略阳煎茶岭铜镍硫化物矿床Re-Os同位素年龄及其地质意义  

Re-Os Isotope Age and Its Application to the Jianchaling Nickel-Copper Sulfide Deposit, Lueyang, Shaanxi Province

作　　者：王瑞廷[1] 赫英[1] 王东生 刘民武[1] 

机构地区：[1]西北大学教育部大陆动力学重点研究实验室,西安710069 [2]西北有色地质勘查局,西安710054

出　　处：《地质论评》2003年第2期205-211,共7页Geological Review

基　　金：国家重点基础研究发展规划项目(编号:G1999043211)及西北有色地质勘查局人才基金联合资助

摘　　要：采用矿石Re-Os同位素方法对陕西省煎茶岭硫化镍矿床矿石进行了成矿年代学研究,获得了878±27Ma(1σ)的等时线年龄,首次厘定了该矿床成矿时代为新元古代,成岩成矿基本同时。通过对878Ma硫化镍矿石初始Re-Os同位素体系的γ_(Os)计算和Re/Os值分析表明,其γ_(Os)和Re/Os值变化范围大,深部条带状矿石的Re/Os值仅为0.05,γ_(Os)为-6.70;块状矿石的Re/Os值范围为4.24～24.43,γ_(Os)为-15.37～+280.65,说明成矿过程中有壳源物质的混染;两件样品的γ_(Os)为负值(-15.37,-6.70),可能指示其超镁铁质岩浆来源于Re亏损地幔。煎茶岭超基性岩体年龄及其镍矿石的Re-Os等时线年龄与扬子克拉通北缘火山岩浆活动时间相对应,它们是扬子克拉通西北缘晋宁期构造岩浆成矿作用的产物。An isochron age of 878±27 Ma(1σ)is defined by Re-Os isotopic geochronologic study on ore samples from the large Jianchaling nickel sulfide deposit, Shaanxi Province, China. The metallogenic age is defined as the new Proterozoic for the first time, which shows that rock-forming and ore-forming processes would happen in the same period. γOs and Re/Os ratio of the Re-Os isotopic system for nickel sulfide ores formed at 878 Ma B. P. are calculated, indicating that the γOs and Re/Os ratio change in a large range. The Re/Os ratio for banded ore in depths is only 0. 05, and γOs is -6. 70, but the range of the Re/Os ratio for massive ore is 4. 24-24. 43, and γOs, is -15. 37- + 280. 65. This proves that substances of the crustal source have contaminated during the ore-forming process. The γOs values of two samples are negative( - 15. 37 and -6. 70), which indicates that the ultramafic magma might be derived from Re-depleted mantle. The Re-Os isochron age of the Jianchaling nickel ore and the Sm-Nd isochron age of its ultrabasic intrusion correspond to the time of volcanic-magmatic movement on the northern margin of the Yangtze craton. Formation of the Jianchaling nickel deposit and intrusion was caused by tectonic magmatic metallogenesis during the Jinning movement on the northern margin of the Yangtze craton.

关 键 词：RE-OS同位素年龄 铜镍硫化物矿床 成矿时代 陕西 成矿作用 岩浆活动 新元古代 

分 类 号：P618.4[天文地球—矿床学]