西藏邦铺斑岩钼(铜)多金属矿床侵入岩锆石微量元素特征及其地质意义  

Zircon Trace Element Characteristics of Intrusions in Bangpu Porphyry Mo(Cu)Polymetallic Deposit of Tibet and Their Geological Significance

作　　者：李壮[1] 王立强[2] 张忠 罗茂澄[4] 冷秋锋[1] 康浩然 孟展[1] 

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]中国地质科学院矿产资源研究所,北京100037 [3]西藏天圆矿业资源开发有限公司,西藏日喀则857000 [4]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《地球科学与环境学报》2015年第6期59-71,共13页Journal of Earth Sciences and Environment

基　　金：国家重点基础研究发展计划("九七三"计划)项目(2011CB403103);中国地质调查局地质大调查项目(1212011085529)

摘　　要：西藏邦铺斑岩钼(铜)多金属矿床位于冈底斯成矿带东段,矿区侵入岩期次和类型多样,主要包括成矿前期黑云母二长花岗岩、成矿期闪长玢岩和二长花岗斑岩及成矿后期石英二长斑岩和辉绿玢岩等5种。在系统总结前人研究成果基础上,利用LA-ICP-MS技术获得了矿区闪长玢岩岩体锆石微量元素特征。结果表明:邦铺矿区侵入岩锆石类型主要包括岩浆锆石和热液锆石;5种侵入岩球粒陨石标准化稀土元素配分模式显示具相似的特征,曲线左倾,整体较陡,表现为明显的Ce正异常和Eu负异常,轻稀土元素亏损,重稀土元素富集。通过锆石Ti含量地质温度计计算出侵入岩锆石结晶温度,显示出成矿期和成矿后期侵入岩体岩浆来源于在水近饱和条件下发生的部分熔融。根据锆石中特定微量元素和稀土元素特征变化,各侵入岩锆石均是从陆壳岩浆中结晶分异形成的,与锆石相对应的寄主岩石均形成于陆壳环境。The Bangpu porphyry Mo（Cu） polymetallic deposit is located in the eastern part of Gangdise metallogenic belt. The period and type of intrusive rocks in this area are various, mainly including biotite monzonitic granite during the early mineralization, diorite porphyrite and monzonitic granite during the mineralization, and quartz monzonitie porphyry and allgovite during the late mineralization. On basis of summarizing the previous research, the characteristics of zircon trace elements from diorite porphyrite in Bangpu deposit were studied by the LA-ICP-MS technology. The results show that the types of zircon from intrusive rocks mainly include magmatic and hydrothermal zircons; chondrite-normalized REE patterns of the above five types of intrusive rocks are similar, and the curves are left deviation and steep with the characteristics of positive Ce anomaly, negative Eu anomaly, LREE enrichment and HREE depletion. Crystallization temperatures of zircon from the above five intrusive rocks calculated by the Ti-in-zircon geothermometer show that the magma of intrusive rock during the mineralization and late mineralization are derived from the partial melting under the condition of nearly water saturation. According to the characteristics of special zircon trace element and REE, the zircons of the above five intrusive rocks are crystallized and differentiated from continental crust magma, and the host rocks corresponding to zircon form in the continental crust environment.

关 键 词：多金属矿床 侵入岩 微量元素 成因类型 锆石Ti含量地质温度计 结晶环境 西藏 

分 类 号：P595[天文地球—地球化学]