of low-moderate temperature; and ④ both chlorites and cassiterite were formed in the Late Yanshanian magmatic hydrothermal ore-forming user that occurred under the low-moderate temperature reducing condition.