《黄金》杂志(月刊) 第38卷 总第398期
2017年04月 第04期
目次
黄金地质
  • 西藏那曲南措金铜矿区酸性侵入岩锆石U-Pb年龄地球化学特征及地质意义……史春清,孙丰月,黄维平,王 启,张志颖
  • 摘 要:对西藏那曲南措金铜矿区内与成矿关系密切的花岗闪长岩和花岗闪长斑岩运用LA-ICP-MS锆石UPb测年与岩石地球化学的分析方法确定其形成时代、岩浆源区性质及成岩构造背景。结果显示,岩石样品的加权平均年龄分别为159.2Ma±0.69 Ma161.5Ma±1.5Ma,形成于中晚侏罗世。地球化学方面,岩石属于钙碱性系列,A/CNK介于0.830.98Mg#值为5359,具有高Sr525×10-6901×10-6)、低Y(12.05××10-613.72×10-6)、Yb1.16×10-61.44×10-6)、富NaNa2OK2O值为2.072.43)的特征,LREE富集,Eu弱正异常,判定岩石属于O型埃达克岩类。岩石轻重稀土元素分馏明显,总体相对富集大离子亲石元素(RbKBa)和轻稀土元素(SrZrHf),相对亏损高场强元素(TaNbTi);无明显的Eu负异常,显示了与火山弧岩浆微量元素地球化学性质的亲缘性。岩石的Nb/Ta值为10.4518.79Zr/Hf值为32.7636.90,判定岩浆起源于洋壳部分熔融并有少量地幔物质混入。结合前人研究结果认为,岩石形成于班公湖怒江洋盆板片向北俯冲活动大陆边缘环境。
  • 关键词:南措金铜矿区;班公湖—怒江成矿带;花岗闪长岩;花岗闪长斑岩;锆石U-Pb年龄;地球化学特征;埃达克岩

    Zircon U-Pb ages and geochemical characteristics of the acidic intrusive rocks in Nancuo Au-Cu deposit,Nakchu,Tibet,and its geological significance……Shi Chunqing,Sun Fengyue,HuangWeiping,Wang Qi,Zhang Zhiying

    AbstractLA-ICP-MS zircon U-Pb dating and lithogeochemical analysis of the granodiorite and granodioriteporphyry that are closely related to the deposit genesis in Nancuo Au-Cu deposit,Nakchu,Tibet,are conducted to determine their geochronology,magmasources and tectonic settings.The zircon dating results show that granodioriteand granodiorite porphyry were formed in Middle-Late Jurassic (159.2 Ma±0.69 Ma and 161.5 Ma±1.5 Ma).Geochemically,these rockshave A/CNK=0.83-0.98,Mg=53-59,belonging to the calc-alkaline series.The rocks are considered O-type adakitic rockswith high Sr (525×10-6-901×10-6),low Y(12.05××10-6-13.72×10-6) and Yb (1.16×10-6-1.44×10-6),Na enrichmentNa2OK2O value of 2.07-2.43,LREE enrichment and minorpositive Eu anomalies.They have high degree of fractionation,generally with LILEs (Rb,K and Ba) and LREEs (Sr,Zr and Hf ) enriched,HFSEs (Ta,Nb and Ti)relatively depleted.No evident negative Eu anomalies are shown,which indicatedits affinity to the geochemical characteristics of the microelements involcanic arc magma.The values of Nb/Ta and Zr/Hf are 10.45-18.79 and32.76-36.90,suggesting a mixed source from partial melting of oceanic crust anddepleted mantle.The paper,combining the study with the predecessors’,thinksthat the rocks were formed in the active continental margin of Bangonghu-Nujiang oceanic crust northward subduction.

    Keywords:Nancuo Au-Cu deposit;Bangonghu-Nujiang metallogenic belt; granodiorite; granodiorite porphyry;zircon U-Pb ages; geochemical characteristics; adakitic rock


黄 金 杂 志 社 地址:吉林省长春市南湖大路6760号 邮编:130012
电话:0431-85529838/0431-89243511(广告部)/0431-89243833(编辑部)
传真:0431-85511548转3235 电子信箱:journal@ccgri.com ggb3068@126.com(广告部)