江西大岭上钨矿含斑细粒花岗岩锆石成因及成岩成矿启示

Origin of the Zircon in Fine Grained Granite in Dalingshang Tungsten Deposit,Jiangxi and Its Petrogenetic and Mineralizing Implications

锆石成因研究成果是锆石定年、源区性质示踪和岩浆演化过程分析的基础。本文利用阴极发光和LA-ICP-MS技术发现研究区含斑细粒花岗岩包含了无继承核锆石和有继承核锆石。无继承核锆石阴极发光暗黑,其Th/U值低,LREE相对富集,Ce弱正异常,Ti温度计得到地质温度为801℃,是形成于富含热液的岩浆环境的锆石。有继承核锆石残留核具有均匀的灰白阴极发光,边缘阴极发光暗黑,其Th/U值较高,LREE相对较低、Ce正异常明显,Ti温度计得到地质温度为771℃,是形成于正常岩浆环境的中、深成岩浆岩中的锆石。结合区域地质情况,推断残留核锆石很可能是晋宁期花岗闪长岩中的锆石,说明矿区晋宁期花岗闪长岩可能是含斑细粒花岗岩的一种源岩。无继承核锆石的结晶环境反映了当时岩浆已经演化到晚期,而且其结晶时的富含热液的岩浆可能是一种良好的成矿物质的载体,值得进一步研究。

Two kinds of zircon were found in the fine grained granite by anglicizing the trace elements in the zircon and its cathodoluminescence characteristics.The simple zircons are characterized by no cathodoluminescence,low ratio of Th/U,relative enrichment of LREE,weak positive anomaly of Ce and Ti thermometer geological temperature of 801℃.And they were classed as the magmatic zircons formed in the magma environment with rich hydrotherm.The relict core zircons were the typical magmatic zircons,which have the features of grey cathodoluminescence of magmatic zircons,high ratio of Th/U,relative low LREE,obvious positive anomaly of Ce and Ti thermometer geological temperature of 771℃.The relict core zircons could only come from the porphyritic granite diorite surrounding rock of Jinning Period because it is the only pluton forming before Yanshanian Period.And we can know the porphyritic granite diorite may be one of the original rocks of the fine grained granite rock.