冀北寿王坟铜矿石英二长岩LA-ICP-MS锆石U-Pb年龄和地球化学特征

LA-ICP-MS Zircon,U-Pb Age and Geochemical Characteristics of Quartz Monzonite of Shouwangfen Copper Mine in North Hebei Province

寿王坟杂岩体为中生代复式岩体，是寿王坟铜矿的容矿围岩，与成矿关系十分密切。本文对杂岩体中石英二长岩进行了岩相学、岩石地球化学、锆石成因矿物学和U-Pb年代学等方面的研究，讨论了岩石成因和源区。年代学结果显示，本区石英二长岩岩浆锆石^206Pb/^238U加权平均年龄为（133.48±0.53）Ma（MSWD=0.70），时代为早白垩世；岩石地球化学研究表明，本区石英二长岩以低K2O / Na2O（0.74～0.89）、低磷（P2O5=0.09%～0.40%）和较高A/CNK（1.24-1.38）为特征，属亚碱过铝质岩石。稀土元素含量较高（262.14×10^-6～279.83×10^-6），富集轻稀土，∑LREE/∑HREE=12.12～17.41，配分曲线平缓右倾，Eu和Ce异常不明显（δEu=0.83～1.26，δCe=0.78～0.93），与上地壳稀土元素特征相似，是一种典型的壳源成因类型。综合分析认为，石英二长岩的地球化学特征及岩浆侵位年龄与成矿时代的耦合关系应代表华北东部中生代大规模岩浆演化与成矿作用在研究区的响应。

The Shouwangfen composite pluton presented the Mesozoic complex massif that was ore surrounding rock,which had close relationship with mineralization.In this study,petrography,lithogeochemistry,zircon genetic mineralogy,U-Pb chronology of uartz monzonite,lithogenesis and source region were all analyzed. Chronology results demonstrated that the^206Pb/^238U weighted average age of magmatic zircon was（133.48±0.53）Ma （MSWD=0.70）,and the era was the Early Cretaceous Epoch in the study area;lithogeochemistry results showed that the quartz monzonite was with the characteristic of low K2O/Na2O（0.74-0.89）,low P（P2O5=0.09%-0.40%）, higher A/CNK（1.24-1.38）and it belonged to the alkali peraluminous rock.Moreover,rare earth element content is higher（262.14×10^-6-279.83×10^-6）with enrichment of light rare earth,∑LREE/∑HREE=12.12-17.41,and the partition curve tended to the right gently.The abnormal of Eu and Ce was not obvious（δEu=0.83-1.26,δCe=0.78-0.93）,which was similar to the characteristic of rare earth element in upper crust,and it was a kind of typical crust source genetic types.Therefore,after comprehensive analysis,the coupling relationship between mineralogenetic epoch and geochemical characteristics,magmatic emplacement age of quartz monzonite should represent the regional response of large-scale magmatic evolution and mineralization during Mesozoic in the east of north China.