江西省花山洞钨矿花岗岩锆石UPb定年及其地质意义
Zircon UPb Geochronology of Granite in the Huashandong Tungsten Deposit, Jiangxi Province, China and Its Geological Significance

摘要： 花山洞钨矿是在江西省西北部新近发现的与花岗岩有关的钨矿床，为了确定矿区花岗岩的物质来源，形成过程以及构造背景环境，探讨成岩与成矿作用之间的关系。利用地球化学方法分析了与花山洞钨矿密切相关的花岗岩的地球化学特征，采用LAICPMS锆石UPb定年的方法测定了花岗岩的形成时代。岩石地球化学表明，花岗岩具有较高的w(SiO2)(6823%~7378%)含量；全碱含量w(Na2O+ K2O)为593%~7%；富Na，K2O/Na2O为038~086，小于1；w(Al2O3)为1441%~1581%，A/CNK均大于11，为过铝质岩石。富集Rb、Tu、U、La、Nd等大离子亲石元素，亏损Ba、Nb、Ti、Sr、P等元素，具大陆地壳的特征；稀土总含量较低，基本无δCe异常。稀土配分型式总体向右倾斜，为典型的‘I’型花岗岩特征；轻稀土斜率较大，分异较为明显，重稀土较为平缓，分异不明显。花岗岩锆石UPb测年结果为(807±8)Ma，与前人测得的辉钼矿ReOs年龄极为接近，故花岗岩应该为成矿岩体。结合区域资料，综合分析可知，矿区花岗岩应主要来源于地壳物质，有部分地幔物质的加入；其可能形成于大陆边缘弧环境。花山洞钨矿床成矿年龄略晚于矿区花岗岩，表明成矿作用是花岗岩分异演化的结果，是晋宁期岩浆活动的产物。
Abstract: Huashandong deposit is a newly found tungsten deposit in northwest Jiangxi Province, China. The exploration report shows that the granite is related to the forming of this deposit.This paper reports LAICPMS zircon UPb age, major and trace elements of the orerelated granite in the Huashandong tungsten deposit. LAICPMS zircon UPb dating yielded the crystallization age of (807±8) Ma for the granite. The granite is calcalkaline, peraluminous and rich in Na,characterized by the SiO2 content from 6823% to 7378%，Al2O3 content from 1441% to 1581%, Na2O+K2O content from 593% to 7%，K2O/Na2O content from 038 to 086，A/CNK＞11.ΣREE is low and there is enrichment of LREE.The fractionation between LREE and HREE is obvious. It is enriched in such LILE as Rb,Tu,U,La,Nd and depleted in HFSE such as Ba,Nb,Ti,Sr,P, with medium anomalies of Eu. In addition to the geological setting of Huanan plate in the Neoproterozoic, it shows that granite was formed in a continental marginal arc setting, and mainly originated from partial melting of crust.The age of Huashandong tungsten deposit is very close to the age of granite,showing that the mineralization is consistent with the differentiation evolution of granite,and the Huashandong tungsten deposit is the product of Jinningian magmatic activities