陕西丹凤富铷伟晶岩中褐钇铌矿矿物学及地球化学特征  

Mineralogy and geochemistry of fergusonite-(Y)from Rb-rich pegmatites in Danfeng,Shaanxi Province

作　　者：金德时 凤永刚 雷如雄[1,2] 梁婷 宋公社[3] JIN Deshi;FENG Yonggang;LEI Ruxiong;LIANG Ting;SONG Gongshe(School of Earth Science and Resource,Chang’an University,Xi'an,710054;Laboratory of Mineralization and Dynamics,Chang’an University,Xi'an,710054;Shaanxi Mineral Resources and Geological Survey,Xi'an,710068)

机构地区：[1]长安大学地球科学与资源学院,西安710054 [2]长安大学成矿作用及其动力学实验室,西安710054 [3]陕西省矿产地质调查中心,西安710068

出　　处：《地质学报》2021年第2期493-505,共13页Acta Geologica Sinica

基　　金：国家重点研发计划项目“深地资源勘查开采”专项“锂、铍等战略性金属矿产资源成矿规律与预测评价”课题“东部锂、铍等战略性金属矿产资源成矿规律与预测评价”(编号2019YFC0605202);国家自然科学基金青年项目(编号41902073);陕西省自然科学基金项目(编号2020JM-215)联合资助成果。

摘　　要：东秦岭的商南—丹凤地区分布着众多含稀有金属矿化的花岗伟晶岩,在该地区的富铷花岗伟晶岩中首次鉴定出褐钇铌矿,其主要产出于富石榴子石的微斜长石花岗伟晶岩中,多与石榴子石、锆石、磷钇矿、铌钽铁矿等副矿物伴生,为花岗质岩浆晚期结晶产物。电子探针分析表明,褐钇铌矿除了含有Y、Nb、REE、Ta、Ti等主要元素,还含有较高含量的放射性元素UO_(2)(>5%)和ThO_(2)(>1%);Pb、Ca和Si等元素含量低于1%,属于微量元素。所分析的褐钇铌矿属于褐钇铌矿—黄钇钽矿系列,其Nb/(Nb+Ta)值接近1;重稀土富集程度很高,属于ΣY的选择配分型矿物。由于褐钇铌矿中含有高含量的U、Th放射性元素,其可能会发生蜕晶质化,本文利用激光拉曼对褐钇铌矿的晶体结构进行分析,以探讨褐钇铌矿中高含量放射性元素对其晶体结构产生的影响。There are numerous granitic pegmatites with rare-metal mineralization in the Shangnan-Danfeng area of East Qinling.We report the presence of fergusonite and yttrium niobate in Rb-rich granitic pegmatites in this area for the first time.This mineral mainly occurs as a late-stage phase in garnet-rich microcline granitic pegmatites and is commonly associated with garnet,zircon,xenotime,columbite,and other accessory minerals.Electron probe micro-analysis(EPMA)shows that in addition to major elements including Y,Nb,REE,Ta and Ti,the fergusonite also contains high contents of radioactive elements:UO_(2)(>5%)and ThO_(2)(>1%).The contents of elements including Pb,Ca and Si are all<1%,suggesting that these elements are minor or trace elements.The analyzed fergusonite belongs to the fergusonite-formanite series whose Nb/(Nb+Ta)value is close to 1.The fergusonite shows strongly enrichment in heavy rare elements(HREE).Due to the high contents of U and Th in fergusonite,the fergusonite may occur in metamict form.This paper attempts to use Laser Raman to analyze the crystal structure of fergusonite and explore the effect of high contents of radioactive elements of fergusonite on its crystal structure.

关 键 词：褐钇铌矿 地球化学特征 矿物学特征 稀有金属花岗伟晶岩 丹凤 

分 类 号：P618.91[天文地球—矿床学] P618.79[天文地球—地质学]