粤北梅子窝钨矿二长花岗岩的发现及其地球化学特征  

Geochemistry of the Meiziwo Monzogranite,Northern Guangdong

作　　者：姜海[1,2] 李文铅[1] 

机构地区：[1]中国科学院,广州地球化学研究所矿物学与成矿学重点实验室,广东广州510640 [2]中国科学院大学,北京100049

出　　处：《大地构造与成矿学》2014年第1期197-207,共11页Geotectonica et Metallogenia

基　　金：全国危机矿山专题项目(编号:200644089)资助

摘　　要：粤北梅子窝钨矿为华南地区典型的与中生代花岗岩有密切成因联系的钨矿床,同时也是丞待实现深部找矿突破的危机矿山。本文对危机矿山项目新发现的梅子窝二长花岗岩进行了报道,并对该岩体的岩石学和地球化学特征进行了研究。结果表明,该二长花岗岩与上部花岗闪长岩呈侵入接触关系,为新一期岩浆活动的产物。该岩体具高硅、富碱、贫钙、镁、铁的特征,属偏铝-弱过铝质、高钾钙碱性岩系。稀土总量较低,表现出富重稀土、强负Eu异常、轻重稀土分馏不明显的特征,具典型的四分组效应;Rb/Sr值较高显示其岩浆结晶分异较充分。从成因上看,梅子窝二长花岗岩为I型花岗岩,可能形成于中生代岩石圈减薄和伸展背景下的后碰撞陆内环境。本次二长花岗岩的发现,提供了很好的找矿远景区,也为深部找矿的顺利实现和对钨矿脉深部延伸和分布规律的研究提供了依据。The Meiziwo tungsten deposit is both spatially and genetically related to the Mesozoic granites, which is now, a crisis mine. During our prospecting study of the ore deposit, a monzogranite pluton was discovered. The monzogranite intruded the granodiorite. The rocks are enriched in SiO2 and K2O＋Na2O, but depleted in CaO, MgO and FeO＊, and belongs to slightly peraluminous high-K cal-alkaline granite series. The Meiziwo monzogranite is characterized by low REE content, relative HREE-enrichment, strong negative Eu anomalies and inconspicuous LREE/HREE fractionation, and shows tetrad effect. The ratio of Rb/Sr is relatively low, suggesting a high degree of fractional crystallization. Our geochemical data reveal that the Meiziwo monzogranite is I-type granite, and formed in intraplate extension tectonic setting of post-collision. The discovery of the granite not only highlighted the prospecting potential, but also provides clues for ore bodies at depth and new constraints on the distribution pattern of ore veins of the Meiziwo tungsten deposit.

关 键 词：梅子窝 钨矿 二长花岗岩 地球化学 

分 类 号：P595[天文地球—地球化学]