川西扎乌龙花岗伟晶岩型稀有金属矿床白云母花岗岩岩石地球化学特征  

Geochemical Features of Muscovite Granite in the Zhawulong Granitic Pegmatite Type Rare Metal Deposit,Western Sichuan

作　　者：李兴杰 李建康[1] 刘永超[1] 熊昌利[2] LI Xingjie;LI Jiankang;LIU Yongchao;XIONG Changli(Key Laboratory of Metallogeny and Mineral Resource Assessment,Institute of Mineral Resourcs,China Academy of Geological Sciences,Beijing,100037;Sichuan Geological Survey Institute,Chengdu,610081)

机构地区：[1]中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点实验室,北京100037 [2]四川省地质调查院,成都610081

出　　处：《地质论评》2018年第4期1005-1016,共12页Geological Review

基　　金：中央级公益性科研院所基本科研业务费项目(编号:JYYWF201814);国家重点研发项目(编号:2017YFC0602701);中国地质调查局地质调查项目(编号:DD20160055);中国地质调查局矿产地质志项目(编号:DD20160346);国家自然科学基金项目(编号:41372088)的成果~~

摘　　要：扎乌龙花岗伟晶岩型稀有金属矿床位于四川西部石渠县呷依乡,矿区出露的白云母花岗岩岩体与含稀有金属伟晶岩脉有密切的时空关系及成因联系。本文对采自扎乌龙白云母花岗岩岩体的新鲜样品进行了全岩岩石地球化学分析,结果表明,该岩体岩石富硅(Si O_2=73.49%~74.78%)、富铝(Al_2O_3=14.37%~14.83%)、高钾(K_2O/Na_2O=1.14~1.91),贫Fe、Mg、Ti,里特曼指数(σ)<3.3,铝饱和指数和Al_2O_3/Ti O_2(>100)较高。以上特征表明该岩体属高压型高钾钙碱性强过铝质花岗岩。微量元素表现出Rb、U等正异常和Ba、Sr、Zr、Ti等负异常的特征;岩石稀土总量较低,具有明显的轻稀土富集,重稀土亏损的特征,且由于较明显的负铕异常(δEu=0.36~0.53)而呈现"V"型谷状。岩石高Rb/Sr(2.08~6.51)和Rb/Ba(1.53~3.26)、低Ca O/Na_2O(<0.3)等地球化学特征,表明其来源于三叠系西康群泥质岩的脱水熔融,是同碰撞造山作用的产物。而扎乌龙式LCT型花岗伟晶岩,主要是由造山过程中变泥质岩部分熔融形成的强过铝质岩浆逐步演化而形成。Objectives：The Zhawulong granitic pegmatite type rare metal deposit is located in Zhawulong, Shiqu County, Western Sichuan Province. There is a close spacial and genetic relations between the exposed muscovite granite pluton and the pegmatite veins containing rare metals. But no report on geochemical characteristics about muscovite granite.Methods：Based on the field work, through the microscope observation, the whole-rock geochemical analysis. Results：The Zhawulong muscovite granite has high contents of SiO2（73.49%～74.78% ） and Al2O3（14.37%～14.83%）, is riched in potassium （K2O/Na2O=1.14～1.91）, low in Fe, Mg and Ti. And the granite has high Aluminum saturation index and Al2O3/TiO2 ratio （〉100）, and its Rittmann Index（σ）〈3.3. Trace elements in the granite show positive anomalies for Rb, U and negative anomalies for Ba, Sr, Zr, Ti. The total amount of REE in the Zhawulong muscovite granite is low, which is characterized by obvious LREE enrichment and HREE loss, and has a ＂V＂ type valley shape because of the obvious negative Eu anomaly（σEu=0.36～0.53）. The muscovite granite has high Rb/Sr （2.08～6.51）, Rb/Ba （1.53～3.26） and low CaO/Na2O （〈0.3）.Conclusions： The Zhawulong muscovite granite is high-K-alkalkine and strongly peraluminous series. It is formed by dehydration melting of the Triassic Xikang Group metapelite, and it is a product of the syn-collisional orogenic processes.The LCT type granitic pegmatite from Zhawulong, mainly formed by the gradual evolution of strongly peraluminous magma, which is fomed by partial melting of metapelite during the orogenic process.

关 键 词：白云母花岗岩 地球化学 稀有金属 扎乌龙 川西 

分 类 号：P588.121[天文地球—岩石学] P618.6[天文地球—地质学]