西藏洞中拉铅锌矿床S,Pb,Sr同位素组成对成矿物质来源的示踪  

S,Pb AND Sr ISOTOPIC COMPOSITIONS FOR TRACING SOURCES OF ORE-FORMING MATERIALS IN DONGZHONGLA LEAD-ZINC DEPOSIT IN TIBET

作　　者：费光春[1] 多吉 温春齐[1] 阳正熙[1] 龙训荣[1] 周雄[1,3] 

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]西藏地质矿产勘查开发局,西藏拉萨850000 [3]中国地质科学院矿产综合利用研究所,四川成都610041

出　　处：《矿物岩石》2011年第4期52-57,共6页Mineralogy and Petrology

基　　金：国家科技支撑计划项目(2006BAB01A04);国家973计划项目(2002CB412607);矿物学;岩石学;矿床学国家重点(培育)学科(SZD0407)

摘　　要：洞中拉铅锌矿床位于西藏冈底斯东段念青唐古拉山地区扎雪—金达成矿带内,为印度-亚洲大陆主碰撞期形成的矿床。在分析该矿床成矿地质条件的基础上,对该矿床的主要金属硫化物的S,Pb,Sr同位素组成进行分析,并对成矿物质来源进行示踪讨论。研究表明:矿石硫化物的δ34S组成变化范围较窄,变化范围为3.0‰～5.7‰,多数集中于4.0‰～6.0‰之间,具有塔式分布效应,估算的总硫同位素值δ34S∑S为4.7‰,具有岩浆硫的特征。矿石铅同位素组成稳定,矿石的206Pb/204Pb,207Pb/204Pb,208Pb/204Pb的变化范围分别为:18.628～18.746,15.698～15.802,39.077～39.430,与矿区岩浆岩的铅同位素组成一致,为正常普通铅,矿石铅来源于早白垩世上地壳物质部分熔融形成的岩浆。矿石锶同位素的初始值(87Sr/86Sr)i较高,介于0.717 32～0.727 67之间,成矿物质来源于地壳。Dongzhongla lead-Zinc deposit in the Zhaxue-Jinda metallogenic beit in the eastern Gangdise formed during the collision period（41 Ma^65 Ma） of Indian-Asian plates in the Nyainqentanglha mineralization belt.Based on the analysis of ore-forming geological conditions in this deposit,S,Pb,Sr isotopic compositions of this deposit were analyzed,and tracer discussions were conducted on the sources of ore-forming metal materials.It was showed that the δ34S composition varied in a narrow range of 3.0‰~5.7‰,mainly 4‰~6‰ with tower-shaped distribution effect.Total sulfur isotopic value δ34S∑S was estimated at 4.7‰ with characteristics of magmatic sulfur and the Pb isotopic composition of ore was stable.The 206Pb/204Pb,207Pb/204Pb,208Pb/204Pb values of ores varied in a range of 18.628~18.746,15.698~15.802 and 39.077~39.430 respectively,consistent with Pb isotopic composition of magmatic rocks in the deposit,classified as normal ordinary lead.It was suggested that ore lead was generated from magma due to partial melting of upper-crust materials in Early Cretaceous.The initial value（87Sr/86Sr）i of Sr isotope was higher,ranging from 0.717 32 to 0.727 67,indicating that ore-forming materials mainly came from the crust.

关 键 词：同位素组成 成矿物质来源 洞中拉铅锌矿床 西藏 

分 类 号：P597.2[天文地球—地球化学]